1.
Latin
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Latin is a classical language belonging to the Italic branch of the Indo-European languages. The Latin alphabet is derived from the Etruscan and Greek alphabets, Latin was originally spoken in Latium, in the Italian Peninsula. Through the power of the Roman Republic, it became the dominant language, Vulgar Latin developed into the Romance languages, such as Italian, Portuguese, Spanish, French, and Romanian. Latin, Italian and French have contributed many words to the English language, Latin and Ancient Greek roots are used in theology, biology, and medicine. By the late Roman Republic, Old Latin had been standardised into Classical Latin, Vulgar Latin was the colloquial form spoken during the same time and attested in inscriptions and the works of comic playwrights like Plautus and Terence. Late Latin is the language from the 3rd century. Later, Early Modern Latin and Modern Latin evolved, Latin was used as the language of international communication, scholarship, and science until well into the 18th century, when it began to be supplanted by vernaculars. Ecclesiastical Latin remains the language of the Holy See and the Roman Rite of the Catholic Church. Today, many students, scholars and members of the Catholic clergy speak Latin fluently and it is taught in primary, secondary and postsecondary educational institutions around the world. The language has been passed down through various forms, some inscriptions have been published in an internationally agreed, monumental, multivolume series, the Corpus Inscriptionum Latinarum. Authors and publishers vary, but the format is about the same, volumes detailing inscriptions with a critical apparatus stating the provenance, the reading and interpretation of these inscriptions is the subject matter of the field of epigraphy. The works of several hundred ancient authors who wrote in Latin have survived in whole or in part and they are in part the subject matter of the field of classics. The Cat in the Hat, and a book of fairy tales, additional resources include phrasebooks and resources for rendering everyday phrases and concepts into Latin, such as Meissners Latin Phrasebook. The Latin influence in English has been significant at all stages of its insular development. From the 16th to the 18th centuries, English writers cobbled together huge numbers of new words from Latin and Greek words, dubbed inkhorn terms, as if they had spilled from a pot of ink. Many of these words were used once by the author and then forgotten, many of the most common polysyllabic English words are of Latin origin through the medium of Old French. Romance words make respectively 59%, 20% and 14% of English, German and those figures can rise dramatically when only non-compound and non-derived words are included. Accordingly, Romance words make roughly 35% of the vocabulary of Dutch, Roman engineering had the same effect on scientific terminology as a whole
2.
NeuroLex
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NeuroLex is a dynamic lexicon of neuroscience concepts. It is a structured as a wiki, using Semantic MediaWiki. NeuroLex is supported by the Neuroscience Information Framework project, one of the big roadblocks to data integration in neuroscience is the inconsistent use of terminology in databases and other resources like the literature. When one uses the terms to mean different things, one cannot easily ask questions that span across multiple resources. For example, if three databases have information about what genes are expressed in cortex, but they all use different definitions of cerebral cortex, the NIF enables discovery and access to public research data and tools worldwide through an open source, networked environment. The Framework is an inventory of neuroscience databases, annotated and integrated with a unified system of biomedical terminology. NIF supports concept-based queries across multiple scales of biological structure and multiple levels of function, making it easier to search for. As part of the NIF, an interface to many different sources of neuroscience information. To make this more effective, the NIF is constructing ontologies to help organize neuroscience concepts into category hierarchies. This allows users to more effective searches and also to organize. But an important adjunct to this activity is to define all of the terms that are used to describe data, e. g. anatomical terms, techniques. The initial entries in the NeuroLex were built from the NIFSTD ontologies which subsumed an earlier vocabulary BIRNLex and it currently contains concepts that span gross anatomy, cells of the nervous system, subcellular structures, diseases, functions and techniques. NIF is soliciting community input to add content and correct what is there. The NIFSTD and BIRNLex vocabularies, building comprehensive ontologies for neuroscience, archived from the original on February 12,2009. The neuroscience information framework, a data and knowledge environment for neuroscience, Gardner D, Goldberg DH, Grafstein B, Robert A, Gardner EP. Terminology for neuroscience data discovery, multi-tree syntax and investigator-derived semantics. Gupta A, Bug W, Marenco L, Qian X, Condit C, Rangarajan A, Müller HM, Miller PL, Sanders B, Grethe JS, Astakhov V, Shepherd G, Sternberg PW, federated access to heterogeneous information resources in the Neuroscience Information Framework. Halavi M, Polavaram S, Donohue DE, Hamilton G, Hoyt J, Smith KP, neuroMorpho. Org implementation of digital neuroscience, dense coverage and integration with the NIF
3.
Glossary of neuroanatomy
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This article attempts to provide definitions to a number of anatomical terminology, definitions and abbreviations, pertinent to the description of the Central Nervous System, particularly in humans. It aims to further information to the description of orientation in neuroanatomy. To understand the terms used for anatomical localisation, consider an animal with a straight CNS, in such animals the terms rostral, caudal, ventral and dorsal mean respectively towards the rostrum, towards the tail, towards the belly and towards the back. For a full discussion of terms, see anatomical terms of location. For many purposes of description, positions and directions are relative to the standard anatomical planes and axes. Such reference to the planes and axes is called the stereotactic approach. However, in humans and most other primates the axis of the CNS is bent and these are shown in the accompanying illustrations and annotations. In particular the anatomical planes and axes that apply to most vertebrate nervous systems need considerable modification before they can be of use in describing the human brain. For example in reference to the brain, rostral still means towards the face, or at any rate. However, in the brain caudal means not towards the tail, alternative terms for this rostro-caudal axis of the brain include medial or antero-posterior axis. Dorsal means in the direction away from the spinal cord i. e. in the direction of the roof of the cranial cavity, ventral means downwards towards floor of the cranial cavity and thence to the body. They lie on the superior-inferior or Dorsoventral axis, the third axis passes through the ears, and is called the left-right, or lateral axis. These three axes of the human brain match the three planes within which they lie, even though the terms for the planes have not been changed from the terms for the bodily planes. The most commonly used reference planes are, Axial, the plane that is horizontal and it contains the lateral and the medial axes of the brain. Coronal, a plane that passes through both ears, and contains the lateral and dorsoventral axes. Sagittal, a plane that passes from between the nostrils, and between the cerebral hemispheres, dividing the brain into left and right halves. It contains the dorsoventral and medial axes of the brain, a parasagittal plane is any plane parallel to the sagittal plane. Afferent An afferent nerve fiber is a fibre originating at the present point, for example a striatal afferent is an afferent originating at the striatum
4.
Ancient Greek
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Ancient Greek includes the forms of Greek used in ancient Greece and the ancient world from around the 9th century BC to the 6th century AD. It is often divided into the Archaic period, Classical period. It is antedated in the second millennium BC by Mycenaean Greek, the language of the Hellenistic phase is known as Koine. Koine is regarded as a historical stage of its own, although in its earliest form it closely resembled Attic Greek. Prior to the Koine period, Greek of the classic and earlier periods included several regional dialects, Ancient Greek was the language of Homer and of fifth-century Athenian historians, playwrights, and philosophers. It has contributed many words to English vocabulary and has been a subject of study in educational institutions of the Western world since the Renaissance. This article primarily contains information about the Epic and Classical phases of the language, Ancient Greek was a pluricentric language, divided into many dialects. The main dialect groups are Attic and Ionic, Aeolic, Arcadocypriot, some dialects are found in standardized literary forms used in literature, while others are attested only in inscriptions. There are also several historical forms, homeric Greek is a literary form of Archaic Greek used in the epic poems, the Iliad and Odyssey, and in later poems by other authors. Homeric Greek had significant differences in grammar and pronunciation from Classical Attic, the origins, early form and development of the Hellenic language family are not well understood because of a lack of contemporaneous evidence. Several theories exist about what Hellenic dialect groups may have existed between the divergence of early Greek-like speech from the common Proto-Indo-European language and the Classical period and they have the same general outline, but differ in some of the detail. The invasion would not be Dorian unless the invaders had some relationship to the historical Dorians. The invasion is known to have displaced population to the later Attic-Ionic regions, the Greeks of this period believed there were three major divisions of all Greek people—Dorians, Aeolians, and Ionians, each with their own defining and distinctive dialects. Often non-west is called East Greek, Arcadocypriot apparently descended more closely from the Mycenaean Greek of the Bronze Age. Boeotian had come under a strong Northwest Greek influence, and can in some respects be considered a transitional dialect, thessalian likewise had come under Northwest Greek influence, though to a lesser degree. Most of the dialect sub-groups listed above had further subdivisions, generally equivalent to a city-state and its surrounding territory, Doric notably had several intermediate divisions as well, into Island Doric, Southern Peloponnesus Doric, and Northern Peloponnesus Doric. The Lesbian dialect was Aeolic Greek and this dialect slowly replaced most of the older dialects, although Doric dialect has survived in the Tsakonian language, which is spoken in the region of modern Sparta. Doric has also passed down its aorist terminations into most verbs of Demotic Greek, by about the 6th century AD, the Koine had slowly metamorphosized into Medieval Greek
5.
Brain
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The brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. The brain is located in the head, usually close to the organs for senses such as vision. The brain is the most complex organ in a vertebrates body, in a human, the cerebral cortex contains approximately 15–33 billion neurons, each connected by synapses to several thousand other neurons. Physiologically, the function of the brain is to exert centralized control over the other organs of the body, the brain acts on the rest of the body both by generating patterns of muscle activity and by driving the secretion of chemicals called hormones. This centralized control allows rapid and coordinated responses to changes in the environment, the operations of individual brain cells are now understood in considerable detail but the way they cooperate in ensembles of millions is yet to be solved. This article compares the properties of brains across the range of animal species. It deals with the human brain insofar as it shares the properties of other brains, the ways in which the human brain differs from other brains are covered in the human brain article. Several topics that might be covered here are instead covered there because more can be said about them in a human context. The most important is brain disease and the effects of brain damage, the shape and size of the brain varies greatly between species, and identifying common features is often difficult. Nevertheless, there are a number of principles of architecture that apply across a wide range of species. Some aspects of structure are common to almost the entire range of animal species, others distinguish advanced brains from more primitive ones. The simplest way to gain information about brain anatomy is by visual inspection, Brain tissue in its natural state is too soft to work with, but it can be hardened by immersion in alcohol or other fixatives, and then sliced apart for examination of the interior. Visually, the interior of the consists of areas of so-called grey matter, with a dark color, separated by areas of white matter. Further information can be gained by staining slices of tissue with a variety of chemicals that bring out areas where specific types of molecules are present in high concentrations. It is also possible to examine the microstructure of brain tissue using a microscope, the brains of all species are composed primarily of two broad classes of cells, neurons and glial cells. Glial cells come in types, and perform a number of critical functions, including structural support, metabolic support, insulation. Neurons, however, are considered the most important cells in the brain. The property that makes neurons unique is their ability to send signals to target cells over long distances
6.
Endocrine system
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The endocrine system is the collection of glands of an organism that secrete hormones directly into the circulatory system to be carried towards distant target organs. The phenomenon of biochemical processes serving to regulate distant tissues by means of directly into the circulatory system is called endocrine signaling. The major endocrine glands include the pineal gland, pituitary gland, pancreas, ovaries, testes, thyroid gland, parathyroid gland, the endocrine system is in contrast to the exocrine system, which secretes its hormones to the outside of the body using ducts. The endocrine system is a signal system like the nervous system, yet its effects. The endocrine systems effects are slow to initiate, and prolonged in their response, the nervous system sends information very quickly, and responses are generally short lived. In vertebrates, the hypothalamus is the control center for all endocrine systems. The field of study dealing with the system and its disorders is endocrinology. Special features of endocrine glands are, in general, their ductless nature, their vascularity, in contrast, exocrine glands, such as salivary glands, sweat glands, and glands within the gastrointestinal tract, tend to be much less vascular and have ducts or a hollow lumen. For example, the kidney secretes endocrine hormones such as erythropoietin and renin, hormones can consist of either amino acid complexes, steroids, eicosanoids, leukotrienes, or prostaglandins. A number of glands that signal each other in sequence are referred to as an axis, for example. The word endocrine derives from the Greek words ἐνδο- endo- inside, within, the pituitary gland is an endocrine gland about the size of a pea and weighing 0.5 grams in humans. It is a protrusion off the bottom of the hypothalamus at the base of the brain, the pituitary is functionally connected to the hypothalamus by the median eminence via a small tube called the infundibular stem or pituitary stalk. Oxytocin and anti-diuretic hormone are not secreted in the posterior lobe, the pancreas is a mixocrine gland and it secretes both enzymes and hormones. In 1998, skeletal muscle was identified as an organ due to its now well-established role in the secretion of myokines. The use of the term myokine to describe cytokines and other peptides produced by muscle as signalling molecules was proposed in 2003, signalling molecules released by adipose tissue are referred to as adipokines. The human endocrine system consists of several systems that operate via feedback loops, several important feedback systems are mediated via the hypothalamus and pituitary. Cortisol has major effects, and dopamine has immunomodulatory functions. On the other hand, cytokines produced during inflammation activate the HPA axis at all three levels, sensible to negative feedback, moreover, cytokines stimulate hepcidin release from the liver, which is eventually responsible for the anemia of chronic disease
7.
Limbic system
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The limbic system is a set of brain structures located on both sides of the thalamus, immediately beneath the cerebrum. It has also referred to as the paleomammalian cortex. It is not a system but a collection of structures from the telencephalon, diencephalon. The limbic system supports a variety of functions including emotion, behavior, motivation, long-term memory, Emotional life is largely housed in the limbic system, and it has a great deal to do with the formation of memories. These structures were known together as the limbic lobe, further studies began to associate these areas with emotional and motivational processes and linked them to subcortical components that were grouped into the limbic system. Therefore, the definition of anatomical structures considered part of the system is a controversial subject. Piriform cortex, part of the olfactory system, entorhinal cortex, related with memory and associative components. Hippocampus and associated structures, which play a role in the consolidation of new memories. Amygdala, located deep within the lobes and related with a number of emotional processes. Nucleus accumbens, involved in reward, pleasure, and addiction and it regulates a great number of autonomic processes. Mammillary bodies, part of the hypothalamus receives signals from the hippocampus via the fornix. Anterior nuclei of thalamus receive input from the mammillary bodies, the structures of the limbic system are involved in motivation, emotion, learning, and memory. The limbic system is where the subcortical structures meet the cerebral cortex, the limbic system operates by influencing the endocrine system and the autonomic nervous system. It is highly interconnected with the nucleus accumbens, which plays a role in sexual arousal and these responses are heavily modulated by dopaminergic projections from the limbic system. The limbic system includes the basal ganglia. The basal ganglia are a set of structures that direct intentional movements. The basal ganglia are located near the thalamus and hypothalamus and they receive input from the cerebral cortex, which sends outputs to the motor centers in the brain stem. A part of the basal ganglia called the striatum controls posture, recent studies indicate that, if there is an inadequate supply of dopamine, the striatum is affected, which can lead to visible behavioral symptoms of Parkinsons disease
8.
Neuroanatomy
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Neuroanatomy is the study of the anatomy and stereotyped organization of nervous systems. In contrast to animals with radial symmetry, whose nervous system consists of a network of cells, animals with bilateral symmetry have segregated, defined nervous systems. Their neuroanatomy is therefore better understood, in vertebrates, the nervous system is segregated into the internal structure of the brain and spinal cord and the routes of the nerves that connect to the rest of the body. The delineation of distinct structures and regions of the system has been critical in investigating how it works. For example, much of what neuroscientists have learned comes from observing how damage or lesions to specific brain areas affects behavior or other neural functions, for information about the composition of animal nervous systems, see nervous system. For information about the structure of the human nervous system. This article discusses information pertinent to the study of neuroanatomy, the first known written record of a study of the anatomy of the human brain is the ancient Egyptian document the Edwin Smith Papyrus. The next major development in neuroanatomy came from the Greek Alcmaeon, who determined that the brain and not the heart ruled the body, herophilus and Erasistratus of Alexandria were perhaps the most influential Greek neuroscientists with their studies involving dissecting the brains. For several hundred years afterward, with the taboo of dissection. However, Pope Sixtus IV effectively revitalized the study of neuroanatomy by altering the papal policy and this resulted in a boom of research in neuroanatomy by artists and scientists of the Renaissance. In 1664, Thomas Willis, a physician and professor at Oxford University, the subsequent three hundred and fifty some years has produced a great deal of documentation and study of the neural systems. At the tissue level, the system is composed of neurons, glial cells. Both neurons and glial cells come in many types, glial cells maintain homeostasis, produce myelin, and provide support and protection for the brains neurons. Some glial cells can even propagate intercellular calcium waves over distances in response to stimulation. The extracellular matrix also provides support on the level for the brains cells. At the organ level, the system is composed of brain regions. These regions are often modular and serve a role within the general pathways of the nervous system. For example, the hippocampus is critical for forming memories, the nervous system also contains nerves, which are bundles of fibers that originate from the brain and spinal cord, and branch repeatedly to innervate every part of the body
9.
Anatomical terms of location
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Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans. All vertebrates have the basic body plan – they are strictly bilaterally symmetrical in early embryonic stages. That is, they have left and right halves if divided down the centre. For these reasons, the directional terms can be considered to be those used in vertebrates. By extension, the terms are used for many other organisms as well. While these terms are standardized within specific fields of biology, there are unavoidable, sometimes dramatic, for example, differences in terminology remain a problem that, to some extent, still separates the terminology of human anatomy from that used in the study of various other zoological categories. The vertebrates and Craniata share a heritage and common structure. To avoid ambiguities this terminology is based on the anatomy of each animal in a standard way, for humans, one type of vertebrate, anatomical terms may differ from other forms of vertebrates. Thus what is on top of a human is the head, whereas the top of a dog may be its back, for example, many species are not even bilaterally symmetrical. In these species, terminology depends on their type of symmetry, all descriptions are with respect to the organism in its standard anatomical position, even when the organism in question has appendages in another position. This helps avoid confusion in terminology when referring to the organism in different postures. In humans, this refers to the body in a position with arms at the side. While the universal vertebrate terminology used in medicine would work in human medicine. Many anatomical terms can be combined, either to indicate a position in two axes simultaneously or to indicate the direction of a movement relative to the body, for example, anterolateral indicates a position that is both anterior and lateral to the body axis. There is no limit to the contexts in which terms may be modified to qualify each other in such combinations. Generally the modifier term is truncated and an o or an i is added in prefixing it to the qualified term, where desirable three or more terms may be agglutinated or concatenated, as in anteriodorsolateral. Such terms sometimes used to be hyphenated, but the tendency is to omit the hyphen. There is however little basis for any rule to interfere with choice of convenience in such usage
10.
Vertebrate
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Vertebrates /ˈvɜːrtᵻbrᵻts/ comprise all species of animals within the subphylum Vertebrata /-ɑː/. Vertebrates represent the majority of the phylum Chordata, with currently about 66,000 species described. Vertebrates include the fish and the jawed vertebrates, which include the cartilaginous fish. A bony fish known as the lobe-finned fishes is included with tetrapods, which are further divided into amphibians, reptiles, mammals. Extant vertebrates range in size from the frog species Paedophryne amauensis, at as little as 7.7 mm, to the blue whale, vertebrates make up less than five percent of all described animal species, the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do not have proper vertebrae due to their loss in evolution, though their closest living relatives, hagfish do, however, possess a cranium. For this reason, the vertebrate subphylum is sometimes referred to as Craniata when discussing morphology, molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys, and so also are vertebrates in a monophyletic sense. Others consider them a group of vertebrates in the common taxon of craniata. The word origin of vertebrate derives from the Latin word vertebratus, the Proto-Indo-European language origins are still unclear. Vertebrate is derived from the vertebra, which refers to any of the bones or segments of the spinal column. All vertebrates are built along the basic body plan, a stiff rod running through the length of the animal, with a hollow tube of nervous tissue above it. In all vertebrates, the mouth is found at, or right below, the remaining part of the body continuing after the anus forms a tail with vertebrae and spinal cord, but no gut. However, a few vertebrates have secondarily lost this anatomy, retaining the notochord into adulthood, such as the sturgeon, jawed vertebrates are typified by paired appendages, but this trait is not required in order for an animal to be a vertebrate. All basal vertebrates breathe with gills, the gills are carried right behind the head, bordering the posterior margins of a series of openings from the pharynx to the exterior. Each gill is supported by a cartilagenous or bony gill arch, the bony fish have three pairs of arches, cartilaginous fish have five to seven pairs, while the primitive jawless fish have seven. The vertebrate ancestor no doubt had more arches than this, as some of their relatives have more than 50 pairs of gills. In amphibians and some primitive fishes, the larvae bear external gills. These are reduced in adulthood, their function taken over by the gills proper in fishes, some amphibians retain the external larval gills in adulthood, the complex internal gill system as seen in fish apparently being irrevocably lost very early in the evolution of tetrapods
11.
Almond
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The almond is a species of tree native to the Middle East, the Indian subcontinent and North Africa. Almond is also the name of the edible and widely cultivated seed of this tree, within the genus Prunus, it is classified with the peach in the subgenus Amygdalus, distinguished from the other subgenera by corrugations on the shell surrounding the seed. The fruit of the almond is a drupe, consisting of a hull and a hard shell with the seed. Shelling almonds refers to removing the shell to reveal the seed, almonds are sold shelled or unshelled. Blanched almonds are shelled almonds that have been treated with hot water to soften the seedcoat, the almond is a deciduous tree, growing 4–10 m in height, with a trunk of up to 30 cm in diameter. The young twigs are green at first, becoming purplish where exposed to sunlight, the leaves are 3–5 inches long, with a serrated margin and a 2.5 cm petiole. The flowers are white to pink, 3–5 cm diameter with five petals, produced singly or in pairs. Almond grows best in Mediterranean climates with warm, dry summers and mild, the optimal temperature for their growth is between 15 and 30 °C and the tree buds have a chilling requirement of 300 to 600 hours below 7.2 °C to break dormancy. Almonds begin bearing an economic crop in the year after planting. Trees reach full bearing five to six years after planting, the fruit matures in the autumn, 7–8 months after flowering. The almond fruit measures 3. 5–6 cm long, in botanical terms, it is not a nut but a drupe. The outer covering or exocarp, fleshy in other members of Prunus such as the plum and cherry, is instead a thick, leathery, grey-green coat, inside the hull is a reticulated, hard, woody shell called the endocarp. Inside the shell is the seed, commonly called a nut. Generally, one seed is present, but occasionally two occur, the almond is native to the Mediterranean climate region of the Middle East, eastward as far as the Yamuna River in India. The wild form of domesticated almond grows in parts of the Levant, the fruit of the wild forms contains the glycoside amygdalin, which becomes transformed into deadly prussic acid after crushing, chewing, or any other injury to the seed. Selection of the type from the many bitter types in the wild marked the beginning of almond domestication. It is unclear as to which wild ancestor of the created the domesticated species. Zohary and Hopf believe that almonds were one of the earliest domesticated fruit trees due to the ability of the grower to raise attractive almonds from seed
12.
Metabolism
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Metabolism is the set of life-sustaining chemical transformations within the cells of living organisms. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, usually, breaking down releases energy and building up consumes energy. The chemical reactions of metabolism are organized into metabolic pathways, in one chemical is transformed through a series of steps into another chemical. Enzymes act as catalysts that allow the reactions to proceed more rapidly, enzymes also allow the regulation of metabolic pathways in response to changes in the cells environment or to signals from other cells. The metabolic system of a particular organism determines which substances it will find nutritious, for example, some prokaryotes use hydrogen sulfide as a nutrient, yet this gas is poisonous to animals. The speed of metabolism, the rate, influences how much food an organism will require. A striking feature of metabolism is the similarity of the metabolic pathways. These striking similarities in metabolic pathways are likely due to their appearance in evolutionary history. Most of the structures that make up animals, plants and microbes are made from three classes of molecule, amino acids, carbohydrates and lipids. These biochemicals can be joined together to make such as DNA and proteins. Proteins are made of amino acids arranged in a linear chain joined together by peptide bonds, many proteins are enzymes that catalyze the chemical reactions in metabolism. Other proteins have structural or mechanical functions, such as those that form the cytoskeleton, Proteins are also important in cell signaling, immune responses, cell adhesion, active transport across membranes, and the cell cycle. Lipids are the most diverse group of biochemicals and their main structural uses are as part of biological membranes both internal and external, such as the cell membrane, or as a source of energy. Lipids are usually defined as hydrophobic or amphipathic biological molecules but will dissolve in organic solvents such as benzene or chloroform, the fats are a large group of compounds that contain fatty acids and glycerol, a glycerol molecule attached to three fatty acid esters is called a triacylglyceride. Several variations on this structure exist, including alternate backbones such as sphingosine in the sphingolipids. Steroids such as cholesterol are another class of lipids. Carbohydrates are aldehydes or ketones, with hydroxyl groups attached. Carbohydrates are the most abundant biological molecules, and fill numerous roles, such as the storage and transport of energy, the basic carbohydrate units are called monosaccharides and include galactose, fructose, and most importantly glucose
13.
Autonomic nervous system
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The autonomic nervous system is a division of the peripheral nervous system that supplies smooth muscle and glands, and thus influences the function of internal organs. This system is the mechanism in control of the fight-or-flight response. Within the brain, the nervous system is regulated by the hypothalamus. Autonomic functions include control of respiration, cardiac regulation, vasomotor activity and those are then subdivided into other areas and are also linked to ANS subsystems and nervous systems external to the brain. The hypothalamus, just above the stem, acts as an integrator for autonomic functions. The autonomic nervous system has two branches, the nervous system and the parasympathetic nervous system. The sympathetic nervous system is considered the fight or flight system. In many cases, both of these systems have opposite actions where one system activates a response and the other inhibits it. An older simplification of the sympathetic and parasympathetic nervous systems as excitory and inhibitory was overturned due to the many exceptions found, there are inhibitory and excitatory synapses between neurons. Although the ANS is also known as the nervous system. Most autonomous functions are involuntary but they can work in conjunction with the somatic nervous system which provides voluntary control. The autonomic nervous system is divided into the nervous system. The sympathetic division emerges from the cord in the thoracic and lumbar areas. The parasympathetic division has craniosacral “outflow”, meaning that the neurons begin at the cranial nerves, the preganglionic, or first, neuron will begin at the “outflow” and will synapse at the postganglionic, or second, neuron’s cell body. The postganglionic neuron will then synapse at the target organ, the sympathetic nervous system consists of cells with bodies in the lateral grey column from T1 to L2/3. These cell bodies are GVE neurons and are the preganglionic neurons, the parasympathetic nervous system consists of cells with bodies in one of two locations, the brainstem or the sacral spinal cord. These sensory neurons monitor the levels of carbon dioxide, oxygen and sugar in the blood, arterial pressure and they also convey the sense of taste and smell, which, unlike most functions of the ANS, is a conscious perception. Blood oxygen and carbon dioxide are in fact directly sensed by the carotid body, primary sensory neurons project onto “second order” visceral sensory neurons located in the medulla oblongata, forming the nucleus of the solitary tract, that integrates all visceral information
14.
Biosynthesis
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Biosynthesis is a multi-step, enzyme-catalyzed process where substrates are converted into more complex products in living organisms. In biosynthesis, simple compounds are modified, converted into other compounds and this process often consists of metabolic pathways. Some of these pathways are located within a single cellular organelle, while others involve enzymes that are located within multiple cellular organelles. Examples of these pathways include the production of lipid membrane components. The prerequisite elements for biosynthesis include, precursor compounds, chemical energy and these elements create monomers, the building blocks for macromolecules. Biosynthesis occurs due to a series of chemical reactions, for these reactions to take place, the following elements are necessary, Precursor compounds, these compounds are the starting molecules or substrates in a reaction. These may also be viewed as the reactants in a chemical process. Chemical energy, chemical energy can be found in the form of high energy molecules and these molecules are required for energetically unfavorable reactions. Furthermore, the hydrolysis of these compounds drives a reaction forward, high energy molecules, such as ATP, have three phosphates. Often, the phosphate is split off during hydrolysis and transferred to another molecule. Catalytic enzymes, these molecules are special proteins that catalyze a reaction by increasing the rate of the reaction, coenzymes or cofactors, cofactors are molecules that assist in chemical reactions. These may be metal ions, vitamin derivatives such as NADH and acetyl CoA, in the case of NADH, the molecule transfers a hydrogen, whereas acetyl CoA transfers an acetyl group, and ATP transfers a phosphate. Two examples of type of reaction occur during the formation of nucleic acids. For some of these steps, chemical energy is required, Precursor molecule + ATP ↽ − − ⇀ product AMP + PP i Simple compounds that are converted into other compounds with the assistance of cofactors. For example, the synthesis of phospholipids requires acetyl CoA, while the synthesis of another component, shingolipids. The general equation for these examples is, Precursor molecule + Cofactor → e n z y m e macromolecule Simple compounds that join together to create a macromolecule, for example, fatty acids join together to form phopspholipids. In turn, phospholipids and cholesterol interact noncovalently in order to form the lipid bilayer and this reaction may be depicted as follows, Molecule 1 + Molecule 2 ⟶ macromolecule Many intricate macromolecules are synthesized in a pattern of simple, repeated structures. For example, the simplest structures of lipids are fatty acids, fatty acids are hydrocarbon derivatives, they contain a carboxyl group “head” and a hydrocarbon chain “tail. ”These fatty acids create larger components, which in turn incorporate noncovalent interactions to form the lipid bilayer
15.
Hormones
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Hormones have diverse chemical structures, mainly of 3 classes, eicosanoids, steroids, and amino acid/protein derivatives. The glands that secrete hormones comprise the endocrine signaling system, the term hormone is sometimes extended to include chemicals produced by cells that affect the same cell or nearby cells. Hormones affect distant cells by binding to receptor proteins in the target cell resulting in a change in cell function. When a hormone binds to the receptor, it results in the activation of a signal transduction pathway, Hormone secretion may occur in many tissues. Endocrine glands are the example, but specialized cells in various other organs also secrete hormones. Hormone secretion occurs in response to specific biochemical signals from a range of regulatory systems. Upon secretion, certain hormones, including hormones and catecholamines, are water-soluble and are thus readily transported through the circulatory system. The endocrine system secretes hormones directly into the bloodstream typically into fenestrated capillaries, Hormones with paracrine function diffuse through the interstitial spaces to nearby target tissue. The reaction of the cells may then be recognized by the original hormone-producing cells. This is an example of a negative feedback loop. Hormone cells are typically of a cell type, residing within a particular endocrine gland, such as the thyroid gland, ovaries. Hormones exit their cell of origin via exocytosis or another means of membrane transport, the hierarchical model is an oversimplification of the hormonal signaling process. Different tissue types may also respond differently to the same hormonal signal, the rate of hormone biosynthesis and secretion is often regulated by a homeostatic negative feedback control mechanism. Such a mechanism depends on factors that influence the metabolism and excretion of hormones, thus, higher hormone concentration alone cannot trigger the negative feedback mechanism. Negative feedback must be triggered by overproduction of an effect of the hormone, for example, thyroid-stimulating hormone causes growth and increased activity of another endocrine gland, the thyroid, which increases output of thyroid hormones. To release active hormones quickly into the circulation, hormone biosynthetic cells may produce and these can then be quickly converted into their active hormone form in response to a particular stimulus. Eicosanoids are considered to act as local hormones and they are considered to be local because they possess specific effects on target cells close to their site of formation. They also have a rapid degradation cycle, making sure they do not reach distal sites within the body, most hormones initiate a cellular response by initially binding to either cell membrane associated or intracellular receptors
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Thermoregulation
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Thermoregulation is the ability of an organism to keep its body temperature within certain boundaries, even when the surrounding temperature is very different. A thermoconforming organism, by contrast, simply adopts the surrounding temperature as its own body temperature, the internal thermoregulation process is one aspect of homeostasis, a state of dynamic stability in an organisms internal conditions, maintained far from thermal equilibrium with its environment. If the body is unable to maintain a temperature and it increases significantly above normal. For humans, this occurs when the body is exposed to constant temperatures of approximately 55 °C, humans may also experience lethal hyperthermia when the wet bulb temperature is sustained above 35 °C for six hours. The opposite condition, when temperature decreases below normal levels, is known as hypothermia. It was not until the introduction of thermometers that any data on the temperature of animals could be obtained. Hence it is important to identify the parts of the body that most closely reflect the temperature of the internal organs, also, for such results to be comparable, the measurements must be conducted under comparable conditions. The rectum has traditionally been considered to reflect most accurately the temperature of internal parts, or in cases of sex or species. Occasionally the temperature of the urine as it leaves the urethra may be of use in measuring body temperature, more often the temperature is taken in the mouth, axilla, ear or groin. Some animals undergo one of forms of dormancy where the thermoregulation process temporarily allows the body temperature to drop. Examples include hibernating bears and torpor in bats, thermoregulation in organisms runs along a spectrum from endothermy to ectothermy. Endotherms create most of their heat via metabolic processes, and are referred to as warm-blooded. Ectotherms use external sources of temperature to regulate their body temperatures and they are colloquially referred to as cold-blooded despite the fact that body temperatures often stay within the same temperature ranges as warm-blooded animals. Ectotherms are the opposite of endotherms when it comes to regulating internal temperatures, in ectotherms, the internal physiological sources of heat are of negligible importance, the biggest factor that enables them to maintain adequate body temperatures is due to environmental influences. Vaporization, Evaporation of sweat and other bodily fluids, convection, Increasing blood flow to body surfaces to maximize heat loss. Conduction, Losing heat by being in contact with a colder surface, for instance, Lying on cool ground. Staying wet in a river, lake or sea, radiation, releasing heat by radiating it away from the body. Convection, Climbing to higher ground up trees, ridges, rocks, entering a warm water or air current
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Maternal bond
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A maternal bond is the relationship between a mother and her child. While typically associated with pregnancy and childbirth, a bond may also develop in cases where the child is unrelated. Both physical and emotional influence the mother-child bonding process. In separation anxiety disorder a child becomes fearful and nervous when away from a loved one, new mothers do not always experience instant love toward their child. Instead, the bond can strengthen over time, bonds can take hours, days, weeks, or months to develop. The maternal bond between a female and her biological child usually begins to develop during pregnancy. The pregnant female adapts her lifestyle to suit the needs of the developing infant, at around 18 to 25 weeks, the mother begins to feel the fetus moving. Similar to seeing her child for the first time in an ultrasound scan, the developing fetus has some awareness of the mothers heartbeat and voice and has the ability to respond to touch or movement. By the seventh month of pregnancy, two-thirds of women report a strong bond with their unborn child. Mothers who did not want the pregnancy typically do not have a relationship with the child. They are more likely to suffer from depression or other mental health problems. Childbirth is an experience that can strengthen the mother and child bond, factors such as a traumatic birth, the mothers childhood, medical stress, lack of support and the influence of a spouse or partner can weaken the bond. Emotional bonding theory first appeared in the mid-1970s, and by the 1980s had become an accepted phenomenon, soon, the process became analyzed and scrutinized to the point of creating another term – poor bonding. Production of oxytocin during childbirth and lactation increases parasympathetic activity, maternal oxytocin circulation can predispose women to bond and show bonding behavior. Breastfeeding is also believed to foster the bond, via touch, response. A2014 study claimed that oxytocin promotes dishonesty when the outcome favors the closely bonded groups to which an individual belongs, a real-world example of this effect can be seen when parents lie about their address to gain admission to better schools for their children. These capacities bring with them separation anxiety as the infant becomes more vulnerable away from mother, most parents welcome these explorations and this increased independence. However, in the context of depression, trauma or disturbed bonding in her own early life
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Thirst
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Thirst is the craving for fluids, resulting in the basic instinct of animals to drink. It is a mechanism involved in fluid balance. It arises from a lack of fluids or an increase in the concentration of certain osmolites, if the water volume of the body falls below a certain threshold or the osmolite concentration becomes too high, the brain signals thirst. Continuous dehydration can cause problems, but is most often associated with renal problems. Excessive thirst, known as polydipsia, along with excessive urination, known as polyuria, there are receptors and other systems in the body that detect a decreased volume or an increased osmolite concentration. They signal to the nervous system, where central processing succeeds. Nevertheless, the craving itself is something generated from central processing in the brain and it is vital for organisms to be able to maintain their fluid levels in very narrow ranges. The goal is to keep the fluid, the fluid outside the cell. This condition is called isotonic and occurs when the level of solutes are present on either side of the cell membrane so that the net water movement is zero. If the interstitial fluid has a concentration of solutes than the intracellular fluid it will pull water out of the cell. This condition is called hypertonic and if enough water leaves the cell it will not be able to perform essential chemical functions, if the interstitial fluid becomes less concentrated the cell will fill with water as it tries to equalize the concentrations. This condition is called hypotonic and can be dangerous because it can cause the cell to swell, one set of receptors responsible for thirst detects the concentration of interstitial fluid. The other set of receptors detects blood volume and this is one of two types of thirst and is defined as thirst caused by loss of blood volume without depleting the intracellular fluid. This can be caused by loss, vomiting, and diarrhea. This loss of volume is problematic if the total blood volume falls too low the heart cannot circulate blood effectively. The vascular system responds by constricting blood vessels thereby creating a volume for the blood to fill. This mechanical solution however has definite limits and usually must be supplemented with increased volume, the loss of blood volume is detected by cells in the kidneys and triggers thirst for both water and salt via the renin-angiotensin system. Hypovolemia leads to activation of the renin angiotensin system and is detected by cells in the kidney, when these cells detect decreased blood flow due to the low volume they secrete an enzyme called renin
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Sleep
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It is distinguished from wakefulness by a decreased ability to react to stimuli, but is more easily reversed than the state of being comatose. Sleep occurs in repeating periods, in which the body alternates between two distinct modes known as non-REM and REM sleep. Although REM stands for rapid eye movement, sleep affects other brain-body functions, during sleep, most systems are in an anabolic state, helping to restore the immune, nervous, skeletal, and muscular systems. The internal circadian clock promotes sleep daily at night, however, sleep patterns vary among individuals. In the last century, artificial light has substantially altered sleep timing in industrialized countries, the diverse purposes and mechanisms of sleep are the subject of substantial ongoing research. Sleep seems to assist with improvements in the body and mind, Research in the 21st century is investigating whether sleep is a period of maintenance for removing metabolic waste compounds from the brain. Sleep is sometimes confused with unconsciousness, but is different in terms of the thought process. REM and non-REM sleep are so different that physiologists classify them as distinct behavioral states, REM sleep is associated with desynchronized and fast brain waves, loss of muscle tone, and suspension of homeostasis. NREM is considered to be sleep, it shows no prominent eye movement or muscle paralysis. Sleep occurs in cycles of approximately 90 minutes and this rhythm is called the ultradian sleep cycle. Sleep proceeds in cycles of NREM and REM, normally in that order, the American Academy of Sleep Medicine divides NREM into three stages, N1, N2, and N3, the last of which is also called delta sleep or slow-wave sleep. The whole period normally proceeds in the order, N1 → N2 → N3 → N2 → REM, REM sleep occurs as a person returns to stage 2 or 1 from a deep sleep. An adult reaches REM approximately every 90 minutes, REM sleep usually lasts for longer during latter half of sleep than in the part of the sleep episode. There is an amount of deep sleep earlier in the night. Key physiological indicators in sleep include EEG of brain waves, electrooculography of eye movements, simultaneous collection of these measurements is called polysomnography, and can be performed in a specialized sleep laboratory. In other words, sleeping persons perceive fewer stimuli, however, they can generally still respond to loud noises and other salient sensory events. Awakening can mean the end of sleep, or simply a moment to survey the environment, sleepers typically awaken from slow-wave sleep, soon after the end of a REM phase or sometimes in the middle of REM. Internal circadian indicators, along with reduction of homeostatic sleep need, typically bring about awakening
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Circadian rhythm
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A circadian rhythm /sɜːrˈkeɪdiən/ is any biological process that displays an endogenous, entrainable oscillation of about 24 hours. These 24-hour rhythms are driven by a clock, and they have been widely observed in plants, animals, fungi. The term circadian comes from the Latin circa, meaning around, the formal study of biological temporal rhythms, such as daily, tidal, weekly, seasonal, and annual rhythms, is called chronobiology. Processes with 24-hour oscillations are generally called diurnal rhythms, strictly speaking. Although circadian rhythms are endogenous, they are adjusted to the environment by external cues called zeitgebers. The earliest recorded account of a circadian process dates from the 4th century B. C. E, when Androsthenes, a ship captain serving under Alexander the Great, described diurnal leaf movements of the tamarind tree. The first recorded observation of an endogenous circadian oscillation was by the French scientist Jean-Jacques dOrtous de Mairan in 1729, in 1896, Patrick and Gilbert observed that during a prolonged period of sleep deprivation, sleepiness increases and decreases with a period of approximately 24 hours. Szymanski showed that animals are capable of maintaining 24-hour activity patterns in the absence of external cues such as light, in the early 20th century, circadian rhythms were noticed in the rhythmic feeding times of bees. Extensive experiments were done by Auguste Forel, Ingeborg Beling, ron Konopka and Seymour Benzer isolated the first clock mutant in Drosophila in the early 1970s and mapped the period gene, the first discovered genetic determinant of behavioral rhythmicity. Joseph Takahashi discovered the first mammalian circadian clock mutation using mice in 1994, however, recent studies show that deletion of clock does not lead to a behavioral phenotype, which questions its importance in rhythm generation. The term circadian was coined by Franz Halberg in the 1950s, to be called circadian, a biological rhythm must meet these three general criteria, The rhythm has an endogenous free-running period that lasts approximately 24 hours. The rhythm persists in constant conditions, with a period of about 24 hours, the period of the rhythm in constant conditions is called the free-running period and is denoted by the Greek letter τ. The rationale for this criterion is to distinguish circadian rhythms from simple responses to external cues. A rhythm cannot be said to be endogenous unless it has been tested, in diurnal animals, in general τ is slightly greater than 24 hours, whereas, in nocturnal animals, in general τ is shorter than 24 hours. The rhythm can be reset by exposure to external stimuli, a process called entrainment, the external stimulus used to entrain a rhythm is called the Zeitgeber, or time giver. In other words, they maintain circadian periodicity over a range of physiological temperatures, many organisms live at a broad range of temperatures, and differences in thermal energy will affect the kinetics of all molecular processes in their cell. In order to track of time, the organisms circadian clock must maintain roughly a 24-hour periodicity despite the changing kinetics. The Q10 Temperature Coefficient is a measure of this compensating effect, if the Q10 coefficient remains approximately 1 as temperature increases, the rhythm is considered to be temperature-compensated
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Human
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Modern humans are the only extant members of Hominina tribe, a branch of the tribe Hominini belonging to the family of great apes. Several of these hominins used fire, occupied much of Eurasia and they began to exhibit evidence of behavioral modernity around 50,000 years ago. In several waves of migration, anatomically modern humans ventured out of Africa, the spread of humans and their large and increasing population has had a profound impact on large areas of the environment and millions of native species worldwide. Humans are uniquely adept at utilizing systems of communication for self-expression and the exchange of ideas. Humans create complex structures composed of many cooperating and competing groups, from families. Social interactions between humans have established a wide variety of values, social norms, and rituals. These human societies subsequently expanded in size, establishing various forms of government, religion, today the global human population is estimated by the United Nations to be near 7.5 billion. In common usage, the word generally refers to the only extant species of the genus Homo—anatomically and behaviorally modern Homo sapiens. In scientific terms, the meanings of hominid and hominin have changed during the recent decades with advances in the discovery, there is also a distinction between anatomically modern humans and Archaic Homo sapiens, the earliest fossil members of the species. The English adjective human is a Middle English loanword from Old French humain, ultimately from Latin hūmānus, the words use as a noun dates to the 16th century. The native English term man can refer to the species generally, the species binomial Homo sapiens was coined by Carl Linnaeus in his 18th century work Systema Naturae. The generic name Homo is a learned 18th century derivation from Latin homō man, the species-name sapiens means wise or sapient. Note that the Latin word homo refers to humans of either gender, the genus Homo evolved and diverged from other hominins in Africa, after the human clade split from the chimpanzee lineage of the hominids branch of the primates. The closest living relatives of humans are chimpanzees and gorillas, with the sequencing of both the human and chimpanzee genome, current estimates of similarity between human and chimpanzee DNA sequences range between 95% and 99%. The gibbons and orangutans were the first groups to split from the leading to the humans. The splitting date between human and chimpanzee lineages is placed around 4–8 million years ago during the late Miocene epoch, during this split, chromosome 2 was formed from two other chromosomes, leaving humans with only 23 pairs of chromosomes, compared to 24 for the other apes. There is little evidence for the divergence of the gorilla, chimpanzee. Each of these species has been argued to be an ancestor of later hominins
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Neurohypophysial hormone
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The neurohypophysial hormones form a family of structurally and functionally related peptide hormones. Their main representatives are oxytocin and vasopressin and they are named for being secreted by the neurohypophysis, i. e. the posterior pituitary gland, itself a neuronal projection from the hypothalamus. Most of the circulating oxytocin and vasopressin hormones are synthesized in magnocellular neurosecretory cells of the supraoptic nucleus, there, they are stored in Herring bodies and can be released into the circulation on the basis of hormonal and synaptic signals with assistance from pituicytes. Thus they can also be considered as hypophysiotropic hormones, oxytocin mediates contraction of the smooth muscle of the uterus and mammary gland, while vasopressin has antidiuretic action on the kidney, and mediates vasoconstriction of the peripheral vessels. Due to the similarity of the two hormones, there is cross-reaction, oxytocin has a slight antidiuretic function, and high levels of AVP can cause uterine contractions. In common with most active peptides, both hormones are synthesised as larger protein precursors that are converted to their mature forms. Members of this family are found in birds, fish, reptiles and amphibians, in worms, octopuses, Locusta migratoria and this article incorporates text from the public domain Pfam and InterPro IPR000981
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Oxytocin
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Oxytocin is a human peptide hormone and neuropeptide. Oxytocin is also used as a medication to facilitate childbirth, Oxytocin is normally produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary. It plays a role in bonding, sexual reproduction in both sexes, and during and after childbirth. Oxytocin is released into the bloodstream as a hormone in response to stretching of the cervix and uterus during labor and this helps with birth, bonding with the baby, and milk production. Oxytocin was discovered by Henry Dale in 1906 and its molecular structure was discovered in 1952. Estrogen has been found to increase the secretion of oxytocin and to increase the expression of its receptor, in women, a single dose of estradiol has been found to be sufficient to increase circulating oxytocin concentrations. The oxytocin peptide is synthesized as a precursor protein from the OXT gene. This precursor protein also includes the oxytocin carrier protein neurophysin I, the inactive precursor protein is progressively hydrolyzed into smaller fragments via a series of enzymes. The last hydrolysis that releases the active oxytocin nonapeptide is catalyzed by peptidylglycine alpha-amidating monooxygenase, the activity of the PAM enzyme system is dependent upon vitamin C, which is a necessary vitamin cofactor. By chance, sodium ascorbate by itself was found to stimulate the production of oxytocin from ovarian tissue over a range of concentrations in a dose-dependent manner, many of the same tissues where PAM is found are also known to store higher concentrations of vitamin C. Oxytocin is known to be metabolized by the oxytocinase, leucyl/cystinyl aminopeptidase, other oxytocinases are also known to exist. It is then released into the blood from the posterior lobe of the pituitary gland and these axons have collaterals that innervate neurons in the nucleus accumbens, a brain structure where oxytocin receptors are expressed. The endocrine effects of oxytocin and the cognitive or behavioral effects of oxytocin neuropeptides are thought to be coordinated through its common release through these collaterals. Oxytocin is also produced by neurons in the paraventricular nucleus that project to other parts of the brain. Depending on the species, oxytocin receptor-expressing cells are located in areas, including the amygdala. Secretion of oxytocin from the nerve endings is regulated by the electrical activity of the oxytocin cells in the hypothalamus. Endogenous oxytocin concentrations in the brain have been found to be as much as 1000-fold higher than peripheral levels, the finding of significant amounts of this classically neurohypophysial hormone outside the central nervous system raises many questions regarding its possible importance in these different tissues. Oxytocin is synthesized by corpora lutea of several species, including ruminants, along with estrogen, it is involved in inducing the endometrial synthesis of prostaglandin F2α to cause regression of the corpus luteum
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Vasopressin
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Vasopressin, also known as antidiuretic hormone, is a neurohypophysial hormone found in most mammals. In most species it contains arginine and is also called arginine vasopressin or argipressin. Its two primary functions are to water in the body and to constrict blood vessels. It also increases peripheral vascular resistance, which in turn increases blood pressure. It plays a key role in homeostasis, by the regulation of water, glucose and it is derived from a preprohormone precursor that is synthesized in the hypothalamus and stored in vesicles at the posterior pituitary. Most of vasopressin is stored in the pituitary to be released into the bloodstream. It has a very short half-life between 16–24 minutes, vasopressin regulates the bodys water retention. It is released from the brain when the body is dehydrated and causes the kidneys to conserve water, thus concentrating the urine, at high concentrations, it also raises blood pressure by inducing moderate vasoconstriction. In addition, it has a variety of effects on the brain, having been found, for example. A very similar substance, lysine vasopressin or lypressin, has the function in pigs and is often used in human therapy. e. This occurs through increased transcription and insertion of water channels into the membrane of distal convoluted tubule. Aquaporins allow water to move down their osmotic gradient and out of the nephron and this effect is mediated by V2 receptors. Vasopressin also increases the concentration of calcium in the collecting duct cells, vasopressin, acting through cAMP, also increases transcription of the aquaporin-2 gene, thus increasing the total number of aquaporin-2 molecules in collecting duct cells. Acute increase of sodium absorption across the loop of henle. This adds to the countercurrent multiplication which aids in water reabsorption later in the distal tubule. Serum osmolarity/osmolality is also affected by vasopressin due to its role in keeping proper electrolytic balance in the blood stream, improper balance can lead to dehydration, alkalosis, acidosis or other life-threatening changes. The hormone ADH is partly responsible for this process by controlling the amount of water the body retains from the kidney when filtering the blood stream, recent evidence suggests that vasopressin may have analgesic effects. The analgesia effects of vasopressin were found to be dependent on both stress and sex, one study has suggested that genetic variation in male humans affects pair-bonding behavior
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Corticotropin-releasing hormone
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Corticotropin-releasing hormone also known as corticotropin-releasing factor or corticoliberin is a peptide hormone involved in the stress response. It is a hormone that belongs to corticotropin-releasing factor family. In humans, it is encoded by the CRH gene and its main function is the stimulation of the pituitary synthesis of ACTH, as part of the HPA Axis. Corticotropin-releasing hormone is a 41-amino acid peptide derived from a 196-amino acid preprohormone, CRH is secreted by the paraventricular nucleus of the hypothalamus in response to stress. In addition to being produced in the hypothalamus, CRH is also synthesized in peripheral tissues, such as T lymphocytes, in the placenta, CRH is a marker that determines the length of gestation and the timing of parturition and delivery. A rapid increase in circulating levels of CRH occurs at the onset of parturition, suggesting that, in addition to its metabolic functions, a recombinant version for diagnostics is called corticorelin. The portal system carries the CRH to the lobe of the pituitary. ACTH stimulates the synthesis of cortisol, glucocorticoids, mineralocorticoids and DHEA, in the short term, CRH can suppress appetite, increase subjective feelings of anxiety, and perform other functions like boosting attention. Although the distal action of CRH is immunosuppression via the action of cortisol, CRH itself can actually heighten inflammation, the CRH-1 receptor antagonist pexacerfont is currently under investigation for the treatment of generalized anxiety disorder. Another CRH-1 antagonist antalarmin has been researched in studies for the treatment of anxiety, depression and other conditions. Also, abnormally high levels of CRH have been found in the fluid of people that have committed suicide. Recent research has linked the activation of the CRH1 receptor with the feelings that accompany alcohol consumption. A CRH1 receptor antagonist developed by Pfizer, CP-154,526 is under investigation for the treatment of alcoholism. Alpha-helical CRH- acts as a CRH antagonist, CRH is also synthesized by the placenta and seems to determine the duration of pregnancy. DHEA has a role in preparing for and stimulating cervical contractions, increases prostaglandin availability in uteroplacental tissues. Prior to parturition it may have a role inhibiting contractions, through increasing cAMP levels in the myometrium, in culture, trophoblast CRH is inhibited by progesterone, which remains high throughout pregnancy. Its release is stimulated by glucocorticoids and catecholamines, which prior to parturition lifting this progesterone block. The 41-amino acid sequence of CRH was first discovered in sheep by Vale et al. in 1981 and its full sequence is, SQEPPISLDLTFHLLREVLEMTKADQLAQQAHSNRKLLDIA The rat and human peptides are identical and differ from the ovine sequence only by 7 amino acids
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Hypophyseal portal system
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The hypophyseal portal system is a system of blood vessels in the brain that connects the hypothalamus with the anterior pituitary. Its main function is the transport and exchange of hormones to allow a fast communication between both glands, peptides released near the median eminence from hypothalamic nuclei are transported to the anterior pituitary, where they apply their effects. Branches from the carotid artery provide the blood supply to the pituitary. The superior hypophyseal arteries form the primary capillary plexus that supplies blood to the median eminence, from this capillary system, the blood is drained in hypophyseal portal veins into the secondary plexus. The peptides released at the median eminence enter the primary plexus capillaries, from there, they are transported to the anterior pituitary via hypophyseal portal veins to the secondary plexus. The secondary plexus is a network of fenestrated sinusoid capillaries that provide blood to the anterior pituitary, the blood supply and direction of flow in the hypophyseal portal system has been studied over several years on laboratory animals and human cadaver specimens with injection methods. Small ascending vessels arising from the anastomoses that connect the upper with the lower hypophyseal arterial system also supply blood to hypophyseal vessels, the majority of these branches penetrate into the neural tissue to break up into capillaries for rapid hormone exchange. Proper hormone secretion in the fetus is crucial for its growth in the womb of the mother. Hormone-exchanging blood vessels between the hypothalamus and the gland, similar to those of the hypophyseal portal system. In some of the fetuses, portal capillary loops had penetrated into the median eminence and these experimental results give evidence for an early development of what is later the fully developed hypophysial portal system. This can have effects on the respective target glands, making it impossible for them to carry out their functions properly. Occlusions and other issues in the vessels of the hypophysial portal system can also cause complications in the exchange of hormones between the hypothalamus and the pituitary gland. Hypopituitarism Functional Anatomy of the Hypothalamus and Pituitary Gland, Colorado State University
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Thyrotropin-releasing hormone
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It is a tropic, tripeptidal hormone. TRH has been used clinically for the treatment of spinocerebellar degeneration and its pharmaceutical form is called protirelin. TRH is produced by the globe in medial neurons of the paraventricular nucleus, at the beginning, it is synthesized as a 242-amino acid precursor polypeptide that contains 6 copies of the sequence -Gln-His-Pro-Gly-, flanked by Lys-Arg or Arg-Arg sequences. To produce the form, a series of enzymes are required. First, a protease cleaves to the C-terminal side of the flanking Lys-Arg or Arg-Arg, second, a carboxypeptidase removes the Lys/Arg residues leaving Gly as the C-terminal residue. Then, this Gly is converted into an amide residue by a series of enzymes known as peptidylglycine-alpha-amidating monooxygenase. Concurrently with these steps, the N-terminal Gln is converted into pyroglutamate. These multiple steps produce 6 copies of the mature TRH molecule per precursor molecule for human TRH, TRH can also be detected in other areas of the body including the gastrointestinal system and pancreatic islets, as well as in the brain. The sequence of TRH was first determined, and the hormone synthesized, by Roger Guillemin, both parties insisted their labs determined the sequence first, Schally first suggested the possibility in 1966, but abandoned it after Guillemin proposed TRH was not actually a peptide. Guillemins chemist began concurring with these results in 1969, as NIH threatened to cut off funding for the project, Schally and Guillemin shared the 1977 Nobel Prize in Medicine for their discoveries concerning the peptide hormone production of the brain. News accounts of their work often focused on their competition and use of a very large amount of sheep. Its molecular weight is 359.5 Da and its logp octanol/water is -2.46 TRH is used clinically by intravenous injection to test the response of the anterior pituitary gland, this procedure is known as a TRH test. This is done as diagnostic test of thyroid disorders such as secondary hypothyroidism, TRH has anti-depressant and anti-suicidal properties, and in 2012 the U. S. Army awarded a research grant to develop a TRH nasal spray in order to prevent suicide amongst its ranks. Side effects after intravenous TRH administration are minimal, nausea, flushing, urinary urgency, and mild rise in blood pressure have been reported. After intrathecal administration, shaking, sweating, shivering, restlessness, TRH belongs to a family of several thyrotropin-releasing hormones
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Somatostatin
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Somatostatin inhibits insulin and glucagon secretion. Among the vertebrates, there exist six different somatostatin genes that have been named SS1, SS2, SS3, SS4, SS5, the six different genes along with the five different somatostatin receptors allows somatostatin to possess a large range of functions. Humans have only one gene, SST. In addition, somatostatin release from cells can act in a paracrine manner. In the stomach, somatostatin acts directly on the parietal cells via a G-protein coupled receptor to reduce acid secretion. Somatostatin is produced by neurons of the ventromedial nucleus of the hypothalamus. These neurons project to the eminence, where somatostatin is released from neurosecretory nerve endings into the hypothalamo-hypophysial system through neuron axons. Somatostatin is then carried to the pituitary gland, where it inhibits the secretion of growth hormone from somatotrope cells. Somatostatin is also produced by other populations that project centrally, i. e. to other areas of the brain. In particular, there are populations of neurons in the arcuate nucleus, the hippocampus. Somatostatin is classified as a hormone, and is induced by low pH. Its actions are spread to different parts of the body, in the anterior pituitary gland, the effects of somatostatin are, Inhibit the release of growth hormone Inhibit the release of thyroid-stimulating hormone Inhibit adenylyl cyclase in parietal cells. Inhibits the release of glucagon Suppresses the exocrine secretory action of pancreas, since it is absorbed poorly from the gut, it is administered parenterally. It is indicated for treatment of carcinoid syndrome and acromegaly. It is also finding increased use in diseases of the liver. Lanreotide is a used in the management of acromegaly and symptoms caused by neuroendocrine tumors. It is a analog of somatostatin, like octreotide. It is available in countries, including the United Kingdom, Australia, and Canada
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