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Anatomy and Physiology
Body structures, tissues, organ systems and how they normally function. 542 evidence-grounded articles.
A B C D E F G H I J K L M N O P Q R S T U V W Y Z
Abdominal Cavity
The region in the abdomen extending from the thoracic diaphragm to the plane of the superior pelvic aperture (pelvic inlet).
Abdominal Fat
Fatty tissue in the region of the abdomen.
Abdominal Wall
The outer margins of the abdomen, extending from the osteocartilaginous thoracic cage to the pelvis.
Acetabulum
The part of the pelvis that comprises the pelvic socket where the head of femur joins to form hip joint (acetabulofemoral joint).
Achilles Tendon
Tendon that connects the muscles in the back of the calf to the heel bone.
Acromioclavicular Joint
The gliding joint formed by the outer extremity of the clavicle and the inner margin of the acromion process of the scapula.
Acromion
The lateral extension of the spine of the scapula and the highest point of the shoulder.
Acrosome
The cap-like structure covering the anterior portion of sperm head.
Acrosome Reaction
Changes that occur to liberate the enzymes of the acrosome of a sperm (spermatozoa).
Adipose Tissue
Specialized connective tissue composed of fat cells (adipocytes).
Adolescent Development
The continuous sequential physiological and psychological changes during adolescence, approximately between the age of 13 and 18.
Adrenal Cortex
The outer layer of the adrenal gland.
Adrenal Glands
A pair of glands located at the cranial pole of each of the two kidneys.
Adrenal Medulla
The inner portion of the adrenal gland.
Aging
The gradual irreversible changes in structure and function of an organism that occur as a result of the passage of time.
Airway Remodeling
The structural changes in the number, mass, size and/or composition of the airway tissues.
Airway Resistance
Physiologically, the opposition to flow of air caused by the forces of friction.
Amelogenesis
The elaboration of dental enamel by ameloblasts, beginning with its participation in the formation of the dentino-enamel junction to the production of the matrix for the enamel prisms and interprismatic substance.
Amnion
The innermost membranous sac that surrounds and protects the developing embryo which is bathed in the amniotic fluid.
Amniotic Fluid
A clear, yellowish liquid that envelopes the fetus inside the sac of amnion.
Ampulla of Vater
A dilation of the duodenal papilla that is the opening of the juncture of the common bile duct and the main pancreatic duct, also known as the hepatopancreatic ampulla.
Anal Canal
The terminal segment of the large intestine, beginning from the ampulla of the rectum and ending at the anus.
Anatomic Landmarks
Reference points located by visual inspection, palpation, or computer assistance, that are useful in localizing structures on or within the human body.
Ankle Joint
The joint that is formed by the inferior articular and malleolar articular surfaces of the tibia; the malleolar articular surface of the fibula; and the medial malleolar, lateral malleolar, and superior surfaces of the talus.
Anovulation
Suspension or cessation of ovulation in animals or humans with follicle-containing ovaries (ovarian follicle).
Anterior Chamber
The space in the eye, filled with aqueous humor, bounded anteriorly by the cornea and a small portion of the sclera and posteriorly by a small portion of the ciliary body, the iris, and that part of the crystalline lens which pres
Anterior Cruciate Ligament
A strong ligament of the knee that originates from the posteromedial portion of the lateral condyle of the femur, passes anteriorly and inferiorly between the condyles, and attaches to the depression in front of the intercondylar
Aponeurosis
The flattened and/or expanded “tendon-like” dense fibrous connective tissue that connects skeletal muscles to each other or to bone.
Appetite
Natural recurring desire for food.
Aqueous Humor
The clear, watery fluid which fills the anterior and posterior chambers of the eye.
Autografts
Transplant comprised of an individual's own tissue, transferred from one part of the body to another.
Axilla
Area of the human body underneath the shoulder joint, also known as the armpit or underarm.
B-Lymphocytes
Lymphoid cells concerned with humoral immunity.
Back
The rear surface of an upright primate from the shoulders to the hip, or the dorsal surface of tetrapods.
Basement Membrane
A darkly stained mat-like extracellular matrix (ECM) that separates cell layers, such as epithelium from endothelium or a layer of connective tissue.
Basilar Membrane
A basement membrane in the cochlea that supports the hair cells of the organ OF corti, consisting keratin-like fibrils.
Basophils
Granular leukocytes characterized by a relatively pale-staining, lobate nucleus and cytoplasm containing coarse dark-staining granules of variable size and stainable by basic dyes.
Beer
An alcoholic beverage usually made from malted cereal grain (as barley), flavored with hops, and brewed by slow fermentation.
Bicuspid
One of the eight permanent teeth, two on either side in each jaw, between the canines (cuspid) and the molars (molar), serving for grinding and crushing food.
Bile
An emulsifying agent produced in the liver and secreted into the duodenum.
Bile Ducts
The channels that collect and transport the bile secretion from the bile canaliculi, the smallest branch of the biliary tract in the liver, through the bile ductules, the bile ducts out the liver, and to the gallbladder for storag
Birth Weight
The mass or quantity of heaviness of an individual at birth.
Blastocyst
A post-morula preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells.
Blastomeres
Undifferentiated cells resulting from cleavage of a fertilized egg (zygote).
Blastula
An early non-mammalian embryo that follows the morula stage.
Bleeding Time
Duration of blood flow after skin puncture.
Blood
The body fluid that circulates in the vascular system (blood vessels).
Blood Coagulation
The process of the interaction of blood coagulation factors that results in an insoluble fibrin clot.
Blood Platelets
Non-nucleated disk-shaped cells formed in the megakaryocyte and found in the blood of all mammals.
Blood-Retinal Barrier
A specialized transport barrier, in the EYE, formed by the retinal pigment epithelium, and the endothelium of the blood vessels of the retina.
Body Height
The distance from the sole to the crown of the head with body standing on a flat surface and fully extended.
Body Mass Index
An indicator of body density as determined by the relationship of body weight to body height.
Body Weight
The mass or quantity of heaviness of an individual.
Body Weight Changes
A clinical manifestation consisting of alterations in an individual's weight from his or her norm.
Bone Development
The growth and development of bones from fetus to adult.
Bone Marrow
The soft tissue filling the cavities of bones.
Bone Marrow Cells
Cells contained in the bone marrow including fat cells (see adipocytes); stromal cells; megakaryocytes; and the immediate precursors of most blood cells.
Bone Matrix
Extracellular substance of bone tissue consisting of collagen fibers, ground substance, and inorganic crystalline minerals and salts.
Bread
Baked food product made of flour or meal that is moistened, kneaded, and sometimes fermented.
Breast
In humans, one of the paired regions in the anterior portion of the thorax.
Breast Density
Measurement of relative composition of different breast tissue types often determined from mammography; ultrasonography; or MRI.
Breech Presentation
A malpresentation of the fetus at near term or during obstetric labor with the fetal cephalic pole in the fundus of the uterus.
Bronchi
The larger air passages of the lungs arising from the terminal bifurcation of the trachea.
Bronchioles
The small airways branching off the tertiary bronchi.
Bronchoconstriction
Narrowing of the caliber of the bronchi, physiologically or as a result of pharmacological intervention.
Bursa of Fabricius
An epithelial outgrowth of the cloaca in birds similar to the thymus in mammals.
Butter
The fatty portion of milk, separated as a soft yellowish solid when milk or cream is churned.
Buttocks
Either of two fleshy protuberances at the lower posterior section of the trunk or HIP in humans and primate on which a person or animal sits, consisting of gluteal muscles and fat.
Calcaneus
The largest of the tarsal bones which is situated at the lower and back part of the FOOT, forming the HEEL.
Caloric Restriction
Reduction in caloric intake without reduction in adequate nutrition.
Cancellous Bone
A type of osseous tissue which makes up the inner part of bone.
Candy
Sweet food products combining cane or beet sugars with other carbohydrates and chocolate, milk, eggs, and various flavorings.
Cardia
That part of the stomach close to the opening from esophagus into the stomach (cardiac orifice), the esophagogastric junction.
Cartilage
A non-vascular form of connective tissue composed of chondrocytes embedded in a matrix that includes chondroitin sulfate and various types of fibrillar collagen.
Cecum
The blind sac or outpouching area of the large intestine that is below the entrance of the small intestine.
Cerebrospinal Fluid
A watery fluid that is continuously produced in the choroid plexus and circulates around the surface of the brain; spinal cord; and in the cerebral ventricles.
Cervical Ripening
A change in the cervix uteri with respect to its readiness to relax.
Cervical Vertebrae
The first seven vertebrae of the spinal column, which correspond to the vertebrae of the NECK.
Cervix Uteri
The neck portion of the uterus between the lower isthmus and the vagina forming the cervical canal.
Cheek
The part of the face that is below the eye and to the side of the nose and mouth.
Cheese
A nutritious food consisting primarily of the curd or the semisolid substance formed when milk coagulates.
Chewing Gum
A preparation of chicle, sometimes mixed with other plastic substances, sweetened and flavored.
Chick Embryo
The developmental entity of a fertilized chicken egg (zygote).
Chin
The anatomical frontal portion of the mandible, also known as the mentum, that contains the line of fusion of the two separate halves of the mandible (symphysis menti).
Chondrogenesis
The formation of cartilage.
Chorioallantoic Membrane
A highly vascularized extra-embryonic membrane, formed by the fusion of the chorion and the allantois.
Chorion
The outermost extra-embryonic membrane surrounding the developing embryo.
Choroid
The thin, highly vascular membrane covering most of the posterior of the eye between the retina and sclera.
Chromaffin Cells
Cells that store epinephrine secretory vesicles.
Chronotype
The natural inclination or preference of time of day in which an individual or an organism has the most activity, particularly as it relates to sleeping pattern and circadian sleep-wake preferences.
Ciliary Body
A ring of tissue extending from the scleral spur to the ora serrata of the retina.
Circadian Clocks
Biological mechanism that controls circadian rhythm.
Circadian Rhythm
The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli.
Clavicle
A bone on the ventral side of the shoulder girdle, which in humans is commonly called the collar bone.
Cloaca
A dilated cavity extended caudally from the hindgut.
Cochlea
The part of the inner ear (labyrinth) that is concerned with hearing.
Coffee
A beverage made from ground coffea beans (seeds) infused in hot water.
Coitus
The sexual union of a male and a female, a term used for human only.
Colon
The segment of large intestine between the cecum and the rectum.
Colostrum
The thin, yellow, serous fluid secreted by the mammary glands during pregnancy and immediately postpartum before lactation begins.
Common Bile Duct
The largest bile duct.
Conjunctiva
The mucous membrane that covers the posterior surface of the eyelids and the anterior pericorneal surface of the eyeball.
Connective Tissue
Tissue that supports and binds other tissues.
Cornea
The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous corneal epithelium; bowman membrane; corneal stroma; descemet membrane; and mesenchymal corneal endothelium.
Corneal Stroma
The lamellated connective tissue constituting the thickest layer of the cornea between the Bowman and Descemet membranes.
Corpus Luteum
The yellow body derived from the ruptured ovarian follicle after ovulation.
Cortical Bone
A type of osseous tissue which makes up the outer layer of bone.
Costal Cartilage
Bars of hyaline cartilage extending from the anterior ends of the upper RIBS.
Crown-Rump Length
In utero measurement corresponding to the sitting height (crown to rump) of the fetus.
Cumulus Cells
The granulosa cells of the cumulus oophorus which surround the OVUM in the graafian follicle.
Cystic Duct
The duct that is connected to the gallbladder and allows the emptying of bile into the common bile duct.
Dairy Products
Raw and processed or manufactured milk and milk-derived products.
Decidua
The hormone-responsive glandular layer of endometrium that sloughs off at each menstrual flow (decidua menstrualis) or at the termination of pregnancy.
Dendritic Cells
Specialized cells of the hematopoietic system that have branch-like extensions.
Dental Arch
The curve formed by the row of teeth in their normal position in the JAW.
Dental Enamel
A hard thin translucent layer of calcified substance which envelops and protects the dentin of the crown of the tooth.
Dental Pulp
A richly vascularized and innervated connective tissue of mesodermal origin, contained in the central cavity of a tooth and delimited by the dentin, and having formative, nutritive, sensory, and protective functions.
Dentin
The hard portion of the tooth surrounding the pulp, covered by enamel on the crown and cementum on the root, which is harder and denser than bone but softer than enamel, and is thus readily abraded when left unprotected.
Dentition
The teeth collectively in the dental arch.
Dermis
A layer of vascularized connective tissue underneath the epidermis.
Descemet Membrane
A layer of the cornea.
Diapause
A period of arrested growth or development in animals that is triggered by external conditions, such as length of day, extreme temperatures, or reduced food availability.
Diaphragm
The musculofibrous partition that separates the thoracic cavity from the abdominal cavity.
Dietary Fiber
The remnants of plant cell walls that are resistant to digestion by the alimentary enzymes of man.
Dietary Supplements
Products in capsule, tablet or liquid form that provide dietary ingredients, and that are intended to be taken by mouth to increase the intake of nutrients.
Digestive System
A group of organs stretching from the mouth to the ANUS, serving to breakdown foods, assimilate nutrients, and eliminate waste.
Disease Susceptibility
A constitution or condition of the body which makes the tissues react in special ways to certain extrinsic stimuli and thus tends to make the individual more than usually susceptible to certain diseases.
Diuresis
An increase in the excretion of urine.
Duodenum
The shortest and widest portion of the small intestine adjacent to the pylorus of the stomach.
Ear
The hearing and equilibrium system of the body.
Ear Canal
The narrow passage way that conducts the sound collected by the ear auricle to the tympanic membrane.
Egg White
The white of an egg, especially a chicken's egg, used in cooking.
Egg Yolk
Cytoplasm stored in an egg that contains nutritional reserves for the developing embryo.
Eggs
Animal reproductive bodies, or the contents thereof, used as food.
Ejaculation
The emission of semen to the exterior, resulting from the contraction of muscles surrounding the male internal urogenital ducts.
Endocrine System
The system of glands that release their secretions (hormones) directly into the circulatory system.
Endometrium
The mucous membrane lining of the uterine cavity that is hormonally responsive during the menstrual cycle and pregnancy.
Endothelium
A layer of epithelium that lines the heart, blood vessels (endothelium, vascular), lymph vessels (endothelium, lymphatic), and the serous cavities of the body.
Enterocytes
Absorptive cells in the lining of the intestinal mucosa.
Eosinophils
Granular leukocytes with a nucleus that usually has two lobes connected by a slender thread of chromatin, and cytoplasm containing coarse, round granules that are uniform in size and stainable by eosin.
Epicardial Adipose Tissue
A fat deposit localized between the myocardium and the visceral layer of the serous pericardium.
Epidermis
The external, nonvascular layer of the skin.
Epididymis
The convoluted cordlike structure attached to the posterior of the testis.
Epiglottis
A thin leaf-shaped cartilage that is covered with laryngeal mucosa and situated posterior to the root of the tongue and hyoid bone.
Epiphyses
The head of a long bone that is separated from the shaft by the epiphyseal plate until bone growth stops.
Epithelioid Cells
Characteristic cells of granulomatous hypersensitivity.
Epithelium
The layers of epithelial cells which cover the inner and outer surfaces of the cutaneous, mucus, and serous tissues and glands of the body.
Erythroblasts
Immature, nucleated erythrocytes occupying the stage of erythropoiesis that follows formation of erythroid precursor cells and precedes formation of reticulocytes.
Erythrocyte Membrane
The semi-permeable outer structure of a red blood cell.
Erythrocytes
Red blood cells.
Esophageal Mucosa
Circular innermost layer of the esophagus wall that mediates esophageal peristalsis which pushes ingested food bolus toward the stomach.
Esophagogastric Junction
The area covering the terminal portion of esophagus and the beginning of stomach at the cardiac orifice.
Esophagus
The muscular membranous segment between the pharynx and the stomach in the upper gastrointestinal tract.
Estrous Cycle
The period of cyclic physiological and behavior changes in non-primate female mammals that exhibit estrus.
Estrus
The period in the estrous cycle associated with maximum sexual receptivity and fertility in non-primate female mammals.
Eustachian Tube
A narrow passageway that connects the upper part of the throat to the tympanic cavity.
Extracellular Fluid
The fluid of the body that is outside of cells.
Extracellular Space
Interstitial space between cells, occupied by interstitial fluid as well as amorphous and fibrous substances.
Eye
The organ of sight constituting a pair of globular organs made up of a three-layered roughly spherical structure specialized for receiving and responding to light.
Eyelids
Each of the upper and lower folds of SKIN which cover the EYE when closed.
Face
The anterior portion of the head that includes the skin, muscles, and structures of the forehead, eyes, nose, mouth, cheeks, and jaw.
Fallopian Tubes
A pair of highly specialized canals extending from the uterus to its corresponding ovary.
Fascia
Layers of connective tissue of variable thickness.
Fascia Lata
Connective tissue of the anterior compartment of the thigh that has its origins on the anterior aspect of the iliac crest and anterior superior iliac spine, and its insertion point on the iliotibial tract.
Feces
Excrement from the intestines, containing unabsorbed solids, waste products, secretions, and bacteria of the digestive system.
Feeding Behavior
Behavioral responses or sequences associated with eating including modes of feeding, rhythmic patterns of eating, and time intervals.
Femur
The longest and largest bone of the skeleton, it is situated between the hip and the knee.
Fermented Foods
Foods that are prepared by using microorganisms to convert their components into various fermentation end products.
Fertility
The capacity to conceive or to induce conception.
Fertilization
The fusion of a spermatozoon (spermatozoa) with an OVUM thus resulting in the formation of a zygote.
Fetal Blood
Blood of the fetus.
Fetal Heart
The heart of the fetus of any viviparous animal.
Fetal Weight
The weight of the fetus in utero.
Fetus
The unborn young of a viviparous mammal, in the postembryonic period, after the major structures have been outlined.
Fibrocartilage
A type of cartilage whose matrix contains large bundles of collagen type I.
Fibula
The bone of the lower leg lateral to and smaller than the tibia.
Flour
A powdery meal obtained from ground up starchy foodstuff, such as seeds of wheat; RICE and other edible grain; legumes; and NUTS; or ground up plant tubers.
Follicular Fluid
The fluid surrounding the OVUM and granulosa cells in the Graafian follicle (ovarian follicle).
Follicular Phase
The period of the menstrual cycle representing follicular growth, increase in ovarian estrogen (estrogens) production, and epithelial proliferation of the endometrium.
Food Additives
Substances used in the processing or storage of foods or animal feed including antioxidants; food preservatives; food coloring agents; flavoring agents; anti-infective agents; excipients and other similarly used substances.
Foot
The distal extremity of the leg in vertebrates, consisting of the tarsus (ankle); metatarsus; phalanges; and the soft tissues surrounding these bones.
Foramen Magnum
The large hole at the base of the skull through which the spinal cord passes.
Forced Expiratory Volume
Measure of the maximum amount of air that can be expelled in a given number of seconds during a forced vital capacity determination .
Forearm
Part of the upper extremity in humans and primates extending from the elbow to the wrist.
Frontal Bone
The bone that forms the frontal aspect of the skull.
Frontal Sinus
One of the paired, but seldom symmetrical, air spaces located between the inner and outer compact layers of the frontal bone in the forehead.
Functional Food
Components of the usual diet that may provide health benefits beyond basic nutrients.
Functional Residual Capacity
The volume of air remaining in the lungs at the end of a normal, quiet expiration.
Gallbladder
A storage reservoir for BILE secretion.
Gastric Fundus
The superior portion of the body of the stomach above the level of the cardiac notch.
Gastric Juice
The liquid secretion of the stomach mucosa consisting of hydrochloric acid (gastric acid); pepsinogens; intrinsic factor; gastrin; mucus; and the bicarbonate ion (bicarbonates).
Gastric Mucosa
Lining of the stomach, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae.
Gastrointestinal Tract
Generally refers to the digestive structures stretching from the mouth to ANUS, but does not include the accessory glandular organs (liver; biliary tract; pancreas).
Gastrula
The developmental stage that follows blastula or blastocyst.
Gastrulation
A process of complicated morphogenetic cell movements that reorganizes a bilayer embryo into one with three germ layers and specific orientation (dorsal/ventral; anterior/posterior).
Germinal Center
The activated center of a lymphoid follicle in secondary lymphoid tissue where b-lymphocytes are stimulated by antigens and helper T cells (t-lymphocytes, helper-inducer) are stimulated to generate memory cells.
Germination
The initial stages of the growth of seeds into a seedlings.
Gestational Age
The age of the conceptus, beginning from the time of fertilization.
Gingival Crevicular Fluid
A fluid occurring in minute amounts in the gingival crevice, believed by some authorities to be an inflammatory exudate and by others to cleanse material from the crevice, containing sticky plasma proteins which improve adhesions
Glomerular Basement Membrane
The layer of extracellular matrix that lies between the endothelium of the glomerular capillaries and the podocytes of the inner or visceral layer of the bowman capsule.
Glomerular Filtration Rate
The volume of water filtered out of plasma through glomerular capillary walls into Bowman's capsules per unit of time.
Glycemic Index
A numerical system of measuring the rate of blood glucose generation from a particular food item as compared to a reference item, such as glucose = 100.
Goblet Cells
A glandular epithelial cell or a unicellular gland.
Granulation Tissue
A vascular connective tissue formed on the surface of a healing wound, ulcer, or inflamed tissue.
Granulosa Cells
Supporting cells for the developing female gamete in the ovary.
Gravidity
The number of pregnancies, complete or incomplete, experienced by a female.
Growth
Gradual increase in the number, the size, and the complexity of cells of an individual.
Growth and Development
The series of changes to the shape, size, components, and functions of an individual organism that occur over time as the organism progresses from its initial form to full size and maturity.
Hair
A filament-like structure consisting of a shaft which projects to the surface of the SKIN from a root which is softer than the shaft and lodges in the cavity of a hair follicle.
Hair Follicle
A tube-like invagination of the epidermis from which the hair shaft develops and into which sebaceous glands open.
Hand
The distal part of the arm beyond the wrist in humans and primates, that includes the palm, fingers, and thumb.
Head
The upper part of the human body, or the front or upper part of the body of an animal, typically separated from the rest of the body by a neck, and containing the brain, mouth, and sense organs.
Head Kidney
A primitive form of vertebrate kidney that is found in adults of some primitive fishes and in the embryos of more advanced fishes.
Heel
The back (or posterior) of the foot in primates, found behind the ankle and distal to the toes.
Hematocrit
The volume of packed red blood cells in a blood specimen.
Hematopoietic Stem Cells
Progenitor cells from which all blood cells derived.
Hemostasis
The process which spontaneously arrests the flow of blood from vessels carrying blood under pressure.
Hibernation
The dormant state in which some warm-blooded animal species pass the winter.
Hip
The projecting part on each side of the body, formed by the side of the pelvis and the top portion of the femur.
Hip Joint
The joint that is formed by the articulation of the head of femur and the acetabulum of the pelvis.
Histiocytes
Macrophages found in the tissues, as opposed to those found in the blood (monocytes) or serous cavities (serous membrane).
Homeostasis
The processes whereby the internal environment of an organism tends to remain balanced and stable.
Honey
A sweet viscous liquid food, produced in the honey sacs of various bees from nectar collected from flowers.
Human Development
Continuous sequential changes which occur in the physiological and psychological functions during the life-time of an individual.
Humeral Head
The upper rounded extremity of the humerus fitting into the glenoid cavity of the scapula.
Hyaline Cartilage
A type of cartilage characterized by a homogenous amorphous matrix containing predominately TYPE II collagen and ground substance.
Hyoid Bone
A mobile U-shaped bone that lies in the anterior part of the neck at the level of the third cervical vertebrae.
Hypopharynx
The bottom portion of the pharynx situated below the oropharynx and posterior to the larynx.
Ideal Body Weight
Expected weight of a healthy normal individual based on age, sex, and height.
Ileum
The distal and narrowest portion of the small intestine, between the jejunum and the ileocecal valve of the large intestine.
Immune Sera
Serum that contains antibodies.
Immune System
The body's defense mechanism against foreign organisms or substances and deviant native cells.
Incisor
Any of the eight frontal teeth (four maxillary and four mandibular) having a sharp incisal edge for cutting food and a single root, which occurs in man both as a deciduous and a permanent tooth.
Insulin Secretion
Production and release of insulin from pancreatic beta cells that primarily occurs in response to elevated blood glucose levels.
Intermittent Fasting
Alternating between fasting for an extended period of time during the day and eating during a restricted time for the day.
Intestinal Mucosa
Lining of the intestines, consisting of an inner epithelium, a middle lamina propria, and an outer muscularis mucosae.
Intestines
The section of the alimentary canal from the stomach to the anal canal.
Intraepithelial Lymphocytes
T Lymphocytes with limited diversity of receptors (e.g., alpha E integrins) in the epidermis of the skin and the mucosal linings.
Iris
The most anterior portion of the uveal layer, separating the anterior chamber from the posterior.
Islets of Langerhans
Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the pancreas among the exocrine acini.
Jaw
Bony structure of the mouth that holds the teeth.
Jejunum
The middle portion of the small intestine, between duodenum and ileum.
Joints
Also known as articulations, these are points of connection between the ends of certain separate bones, or where the borders of other bones are juxtaposed.
Jurkat Cells
A cell line derived from human t-cell leukemia and used to determine the mechanism of differential susceptibility to anti-cancer drugs and radiation.
Keloid
A sharply elevated, irregularly shaped, progressively enlarging scar resulting from formation of excessive amounts of collagen in the dermis during connective tissue repair.
Kidney
Body organ that filters blood for the secretion of urine and that regulates ion concentrations.
Kidney Cortex
The outer zone of the kidney, beneath the capsule, consisting of kidney glomerulus; kidney tubules, distal; and kidney tubules, proximal.
Kupffer Cells
Specialized phagocytic cells of the mononuclear phagocyte system found on the luminal surface of the hepatic sinusoids.
Lactation
The processes of milk secretion by the maternal mammary glands after parturition.
Langerhans Cells
Recirculating, dendritic, antigen-presenting cells containing characteristic racket-shaped granules (Birbeck granules).
Larva
Wormlike or grublike stage, following the egg in the life cycle of insects, worms, and other metamorphosing animals.
Larynx
A tubular organ of voice production.
Leydig Cells
Steroid-producing cells in the interstitial tissue of the testis.
Ligaments
Shiny, flexible bands of fibrous tissue connecting together articular extremities of bones.
Ligamentum Flavum
The paired bands of yellow elastic tissue that connect adjoining laminae of the vertebrae.
Live Birth
The event that a fetus is born alive with heartbeats or respiration regardless of gestational age.
Liver
A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.
Locomotion
Movement or the ability to move from one place or another.
Lower Extremity
The region of the lower limb in animals, extending from the gluteal region to the FOOT, and including the buttocks; HIP; and LEG.
Lumbar Vertebrae
Vertebrae in the region of the lower BACK below the thoracic vertebrae and above the sacral vertebrae.
Lung
Either of the pair of organs occupying the cavity of the thorax that effect the aeration of the blood.
Lung Compliance
The capability of the lungs to distend under pressure as measured by pulmonary volume change per unit pressure change.
Luteal Cells
Progesterone-producing cells in the corpus luteum.
Luteal Phase
The period in the menstrual cycle that follows ovulation, characterized by the development of corpus luteum, increase in progesterone production by the ovary and secretion by the glandular epithelium of the endometrium.
Luteolysis
Degradation of corpus luteum.
Lymph Nodes
They are oval or bean shaped bodies (1 - 30 mm in diameter) located along the lymphatic system.
Lymphocytes
White blood cells formed in the body's lymphoid tissue.
Macrophages
The relatively long-lived phagocytic cell of mammalian tissues that are derived from blood monocytes.
Mandible
The largest and strongest bone of the FACE constituting the lower jaw.
Mandibular Condyle
The posterior process on the ramus of the mandible composed of two parts: a superior part, the articular portion, and an inferior part, the condylar neck.
Mast Cells
Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract.
Masticatory Muscles
Muscles arising in the zygomatic arch that close the jaw.
Mastoid
The posterior part of the temporal bone.
Maxilla
One of a pair of irregularly shaped bones that form the upper jaw.
Maxillary Sinus
The air space located in the body of the maxillary bone near each cheek.
Meals
A portion of the food eaten for the day, usually at regular occasions during the day.
Meat
The edible portions of any animal used for food including cattle, swine, goats/sheep, poultry, fish, shellfish, and game.
Meat Products
Articles of food which are derived by a process of manufacture from any portion of carcasses of any animal used for food (e.g., head cheese, sausage, scrapple).
Meconium
The thick green-to-black mucilaginous material found in the intestines of a full-term fetus.
Mediastinum
A membrane in the midline of the thorax of mammals.
Membranes
Thin layers of tissue which cover parts of the body, separate adjacent cavities, or connect adjacent structures.
Memory B Cells
A subset of activated B cells generated in response to primary immune challenge or immunization which are capable of giving rise to antibody-secreting cells upon re-challenge (see immunologic memory).
Memory T Cells
A subset of activated T cells generated in response to primary immune challenge or immunization upon re-challenge (see immunologic memory).
Menopause
The last menstrual period.
Menstrual Cycle
The period from onset of one menstrual bleeding (menstruation) to the next in an ovulating woman or female primate.
Menstruation
The periodic shedding of the endometrium and associated menstrual bleeding in the menstrual cycle of humans and primates.
Merozoites
Uninuclear cells or a stage in the life cycle of sporozoan protozoa.
Mesangial Cells
Smooth muscle-like cells adhering to the wall of the small blood vessels of the kidney at the glomerulus and along the vascular pole of the glomerulus in the juxtaglomerular apparatus.
Mesentery
A layer of the peritoneum which attaches the abdominal viscera to the abdominal wall and conveys their blood vessels and nerves.
Mesoderm
The middle germ layer of an embryo derived from three paired mesenchymal aggregates along the neural tube.
Metacercariae
Encysted cercaria which house the intermediate stages of trematode parasites in tissues of an intermediate host.
Milk
The off-white liquid secreted by the mammary glands of humans and other mammals.
Milk Proteins
The major protein constituents of milk are caseins and whey proteins such as lactalbumin and lactoglobulins.
Molar
The most posterior teeth on either side of the jaw, totaling eight in the deciduous dentition (2 on each side, upper and lower), and usually 12 in the permanent dentition (three on each side, upper and lower).
Molasses
The syrup remaining after sugar is crystallized out of sugarcane or sugar beet juice.
Molting
Periodic casting off feathers; HAIR; or cuticle.
Monocytes
Large, phagocytic mononuclear leukocytes produced in the vertebrate bone marrow and released into the blood; contain a large, oval or somewhat indented nucleus surrounded by voluminous cytoplasm and numerous organelles.
Morphogenesis
The development of anatomical structures to create the form of a single- or multi-cell organism.
Morula
An early embryo that is a compact mass of about 16 blastomeres.
Mouth
The oval-shaped oral cavity located at the apex of the digestive tract and consisting of two parts: the vestibule and the oral cavity proper.
Movement
The act, process, or result of passing from one place or position to another.
Mucociliary Clearance
A non-specific host defense mechanism that removes mucus and other material from the lungs by ciliary and secretory activity of the tracheobronchial submucosal glands.
Mucous Membrane
An epithelium with mucus-secreting cells, such as goblet cells.
Mucus
The viscous secretion of mucous membranes.
Muscle Development
Developmental events leading to the formation of adult muscular system, which includes differentiation of the various types of muscle cell precursors, migration of myoblasts, activation of myogenesis and development of muscle anch
Myocardium
The muscle tissue of the heart.
Myocutaneous Flap
A mass of tissue, including skin and muscle, that has been cut away from surrounding areas for transplantation.
Myofibrils
The long cylindrical contractile organelles of striated muscle cells composed of actin filaments; myosin filaments; and other proteins organized in arrays of repeating units called sarcomeres .
Myometrium
The smooth muscle coat of the uterus, which forms the main mass of the organ.
Nails
The thin, horny plates that cover the dorsal surfaces of the distal phalanges of the fingers and toes of primates.
Nasal Cavity
The proximal portion of the respiratory passages on either side of the nasal septum.
Nasal Mucosa
The mucous lining of the nasal cavity, including lining of the nostril (vestibule) and the olfactory mucosa.
Nasal Septum
The partition separating the two nasal cavities in the midplane.
Nasopharynx
The top portion of the pharynx situated posterior to the nose and superior to the soft palate.
Natural Killer T-Cells
A specialized subset of t-lymphocytes that exhibit features of innate immunity similar to that of natural killer cells.
Neck
The part of a human or animal body connecting the HEAD to the rest of the body.
Nerve Tissue
Differentiated tissue of the central nervous system composed of nerve cells, fibers, dendrites, and specialized supporting cells.
Neural Crest
The two longitudinal ridges along the primitive streak appearing near the end of gastrulation during development of nervous system (neurulation).
Neural Plate
The region in the dorsal ectoderm of a chordate embryo that gives rise to the future central nervous system.
Neural Tube
A tube of ectodermal tissue in an embryo that will give rise to the central nervous system, including the spinal cord and the brain.
Neutrophils
Granular leukocytes having a nucleus with three to five lobes connected by slender threads of chromatin, and cytoplasm containing fine inconspicuous granules and stainable by neutral dyes.
Nose
A part of the upper respiratory tract.
Notochord
A cartilaginous rod of mesodermal cells at the dorsal midline of all chordate embryos.
Nucleus Pulposus
Fibrocartilage inner core of the intervertebral disc.
Nutritional Requirements
The amounts of various substances in food needed by an organism to sustain healthy life.
Nutritive Value
An indication of the contribution of a food to the nutrient content of the diet.
Nuts
Botanically, a type of single-seeded fruit in which the pericarp enclosing the seed is a hard woody shell.
Nymph
The immature stage in the life cycle of those orders of insects characterized by gradual metamorphosis, in which the young resemble the imago in general form of body, including compound eyes and external wings; also the 8-legged s
Omentum
A double-layered fold of peritoneum that attaches the stomach to other organs in the abdominal cavity.
Oocysts
Zygote-containing cysts of sporozoan protozoa.
Oocytes
Female germ cells derived from oogonia and termed oocytes when they enter meiosis.
Organ of Corti
The spiral epithelium containing sensory auditory hair cells and supporting cells in the cochlea.
Organoids
An organization of cells into an organ-like structure.
Organs at Risk
Organs which might be damaged during exposure to a toxin or to some form of therapy.
Oropharynx
The middle portion of the pharynx that lies posterior to the mouth, inferior to the soft palate, and superior to the base of the tongue and epiglottis.
Ovarian Follicle
An oocyte-containing structure in the cortex of the ovary.
Ovary
The reproductive organ (gonads) in female animals.
Overweight
A status with body weight that is above certain standards.
Oviposition
The process of laying or shedding fully developed eggs (OVA) from the female body.
Palate
The structure that forms the roof of the mouth.
Pancreas
A nodular organ in the abdomen that contains a mixture of endocrine glands and exocrine glands.
Pancreatic Juice
The fluid containing digestive enzymes secreted by the pancreas in response to food in the duodenum.
Papillary Muscles
Conical muscular projections from the walls of the cardiac ventricles, attached to the cusps of the atrioventricular valves by the chordae tendineae.
Paranasal Sinuses
Air-filled spaces located within the bones around the nasal cavity.
Parathyroid Glands
Two pairs of small oval-shaped glands located in the front and the base of the NECK and adjacent to the two lobes of thyroid gland.
Parity
The number of offspring a female has borne.
Parotid Gland
The largest of the three pairs of salivary glands.
Partial Thromboplastin Time
The time required for the appearance of fibrin strands following the mixing of plasma with phospholipid platelet substitute (e.g., crude cephalins, soybean phosphatides).
Patellofemoral Joint
The articulation between the articular surface of the patella and the patellar surface of the femur.
Peak Expiratory Flow Rate
Measurement of the maximum rate of airflow attained during a forced vital capacity determination.
Pelvic Floor
Soft tissue formed mainly by the pelvic diaphragm, which is composed of the two levator ani and two coccygeus muscles.
Pelvis
The space or compartment surrounded by the pelvic girdle (bony pelvis).
Penile Erection
The state of the penis when the erectile tissue becomes filled or swollen (tumid) with blood and causes the penis to become rigid and elevated.
Penis
The external reproductive organ of males.
Perforator Flap
A mass of tissue for transplantation that includes the skin and/or the subcutaneous fat, and the perforating blood vessel that traverses the underlying tissue to supply blood to the skin.
Pericardium
A conical fibro-serous sac surrounding the heart and the roots of the great vessels (aorta; venae cavae; pulmonary artery).
Pericytes
Unique slender cells with multiple processes extending along the capillary vessel axis and encircling the vascular wall, also called mural cells.
Perilymph
The fluid separating the membranous labyrinth from the osseous labyrinth of the ear.
Perineum
The body region lying between the genital area and the ANUS on the surface of the trunk, and to the shallow compartment lying deep to this area that is inferior to the pelvic diaphragm.
Periodicity
The tendency of a phenomenon to recur at regular intervals; in biological systems, the recurrence of certain activities (including hormonal, cellular, neural) may be annual, seasonal, monthly, daily, or more frequently (ultradian)
Periodontal Ligament
The fibrous connective tissue surrounding the tooth root, separating it from and attaching it to the alveolar bone (alveolar process).
Periodontium
The structures surrounding and supporting the tooth.
Periosteum
Thin outer membrane that surrounds a bone.
Peritoneal Cavity
The space enclosed by the peritoneum.
Peritoneum
A membrane of squamous epithelial cells, the mesothelial cells, covered by apical microvilli that allow rapid absorption of fluid and particles in the peritoneal cavity.
Pharynx
A funnel-shaped fibromuscular tube that conducts food to the esophagus, and air to the larynx and lungs.
Phonation
The process of producing vocal sounds by means of vocal cords vibrating in an expiratory blast of air.
Placenta
A highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products.
Placentation
The development of the placenta, a highly vascularized mammalian fetal-maternal organ and major site of transport of oxygen, nutrients, and fetal waste products between mother and fetus.
Plant Development
Processes orchestrated or driven by a plethora of genes, plant hormones, and inherent biological timing mechanisms facilitated by secondary molecules, which result in the systematic transformation of plants and plant parts, from o
Plasma
The residual portion of blood that is left after removal of blood cells by centrifugation without prior blood coagulation.
Plasma Cells
Specialized forms of antibody-producing b-lymphocytes.
Platelet Activation
A series of progressive, overlapping events, triggered by exposure of the platelets to subendothelial tissue.
Platelet Aggregation
The attachment of platelets to one another.
Platelet-Rich Fibrin
A fibrin matrix derived from platelet-rich plasma that contains high concentration of blood platelets; leukocytes; cytokines; and growth factors.
Platelet-Rich Plasma
A preparation consisting of platelets concentrated in a limited volume of plasma.
Pleura
The thin serous membrane enveloping the lungs (LUNG) and lining the thoracic cavity.
Pleural Cavity
Paired but separate cavity within the thoracic cavity.
Podocytes
Highly differentiated epithelial cells of the visceral layer of bowman capsule of the kidney.
Posterior Cruciate Ligament
A strong ligament of the knee that originates from the anterolateral surface of the medial condyle of the femur, passes posteriorly and inferiorly between the condyles, and attaches to the posterior intercondylar area of the tibia
Prebiotics
Non-digestible food ingredients mostly of a carbohydrate base that improve human health by selectively stimulating the growth and/or activity of existing bacteria in the colon.
Pregnancy
The status during which female mammals carry their developing young (embryos or fetuses) in utero before birth, beginning from fertilization to birth.
Pregnancy Outcome
Results of conception and ensuing pregnancy, including live birth; stillbirth; or spontaneous abortion.
Probiotics
Live microbial dietary supplements which beneficially affect the host animal by improving its intestinal microbial balance.
Proestrus
A phase of the estrous cycle that precedes estrus.
Prostate
A gland in males that surrounds the neck of the urinary bladder and the urethra.
Prothrombin Time
Clotting time of plasma recalcified in the presence of excess tissue thromboplastin.
Puberty
A period in the human life in which the development of the hypothalamic-pituitary-gonadal system takes place and reaches full maturity.
Pulmonary Gas Exchange
The exchange of oxygen and carbon dioxide between alveolar air and pulmonary capillary blood that occurs across the blood-air barrier.
Pulmonary Ventilation
The total volume of gas inspired or expired per unit of time, usually measured in liters per minute.
Pupa
An inactive stage between the larval and adult stages in the life cycle of insecta.
Pylorus
The region of the stomach at the junction with the duodenum.
Quadriceps Muscle
The quadriceps femoris.
Radius
The outer shorter of the two bones of the forearm, lying parallel to the ULNA and partially revolving around it.
Rectum
The distal segment of the large intestine, between the sigmoid colon and the anal canal.
Rectus Abdominis
A long flat muscle that extends along the whole length of both sides of the abdomen.
Red Meat
Meat such as beef, goat, pork, or lamb which contains more myoglobin than poultry or seafood.
Residual Volume
The volume of air remaining in the lungs at the end of a maximal expiration.
Resistant Starch
Dietary starch and related high-molecular carbohydrate incapable of enzymatic hydrolysis in the small intestine and instead ferments in the colon, producing short-chain fatty acids by-products.
Respiration
The act of breathing with the lungs, consisting of inhalation, or the taking into the lungs of the ambient air, and of exhalation, or the expelling of the modified air which contains more carbon dioxide than the air taken in (Blak
Respiratory Mechanics
The physical or mechanical action of the lungs; diaphragm; RIBS; and chest wall during respiration.
Respiratory Rate
The number of times an organism breathes with the lungs (respiration) per unit time, usually per minute.
Respiratory System
The tubular and cavernous organs and structures, by means of which pulmonary ventilation and gas exchange between ambient air and the blood are brought about.
Reticulocytes
Immature erythrocytes.
Retina
The ten-layered nervous tissue membrane of the eye.
Retinal Pigment Epithelium
The single layer of pigment-containing epithelial cells in the retina, situated closely to the tips (outer segments) of the retinal photoreceptor cells.
Retroperitoneal Space
An area occupying the most posterior aspect of the abdominal cavity.
Rib Cage
The bony thoracic enclosure consisting of the vertebral column; the RIBS; the sternum; and the costal cartilage.
Ribs
A set of twelve curved bones which connect to the vertebral column posteriorly, and terminate anteriorly as costal cartilage.
Rotator Cuff
The musculotendinous sheath formed by the supraspinatus, infraspinatus, subscapularis, and teres minor muscles.
Sacrum
Five fused vertebrae forming a triangle-shaped structure at the back of the pelvis.
Saliva
The clear, viscous fluid secreted by the salivary glands and mucous glands of the mouth.
Salivary Glands
Glands that secrete saliva in the mouth.
Salivation
The discharge of saliva from the salivary glands that keeps the mouth tissues moist and aids in digestion.
Salt Tolerance
The ability of organisms to sense and adapt to high concentrations of salt in their growth environment.
Sarcoplasmic Reticulum
A network of tubules and sacs in the cytoplasm of skeletal muscle fibers that assist with muscle contraction and relaxation by releasing and storing calcium ions.
Scalp
The outer covering of the calvaria.
Scapula
Also called the shoulder blade, it is a flat triangular bone, a pair of which form the back part of the shoulder girdle.
Sclera
The white, opaque, fibrous, outer tunic of the eyeball, covering it entirely excepting the segment covered anteriorly by the cornea.
Seafood
Marine fish and shellfish used as food or suitable for food.
Sebaceous Glands
Small, sacculated organs found within the dermis.
Sebum
The oily substance secreted by sebaceous glands.
Secretome
The set of all the soluble factors and extracellular vesicles secreted into the extracellular space by cells, or an organ or organism.
Seeds
The encapsulated embryos of flowering plants.
Sella Turcica
A bony prominence situated on the upper surface of the body of the sphenoid bone.
Semen
The thick, yellowish-white, viscid fluid secretion of male reproductive organs discharged upon ejaculation.
Semicircular Canals
Three long canals (anterior, posterior, and lateral) of the bony labyrinth.
Seminal Vesicles
A saclike, glandular diverticulum on each ductus deferens in male vertebrates.
Seminiferous Epithelium
The epithelium lining the seminiferous tubules composed of primary male germ cells (spermatogonia) and supporting sertoli cells.
Seminiferous Tubules
The convoluted tubules in the testis where sperm are produced (spermatogenesis) and conveyed to the rete testis.
Sentinel Lymph Node
First lymph node to receive drainage from the primary tumor.
Sertoli Cells
Supporting cells projecting inward from the basement membrane of seminiferous tubules.
Serum
The clear portion of blood that is left after blood coagulation to remove blood cells and clotting proteins.
Sesame Oil
The refined fixed oil obtained from the seed of one or more cultivated varieties of Sesamum indicum.
Sex
The totality of characteristics of reproductive structure, functions, phenotype, and genotype, differentiating the MALE from the female organism.
Sex Differentiation
The process in developing sex- or gender-specific tissue, organ, or function after sex determination processes have set the sex of the gonads.
Sexual Development
The processes of anatomical and physiological changes related to sexual or reproductive functions during the life span of a human or an animal, from fertilization to death.
Sexuality
The sexual functions, activities, attitudes, and orientations of an individual.
Shellfish
Aquatic invertebrates belonging to the phylum mollusca or the subphylum crustacea, and used as food.
Shivering
Involuntary contraction or twitching of the muscles.
Shoulder
Part of the body in humans and primates where the arms connect to the trunk.
Shoulder Joint
The articulation between the head of the humerus and the glenoid cavity of the scapula.
Silage
Fodder converted into succulent feed for livestock through processes of anaerobic fermentation (as in a silo).
Skeleton
The rigid framework of connected bones that gives form to the body, protects and supports its soft organs and tissues, and provides attachments for muscles.
Skin
The outer covering of the body that protects it from the environment.
Skinfold Thickness
The measurement of subcutaneous fat located directly beneath the skin by grasping a fold of skin and subcutaneous fat between the thumb and forefinger and pulling it away from the underlying muscle tissue.
Skull
The skeleton of the HEAD including the facial bones and the bones enclosing the brain.
Skull Base
The inferior region of the skull consisting of an internal (cerebral), and an external (basilar) surface.
Sneezing
The sudden, forceful, involuntary expulsion of air from the NOSE and mouth caused by irritation to the mucous membranes of the upper respiratory tract.
Somites
Paired, segmented masses of mesenchyme located on either side of the developing spinal cord (neural tube).
Sperm Head
The anterior portion of the spermatozoon (spermatozoa) that contains mainly the nucleus with highly compact chromatin material.
Spermatic Cord
Either of a pair of tubular structures formed by ductus deferens; arteries; veins; lymphatic vessels; and nerves.
Spermatids
Male germ cells derived from the haploid secondary spermatocytes.
Spermatocytes
Male germ cells derived from spermatogonia.
Spermatogonia
Euploid male germ cells of an early stage of spermatogenesis, derived from prespermatogonia.
Spermatozoa
Mature male germ cells derived from spermatids.
Sphenoid Sinus
One of the paired air spaces located in the body of the sphenoid bone behind the ethmoid bone in the middle of the skull.
Sphincter of Oddi
The sphincter of the hepatopancreatic ampulla within the duodenal papilla.
Spices
The dried seeds, bark, root, stems, buds, leaves, or fruit of aromatic plants used to season food.
Sputum
Material coughed up from the lungs and expectorated via the mouth.
Stapes
One of the three ossicles of the middle ear.
Sternum
A long, narrow, and flat bone commonly known as breastbone occurring in the midsection of the anterior thoracic segment or chest region, which stabilizes the rib cage and serves as the point of origin for several muscles that move
Stomach
An organ of digestion situated in the left upper quadrant of the abdomen between the termination of the esophagus and the beginning of the duodenum.
Stria Vascularis
A layer of stratified epithelium forming the endolymphatic border of the cochlear duct at the lateral wall of the cochlea.
Subcutaneous Tissue
Loose connective tissue lying under the dermis, which binds SKIN loosely to subjacent tissues.
Submandibular Gland
One of two salivary glands in the neck, located in the space bound by the two bellies of the digastric muscle and the angle of the mandible.
Subretinal Fluid
An exudate between the retina and choroid from various sources including the vitreous cavity, subarachnoid space, or abnormal vessels.
Superovulation
Occurrence or induction of release of more ova than are normally released at the same time in a given species.
Sweat
The fluid excreted by the sweat glands.
Sweat Glands
Sweat-producing structures that are embedded in the dermis.
Sweating
The process of exocrine secretion of the sweat glands, including the aqueous sweat from the eccrine glands and the complex viscous fluids of the apocrine glands.
Synovial Fluid
The clear, viscous fluid secreted by the synovial membrane.
Synovial Membrane
The inner membrane of a joint capsule surrounding a freely movable joint.
T-Lymphocyte Subsets
A classification of T-lymphocytes, especially into helper/inducer, suppressor/effector, and cytotoxic subsets, based on structurally or functionally different populations of cells.
T-Lymphocytes
Lymphocytes responsible for cell-mediated immunity.
Talus
The second largest of the tarsal bones.
Tea
The infusion of leaves of camellia sinensis (formerly Thea sinensis) as a beverage, the familiar Asian tea, which contains catechin (especially epigallocatechin gallate) and caffeine.
Temporal Bone
Either of a pair of compound bones forming the lateral (left and right) surfaces and base of the skull which contains the organs of hearing.
Temporomandibular Joint
An articulation between the condyle of the mandible and the articular tubercle of the temporal bone.
Tendons
Fibrous bands or cords of connective tissue at the ends of skeletal muscle fibers that serve to attach the muscles to bones and other structures.
Term Birth
Childbirth at the end of a normal duration of pregnancy, between 37 to 40 weeks of gestation or about 280 days from the first day of the mother's last menstrual period.
Testis
The male gonad containing two functional parts: the seminiferous tubules for the production and transport of male germ cells (spermatogenesis) and the interstitial compartment containing leydig cells that produce androgens.
Th1 Cells
A subset of helper-inducer T-lymphocytes which synthesize and secrete interleukin-2; interferon-gamma; and interleukin-12.
Th17 Cells
A subset of helper-effector T-lymphocytes which synthesize and secrete interleukins il-17; il-17f; and il-22.
Th2 Cells
A subset of helper-inducer T-lymphocytes which synthesize and secrete the interleukins il-4; IL-5; IL-6; and il-10.
Thermogenesis
The generation of heat in order to maintain body temperature.
Thermotolerance
The ability of an organism to reduce susceptibility to heat shock, and adapt to hot temperature.
Thinness
A state of insufficient flesh on the body usually defined as having a body weight less than skeletal and physical standards, such as body mass index, and dependent on age, sex, and genetic background.
Thoracic Duct
The largest lymphatic vessel that passes through the chest and drains into the subclavian vein.
Thoracic Vertebrae
A group of twelve vertebrae connected to the ribs that support the upper trunk region.
Thoracic Wall
The outer margins of the thorax containing SKIN, deep fascia; thoracic vertebrae; RIBS; sternum; and muscles.
Thorax
The upper part of the trunk between the NECK and the abdomen.
Thumb
The first digit on the radial side of the hand which in humans lies opposite the other four.
Thyroid Gland
A highly vascularized endocrine gland consisting of two lobes joined by a thin band of tissue with one lobe on each side of the trachea.
Tibia
The second longest bone of the skeleton.
Tidal Volume
The volume of air inspired or expired during each normal, quiet respiratory cycle.
Time-to-Pregnancy
Time interval, or number of non-contraceptive menstrual cycles that it takes for a couple to conceive.
Tissues
Collections of differentiated cells, such as epithelium; connective tissue; muscles; and nerve tissue.
Tongue
A muscular organ in the mouth that is covered with pink tissue called mucosa, tiny bumps called papillae, and thousands of taste buds.
Tooth
One of a set of bone-like structures in the mouth used for biting and chewing.
Total Lung Capacity
The volume of air contained in the lungs at the end of a maximal inspiration.
Trabecular Meshwork
A porelike structure surrounding the entire circumference of the anterior chamber through which aqueous humor circulates to the schlemm's canal.
Trachea
The cartilaginous and membranous tube descending from the larynx and branching into the right and left main bronchi.
Transplants
Organs, tissues, or cells taken from the body for grafting into another area of the same body or into another individual.
Trigger Points
Discrete spots in taut bands of muscle that produce local and referred pain when muscle bands are compressed.
Trophoblasts
Cells lining the outside of the blastocyst.
Trophozoites
Cells or feeding stage in the life cycle of sporozoan protozoa.
Tropism
The directional growth of an organism in response to an external stimulus such as light, touch, or gravity.
Tumor-Associated Macrophages
Various macrophages found in tumor microenvironment.
Turbinates
The scroll-like bony plates with curved margins on the lateral wall of the nasal cavity.
Tympanic Membrane
An oval semitransparent membrane separating the external ear canal from the tympanic cavity (EAR, middle).
Umbilical Cord
The flexible rope-like structure that connects a developing fetus to the placenta in mammals.
Umbilicus
The pit in the center of the abdominal wall marking the point where the umbilical cord entered in the fetus.
Upper Extremity
The region of the upper limb in animals, extending from the deltoid region to the HAND, and including the ARM; axilla; and shoulder.
Ureter
One of a pair of thick-walled tubes that transports urine from the kidney pelvis to the urinary bladder.
Urethra
A tube that transports urine from the urinary bladder to the outside of the body in both the sexes.
Urinary Bladder
A musculomembranous sac along the urinary tract.
Urinary Tract
The duct which coveys urine from the pelvis of the kidney through the ureters, bladder, and urethra.
Urine
Liquid by-product of excretion produced in the kidneys, temporarily stored in the bladder until discharge through the urethra.
Uterus
The hollow thick-walled muscular organ in the female pelvis.
Vagina
The genital canal in the female, extending from the uterus to the vulva.
Vas Deferens
The excretory duct of the testes that carries spermatozoa.
Venoms
Poisonous animal secretions forming fluid mixtures of many different enzymes, toxins, and other substances.
Vestibular System
The vestibular apparatus in the inner ear, the eye, the central nervous system and various nerves, tracts and nuclei connecting them as they relate to proprioception and spatial orientation.
Viscera
Any of the large interior organs in any one of the three great cavities of the body, especially in the abdomen.
Vital Capacity
The volume of air that is exhaled by a maximal expiration following a maximal inspiration.
Vitreous Body
The transparent, semigelatinous substance that fills the cavity behind the crystalline lens of the EYE and in front of the retina.
Vocal Cords
A pair of cone-shaped elastic mucous membrane projecting from the laryngeal wall and forming a narrow slit between them.
Voice
The sounds produced by humans by the passage of air through the larynx and over the vocal cords, and then modified by the resonance organs, the nasopharynx, and the mouth.
Voice Quality
That component of speech which gives the primary distinction to a given speaker's voice when pitch and loudness are excluded.
Vulva
The external genitalia of the female.
Waist Circumference
The measurement around the body at the level of the abdomen and just above the hip bone.
Waist-Hip Ratio
The waist circumference measurement divided by the hip circumference measurement.
Weaning
Permanent deprivation of breast milk and commencement of nourishment with other food.
Whey
The liquid components of milk that remain after the casein, fat, and fat soluble components have been removed.
Wine
Fermented juice of fresh grapes or of other fruit or plant products used as a beverage.
Work of Breathing
Respiratory muscle contraction during inhalation.
Wrist Joint
The joint that is formed by the distal end of the radius, the articular disc of the distal radioulnar joint, and the proximal row of carpal bones; (scaphoid bone; lunate bone; triquetral bone).
Yogurt
A slightly acid milk food produced by fermentation due to the combined action of Lactobacillus acidophilus and Streptococcus thermophilus.
Yolk Sac
The first of four extra-embryonic membranes to form during embryogenesis.
Zona Glomerulosa
The narrow subcapsular outer zone of the adrenal cortex.
Zona Pellucida
A tough transparent membrane surrounding the OVUM.