Anatomical terminology
Anatomical terminology is a form of scientific terminology used by anatomists and health professionals such as doctors. Anatomical terminology uses many unique terms and prefixes deriving from Ancient Greek and Latin; these terms can be confusing to those unfamiliar with them, but can be more precise, reducing ambiguity and errors. Since these anatomical terms are not used in everyday conversation, their meanings are less to change, less to be misinterpreted. To illustrate how inexact day-to-day language can be: a scar "above the wrist" could be located on the forearm two or three inches away from the hand or at the base of the hand. 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 same prefixes and suffixes are used to add meanings to different roots; the root of a term refers to an organ or tissue. For example, the Latin names of structures such as musculus biceps brachii can be split up and refer to, musculus for muscle, biceps for "two-headed", brachii as in the brachial region of the arm.
The first word describes what is being spoken about, the second describes it, the third points to location. 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, such as the midclavicular line from the centre of the clavicle. The cephalon or cephalic region refers to the head; this area is further differentiated into the cranium, frons, auris, nasus and mentum. The neck area is called 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, is used when describing the skull.
Different terminology is used in the arms, in part to reduce ambiguity as to what the "front", "back", "inner" and "outer" surfaces are. For this reason, the terms below are used: Radial referring to the radius bone, seen laterally in the standard anatomical position. 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, other structures such as the eye. International morphological terminology is used by the colleges of medicine and dentistry and other areas of the health sciences, it facilitates communication and exchanges between scientists from different countries of the world and it is used daily in the fields of research 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, it is functional.
It covers the gross anatomy and the microscopic of living beings. It involves the anatomy of the adult, it includes comparative anatomy between different species. The vocabulary is extensive and complex, requires a systematic presentation. Within the international field, a group of experts reviews and discusses the morphological terms of the structures of the human body, forming today's Terminology Committee from the International Federation of Associations of Anatomists, it deals with the anatomical and embryologic terminology. In the Latin American field, there are meetings called Iberian Latin American Symposium Terminology, where a group of experts of the Pan American Association of Anatomy that speak Spanish and Portuguese and studies the international morphological terminology; the current international standard for human anatomical terminology is based on the Terminologia Anatomica. It was developed by the Federative Committee on Anatomical Terminology and the International Federation of Associations of Anatomists and was released in 1998.
It supersedes Nomina Anatomica. Terminologia Anatomica contains terminology for about 7500 human gross anatomical structures. For microanatomy, known as histology, a similar standard exists in Terminologia Histologica, for embryology, the study of development, a standard exists in Terminologia Embryologica; these standards specify accepted names that can be used to refer to histological and embryological structures in journal articles and other areas. As of September 2016, two sections of the Terminologia Anatomica, including central nervous system and peripheral nervous system, were merged to form the Terminologia Neuroanatomica; the Terminologia Anatomica has been perceived with a considerable criticism regarding its content including coverage and spelling mistakes and errors. Anatomical terminology is chosen to highlight the relative location of body structures. For instance, an anatomist might describe one band of tissue as "inferior to" another or a physician might describe a tumor as "superficial to" a deeper body structure.
Anatomical terms used to describe location
Esophageal gland
The esophageal glands are glands that are part of the digestive system of various animals, including humans. Esophageal glands in humans are a part of a human digestive system, they are a small compound racemose exocrine glands of the mucous type. There are two types: Esophageal glands proper- mucous glands located in the submucosa, they are compound tubulo-alveolar glands. Some serous cells are present; these glands are more numerous in the lower third of the esophagus. They secrete acid mucin for lubrication. Esophageal cardiac glands- mucous glands located near the cardiac orifice in the lamina propria mucosae, they secrete neutral mucin. They are simple tubular or branched tubular glands. There are mucous glands present at the pharyngo-esophageal junction in the lamina propria mucosae; these are simple tubular or branched tubular glands. Each opens upon the surface by a long excretory duct. Oesophageal gland is enlarged in large monoplacophoran species. Oesophageal gland or oesophageal pouch is a part of the digestive system of some gastropods.
Oesophageal gland or pouch is a common feature in so-called basal gastropod clades, including Patelloidea, Cocculiniformia and Neomphalina. The size of oesophageal gland of scaly-foot gastropod Chrysomallon squamiferum is about two orders of magnitude over the usual size; the scaly-foot gastropod houses endosymbiotic Bacteria in the oesophageal gland. Chrysomallon squamiferum was thought to be the only species of Peltospiridae, that has enlarged oesophageal gland, but it was shown that both species Gigantopelta has the oesophageal gland enlarged. In other peltospirids, the posterior portion of the oesophagus forms a pair of blind mid-oesophageal pouches or gutters extending only to the anterior end of the foot; the same situation is in Melanodrymia within the family Melanodrymiidae. Bathyphytophilidae and Lepetellidae are known to have enlarged oesophageal pouches, though not to the extent of Chrysomallon. Both are known to house endosymbiotic bacteria, in the case of bathyphytophilids most also in the oesophageal glands but in the lepetellids the endosymbionts are spread in the haemocoel.
This article incorporates text in the public domain from page 1146 of the 20th edition of Gray's Anatomy. This article incorporates Creative Commons text from the reference Histology image: 49_07 at the University of Oklahoma Health Sciences Center Histology image: 10802loa – Histology Learning System at Boston University
Circular folds
The circular folds are large valvular flaps projecting into the lumen of the small intestine. The entire small intestine has circular folds of mucous membrane called the valves of Kerckring and plicae circulares; the majority extend transversely around the cylinder of the small intestine for about one-half or two-thirds of its circumference, but some form complete circles, others have a spiral direction. The larger folds are about 1 cm. in depth at their broadest part. The larger and smaller folds alternate with each other, they are not found at the commencement of the duodenum, but begin to appear about 2.5 or 5 cm beyond the pylorus. In the lower part of the descending portion, below the point where the bile and pancreatic ducts enter the small intestine, they are large and approximated. In the horizontal and ascending portions of the duodenum and upper half of the jejunum they are large and numerous, but from this point, down to the middle of the ileum, they diminish in size. In the lower part of the ileum they entirely disappear.
Unlike the gastric folds in the stomach, they are permanent, are not obliterated when the intestine is distended. The spaces between circular folds are smaller than the haustra of the colon, and, in contrast to haustra, circular folds reach around the whole circumference of the intestine; these differences can assist in distinguishing the small intestine from the colon on an abdominal x-ray. The circular folds slow the passage of the digested food along the intestines, afford an increased surface for absorption, they are covered with small finger-like projections called villi. Each villus, in turn, is covered with microvilli; the microvilli absorb nutrients from the chyme. This article incorporates text in the public domain from page 1173 of the 20th edition of Gray's Anatomy Anatomy photo:39:12-0302 at the SUNY Downstate Medical Center - "Intestines and Pancreas: The Jejunum and the Ileum"
Microvillus
Microvilli are microscopic cellular membrane protrusions that increase the surface area for diffusion and minimize any increase in volume, are involved in a wide variety of functions, including absorption, cellular adhesion, mechanotransduction. Microvilli are covered in plasma membrane, which microfilaments. Though these are cellular extensions, there are little or no cellular organelles present in the microvilli; each microvillus has a dense bundle of cross-linked actin filaments, which serves as its structural core. 20 to 30 bundled actin filaments are cross-linked by bundling proteins fimbrin and espin to form the core of the microvilli. In the enterocyte microvillus, the structural core is attached to the plasma membrane along its length by lateral arms made of myosin 1a and Ca2+ binding protein calmodulin. Myosin 1a functions through a binding site for filamentous actin on one end and a lipid binding domain on the other; the plus ends of the actin filaments are located at the tip of the microvillus and are capped by capZ proteins, while the minus ends are anchored in the terminal web composed of a complicated set of proteins including spectrin and myosin II.
The space between microvilli at a cell's surface is called the intermicrovillous space. Intermicrovillous space increases with contractile activity of myosin II and tropomyosin, decreases when contraction ceases. Thousands of microvilli form a structure called the brush border, found on the apical surface of some epithelial cells, such as the small intestines. Microvilli are observed on the plasma surface of eggs, aiding in the anchoring of sperm cells that have penetrated the extracellular coat of egg cells. Clustering of elongated microtubules around a sperm allows for it to be drawn closer and held so fusion can occur, they are large objects. Microvilli are of importance on the cell surface of white blood cells, as they aid in the migration of white blood cells; as mentioned, microvilli are formed as cell extensions from the plasma membrane surface. Actin filaments, present in the cytosol, are most abundant near the cell surface; these filaments are thought to determine the movement of the plasma membrane.
The nucleation of actin fibers occurs as a response to external stimuli, allowing a cell to alter its shape to suit a particular situation. This could account for the uniformity of the microvilli, which are observed to be of equal length and diameter; this nucleation process occurs from the minus end. Though the length and composition of microvilli is consistent within a certain group of homogenous cells, it can differ in a different part of the same organism. For example, the microvilli in the small and large intestines in mice are different in length and amount of surface coat covering. Microvilli function as the primary surface of nutrient absorption in the gastrointestinal tract; because of this vital function, the microvillar membrane is packed with enzymes that aid in the breakdown of complex nutrients into simpler compounds that are more absorbed. For example, enzymes that digest carbohydrates called glycosidases are present at high concentrations on the surface of enterocyte microvilli.
Thus, microvilli not only increase the cellular surface area for absorption, they increase the number of digestive enzymes that can be present on the cell surface. The microvilli are covered with glycocalyx, consisting of peripheral glycoproteins that can attach themselves to a plasma membrane via transmembrane proteins; this layer may be used to aid binding of substances needed for uptake, to adhere nutrients or as protection against harmful elements. It can be another location for functional enzymes to be localized; the destruction of microvilli can occur in certain diseases because of the rearrangement of cytoskeleton in host cells. This can lead to malabsorption of nutrients and persistent osmotic diarrhea accompanied by fever; this is seen in infections caused by EPEC subgroup Escherichia coli, in celiac disease, microvillus inclusion disease. The destruction of microvilli can be beneficial sometimes, as in the case of elimination of microvilli on white blood cells which can be used to combat auto immune diseases.
Congenital lack of microvilli in the intestinal tract causes microvillous atrophy, a rare fatal condition found in new-born babies. Brush border Cilia Flagellum Intestinal villus Stereocilia Terminal web Anatomy photo: TermsCells&Tissues/structures/microvilli - Comparative Organology at University of California, Davis Histology image: 21904loa – Histology Learning System at Boston University - "Ultrastructure of the Cell: microvilli and basal enfoldings, endocytic vesicles" Histology image: 20601loa – Histology Learning System at Boston University - "Ultrastructure of the Cell: microvillous border and Junctional Complex, oblique section"
Organ system
An organ system is a group of organs that work together as a biological system to perform one or more functions. Each organ system does a particular job in the body, is made up of certain tissues; these specific systems are studied in anatomy. They are present in many types of animals. Respiratory system: the organs used for breathing, the pharynx, bronchi and diaphragm. Digestive system: digestion and processing food with salivary glands, stomach, gallbladder, intestines and anus. Cardiovascular system: and channeling blood to and from the body and lungs with heart and blood vessels. Urinary system: kidneys, ureters and urethra involved in fluid balance, electrolyte balance and excretion of urine. Integumentary system: skin, hair and nails. Skeletally system: structural support and protection with bones, cartilage and tendons. Endocrine system: communication within the body using hormones made by endocrine glands such as the hypothalamus, pituitary gland, pineal gland, thyroid and adrenal glands.
Lymphatic system: the transfer of lymph between tissues and the blood stream. Includes the functions of immune responses and the development of antibodies. Our bodies consist of a number of biological systems that carry out specific functions necessary for everyday living; the job of the circulatory system is to move blood, oxygen, carbon dioxide, hormones, around the body. It consists of the heart, blood vessels and veins. Immune system: protects the organism from foreign bodies. Nervous system: collecting and processing information with brain, spinal cord, peripheral nervous system and sense organs. Sensory systems: visual system, auditory system, olfactory system, gustatory system, somatosensory system, vestibular system. Muscular system: allows for manipulation of the environment, provides locomotion, maintains posture, produces heat. Includes skeletal muscles, smooth muscles and cardiac muscle. Reproductive system: the sex organs, such as ovaries, fallopian tubes, vagina, mammary glands, testes, vas deferens, seminal vesicles and prostate
Digestion
Digestion is the breakdown of large insoluble food molecules into small water-soluble food molecules so that they can be absorbed into the watery blood plasma. In certain organisms, these smaller substances are absorbed through the small intestine into the blood stream. Digestion is a form of catabolism, divided into two processes based on how food is broken down: mechanical and chemical digestion; the term mechanical digestion refers to the physical breakdown of large pieces of food into smaller pieces which can subsequently be accessed by digestive enzymes. In chemical digestion, enzymes break down food into the small molecules. In the human digestive system, food enters the mouth and mechanical digestion of the food starts by the action of mastication, a form of mechanical digestion, the wetting contact of saliva. Saliva, a liquid secreted by the salivary glands, contains salivary amylase, an enzyme which starts the digestion of starch in the food. After undergoing mastication and starch digestion, the food will be in the form of a small, round slurry mass called a bolus.
It will travel down the esophagus and into the stomach by the action of peristalsis. Gastric juice in the stomach starts protein digestion. Gastric juice contains hydrochloric acid and pepsin, it contains rennin in case of infants and toddlers. As the first two chemicals may damage the stomach wall, mucus is secreted by the stomach, providing a slimy layer that acts as a shield against the damaging effects of the chemicals. At the same time protein digestion is occurring, mechanical mixing occurs by peristalsis, waves of muscular contractions that move along the stomach wall; this allows the mass of food to further mix with the digestive enzymes. After some time, the resulting thick liquid is called chyme; when the pyloric sphincter valve opens, chyme enters the duodenum where it mixes with digestive enzymes from the pancreas and bile juice from the liver and passes through the small intestine, in which digestion continues. When the chyme is digested, it is absorbed into the blood. 95% of absorption of nutrients occurs in the small intestine.
Water and minerals are reabsorbed back into the blood in the colon where the pH is acidic about 5.6 ~ 6.9. Some vitamins, such as biotin and vitamin K produced by bacteria in the colon are absorbed into the blood in the colon. Waste material is eliminated from the rectum during defecation. Digestive systems take many forms. There is a fundamental distinction between external digestion. External digestion developed earlier in evolutionary history, most fungi still rely on it. In this process, enzymes are secreted into the environment surrounding the organism, where they break down an organic material, some of the products diffuse back to the organism. Animals have a tube in which internal digestion occurs, more efficient because more of the broken down products can be captured, the internal chemical environment can be more efficiently controlled; some organisms, including nearly all spiders secrete biotoxins and digestive chemicals into the extracellular environment prior to ingestion of the consequent "soup".
In others, once potential nutrients or food is inside the organism, digestion can be conducted to a vesicle or a sac-like structure, through a tube, or through several specialized organs aimed at making the absorption of nutrients more efficient. Bacteria use several systems to obtain nutrients from other organisms in the environments. In a channel transupport system, several proteins form a contiguous channel traversing the inner and outer membranes of the bacteria, it is a simple system, which consists of only three protein subunits: the ABC protein, membrane fusion protein, outer membrane protein. This secretion system transports various molecules, from drugs, to proteins of various sizes; the molecules secreted vary in size from the small Escherichia coli peptide colicin V, to the Pseudomonas fluorescens cell adhesion protein LapA of 900 kDa. A type III secretion system means that a molecular syringe is used through which a bacterium can inject nutrients into protist cells. One such mechanism was first discovered in Y. pestis and showed that toxins could be injected directly from the bacterial cytoplasm into the cytoplasm of its host's cells rather than be secreted into the extracellular medium.
The conjugation machinery of some bacteria is capable of transporting proteins. It was discovered in Agrobacterium tumefaciens, which uses this system to introduce the Ti plasmid and proteins into the host, which develops the crown gall; the VirB complex of Agrobacterium tumefaciens is the prototypic system. The nitrogen fixing Rhizobia are an interesting case, wherein conjugative elements engage in inter-kingdom conjugation; such elements as the Agrobacterium Ti or Ri plasmids contain elements that can transfer to plant cells. Transferred genes enter the plant cell nucleus and transform the plant cells into factories for the production of opines, which the bacteria use as carbon and energy sources. Infected plant cells form crown root tumors; the Ti and Ri plasmids are thus endosymbionts of the bacteria, which are in turn endosymbionts of the infected plant. The Ti and Ri plasmids are themselves conjugative. Ti and Ri transfer between bacteria uses an inde
Piriform sinus
On either side of the laryngeal orifice in humans is a recess, termed the piriform sinus, bounded medially by the aryepiglottic fold, laterally by the thyroid cartilage and thyrohyoid membrane. The fossae are involved in speech; the term "piriform," which means "pear-shaped," is sometimes spelled "pyriform" Deep to the mucous membrane of the piriform fossa lie the recurrent laryngeal nerve as well as the internal laryngeal nerve, a branch of the superior laryngeal nerve. The internal laryngeal nerve supplies sensation to the area, it may become damaged if the mucous membrane is inadvertently punctured; the piriform sinus is a subsite of the hypopharynx. This distinction is important for treatment; this sinus is a common place for food particles to become trapped. If the area is injured, it can give the sensation of food stuck in the subject's throat; the persistency of the piriform sinus is a common cause of acute thyroiditis in children and adolescents. Local anesthesia can be given here because of the presence of the internal laryngeal nerve underneath the mucous membrane.
This article incorporates text in the public domain from page 1142 of the 20th edition of Gray's Anatomy Anatomy photo:31:17-0105 at the SUNY Downstate Medical Center - "Pharynx: The Laryngopharynx"
