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Anatomical terminology
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Anatomical terminology is a form of scientific terminology used by anatomists, zoologists, and health professionals such as doctors. Anatomical terminology uses many terms, suffixes, and prefixes deriving from Ancient Greek. These terms can be confusing to those unfamiliar with them, but can be more precise reducing ambiguity, also, since these anatomical terms are not used in everyday conversation, their meanings are less likely to change, and less likely to be misinterpreted. By using precise anatomical terminology such ambiguity is eliminated, an international standard for anatomical terminology, Terminologia Anatomica has been created. Anatomical terminology has quite regular morphology, the prefixes and suffixes are used to add meanings to different roots. The root of a term refers to an organ, tissue. For example, in the disorder hypertension, the prefix hyper- means high or over, the roots, prefixes and suffixes are often derived from Greek or Latin, and often quite dissimilar from their English-language variants. Latin names of such as musculus biceps brachii can be split up and refer to, musculus for muscle, biceps for two-headed. The first word tells us what we are speaking about, the second describes it, when describing the position of anatomical structures, structures may be described according to the anatomical landmark they are near. These landmarks may include structures, such as the umbilicus or sternum, or anatomical lines, the cephalon or cephalic region refers to the head. This area is differentiated into the cranium, facies, frons, oculus, auris, bucca, nausus, oris. The neck area is called the cervicis or cervical region, examples of structures named according to this include the frontalis muscle, submental lymph nodes, buccal membrane and orbicularis oculi muscle. Sometimes, unique terminology is used to reduce confusion in different parts of the body, for example, different terms are used when it comes to the skull in compliance with its embryonic origin and its tilted position compared to in other animals. Here, Rostral refers to proximity to the front of the nose, similarly, in the arms, different terminology is often used in the arms, in part to reduce ambiguity as what is the front, back, inner and outer surfaces. For this reason, the terms below are used, Radial referring to the radius bone, ulnar referring to the ulna bone, medially positioned when in the standard anatomical position. Other terms are used to describe the movement and actions of the hands and feet. International morphological terminology is used by the colleges of medicine and dentistry and it facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields of research, teaching and medical care. The international morphological terminology refers to morphological sciences as a biological sciences branch, in this field, the form and structure are examined as well as the changes or developments in the organism
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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
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Spinal cord
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The spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column. The brain and spinal cord make up the central nervous system. The spinal cord begins at the bone and extends down to the space between the first and second lumbar vertebrae, it does not extend the entire length of the vertebral column. It is around 45 cm in men and around 43 cm long in women, also, the spinal cord has a varying width, ranging from 13 mm thick in the cervical and lumbar regions to 6.4 mm thick in the thoracic area. The enclosing bony vertebral column protects the relatively shorter spinal cord, the spinal cord is the main pathway for information connecting the brain and peripheral nervous system. The length of the cord is much shorter as compared to the length of the vertebral column. The human spinal cord extends from the magnum and continues through to the conus medullaris near the second lumbar vertebra. It is about 45 cm long in men and around 43 cm in women, ovoid-shaped, the cervical enlargement, located from C5 to T1 spinal segments, is where sensory input comes from and motor output goes to the arms. The lumbar enlargement, located between L1 and S3 spinal segments, handles input and motor output coming from and going to the legs. The spinal cord is continuous with the portion of the medulla. It does not run the length of the vertebral column in adults. It is made of 31 segments that contain sensory nerve root. The first cervical segment is very small and may be absent in most individuals. Nerve roots merge into 31 bilaterally symmetric pairs of spinal nerves, the peripheral nervous system is made up of these spinal roots, nerves, and ganglia. Dorsal root ganglia hold the bodies of dorsal root ganglia in the spinal ganglia related with that spinal segment. Ventral roots only have efferent fibers that arise from motor neurons whose cell bodies are found in the ventral horns of the spinal cord. The spinal cord are protected by three layers of tissue or membranes called meninges, that surround the canal, the dura mater is the outermost layer, and it forms a tough protective coating. Between the dura mater and the bone of the vertebrae is a space called the epidural space
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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
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Arachnoid granulation
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Arachnoid granulations are small protrusions of the arachnoid through the dura mater. They protrude into the sinuses of the brain, and allow cerebrospinal fluid to exit the sub-arachnoid space. Largest granulations lie along the sagittal sinus, a large venous space running from front to back along the center of the head. They are, however, present along other dural sinuses as well, smaller granulations are called villi, large calcified ones are referred to as pacchionian bodies. Diffusion across the arachnoid granulations into the superior sagittal sinus returns CSF to the venous circulation, the arachnoid granulations act as one-way valves. Normally the pressure of the CSF is higher than that of the system, so CSF flows through the villi. If the pressure is reversed for some reason, fluid will not pass back into the subarachnoid space, the reason for this is not known. It has been suggested that the cells of the venous sinus create vacuoles of CSF. The importance of arachnoid granulations for the drainage of CSF is controversial, by some accounts, a large portion of CSF is drained through lymphatics associated with extracranial segments of the cranial nerves. A large proportion of CSF is believed to leave the vault through the axons of CN I through their extension through the cribiform plate. On the inner surface of bones, small pits called granular fovea are produced by arachnoid granulations. Occasionally, they are referred to by their old name, Pacchionis granulations or pacchionian bodies, named after Italian anatomist Antonio Pacchioni
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Immunological
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Immunology is a branch of biology that covers the study of immune systems in all organisms. It was the Russian biologist Ilya Ilyich Mechnikov who boosted studies on immunology and he jabbed the thorn of a rose on a starfish and noted that,24 hours later, cells were surrounding the tip. It was a response of the body, trying to maintain its integrity. It was Mechnikov who first observed the phenomenon of phagocytosis, in which the body defends itself against a foreign body, Immunology has applications in numerous disciplines of medicine, particularly in the fields of organ transplantation, oncology, virology, bacteriology, parasitology, psychiatry, and dermatology. The important lymphoid organs of the system are the thymus and bone marrow, and chief lymphatic tissues such as spleen, tonsils, lymph vessels, lymph nodes, adenoids. Classical immunology ties in with the fields of epidemiology and medicine and it studies the relationship between the body systems, pathogens, and immunity. The earliest written mention of immunity can be traced back to the plague of Athens in 430 BCE, thucydides noted that people who had recovered from a previous bout of the disease could nurse the sick without contracting the illness a second time. Many other ancient societies have references to this phenomenon, but it was not until the 19th and 20th centuries before the concept developed into scientific theory. The study of the molecular and cellular components that comprise the immune system, the immune system has been divided into a more primitive innate immune system and, in vertebrates, an acquired or adaptive immune system. The latter is divided into humoral and cell-mediated components. The humoral response is defined as the interaction between antibodies and antigens, antibodies are specific proteins released from a certain class of immune cells known as B lymphocytes, while antigens are defined as anything that elicits the generation of antibodies. Immunology rests on an understanding of the properties of two biological entities and the cellular response to both. Immunological research continues to more specialized, pursuing non-classical models of immunity and functions of cells, organs. Clinical immunology is the study of diseases caused by disorders of the immune system and it also involves diseases of other systems, where immune reactions play a part in the pathology and clinical features. Other immune system include various hypersensitivities that respond inappropriately to otherwise harmless compounds. Clinical immunologists also study ways to prevent the immune systems attempts to destroy allografts, the body’s capability to react to antigen depends on a persons age, antigen type, maternal factors and the area where the antigen is presented. Neonates are said to be in a state of physiological immunodeficiency, once born, a child’s immune system responds favorably to protein antigens while not as well to glycoproteins and polysaccharides. In fact, many of the infections acquired by neonates are caused by low virulence organisms like Staphylococcus, in neonates, opsonic activity and the ability to activate the complement cascade is very limited
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Skull
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The skull is a bony structure that forms the head of the skeleton in most vertebrates. It supports the structures of the face and provides a cavity for the brain. The skull is composed of two parts, the cranium and the mandible, in the human these two parts are the neurocranium and the viscerocranium or facial skeleton that includes the mandible as its largest bone. The skull forms the anterior most portion of the skeleton and is a product of cephalisation—housing the brain, and several sensory structures such as the eyes, ears, nose, in the human these sensory structures are part of the facial skeleton. In some animals such as horned ungulates, the skull also has a function by providing the mount for the horns. The English word skull is probably derived from Old Norse skulle, while the Latin word cranium comes from the Greek root κρανίον, the skull is made up of a number of fused flat bones, and contains many foramina and processes, and several cavities or sinuses. For details and the constituent bones, see neurocranium and viscerocranium, the human skull is the bony structure that forms the head in the human skeleton. It supports the structures of the face and forms a cavity for the brain, like the skulls of other vertebrates, it protects the brain from injury. The skull consists of two parts, of different embryological origin—the neurocranium and the facial skeleton, the neurocranium forms the protective cranial cavity that surrounds and houses the brain and brainstem. The facial skeleton is formed by the supporting the face. Except for the mandible, all of the bones of the skull are joined together by sutures—synarthrodial joints formed by bony ossification, sometimes there can be extra bone pieces within the suture known as wormian bones or sutural bones. The human skull is considered to consist of twenty-two bones—eight cranial bones. In the neurocranium these are the bone, two temporal bones, two parietal bones, the sphenoid, ethmoid and frontal bones. The bones of the skeleton are the vomer, two nasal conchae, two nasal bones, two maxilla, the mandible, two palatine bones, two zygomatic bones, and two lacrimal bones. Some of these bones—the occipital, parietal, frontal, in the neurocranium, and the nasal, lacrimal, the skull also contains sinus cavities and numerous foramina. The sinuses are lined with respiratory epithelium and their known functions are the lessening of the weight of the skull, the aiding of resonance to the voice and the warming and moistening of the air drawn through the nasal cavity. The foramina are openings in the skull, the largest of these is the foramen magnum that allows the passage of the spinal cord as well as nerves and blood vessels. The many processes of the include the mastoid process and the zygomatic process
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Cerebral autoregulation
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Cerebral autoregulation is a process in mammals, which aims to maintain adequate and stable cerebral blood flow. While most systems of the show some degree of autoregulation. Cerebral autoregulation plays an important role in maintaining an appropriate blood flow to that region, brain perfusion is essential for life since the brain has a high metabolic demand. By means of cerebral autoregulation the body is able to deliver sufficient blood containing oxygen and nutrients to the tissue for this metabolic need. Cerebral autoregulation refers to the mechanisms that maintain blood flow at an appropriate level during changes in blood pressure. This field includes areas such as CO2 reactivity, neurovascular coupling and this regulation of cerebral blood flow is achieved primarily by small arteries, arterioles, which either dilate or contract under the influence of multiple complex physiological control systems. Impairment of these systems may occur e. g. following stroke, trauma or anaesthesia, the non-invasive measurement of relevant physiological signals like cerebral blood flow, intracranial pressure, blood pressure, CO2 levels, cerebral oxygen consumption, etc. is challenging. Even more so is the subsequent assessment of the control systems, much remains unknown about the physiology of blood flow control and the best clinical interventions to optimize patient outcome. Three different mechanisms are thought to contribute to the process of cerebral autoregulation and these are metabolic, myogenic and neurogenic. Metabolic regulation is driven by the balance between cerebral metabolism and oxygen delivery through cerebral blood flow and acts by means of a vasoactive substance, in principle, this is a negative feedback control system that seeks to balance cerebral blood flow to its demand. The effect of blood pressure changes are directly detected by the vascular smooth muscle in arterioles. Then, the calibers are adjusted accordingly to keep blood flow constant, the vascular smooth muscle actuators in the resistance arterioles are controlled via sympathetic innervation, receiving the input from the appropriate brainstem autonomous control center. Nitric oxide released by parasympathetic fibers may also play a role, in order to assess cerebral autoregulation one must at least continuously measure arterial blood pressure and cerebral blood flow. Because CO2 levels are of great influence to cerebral autoregulation it is recommended to also continuously measure CO2, arterial blood pressure can be measured invasive using an arterial line. However, noninvasive finger arterial pressure can also be measured using a volume clamp technique and this technique uses a combination of an inflatable finger cuff and an infrared plethysmograph. Cerebral blood flow can be quantified in various ways of which three noninvasive means are currently much used and these are Transcranial Doppler sonography, Magnetic Resonance Imaging and Near Infrared Spectroscopy. The quantification of cerebral autoregulation always involves variation seen in blood flow in relation to changes in blood pressure. This blood pressure variation can either be evoked or spontaneous, measuring and understanding cerebral autoregulation remains a big challenge
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Cerebral circulation
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Cerebral circulation is the movement of blood through the network of cerebral arteries and veins supplying the brain. The rate of the blood flow in the adult is typically 750 milliliters per minute. The amount of blood that the cerebral circulation carries is known as blood flow. The presence of fields or accelerations also determine variations in the movement and distribution of blood in the brain. The following description is based on idealized human cerebral circulation, the pattern of circulation and its nomenclature vary between organisms. Blood supply to the brain is divided into anterior and posterior segments. The two main pairs of arteries are the Internal carotid arteries and vertebral arteries, the anterior and posterior cerebral circulations are interconnected via bilateral posterior communicating arteries. They are part of the Circle of Willis, which provides backup circulation to the brain, the anterior cerebral circulation is the blood supply to the anterior portion of the brain. Middle cerebral artery The posterior cerebral circulation is the supply to the posterior portion of the brain, including the occipital lobes, cerebellum. It is supplied by the arteries, Vertebral arteries, These smaller arteries branch from the subclavian arteries which primarily supply the shoulders, lateral chest. Within the cranium the two vertebral arteries fuse into the basilar artery, the superficial system is composed of dural venous sinuses, which have wall composed of dura mater as opposed to a traditional vein. The dural sinuses are, therefore located on the surface of the cerebrum, from here, two transverse sinuses bifurcate and travel laterally and inferiorly in an S-shaped curve that form the sigmoid sinuses which go on to form the two jugular veins. In the neck, the jugular veins parallel the course of the carotid arteries. The deep venous drainage is primarily composed of traditional veins inside the structures of the brain. This vein merges with the inferior sagittal sinus to form the straight sinus which then joins the superficial venous system mentioned above at the confluence of sinuses, Cerebral blood flow is the blood supply to the brain in a given period of time. In an adult, CBF is typically 750 millilitres per minute or 15% of the cardiac output and this equates to an average perfusion of 50 to 54 millilitres of blood per 100 grams of brain tissue per minute. CBF is tightly regulated to meet the metabolic demands. Too much blood can raise intracranial pressure, which can compress and damage delicate brain tissue
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Subarachnoid cisterns
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The subarachnoid cisterns are spaces formed by openings, where the arachnoid mater and the pia mater are separated, in the subarachnoid space of the brain. These spaces are filled with cerebrospinal fluid, although the pia mater adheres to the surface of the brain, closely following the contours of its gyri and sulci, the arachnoid covers only its superficial surface. It follows from this that in areas around the brain the pia and arachnoid are separated widely. Although they are described as distinct compartments, the subarachnoid cisterns are in fact not truly anatomically distinct. Rather, these spaces are separated from each other by a trabeculated porous wall with various-sized openings. There are many cisterns in the brain with several especially large, some major subarachnoid cisterns, Cisterna magna also called cerebellomedullary cistern - the largest of the subarachnoid cisterns. It lies between the cerebellum and the medulla oblongata and it receives CSF from the fourth ventricle via the median aperture named foramen of Magendie. The cisterna magna contains, The vertebral artery and the origin of the posteroinferior cerebellar artery, the ninth, tenth, eleventh and twelfth cranial nerves. Surrounds the ventral aspect of the pons and it receives CSF via the paired lateral apertures. It contains, The basilar artery and the origin of the anteroinferior cerebellar artery, the origin of the superior cerebellar arteries. It is situated in the angle between the cerebellum and the pons. It contains, The seventh and eighth cranial nerves, the fifth cranial nerve and the petrosal vein. It is situated at the base of the brain, between the two cerebral peduncles of midbrain and dorsum sellae and continuous below with pontine cistern and superiorly with suprasellar cistern and it contains, The optic chiasm The bifurcation of the basilar artery. Peduncular segments of the cerebral arteries. Peduncular segments of the superior cerebellar arteries, the third cranial nerve, which passes between the posterior cerebral and superior cerebellar arteries. Superior cistern - It is situated dorsal to the midbrain, thin, sheet-like extensions of the superior cistern that extend laterally about the midbrain, connecting it to the interpeduncular cistern. Ambient cistern may also refer to the combination of these extensions and it is composed of a supratentorial and an infratentorial compartment. It contains, The great cerebral vein. The third portion of the superior cerebellar arteries, perforating branches of the posterior cerebral and superior cerebellar arteries
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Sulcus (neuroanatomy)
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In neuroanatomy, a sulcus is a depression or groove in the cerebral cortex. It surrounds a gyrus, creating the characteristic folded appearance of the brain in humans, Sulci are one of three parts of the cerebral cortex, the others being the gyri and the fissures. The three different parts create a surface area for the human brain and other mammalian brains. When looking at the brain, two-thirds of the surface are hidden in the grooves. The sulci and fissures are both grooves in the cortex but they are differentiated by size, a sulcus is a shallower groove that surrounds a gyrus. A fissure is a furrow that divides the brain into lobes. However this distinction is not always clear, for example, the lateral sulcus is also known as the lateral fissure or the Sylvian fissure, and the central sulcus is also known as the central fissure or the Rolandic fissure. As the surface area of the brain increases more functions are made possible, a smooth-surfaced brain is only able to grow to a certain extent. A depression, sulcus, in the area allows for continued growth. This in turn allows for the functions of the brain to continue growing, the sulcal pattern varies between human individuals, and the most elaborate overview on this variation is probably an atlas by Ono, Kubick and Abernathey, Atlas of the Cerebral Sulci. Some of the more prominent sulci are, however, seen across individuals - and even species - making a common nomenclature across individuals, in humans, cerebral convolutions appear at about 5 months and take at least into the first year after birth to fully develop. The potential influences of genetic, epigenetic and environmental factors are not fully understood and it has been found that the width of cortical sulci not only increases with age, but also with cognitive decline in the elderly. Axial sulcus develops in the axis of a rapidly growing homogeneous area e. g. postcalcarine sulcus in the long axis of the striate area. Operculated sulcus separates by its lips into two areas and contains an area in the walls of the sulcus. On the basis of formation, Primary sulci, formed before birth, secondary sulcus, is produced by factors other than the exuberant growth in the adjoining areas of the cortex. Examples are the lateral and parieto-occipital sulci, on the basis of Depth, Complete sulcus is very deep so as to cause elevation in the walls of the lateral ventricle. Examples are the collateral and calcarine sulci, incomplete sulci are superficially situated and are not very deep, E. g. paracentral sulcus. Mammals that have smooth-surfaced or nonconvoluted brains are called lissencephalics and those that have folded or convoluted brains gyrencephalics, the division between the two groups occurs when cortical surface area is about 10 cm2 and the brain has a volume of 3–4 cm3
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Central canal
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For the engineering project, see Indiana Central Canal. The central canal, also known as ependymal canal, is the cerebrospinal fluid-filled space that runs longitudinally through the length of the spinal cord. The central canal is continuous with the system of the brain. The fourth ventricle narrows at a called the obex to become the central canal of the spinal cord. Syringomyelia is a disease caused by the occlusion of the central canal, occlusions of the central canal typically occur at the lower cervical and upper thoracic levels. This typically damages white matter fibers that cross in anterior white commissure, leading to the loss of temperature, pain, archived from the original on 2014-01-01
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Bony labyrinth
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The bony labyrinth is the rigid, bony outer wall of the inner ear in the temporal bone. It consists of three parts, the vestibule, semicircular canals, and cochlea and these are cavities hollowed out of the substance of the bone, and lined by periosteum. They contain a fluid, the perilymph, in which the membranous labyrinth is situated. On radiographic images, the capsule is the most dense portion of the temporal bone. In otospongiosis, a cause of adult-onset hearing loss, the otic capsule is exclusively affected. This area normally undergoes no remodeling in adult life, and is extremely dense and this results in hypodensity on CT, with the portion first affected usually being the fissula ante fenestram. This article incorporates text in the domain from the 20th edition of Grays Anatomy
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Perilymph
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Perilymph is an extracellular fluid located within the cochlea in two of its three compartments, the scala tympani and scala vestibuli. The ionic composition of perilymph is comparable to that of plasma, the major cation in perilymph is sodium, The values of sodium and potassium concentration in the perilymph are 138 mM and 6.9 mM, respectively. The inner ear has two parts, the labyrinth and the membranous labyrinth. The membranous labyrinth is contained within the labyrinth, and contains a fluid called endolymph. Between the outer wall of the labyrinth and the wall of the bony labyrinth is the perilymphatic space which contains the perilymph. The membranous labyrinth is suspended in the perilymph, the perilymph in the bony labyrinth is continuous with the cerebrospinal fluid of the subarachnoid space via the perilymphatic duct. Perilymph and endolymph have unique ionic compositions suited to their functions in regulating electrochemical impulses of hair cells, the electric potential of endolymph is ~80-90 mV more positive than perilymph due to a higher concentration of potassium cations than sodium. Endolymph is the fluid contained within the labyrinth of the inner ear. It has also suggested that perilymph and endolymph participate in a unidirectional flow that is interrupted in Ménières disease
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Intracranial pressure
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Intracranial pressure is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid. ICP is measured in millimeters of mercury and, at rest, is normally 7–15 mmHg for a supine adult. The body has various mechanisms by which it keeps the ICP stable, changes in ICP are attributed to volume changes in one or more of the constituents contained in the cranium. CSF pressure has been shown to be influenced by changes in intrathoracic pressure during coughing, valsalva maneuver. Intracranial hypertension, commonly abbreviated IH, IICP or raised ICP, is elevation of the pressure in the cranium, ICP is normally 7–15 mm Hg, at 20–25 mm Hg, the upper limit of normal, treatment to reduce ICP may be needed. The pressure-volume relationship between ICP, volume of CSF, blood, and brain tissue, and cerebral perfusion pressure is known as the Monro-Kellie doctrine or the Monro-Kellie hypothesis. The Monro-Kellie hypothesis states that the compartment is incompressible. The cranium and its constituents create a state of volume equilibrium, the principal buffers for increased volumes include CSF and, to a lesser extent, blood volume. These buffers respond to increases in volume of the remaining intracranial constituents, for example, an increase in lesion volume will be compensated by the downward displacement of CSF and venous blood. These compensatory mechanisms are able to maintain a normal ICP for any change in less than approximately 100–120 mL. The Monro-Kellie hypothesis is named after Edinburgh doctors Alexander Monro and George Kellie, one of the most damaging aspects of brain trauma and other conditions, directly correlated with poor outcome, is an elevated intracranial pressure. ICP is very likely to cause harm if it rises too high. Very high intracranial pressures are usually fatal if prolonged, but children can tolerate higher pressures for longer periods and it is a cause of reflex bradycardia. In general, symptoms and signs that suggest a rise in ICP including headache, vomiting without nausea, ocular palsies, altered level of consciousness, back pain, if papilledema is protracted, it may lead to visual disturbances, optic atrophy, and eventually blindness. The headache is classically a morning headache which may wake them from sleep, the brain is relatively poorly supplied by oxygen as a result of mild hypoventilation during the sleeping hours, and also cerebral edema may worsen during the night due to the lying position. The headache is worse on coughing / sneezing / bending, there may also be personality or behavioral changes. In addition to the above, if mass effect is present with resulting displacement of brain tissue, additional signs may include pupillary dilatation, abducens palsies, Cushings triad involves an increased systolic blood pressure, a widened pulse pressure, bradycardia, and an abnormal respiratory pattern. In children, a low rate is especially suggestive of high ICP
16.
Hippocrates
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Hippocrates of Kos, also known as Hippocrates II, was a Greek physician of the Age of Pericles, and is considered one of the most outstanding figures in the history of medicine. He is referred to as the Father of Modern Medicine in recognition of his contributions to the field as the founder of the Hippocratic School of Medicine. Hippocrates is commonly portrayed as the paragon of the ancient physician, historians agree that Hippocrates was born around the year 460 BC on the Greek island of Kos, other biographical information, however, is likely to be untrue. Soranus of Ephesus, a 2nd-century Greek gynecologist, was Hippocrates first biographer and is the source of most personal information about him, later biographies are in the Suda of the 10th century AD, and in the works of John Tzetzes, which date from the 12th century AD. Hippocrates is mentioned in passing in the writings of two contemporaries, Plato, in Protagoras and Phaedrus, and, Aristotles Politics, which date from the 4th century BC. Soranus wrote that Hippocrates father was Heraclides, a physician, and his mother was Praxitela, the two sons of Hippocrates, Thessalus and Draco, and his son-in-law, Polybus, were his students. According to Galen, a physician, Polybus was Hippocrates true successor, while Thessalus. Soranus said that Hippocrates learned medicine from his father and grandfather, Hippocrates was probably trained at the asklepieion of Kos, and took lessons from the Thracian physician Herodicus of Selymbria. Hippocrates taught and practiced medicine throughout his life, traveling at least as far as Thessaly, Thrace, several different accounts of his death exist. He died, probably in Larissa, at the age of 83,85 or 90, Hippocrates is credited with being the first person to believe that diseases were caused naturally, not because of superstition and gods. Hippocrates was credited by the disciples of Pythagoras of allying philosophy, indeed there is not a single mention of a mystical illness in the entirety of the Hippocratic Corpus. However, Hippocrates did work with many convictions that were based on what is now known to be incorrect anatomy and physiology, ancient Greek schools of medicine were split on how to deal with disease. The Knidian school of medicine focused on diagnosis, Medicine at the time of Hippocrates knew almost nothing of human anatomy and physiology because of the Greek taboo forbidding the dissection of humans. The Knidian school consequently failed to distinguish when one disease caused many possible series of symptoms, the Hippocratic school or Koan school achieved greater success by applying general diagnoses and passive treatments. Its focus was on patient care and prognosis, not diagnosis and it could effectively treat diseases and allowed for a great development in clinical practice. Hippocratic medicine and its philosophy are far removed from that of modern medicine, now, the physician focuses on specific diagnosis and specialized treatment, both of which were espoused by the Knidian school. S. Houdart called the Hippocratic treatment a meditation upon death, after a crisis, a relapse might follow, and then another deciding crisis. According to this doctrine, crises tend to occur on critical days, if a crisis occurred on a day far from a critical day, a relapse might be expected
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Emanuel Swedenborg
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Emanuel Swedenborg was a Swedish scientist, philosopher, theologian, revelator, and mystic. He is best known for his book on the afterlife, Heaven, Swedenborg had a prolific career as an inventor and scientist. In 1741, at age 53, he entered into a phase in which he began to experience dreams and visions. This culminated in a spiritual awakening, in which he received revelation that he was appointed by the Lord Jesus Christ to write The Heavenly Doctrine to reform Christianity. For the remaining 28 years of his life, Swedenborg wrote eighteen published theological works and he termed himself a Servant of the Lord Jesus Christ in True Christian Religion, a work he published himself. Some followers of The Heavenly Doctrine believe that, of his theological works, Swedenborgs father, Jesper Swedberg, descended from a wealthy mining family. He travelled abroad and studied theology, and on returning home he was eloquent enough to impress the Swedish king, Charles XI, through the Kings influence he would later become professor of theology at Uppsala University and Bishop of Skara. Jesper took an interest in the beliefs of the dissenting Lutheran Pietist movement, sola fide is a tenet of the Lutheran Church, and Jesper was charged with being a pietist heretic. While controversial, the beliefs were to have a impact on his son Emanuels spirituality. Jesper furthermore held the belief that angels and spirits were present in everyday life. This also came to have a impact on Emanuel. In 1703–1709 Swedenborg lived in Erik Benzelius the youngers house and it was also a flourishing center of scientific ideas and discoveries. Swedenborg studied physics, mechanics and philosophy and read and wrote poetry, in 1715 Swedenborg returned to Sweden, where he devoted himself to natural science and engineering projects for the next two decades. A first step was his meeting with King Charles XII of Sweden in the city of Lund, the Swedish inventor Christopher Polhem, who became a close friend of Swedenborg, was also present. Swedenborgs purpose was to persuade the king to fund an observatory in northern Sweden, however, the warlike king did not consider this project important enough, but did appoint Swedenborg assessor-extraordinary on the Swedish Board of Mines in Stockholm. From 1716 to 1718, Swedenborg published a periodical entitled Daedalus Hyperboreus. One notable description was that of a machine, the same he had been sketching a few years earlier. In 1718 Swedenborg published an article that attempted to explain spiritual and mental events in terms of minute vibrations or tremulations, upon the death of Charles XII, Queen Ulrika Eleonora ennobled Swedenborg and his siblings
18.
Harvey Cushing
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Harvey Williams Cushing was an American neurosurgeon. A pioneer of brain surgery, he was the first person to describe Cushings disease, together with Ernest Sachs, he is known as the father of neurosurgery. Harvey Cushing was born in Cleveland, Ohio and his parents were Betsey M. Williams and Henry Kirke Cushing, a physician whose ancestors came to Hingham, Massachusetts, as Puritans in the 17th century. Harvey was the youngest of ten children, as a child, Cushing attended the Cleveland Manual Training School which expanded his interest in science and medicine. The school’s emphasis on training and a “physics-focused” approach to education played an important role in influencing Cushing towards a career in medical surgery. The schools manual dexterity training program also contributed to Cushing’s future success as a surgeon and he graduated with an A. B. degree in 1891 from Yale University, where he was a member of Scroll and Key and Delta Kappa Epsilon. He studied medicine at Harvard Medical School and earned his degree in 1895. After doing exceptional cerebral surgery abroad under Kocher at Bern and Sherrington at Liverpool, during his time with Kocher, he first encountered the Cushing reflex which describes the relationship between blood pressure and intracranial pressure. At the age of 32, he was associate professor of surgery at Johns Hopkins Hospital. Yet he found time to numerous monographs on surgery of the brain and spinal column. He made a study of pressure and contributed much to the localization of the cerebral centers. In Baltimore, he developed the method of operating with local anaesthesia, in 1911, he was appointed surgeon-in-chief at the Peter Bent Brigham Hospital in Boston. He became a professor of surgery at the Harvard Medical School starting in 1912, in 1913, he was made an honorary F. R. C. S. He was elected a Fellow of the American Academy of Arts, in 1915, before the Clinical Congress of Surgeons in Boston, he showed the possibility of influencing stature by operating on the pituitary gland. Shortly after the entry of the United States into the First World War and he was director of the U. S. base hospital attached to the British Expeditionary Force in France. Cushing also served as the head of a unit in a French military hospital outside of Paris. During his time at the French military hospital, Cushing experimented with the use of electromagnets to extract fragments of metallic missile shrapnel that were lodged severely within the brain and he was mentioned in a dispatch by Field Marshal Sir Douglas Haig in November 1917. On June 6,1918, he was promoted to lieutenant colonel and was assigned as senior consultant in surgery for the American Expeditionary Forces in Europe
19.
Third ventricle
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The third ventricle is one of four connected fluid-filled cavities comprising the ventricular system within the mammalian brain. It is a cleft in the diencephalon between the two thalami, and is filled with cerebrospinal fluid. It is in the midline, between the left and right lateral ventricles, running through the third ventricle is the interthalamic adhesion, which contains thalamic neurons and fibers that may connect the two thalami. The third ventricle communicates with the lateral ventricles anteriorly by the interventricular foramina and it also communicates with the fourth ventricle posteriorly by the cerebral aqueduct. The third ventricle, like parts of the ventricular system of the brain. Specifically, it originates from the portion of the tube that is present in the developing prosencephalon, the third ventricle is bounded by the thalamus and hypothalamus on both the left and right sides. The lamina terminalis forms the anterior wall, the floor is formed by hypothalamic structures. The roof is formed by the ependyma, lining the undersurface of the tela choroidea of the third ventricle, there are two protrusions on the anterior aspect of the third ventricle, the supra-optic recess the infundibular recess. This is formed where the two thalami are joined together at the interthalamic adhesion, an endoscopic third ventriculostomy can be performed in order to release extra fluid caused by hydrocephalus. Several studies have found evidence of enlargement to be associated with major depression. Biology of depression Suprapineal recess Tanycytes line the bottom of the ventricle Stained brain slice images which include the third%20ventricle at the BrainMaps project
20.
Median aperture
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The median aperture drains cerebrospinal fluid from the fourth ventricle into the cisterna magna. The two other openings of the ventricle are the lateral apertures, one on the left and one on the right. The median foramen on axial images is posterior to the pons and it is surrounded by the obex and gracile tubercles of the medulla, tela choroidea of the fourth ventricle and its choroid plexus, which is attached to the cerebellar vermis. The foramen of Magendie is named for François Magendie, who first described it
21.
Blood plasma
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Blood plasma is a straw coloured liquid component of blood that normally holds the blood cells in whole blood in suspension, this makes plasma the extracellular matrix of blood cells. It makes up about 55% of the total blood volume. It is the fluid part of extracellular fluid. It is mostly water, and contains dissolved proteins, glucose, clotting factors, electrolytes, hormones, carbon dioxide, Plasma also serves as the protein reserve of the human body. It plays a role in an intravascular osmotic effect that keeps electrolytes in balanced form and protects the body from infection. Blood plasma is prepared by spinning a tube of fresh blood containing an anticoagulant in a centrifuge until the blood fall to the bottom of the tube. The blood plasma is then poured or drawn off, Blood plasma has a density of approximately 1025 kg/m3, or 1.025 g/ml. Blood serum is blood plasma without clotting factors, in other words, plasmapheresis is a medical therapy that involves blood plasma extraction, treatment, and reintegration. Fresh frozen plasma is on the WHO Model List of Essential Medicines, Blood plasma volume may be expanded by or drained to extravascular fluid when there are changes in Starling forces across capillary walls. For example, when blood pressure drops in circulatory shock, Starling forces drive fluid into the interstitium, standing still for a prolonged period will cause an increase in transcapillary hydrostatic pressure. As a result, approximately 12% of blood plasma volume will cross into the extravascular compartment and this causes an increase in hematocrit, serum total protein, blood viscosity and, as a result of increased concentration of coagulation factors, it causes orthostatic hypercoagulability. The use of plasma as a substitute for whole blood and for transfusion purposes was proposed in March 1918, in the correspondence columns of the British Medical Journal. Dried plasmas in powder or strips of material format were developed, prior to the United States involvement in the war, liquid plasma and whole blood were used. The Blood for Britain program during the early 1940s was quite successful based on Charles Drews contribution, a large project began in August 1940 to collect blood in New York City hospitals for the export of plasma to Britain. Drew was appointed supervisor of the Plasma for Britain project. His notable contribution at this time was to transform the test tube methods of many blood researchers into the first successful mass production techniques. Nonetheless, the decision was made to develop a dried plasma package for the forces as it would reduce breakage and make the transportation, packaging. The resulting dried plasma package came in two tin cans containing 400 cc bottles, one bottle contained enough distilled water to reconstitute the dried plasma contained within the other bottle
22.
Electrolyte
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An electrolyte is a substance that produces an electrically conducting solution when dissolved in a polar solvent, such as water. The dissolved electrolyte separates into cations and anions, which disperse uniformly through the solvent, electrically, such a solution is neutral. The movement of anions and cations in opposite directions within the solution amounts to a current and this includes most soluble salts, acids, and bases. Some gases, such as chloride, under conditions of high temperature or low pressure can also function as electrolytes. Electrolyte solutions can also result from the dissolution of some biological and synthetic polymers, termed polyelectrolytes, a substance that dissociates into ions in solution acquires the capacity to conduct electricity. Sodium, potassium, chloride, calcium, magnesium, and phosphate are examples of electrolytes, in medicine, electrolyte replacement is needed when a patient has prolonged vomiting or diarrhea, and as a response to strenuous athletic activity. Commercial electrolyte solutions are available, particularly for children and athletes. Electrolyte monitoring is important in the treatment of anorexia and bulimia, the word electrolyte derives from the Greek lytós, meaning able to be untied or loosened. Arrheniuss explanation was that in forming a solution, the salt dissociates into charged particles, faradays belief had been that ions were produced in the process of electrolysis. Arrhenius proposed that, even in the absence of an electric current and he thus proposed that chemical reactions in solution were reactions between ions. For example, carbon dioxide gas dissolves in water to produce a solution that contains hydronium, carbonate, molten salts can also be electrolytes as, for example, when sodium chloride is molten, the liquid conducts electricity. An electrolyte in a solution may be described as concentrated if it has a concentration of ions. If a high proportion of the solute dissociates to form ions, the electrolyte is strong, if most of the solute does not dissociate. The properties of electrolytes may be exploited using electrolysis to extract constituent elements, in physiology, the primary ions of electrolytes are sodium, potassium, calcium, magnesium, chloride, hydrogen phosphate, and hydrogen carbonate. The electric charge symbols of plus and minus indicate that the substance is ionic in nature and has a distribution of electrons. Sodium is the main electrolyte found in extracellular fluid and potassium is the main intracellular electrolyte, all known higher lifeforms require a subtle and complex electrolyte balance between the intracellular and extracellular environments. In particular, the maintenance of precise osmotic gradients of electrolytes is important, such gradients affect and regulate the hydration of the body as well as blood pH, and are critical for nerve and muscle function. Various mechanisms exist in living species that keep the concentrations of different electrolytes under tight control, both muscle tissue and neurons are considered electric tissues of the body
23.
Chloride
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The chloride ion /ˈklɔəraɪd/ is the anion Cl−. It is formed when the element chlorine gains an electron or when a compound such as chloride is dissolved in water or other polar solvents. Chloride salts such as sodium chloride are often soluble in water. It is an essential electrolyte located in all body fluids responsible for maintaining acid/base balance, transmitting nerve impulses and regulating fluid in, less frequently, the word chloride may also form part of the common name of chemical compounds in which one or more chlorine atoms are covalently bonded. For example, methyl chloride, with the standard name chloromethane is a compound with a covalent C−Cl bond in which the chlorine is not an anion. A chloride ion is much larger than an atom,167 and 99 pm. The ion is colorless and diamagnetic, in aqueous solution, it is highly soluble in most cases, however, some chloride salts, such as silver chloride, lead chloride, and mercury chloride are slightly soluble in water. In aqueous solution, chloride is bound by the end of the water molecules. Some chloride-containing minerals include the chlorides of sodium, potassium, and magnesium, called serum chloride, the concentration of chloride in the blood is regulated by the kidneys. A chloride ion is a component of some proteins, e. g. it is present in the amylase enzyme. The chlor-alkali industry is a consumer of the worlds energy budget. This process converts sodium chloride into chlorine and sodium hydroxide, which are used to make many other materials and chemicals, in the petroleum industry, the chlorides are a closely monitored constituent of the mud system. An increase of the chlorides in the mud system may be an indication of drilling into a high-pressure saltwater formation and its increase can also indicate the poor quality of a target sand. Chloride is also a useful and reliable chemical indicator of river / groundwater fecal contamination, as chloride is a non-reactive solute, many water regulating companies around the world utilize chloride to check the contamination levels of the rivers and potable water sources. Chloride salts such as sodium chloride are used to preserve food, chloride is an essential electrolyte, trafficking in and out of cells through chloride channels and playing a key role in maintaining cell homeostasis and transmitting action potentials in neurons. Characteristic concentrations of chloride in model organisms are, in both E. coli and budding yeast are 10-200mM, in mammalian cell 5-100mM and in blood plasma 100mM, chloride can be oxidized but not reduced. The first oxidation, as employed in the process, is conversion to chlorine gas. Chlorine can be oxidized to other oxides and oxyanions including hypochlorite, chlorine dioxide, chlorate
24.
Sodium
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Sodium is a chemical element with symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal, Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation. Its only stable isotope is 23Na, the free metal does not occur in nature, but must be prepared from compounds. Sodium is the sixth most abundant element in the Earths crust, Sodium was first isolated by Humphry Davy in 1807 by the electrolysis of sodium hydroxide. Among many other useful compounds, sodium hydroxide is used in soap manufacture, and sodium chloride is a de-icing agent. Sodium is an element for all animals and some plants. Sodium ions are the major cation in the fluid and as such are the major contributor to the ECF osmotic pressure. Loss of water from the ECF compartment increases the sodium concentration, isotonic loss of water and sodium from the ECF compartment decreases the size of that compartment in a condition called ECF hypovolemia. In nerve cells, the charge across the cell membrane enables transmission of the nerve impulse—an action potential—when the charge is dissipated. The melting and boiling points of sodium are lower than those of lithium but higher than those of the alkali metals potassium, rubidium. All of these high-pressure allotropes are insulators and electrides.3 nm, spin-orbit interactions involving the electron in the 3p orbital split the D line into two, at 589.0 and 589.6 nm, hyperfine structures involving both orbitals cause many more lines. Twenty isotopes of sodium are known, but only 23Na is stable, 23Na is created in the carbon-burning process in stars by fusing two carbon atoms together, this requires temperatures above 600 megakelvins and a star of at least three solar masses. Two nuclear isomers have been discovered, the one being 24mNa with a half-life of around 20.2 milliseconds. Sodium atoms have 11 electrons, one more than the stable configuration of the noble gas neon. This process requires so little energy that sodium is oxidized by giving up its 11th electron. In contrast, the ionization energy is very high, because the 10th electron is closer to the nucleus than the 11th electron. As a result, sodium usually forms ionic compounds involving the Na+ cation, the most common oxidation state for sodium is +1. It is generally less reactive than potassium and more reactive than lithium, Sodium metal is highly reducing, with the reduction of sodium ions requiring −2.71 volts, though potassium and lithium have even more negative potentials
25.
Venous system
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Veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the back to the heart, exceptions are the pulmonary and umbilical veins. In contrast to veins, arteries carry blood away from the heart, veins are less muscular than arteries and are often closer to the skin. There are valves in most veins to prevent backflow, veins are present throughout the body as tubes that carry blood back to the heart. Veins are classified in a number of ways, including superficial vs. deep, pulmonary vs. systemic, superficial veins are those closer to the surface of the body, and have no corresponding arteries. Deep veins are deeper in the body and have corresponding arteries, perforator veins drain from the superficial to the deep veins. These are usually referred to in the limbs and feet. Communicating veins are veins that directly connect superficial veins to deep veins, pulmonary veins are a set of veins that deliver oxygenated blood from the lungs to the heart. Systemic veins drain the tissues of the body and deliver deoxygenated blood to the heart, most veins are equipped with valves to prevent blood flowing in the reverse direction. Veins appear blue because the subcutaneous fat absorbs low-frequency light, permitting only the highly energetic blue wavelengths to penetrate through to the dark vein and reflect back to the viewer. The colour of a vein can be affected by the characteristics of a skin, how much oxygen is being carried in the blood. When a vein is drained of blood and removed from an organism, the largest veins in the human body are the venae cavae. These are two large veins which enter the right atrium of the heart from above and below. The superior vena cava carries blood from the arms and head to the atrium of the heart, while the inferior vena cava carries blood from the legs. The inferior vena cava is retroperitoneal and runs to the right, large veins feed into these two veins, and smaller veins into these. Together this forms the venous system, whilst the main veins hold a relatively constant position, the position of veins person to person can display quite a lot of variation. The pulmonary veins carry relatively oxygenated blood from the lungs to the heart, the superior and inferior venae cavae carry relatively deoxygenated blood from the upper and lower systemic circulations, respectively. The portal venous system is a series of veins or venules that directly connect two capillary beds, examples of such systems include the hepatic portal vein and hypophyseal portal system
26.
Red blood cell
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RBCs take up oxygen in the lungs, or gills of fish, and release it into tissues while squeezing through the bodys capillaries. The cytoplasm of erythrocytes is rich in hemoglobin, a biomolecule that can bind oxygen and is responsible for the red color of the cells. In humans, mature red cells are flexible and oval biconcave disks. They lack a nucleus and most organelles, in order to accommodate maximum space for hemoglobin, they can be viewed as sacks of hemoglobin. Approximately 2.4 million new erythrocytes are produced per second in human adults, the cells develop in the bone marrow and circulate for about 100–120 days in the body before their components are recycled by macrophages. Each circulation takes about 60 seconds, approximately a quarter of the cells in the human body are red blood cells. Nearly half of the volume is red blood cells. Red blood cells are known as RBCs, red cells, red blood corpuscles, haematids. Packed red blood cells are red blood cells that have donated, processed. Almost all vertebrates, including all mammals and humans, have red blood cells, red blood cells are cells present in blood in order to transport oxygen. The only known vertebrates without red blood cells are the crocodile icefish, they live in very cold water. While they no longer use hemoglobin, remnants of hemoglobin genes can be found in their genome, oxygen can easily diffuse through the red blood cells cell membrane. Myoglobin, a related to hemoglobin, acts to store oxygen in muscle cells. The color of red cells is due to the heme group of hemoglobin. However, blood can appear bluish when seen through the vessel wall, pulse oximetry takes advantage of the hemoglobin color change to directly measure the arterial blood oxygen saturation using colorimetric techniques. Hemoglobin also has a high affinity for carbon monoxide, forming carboxyhemoglobin which is a very bright red in color. Flushed, confused patients with a reading of 100% on pulse oximetry are sometimes found to be suffering from carbon monoxide poisoning. The red blood cells of mammals are typically shaped as disks, flattened and depressed in the center, with a dumbbell-shaped cross section
27.
White blood cell
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White blood cells, also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone known as hematopoietic stem cells. Leukocytes are found throughout the body, including the blood and lymphatic system, all white blood cells have nuclei, which distinguishes them from the other blood cells, the anucleated red blood cells and platelets. Types of white cells can be classified in standard ways. Two pairs of broadest categories classify them either by structure or by cell division lineage and these broadest categories can be further divided into the five main types, neutrophils, eosinophils, basophils, lymphocytes, and monocytes. These types are distinguished by their physical and functional characteristics, further subtypes can be classified, for example, among lymphocytes, there are B cells, T cells, and NK cells. The number of leukocytes in the blood is often an indicator of disease, the normal white cell count is usually between 4 × 109/L and 11 × 109/L. In the US this is expressed as 4,000 to 11,000 white blood cells per microliter of blood. They make up approximately 1% of the blood volume in a healthy adult. However, this 1% of the blood makes a difference to health. An increase in the number of leukocytes over the limits is called leukocytosis. It is normal when it is part of immune responses. It is occasionally abnormal, when it is neoplastic or autoimmune in origin, a decrease below the lower limit is called leukopenia. The name white blood cell derives from the appearance of a blood sample after centrifugation. White cells are found in the buff, a thin, typically white layer of nucleated cells between the red blood cells and the blood plasma. The scientific term leukocyte directly reflects its description and it is derived from the Greek roots leuk- meaning white and cyt- meaning cell. The buffy coat may sometimes be green if there are large amounts of neutrophils in the sample, all white blood cells are nucleated, which distinguishes them from the anucleated red blood cells and platelets. Types of leukocytes can be classified in standard ways, two pairs of broadest categories classify them either by structure or by cell lineage
28.
Cell counting
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Cell counting is any of various methods for the counting or similar quantification of cells in the life sciences, including medical diagnosis and treatment. It is an important subset of cytometry, with applications in research, for example, the complete blood count can help a physician to determine why a patient feels unwell and what to do to help. Cell counts within liquid media are usually expressed as a number of cells per unit of volume, numerous procedures in biology and medicine require the counting of cells. By the counting of cells in a small volume, the concentration can be mediated. In cell therapy, to control the dose of cells administered to a patient, the cell concentration needs to be known for many experiments in molecular biology, in order to adjust accordingly the amount of reagents and chemicals that are to be applied in the experiment. Studies that examine the rate of microorganisms require cell counting. Measurements of cell viability, i. e. measuring and calculating the fraction of dead and live cells, there are several methods for cell counting. Some are primitive and do not require equipment, thus can be done in any biological laboratory. A counting chamber, is a slide that is especially designed to enable cell counting. The hemocytometer has two gridded chambers in its middle, which are covered with a glass slide when counting. A drop of cell culture is placed in the space between the chamber and the cover, filling it by capillarity. Looking at the sample under the microscope, the uses the grid to manually count the number of cells in a certain area of known size. The separating distance between the chamber and the cover is predefined, thus the volume of the culture can be calculated. Cell viability can also be determined if viability dyes are added to the fluid, usually the culture examined needs to be diluted, otherwise the high density of cells would make counting impossible. The need for dilution is a disadvantage, as every dilution adds inaccuracy to the measurement, to quantify the number of cells in a culture, the cells can be simply plated on a petri dish with growth medium. If the cells are distributed on the plate, it can be generally assumed that each cell will give rise to a single colony or Colony Forming Unit. The colonies can then be counted, and based on the volume of culture that was spread on the plate. Additionally, plating is the slowest method of all, most microorganisms need at least 12 hours to form visible colonies, although this method can be time consuming, it gives an accurate estimate of the number of viable cells
. PMID 25089184.
