click below
click below
Normal Size Small Size show me how
endocrine system
Anatomy & Physiology
Question | Answer |
---|---|
endocrine system | regulates and controls metabolic processes, helps maintain body homeostasis (i.e. maintaining blood glucose levels during erratic food intake), and serves as one of the two major control systems of the body (with the nervous system) |
endocrine system composition | endocrine glands located throughout the body (i.e. synthesize and secrete hormones that are released into the blood and transported through the body) |
target cells of the endocrine system | cells with a specific receptor for a hormone, bind hormone (initiates and inhibits selective cell activities) |
functions of the endocrine system | maintaining homeostasis of blood composition and volume, controlling reproductive activities, regulating development, growth, and metabolism, and controlling digestive processes |
maintaining homeostasis of blood composition and volume | regulate amount of substances dissolved in blood and regulate blood volume, cellular concentration, and platelet number |
controlling reproductive activities | affect development and function |
regulating development, growth, and metabolism | regulatory roles in embryonic cell division and differentiation and involved in catabolism and anabolism of proteins, carbohydrates and lipids |
controlling digestive processes | influence secretory processes and influence movement through digestive tract |
endocrine organs are... | scattered throughout the body |
types of endocrine organs | pure endocrine organs and organs that contain endocrine cells |
pure endocrine organs | pituitary, pineal, thyroid, parathyroid, and adrenal glands |
organs containing endocrine cells | pancreas, thymus, gonads, and the hypothalamus |
endocrine reflexes | regulated secretion of hormone controlled through reflex, preprogrammed response to certain stimuli, and initiated by three types of stimulation |
three types of stimulation | hormonal, humoral, and nervous |
hormonal stimulation | release of a hormone in response to another hormone |
hormonal stimulation example | thyroid stimulating hormone released from anterior pituitary which stimulates thyroid gland to secrete thyroid hormone |
humoral stimulation | response to changing levels of nutrients or ions - hormones act on target cells to offset further loss or eliminate excess (due to changes of hormonal levels in human body) |
nervous stimulation | release of epinephrine and norepinephrine by adrenal medulla in response to sympathetic nervous stimulation |
control of hormone secretions | always controlled by feedback loops |
negative feedback | blood concentration declines below a minimum (more hormone is secreted) and blood concentration exceeds maximum (hormone production is halted) |
positive feedback | blood concentration of hormones increase (even more hormones are secreted) |
pure endocrine organs | single organ that is entirely endocrine in function |
pure endocrine organs include | pituitary gland, thyroid gland, parathyroid gland, pineal gland, and adrenal glands |
pituitary gland | attached to the hypothalamus and has two basic divisions |
two basic divisions of the pituitary gland | anterior lobe and posterior lobe |
anterior lobe | growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, melanocyte-stimulating hormone, gonadotropins, and prolactin |
posterior lobe | antidiuretic hormone, oxytocin |
growth hormone | stimulates cell growth and cell division, stimulates body growth by stimulating increased protein production and growth of epiphyseal plates, and particularly affects skeletal and muscular system |
thyroid-stimulating hormone | signals thyroid gland to secrete hormone for regulation of metabolism |
adrenocorticotropic hormone (ACTH) | stimulates adrenal cortex to stimulate hormones that help cope with stress (stimulates adrenal gland) |
melanocyte-stimulating hormone (MSH) | stimulates rate of melanin-synthesis by melanocytes in skin, and functions in appetite suppression |
gonadotropins | follicle-stimulating hormone and luteinizing hormone, regulate hormone synthesis by gonads, and regulate production and maturation of gametes |
prolactin | targets milk-producing glands in the breast - stimulates milk production |
posterior lobe | does not make hormones, stores and releases hormones made in the hypothalamus, and releases two hormones |
antidiuretic hormone (ADH) | targets kidneys to reabsorb water |
oxytocin | induces smooth muscle contraction of reproductive organs, ejects milk during feedings, and signals contraction of the uterus during childbirth |
thyroid gland | located in the anterior neck, largest pure endocrine gland, and produces two hormones |
thyroid hormone (TH) | increases basal metabolic rate |
calcitonin | lowers calcium blood levels when they are too high |
parathyroid glands | lie on the posterior surface of the thyroid gland, produce parathyroid hormone |
parathyroid hormone (PTH) | regulate blood concentration of calcium (released in response to decreased blood calcium levels and returns blood calcium to normal levels) |
pineal gland | located on the roof of the diencephalon, shaped like a pine cone and is composed primarily of pinealocytes secreting melatonin |
melatonin | hormone that regulates circadian rhythms, makes us drowsy, cyclic production with increased levels at night, and affects synthesis of hypothalamic hormone |
adrenal (suprarenal glands) | pyramid-shaped glands located on the superior surface of each kidney that is two endocrine glands in one |
two endocrine glands in the adrenal gland | adrenal medulla and adrenal cortex |
adrenal medulla | part of the sympathetic nervous system, forms inner core of each adrenal gland, red-brown color due to extensive blood vessels, and released epinephrine and norepinephrine with sympathetic stimulation |
adrenal cortex | derived from somatic nervous system, synthesizes more than 25 corticosteroids, yellow color due to lipids within cells, and three regions producing different steroid hormones |
adrenal medulla | secrete amine hormones epinephrine and norepinephrine |
epinephrine and norepinephrine | enhance "fight-or-flight" response |
adrenal coretex | secrete corticosteroids |
corticosteroids | mineralocorticosteriods, glucocorticoids, and gonadocorticoids |
mineralocorticoids | aldosterone |
aldosterone | secreted in response to decline in blood volume or blood pressure, stimulates sodium retention and potassium secretion |
glucocorticoids | corisol and corticosterone |
cortisol and corticosterone | helps the body deal with stressful situations, repair damaged tissue |
gonadocorticoids | androgen |
androgen | male sex hormones (small amounts) |
organs that contain endocrine cells | thymus, gonads, pancreas, and hypothalamus |
thymus | located in the lower neck and anterior thorax, important immune organ, site at which T-lymphocytes mature, and secretes thymic hormones |
the gonads | main sources of sex hormones - androgens |
gonads - organs | testes and ovaries |
testosterone | promotes the formation of sperm and maintains secondary sex characteristics |
male sex hormone | testosterone |
female sex hormone | estrogen and progesterone |
estrogen | maintain secondary sex characteristics |
progesterone | prepares the uterus for pregnancy |
pancreas characteristics | elongated organ between duodenum and spleen, posterior to the stomach, performs exocrine and endocrine activities, mostly composed of groups of cells, pancreatic acini (secreted through pancreatic ducts into small intestine) |
pancreatic islet cells | small clusters of endocrine cells scattered among acini, composed of two primary cell types |
two primary cell types of the pancreatic islet cells | alpha cells and beta cells |
other minor cell types (delta cells and F cells) of the pancreas | secretes somatostatin and pancreatic polypeptide respectively |
digestive hormones of the pancreas | glucagon, insulin, somatostatin, and pancreatic polypeptide |
glucagon | signals liver to release glucose from glycogen, raises blood sugar |
insulin | signals most body cells to take up glucose from the blood, promotes storage of glucose as glycogen in liver, and lowers blood sugar |
somatostatin | inhibits secretion of insulin and glucagon |
pancreatic polypeptide | regulates pancreatic secretions |
blood glucose concentration | pancreatic endocrine function - maintaining normal blood glucose, normal range 70-110 mg of glucose/deciliter, chronically high levels damaging to blood vessels & kidneys, low levels result in lethargy, mental & physical impairment, & death (if too low) |
hypothalamus | influences or controls many endocrine glands, has direct control over hormone release from pituitary gland, has indirect control over hormone release from thyroid and adrenal glands, liver, testes, and ovaries |
two hormones stored in posterior pituitary | oxytocin and antidiuretic hormone (ADH) |
hormones stored in the posterior pituitary | nerve signal sent from hypothalamus, hormones released into bloodstream from posterior pituitary |
hormones of hypothalamus | termed regulatory hormones, releasing hormones, or inhibiting hormones |
regulatory hormones | secreted into blood to regulate anterior pituitary hormones |
releasing hormones | stimulate secretion of specific anterior pituitary hormones |
inhibiting hormones | deter secretion of specific anterior pituitary hormones |
six major hormones of the anterior pituitary | growth hormone, thyroid-stimulating hormone, adrenocorticotropic hormone, melanocyte-stimulating hormone, gonadotropins, prolactin |
hormones of the hypothalamus | thyrotropin-releasing hormone, prolactin-releasing hormone, gonadotropin-releasing hormone, corticotropin-releasing hormone, growth hormone-releasing hormone |
thyrotropin-releasing hormone | increases secretion of thyroid-stimulating hormone |
rolactin-releasing hormone | increases secretion of prolactin |
gonadotropin-releasing hormone | increases secretion of follicle-stimulating hormone and luteinizing hormone |
corticotropin-releasing hormone | increases secretion of adrenocorticotropic hormone |
growth hormone-releasing hormone | increases secretion of growth hormone |
growth hormone characteristics | release controlled by growth hormone-releasing hormone (GHRH) and this release is influenced by age, time of day, nutrient levels, stress, and exercies |