Unit 5
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myragarcia on March 2, 2012
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Endocrine system
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208 terms
Terms | Definitions |
|---|---|
 Characteristics of an Endocrine gland: | -do not have a duct -make an internal secretion (into blood vessel) -secrete hormones into the blood to be carried elsewhere |
| Organs that release hormones are collectively called: | Endocrine system |
| Paracrine | A chemical that is secreted by a cell to act locally on neighboring cells |
| Autocrine | chemical signal that acts on the cell that secreted it |
| Review of Neurotransmitters: | -chemicals secreted by neurons of the nervous system -use receptors -short-lived (broken down quickly; short term effects) |
| Hormones: | chemicals secreted by endocrine glands |
| Neurohormones: | chemicals secreted by neurons of the nervous system |
| Neuroendocrine organs: | organs (e.g. the hypothalamus) that contain nuerohormones |
| Neurohormones and hormones are carried in the | blood to target cells with receptors for the given hormone |
| Both hormones and neurohormones are | long-lived (long lasting effects) |
| Hormones and neurohormones act as | chemical messengers |
| Hormones and neurohormones share the following properties: | -produced by specific secretory cells (specialized cells) -secreted into the blood, present in very low concentrations -released in response to a specific stimulus -exert a specific effect on target tissue(s) some distance from the gland -are required in low concentrations -important in control of various physiological systems, functions, and maintaining homeostasis |
| Hormones and neurohormones achieve their effect by controlling: | -the rate of enzymatic reactions -the transport of ions or molecules across cell membranes -or gene expression (transcription) and synthesis of proteins (translation) |
| Types of hormones: | peptides, amines, and steriods |
| Peptides: | chains of amino acids (most hormones are this) |
| Amines: | all are constructed from the amino acid tyrosine 1. catecholamines - include epinephrine, norepinephrine, and dopamine 2. thyroid hormones |
| Steroids: | all are derivatives of cholesterol |
| 2 hormones that are water-soluble are: | catecholamines and peptides |
| 2 hormones that are lipid-soluble are: | thyroid hormones and steroids |
| water-soluble hormone characteristics: | -dissolved in plasma of blood for transport -location of target receptors in on cell membrane -bonding to receptor causes activation of second messenger systems -are made in advance and stored in secretory vesicles -released by exocytosis -duration of action = minutes (short half-life) |
| lipid-soluble hormone characteristics: | -bound to carrier proteins in blood for transport -location of target receptors in cytoplasm or nucleus of cell -bonding to receptor causes activation of genes for transcription and translation -released by simple diffusion -duration of action = hours (long half-life) |
| steroid hormones are made | on demand |
| thyroid hormones are made | in advance and stored |
| The pituitary gland, aka: | hypophysis |
| The hypophysis is composed of an anterior lobe and a posterior lobe that are also known as: | anterior lobe = andenohypophysis & posterior lobe = neurohypophysis. histologically VERY different! |
| adenohypophysis is made up of | glandular tissue |
| neurohypophysis is made up of | neural tissue |
| the hypothalamus of the brain produces inhibiting and releasing hormones that affect the | adenohypophysis |
| Releasing hormones are also known as: | tropic hormones |
| examples of tropic hormones produced by the hypothalamus are: | thyrotropin-releasing hormone (TRH) and corticotropin-releasing hormone (CRH) |
| characteristics of adenohypophysis: | -produces several different tropic hormones with various targets in the body -the tropic hormone is transported from the hypothalamus to the adenohypophysis via the hypothalamic-hypopyseal portal system causing the release of a different hormone from the adenohypophysis |
| the adenohypophysis releases 6 different hormones: | growth hormone (GH), thyroid-stimulating hormone (TSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and prolactin (PRL) |
| tropic hormones cause the release of | other hormones. (e.g. thyrotropin-releasing hormone (TRH) from the hypothalamus causes the release of thyroid-stimulating hormone (TSH)from the adenohypophysis, which in turn causes the release of another hormone from the thyroid gland) |
| characteristics of neurohypophysis : | -does not have a portal-vein system connected to the hypothalamus -hormones released by nuerohypophysis are actually produced in expansions of hypothalamic neurons |
| hormones released by the neurohypophysis: | vasopressin (antidiuretic hormone - ADH), oxytocin |
| vasopressin is also known as: | antidiuretic hormone (ADH) |
| Vasopression (ADH) affects the | kidneys and blood vessels |
| Vasopressin (ADH) leads to | reabsorption of water in the kidneys and thus helps the body to retain fluid; also helps control blood pressure |
| Oxycotin causes | contraction of the uterus during childbirth and milk ejection |
| thyroid hormones are produced by the | thyroid gland |
| thyroid gland: | butterfly-shaped gland that lies across the trachea, just below the larynx |
| thyroid gland contains 2 different cell types: | C (clear) cells & follice cells |
| C "clear" cells secrete the hormone | calcitonin |
| follicle cells form the | outer wall of the thyroid follicles and secrete thyroid hormones |
| thyroid hormones have long-term effects on | metabolism and target most cells of the body |
| thyroid hormones are amines derived from the amino acid | tyrosine |
| the thyroid hormones ____ & ____ contain the element iodine. | Triiodothyronine (T3) - contains 3 iodines & Thyroxine (T4) - contains 4 iodines |
| Synthesis of thyroid hormones takes place in the | thyroid follicles |
| thyroid follicles are composed of walls made of a single layer of epithelial cells (follicle cells) and a hollow center filled with a sticky protein mixture called | colloid |
| colloid holds a 2-3 month supply of | thyroid hormones |
| hypothalamus secretes thyrotropin-releasing hormone (TRH) into the | hypothalamic-hypophyseal portal system |
| TRH stimulates the release of thyroid-stimulating hormone from the | adenohypophysis (anterior pituitary gland) |
| TSH acts on the thyroid gland to promote | thyroid hormone (T3 & T4) synthesis |
| T3 acts as a negative feedback signal to inhibit | TRH and TSH secretion |
| as the thyroid hormone is created it acts to inhibit the | tropic hormones which created it |
| Goiters | huge mass; excessive TSH levels can lead to this |
| the normal tropic action of TSH on the thyroid gland causes hypertrophy or enlargement of the | follicle cells |
| both ___ & ___ can lead to a goiter | hypothyroidism & hyperthyroidism |
| hypothyroidism | is due to low iodine |
| without iodine _____ cannot be produced | thyroid hormones (T3 & T4) |
| hypothyroidism slows | metabolic rate and oxygen consumption; may also experience slow heart rate |
| in hypothyroidism, protein synthesis is decreased and this causes: | brittle nails, thinning hair, and dry, thin skin in adult; children with condition have slow bone and tissue growth and are shorter than normal. |
| symptoms for hypothyroidism also include: | slowed reflexes, slow speech and thought processes, and feelings of fatigue |
| Hyperthyroidism: | hyper secretion of thyroid hormones causes changes in metabolism, nervous system and heart |
| hyperthyroidism increases | oxygen consumption, metabolic heat production, and protein catabolism (may cause muscle weakness) |
| hyperthyroidism causes | psychological disturbances ranging from irritability and insomnia to psychosis and rapid heart rate |
| an autoimmune disease and an example of hyperthyroidism causing a goiter | grave's disease |
| in graves' disease negative feedback action of T3 shuts down TRH and TSH secretion but does not block the action of antibodies called | thyroid-stimulating immunoglobulins (TSI) (causes enlargement on thyroid gland) |
| Graves' disease is often accompanied by | exophthalmos |
| exophthalmos: | bulging of the eyes from the enlargement of muscles and tissues of the eye socket |
| parathyroid glands: | a cluster of small glands on the posterior of the thyroid gland |
| the parathyroid glands secrete the peptide hormone | PTH (parathyroid hormone) |
| PTH is secreted in response to a drop in blood calcium levels; it acts to | raise blood calcium levels |
| PTH targets: | kidneys - causing an increased reabsorption of calcium, and bone - causing an increased breakdown of bone and release of its stored calcium |
| PTH stimulates | osteoclast activity |
| PTH stimulates the conversion of vitamin D to | calcitriol |
| calcitriol | regulates calcium absorption |
| each adrenal gland has two distinct tissues: | adrenal medulla and adrenal cortex |
| adrenal medulla is composed of modified sympathetic ganglia that secrete the | catecholamines (epinephrine and norepinephrine) |
| adrenal medulla contributes to the | sympathetic "fight or flight" response |
| adrenal cortex for the outer | 3/4 of the adrenal gland |
| the adrenal cortex secretes a variety of steroid hormones including: | aldosterone, glucocorticoids (e.g. cortisol), and sex hormones (e.g. androgens) |
| glucocorticoids increase | plasma glucose concentrations |
| all steroid hormones begin with | cholesterol |
| all steroid hormones end up as | aldosterone, glucocorticoids, or sex hormones |
| because steroid hormones are structurally similar... | the binding sites for the receptors on their target cells are also similar thus crossover effects can occur |
| crossover effects mean that | a hormone can sometimes bind to a receptor for a related molecule |
| crossover effects complicates | diagnosing endocrine pathologies |
| cortisol: | a steroid hormone produced by the adrenal cortex; essential for life |
| all nucleated cells in the body have receptors in their cytoplasm for this hormone; thus having wide-ranging effects on the body | cortisol |
| control pathway for cortisol secretion (1): | hypothalamus secretes corticotropin-releasing hormone (CRH) in hypothalamic-hypophyseal portal system |
| control pathway for cortisol secretion (2): | CRH stimulates the release of adrenocorticotropic hormone (ACTH) from the anterior pituitary (adenohypophysis) |
| control pathway for cortisol secretion (3): | ACTH acts on the adrenal cortex to promote synthesis and release of cortisol |
| control pathway for cortisol secretion (4): | cortisol acts as a negative feedback signal to inhibit ACTH and CRH secretion |
| other factors controlling cortisol secretion: | circadian rhythm (peaks in morning / diminishes during night) & stress increases cortisol secretion |
| the effects of cortisol on the body: | -mediation of long-term stress on body -required for other hormones to be effective -catabolic (breaks down) -protects against hypoglycemia (low blood glucose) -suppresses immune system -influences brain function (mood changes and alteration in memory and learning) |
| aldosterone targets the ____ and causes ____ | kidneys; reabsorption of sodium and the secretion of potassium |
| the pancreas is both an | endocrine and an exocrine gland |
| the exocrine portion of the pancreas produces | digestive enzymes |
| comprise the endocrine portion of the pancreas | islet of langerhans |
| two major hormones secreted by the islet of langerhans: | insulin and glucagon |
| insulin is produced by the | beta cells |
| insulin stimulates the uptake of glucose into the cells of the body thereby: | lowering the blood glucose levels |
| insulin stimulates | glycogen synthesis (glucose storage) by the liver and triglyceride synthesis (fat storage) by adipose cells |
| insulin is secreted after | a meal when blood glucose levels are high |
| glucagon is produced by the | alpha cells |
| glucagon stimulates the breakdown of glycogen by the liver and the synthesis of glucose thereby | raising blood glucose levels |
| glucagon is secreted | between meals when blood sugar levels have dropped |
| diabetes mellitus | results from either hyper secretion or hypo activity of insulin |
| when insulin is absent or deficient, blood glucose levels... | remain high after a meal because glucose is unable to enter most tissue cells |
| gonads = | ovaries and testes |
| ovaries secrete the female steroid sex hormones: | estrogen and progesterone |
| estrogen is important for | egg development inside the ovarian follicles and has effects throughout the body |
| progesterone is important after ovulation for maintaining | the integrity of the uterine lining, and during pregnancy |
| testes secrete the male steroid sex hormone | testosterone |
| testosterone aids in the development of ____ and is responsible for ____ | gametes; secondary sex characteristics (controls libido) |
| pineal gland is located in the | diencephalon of the brain |
| pineal gland produces the amine hormone: | melatonin in response to darkness |
| melatonin helps to maintain proper | circadian rhythms (sleep-wake cycles) |
| melatonin helps in the control of the body's | "biological clock" |
| melatonin is also a powerful | antioxidant (protection against free radicals) |
| the thymus is located | anterior to the aorta of the heart |
| the thymus is ____ at birth and ____ in size until puberty | large; increases |
| the thymus ____ in size until being almost ____ in adults | decreases; unnoticeable |
| the thymus secretes the peptide hormones: | thymosin and thymopoietin |
| thymosin and thymopoietin play a role in the development of | T cells (lymphocytes) and normal function of the immune system |
| other hormone-producing structures: | heart, gastrointestinal tract, placenta, kidneys |
| the atria of the heart have some specialized cardiac muscle cells that secrete: | atrial natriuretic peptide |
| atrial natriuretic peptide reduces | blood volume, blood pressure, and blood sodium concentration by signaling the kidneys to increase production of salty urine and by inhibiting release of aldosterone by the adrenal cortex |
| gastrointestinal tract release several peptide hormones that help regulate a wide variety of | digestive functions |
| placenta secretes several | steroid and protein hormones that influence the course of pregnancy |
| kidneys secrete | erythropoietin and renin |
| erythropoietin is secreted from kidneys in response to | low oxygen levels in kidney tissues |
| erythropoietin signals the | bone marrow to increase production of red blood cells |
| renin initiates the | renin-angiotensin mechanism |
| Anterior pituitary gland secretes: | TSH, ACTH, FSH, LH, Prolactin, GH |
| TSH Targets: | thyroid gland |
| TSH hormonal effects: | triggers release of thyroid hormones |
| TSH regulated by: | TRH secreted from the hypothalamus |
| ACTH targets: | adrenal cortex |
| ACTH hormonal effects: | glucocorticoid secretion |
| ACTH regulated by: | CRH from hypothalamus |
| FSH targets: | follicles in the ovaries/testes |
| FSH hormonal effects: | follicle growth and estrogen secretion/sperm production |
| FSH regulated by: | GnRH from hypothalamus |
| LH targets: | follicles in the ovaries/testes |
| LH hormonal effects: | ovulation and corpus luteum formation / promotes testosterone production |
| LH regulated by: | GnRH from the hypothalamus |
| Prolactin targets: | mammary glands |
| Prolactin hormonal effects: | promotes milk production |
| Prolactin regulated by: | PRH and PIH from hypothalamus |
| GH (growth hormone) targets: | all cells |
| GH (growth hormone) hormonal effects: | growth, protein synthesis, lipid catabolism |
| GH (growth hormone) regulated by: | GHRH and GHIH from the hypothalamus |
| Posterior pituitary secretes: | ADH & Oxytocin |
| ADH targets: | kidneys |
| ADH hormonal effects: | reabsorption of water, increased blood volume |
| ADH regulated by: | osmoreceptors in the hypothalamus |
| oxytocin targets: | uterus and mammary glands |
| oxytocin hormonal effects: | labor contractions and milk ejection |
| oxytocin regulated by: | uterine stretch and nipple stimulation |
| thyroid gland secretes: | T3 & T4 and calcitonin |
| T3 & T4 targets: | most cells |
| T3 & T4 hormonal effects: | increased metabolism |
| T3 & T4 regulated by: | TSH from the anterior pituitary |
| Calcitonin targets: | bone and kidneys |
| Calcitonin hormonal effects: | decreases blood Ca++ levels |
| Calcitonin regulated by: | elevated blood Ca++ levels |
| parathyroid secretes: | PTH |
| PTH targets: | bone and kidneys |
| PTH hormonal effects: | increases blood Ca++ levels |
| PTH regulated by: | low blood Ca++ levels |
| Adrenal cortex secretes: | aldosterone, cortisol, androgens |
| aldosterone targets: | kidneys |
| aldosterone hormonal effects: | increased Na+ and water reabsorption |
| aldosterone regulated by: | low Na+ and angiotensin II |
| cortisol targets: | most cells |
| cortisol hormonal effects: | glucose, amino acid, and lipid metabolism |
| cortisol regulated by: | ACTH from the anterior pituitary |
| androgens target: | uncertain |
| androgens hormonal effects: | female sex drive, development of pubic and axillary hair (females) |
| androgens regulated by: | ACTH from the anterior pituitary |
| adrenal medulla secretes: | epinephrine |
| epinephrine targets: | most cells |
| epinephrine hormonal effects: | increases heart rate, BP, blood glucose levels |
| epinephrine regulated by: | sympathetic stimulation |
| pancreas secretes: | insulin and glucagon |
| insulin targets: | most cells |
| insulin hormonal effects: | facilitates uptake of glucose into target cells; glycogen production |
| insulin regulated by: | high blood glucose |
| glucagon targets: | liver and adipose tissues |
| glucagon hormonal effects: | glycogen breakdown in liver |
| glucagon regulated by: | low blood glucose levels |
| testis secrete: | testosterone |
| testosterone targets: | most male cells |
| testosterone hormonal effects: | sperm development, secondary sex characteristics |
| testosterone regulated by: | FSH and LH from anterior pituitary |
| ovaries secrete: | estrogen & progesterone |
| estrogen targets: | most female cells |
| estrogen hormonal effects: | follicle development, secondary sex characteristics |
| estrogen regulated by: | FSH and LH from anterior pituitary |
| progesterone targets: | uterus and mammary glands |
| progesterone hormonal effects: | prepares uterus for implantation, aids in development of mammary glands |
| progesterone regulated by: | LH from anterior pituitary |
| pineal gland secretes: | melatonin |
| melatonin targets: | uncertain |
| melatonin hormonal effects: | affects the "biological clock" by resetting the clock timing |
| melatonin regulated by: | light stimulating visual pathways to pineal gland |
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