DAT Endocrinology

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Terms from Kaplan's DAT Endocrinology section

Endocrinology

The branch of physiology and medicine concerned with endocrine glands and hormones

Hormones

A regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action

Exocrine Glands

A type of ductal glands that secrete their products (including digestive enzymes, and some hormone chemical messengers) into ducts that lead directly into the external environment.

Specificity

Of hormonal action is usually determined by the presence of specific receptors n or in the target cells.

Adrenal Glands

Endocrine glands that sit atop the kidneys; in humans, the right suprarenal gland is triangular shaped, while the left suprarenal gland is semilunar shaped. They are chiefly responsible for releasing hormones in response to stress through the synthesis of corticosteroids such as cortisol and catecholamines such as epinephrine. The adrenal glands affect kidney function through the secretion of aldosterone, a hormone involved in regulating the osmolarity of blood plasma.

Adrenal Cortex

Situated along the perimeter of the adrenal gland, this endocrine gland mediates the stress response through the production of mineralocorticoids and glucocorticoids, including aldosterone and cortisol respectively. It is also a secondary site of androgen synthesis.

ACTH

A hormone produced by the anterior pituitary gland that stimulates the adrenal cortex

Corticosteroids

Any of a group of steroid hormones produced in the adrenal cortex or made synthetically. There are two kinds: glucocorticoids and mineralocorticoids. They have various metabolic functions and some are used to treat inflammation

Glucocorticoids

A class of steroids (including cortisol and cortisone) involved in glucose regulation and protein metabolism. They raise blood glucose levels by promoting protein breakdown and gluconeogenesis and decreasing protein synthesis. They raise the plasma glucose levels and are antagonistic to the effects of insulin.

Gluconeogenesis

A metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids.

Circadian Rhythms

A roughly 24-hour cycle in the biochemical, physiological, or behavioral processes of living entities, including plants, animals, fungi and cyanobacteria

Cyclic Adenosine Monophosphate (CAMP)

A second messenger that is a cyclic form of adenosine monophosphate (adenylic acid) that plays a major role in controlling many enzyme-catalyzed processes in living cells.

Second Messenger

A substance whose release within a cell is promoted by a hormone and that brings about a response by the cell.

Steroid

Any of a large class of organic compounds with a characteristic molecular structure containing four rings of carbon atoms (three six-membered and one five). They include many hormones, alkaloids, and vitamins.

Meristematic Tissues

Embryonic tissue located at the tips of stems and roots and occasionally along their entire length; can divide to produce new cells; one of the four main tissue systems in plants.

Auxins

A plant hormone that causes the elongation of cells in shoots and is involved in regulating plant growth

Phototropism

Directional growth in which the direction of growth is determined by the direction of the light source. In other words, it is the growth and response to a light stimulus.

Indoleacetic Acid

A plant hormone promoting elongation of stems and roots and plays a role in phototropism.

Geotropism

The growth of the parts of plants with respect to the force of gravity.

Negative Geotropism

The upward growth of plant shoots.

Positive Geotropism

The downward growth of roots.

Gibberellins

Any of a group of plant hormones that stimulate stem elongation, germination, and flowering.

Kinins

Any of a group of substances formed in body tissue in response to injury. They are polypeptides and cause vasodilation and smooth muscle contraction

Kinetin

A kind of cytokinin, a class of plant hormone that promotes cell division.

Senescence

The condition or process of deterioration with age (induced by ethylene).

Abscisic Acid

A plant hormone that promotes leaf detachment, induces seed and bud dormancy, and inhibits germination.

Anti-Auxins

Regulates the activity of auxins.

Indoleacetic Acid Oxidase

Regulates indoleacetic acid and is an anti-auxin.

Mineralocorticoids

ex) aldosterone; regulates levels of sodium and potassium and therefore the total extracellular water volume; aldosterone causes active reabsorption of sodium and passive reabsorption of water in the nephron; causes increase in blood volume and increase in blood pressure

Nephron

Any of the small tubules that are the excretory units of the vertebrate kidney

Cortical sex hormones

Adrenal cortex secretes small quantities of androgens (male sex hormones) in both males and females; in males, most androgens secreted by testes and the adrenal cortex has little effect but in females, overproduction of androgens by adrenal cortex can cause masculine characteristics ( like facial hair)

Androgens

Male sex hormones

Adrenal Medulla

Produces epinephrine (adrenaline) and norepinephrine (noradrenaline)

Catecholamines

Class of amino acid derivatives that epinephrine and norepinephrine belong to

Epinephrine - physiological details

Increases conversion of glycogen to glucose in liver and muscle tissue which increases the blood glucose and basal metabolic rate

Epinephrine and Norepinephrine Overall Effects

Increases rate and strength of heart beat; shunts blood to skeletal muscle, heart and brain; causes "fight or flight" response; controlled by sympathetic nerve system; also neurotransmitters in addition to hormomes

Pituitary Gland (hypophysis)

Small, 3-lobed gland at base of brain; 2 main lobes = anterior and posterior; in humans the third intermediate lobe is rudimentary

Anterior Pituitary

Releases both direct and trophic hormones; is regulated by hypothalamic secretions ("releasing/inhibiting hormones or factors); FLAT PIG = FSH;LH; ACTH; Prolactin; (I)gnore; GH

Direct Hormones

Hormones which effect target organs; those released from anterior pituitary = Prolactin and GH

Trophic Hormones

Hormones that stimulate other endocrine glands to release hormones; those released from the anterior pituitary= FSH, LH, ATCH,TSH

GH

Secreted directly by anterior pituitary; Growth Hormone, aka Somatotrophin; promotes bone and muscle growth

Dwarfism

Stunted growth, in children lack of GH

Gigantism

Overproduction of GH in children

Acromegaly

Overproduction of GH in adults; results in a disproportionate overgrowth of bone, localized especially in the skull, jaw, feet, hands

Prolactin

Secreted directly by anterior pituitary; stimulates milk production and secretion in female mammary glands

ACTH

Adrenocorticotrophic hormone; stimulates adrenal cortex to syntesize and secrete glucocorticoids; regulated by releasing hormone corticotrophin-releasing factor (CRF)

CRF

Corticotrophin-releasing factor; regulates anterior pituitary's trophic hormone ACTH

TSH

Thyroid stimulating hormone; stimulates thyroid gland to synthesize and release thyroid hormones, including thyroxin (hormone produced by the thyroid glands to regulate metabolism by controlling the rate of oxidation in cells)

LH

Luteinizing hormone; females: stimulates ovulation and formation of corpus luteum; males: stimulates interstitial cells of testes to synthesize testosterone

FSH

Follicle-stimulating hormone; females: causes maturation of ovarian follicles which begin secreting estrogen; males: stimulates maturation of seminiferous tubules and sperm production

MSH

Intermediate lobe of the pituitary; in mammals its function is unclear; in frogs, MSH causes darkening of the skin via induced dispersion of molecules of pigment in melanophore cells

Posterior Pituitary (neurohypophysis)

Does not synthesize hormones; stores and releases peptide hormones oxytocin and ADH which are produced by neurosecretory cells of hypothalamus; hormone secretion is stimulated by action potentials from hypothalamus

Oxytocin

Synthesized by neurosecretory cells of hypothalamus; transported via axons; stored and released by posterior pituitary; secreted during childbirth; increases the strength and frequency of contractions; secretion induced by suckling; stimulates milk secretion in mammary glands

ADH/ Vasopressin (Antidiuretic hormone)

Synthesized by neurosecretory cells of hypothalamus; transported via axons; stored and released by posterior pituitary; increases permeability of nephron's collecting duct to water which promotes water reabsorption; which increases blood volume; it is released when plasma osmolarity increases or blood volume decreases

Hypothalamus

Part of forebrain, located above pituitary gland; neurosecretory cells in hypothalamus regulate pituitary gland secretions by negative feedback mech. and through the actions of inhibiting and releasing hormones

Hypothalamic- hypophyseal portal system; System that allows releasing hormones from hypothalamus to immediately reach anterior pituitary

blood from capillary bed in hypothalamus flows through a portal vein into the anterior pituitary where it goes into a second capillary network

Thyroid

2-lobed, located ventral surface of trachea; produces and secretes thyroxin and triiodothyronine (the two thyroid hormones) and calcitonin

Thyroid hormones

Thyroxine (T4) and triiodothyronine (T3); necessary in children for growth and neurological development; increases rate of metabolism throughout body

Hypothyroidism

Thyroid hormones (thyroxine and triiodothyronine) are undersecreted or not at all; symptoms: slow h.r., resp. rate, fatigue, cold intolerance, weight gain; thyroid often enlarges (as with hyperthyroidism) and forms a bulge in neck;called cretinism in infants

Cretinism

Hypothyroidism in infants; characterized by short stature and mental retardation

Hyperthyroidism

Thyroid over stimulated, hormones over secreted; symptoms: increased metabolic rate, feelings of excessive warmth, profuse sweating, palpitations, weight loss, protruding eyes; thyroid often enlarges (as with hypothyroidism) and forms a bulge in neck

Calcitonin

Decreases plasma Ca2+ concentration by inhibiting Ca2+ release from bone; regulated by plasma Ca2+ levels; antagonistic to parathyroid hormone

Pancreas

Both an exocrine (secretes digestive enzymes into small intestine via series of ducts) and endocrine organ ( islets of Langerhans)

Islets of Langerhans

Alpha cells produces/ secrete glucagone; Beta cells produce/ secrete insulin

Glucagon

Stimulates protein and fat degradation; conversion of glycogen to glucose and gluconeogenesis; all of which increases blood glucose levels; antagonistic to insulin

Insulin

Secreted in response to high blood glucose; stimulates uptake of glucose by muscle and adipose cells and storage of glucose as glycogen in muscle and liver cells; stimulates synthesis of fats from glucose and stimulates uptake of amino acids; decreases blood glucose level; antagonistic to glucagon and glucocorticoids

Parathyroid Glands

Located on posterior surface of thyroid; synthesize and secrete PTH

PTH

Increases [Ca2+] in blood by increasing bone resorption and decreases Ca2+ excretion in kidneys; calcium is bonded to phosphate in bone and breakdown of bone releases phosphate as well as calcium so parathyroid compensates by stimulating kidneys to excrete phosphate

Kidneys and the Endocrine System

As blood volume decreases, kidneys produce renin, renin converts plasma protein angiotensinogen to angiotensin 1, angiotensin 1 converted to angiotension 2, angiotension 2 stimulates adrenal cortex to secrete aldosterone, aldosterone increases blood volume by reabsorbing calcium at the kidney which increases water

Gastrin gastrointestinal hormone

Food stimulates stomach to release gastrin which stimulates gastric glands to release HCl

Secretin

Hormone released by small intestine when acidic food from stomach enters, stimulates secretion of alkaline bicarbonate solution from pancreas which neutralizes the acidity of chyme

Cholecystokinin

Hormone release from small intestine in response to presence of fats, causes contraction of gall bladder and release of bile to small intestine (to aid in digestion of fats)

Pinal Gland

Located at base of brain, secretes melatonin

Melatonin

Functions in humans is unclear (thought to be involved in circadian rhythms; secretion regulated by light and dark cycles in environment; in primitive vertebrates, melatonin lightens skin by concentrating pigment granules in melanophores (antagonistic to MSH)

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