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APHY 201 Exam 5a
Ch. 11 Part 1, Endocrine Glands - Secretion and Action of Hormones
| Question | Answer |
|---|---|
| What are the 4 mechanisms of cell communication? | The mechanisms of cell communication include gap junctions, neurotransmitters, paracrine (local) hormones, and hormones. |
| What are the main components of the endocrine system? | The endocrine system includes endocrine organs like the thyroid and pineal glands, as well as hormone-producing cells in organs such as the brain, heart, and small intestine. |
| How do endocrine glands differ from exocrine glands structurally? | Exocrine: ducts carry secretions (enzymes, mucus) w/ extracellular effects (food digestion), endocrine: no ducts, release hormones into tissue fluids and dense capillary networks w/ intracellular effects that alter target cell metabolism |
| 8-9 major organs of endocrine system | pituitary gland, pineal gland, thyroid gland, parathyroid glands, thymus, adrenal glands, pancreas, gonads (ovaries and testes) |
| How does the speed of response differ between the nervous and endocrine systems? | The nervous system reacts quickly within 1 to 10 milliseconds and stops quickly, while the endocrine system reacts slowly over seconds or days and can have effects lasting for weeks. |
| what are the 4 categories of difference between nervous and endocrine systems? | means of communication, speed and persistence of response, adaptation to long-term stimuli, area of effect |
| how do the nervous and endocrine systems differ regarding their means of communicaton? | nervous system has both electrical and chemical methods, endocrine system has only chemical methods |
| how do the nervous and endocrine systems differ regarding adapation to long-term stimuli? | nervous system adapts quickly and response declines; endocrine system has more persistent responses |
| how do the nervous and endocrine systems differ regarding area of effect? | nervous system effects are targeted and specific (one organ); endocrine system may have general, widespread effects on many organs |
| Which 5 chemicals function as both neurotransmitters and hormones? | Norepinephrine, cholecystokinin, thyrotropin-releasing hormone (TRH), dopamine, and antidiuretic hormone (ADH) function as both. |
| what are 2 groups/hormones secreted by neuroendocrine cells? | oxytocin and catecholamines (!) |
| what are similarities in nervous and endocrine systems? | several chemicals function as both hormones and neurotransmitters, some hormones are secreted by neuroendocrine cells, both systems with overlapping effects on same target cells, systems regulate each other |
| what are 2 examples of nervous and endocrine systems having overlapping effects on the same target cells? | NE from nervous system and glucagon from the endocrine system both cause glycogen hydrolysis in liver |
| how do the nervous and endocrine systems regulate each other? | neurons trigger hormone secretion; hormones stimulate or inhibit neurons |
| which structure is shaped like a flattened funnel and forms the floor and walls of the third ventricle in the diencephalon? | The hypothalamus |
| what does the hypothalamus regulate (7 on list)? | temperature, hunger, thirst, sleep-wake cycles, blood pressure, stress responses, and hormone production through the pituitary gland. |
| Which nuclei in the hypothalamus drive the synthesis of ADH and oxytocin? | The paraventricular and supraoptic nuclei drive the synthesis of antidiuretic hormone (ADH) and oxytocin, respectively. |
| Where is the pituitary gland (hypophysis) housed and how is it attached to the hypothalamus? | The pituitary gland is housed in the sella turcica of the sphenoid bone and is suspended from the hypothalamus by a stalk called the infundibulum. |
| From which embryological tissues do the 2 lobes of the pituitary gland originate? | The anterior adenohypophysis grows up from the pharynx (pars distalis, pars tuberalis, and in the fetus the pars intermedialis), while the posterior neurohypophysis grows down from the developing brain (pars nervosa). |
| What is the primary function of tropic hormones? | Tropic hormones target other endocrine glands to promote their growth and maintain them. |
| Gonads are targeted by what 2 gonadotropins? | FSH and LH |
| what are the 5 tropic hormones according to Fox's textbook? | gonadotropins FSH and LH, TSH, ACTH, GH |
| Which anterior pituitary hormone is not classified as a tropic hormone? | Prolactin (PRL) is an anterior pituitary hormone but is not classified as a tropic hormone. |
| the posterior pituitary lobe does not produce hormones; it stores and releases oxytocin and ADH. where are these hormones produced? | in the hypothalamus. |
| what are cells of the anterior pituitary that produce the tropic hormones? (hint: -trope cells) | gonadotropes, thyrotropes, corticotropes, somatotropes, lactotropes |
| (starred) which nuclei produce oxytocin (OT) and ADH? | paraventricular and supraoptic nuclei, respectively and then they are transported down to posterior lobe by hypothalamo-hypophyseal tract |
| what are the anterior pituitary hormones? | FSH, LH, ACTH, TSH, PRL, MSH, GH (FLAT PeG) |
| What is thyroid-stimulating hormone (TSH) secreted by and what role does it play? | Secreted by thyrotropes, TSH stimulates the growth of the thyroid gland and its secretion of thyroid hormone (T3 and T4). |
| What is the function of luteinizing hormone (LH) in females and males? | In females, LH stimulates ovulation and corpus luteum development, while in males, it stimulates the interstitial cells of the testes to secrete testosterone. |
| How does the hypothalamus control the release of thyroid hormone? | The hypothalamus releases thyrotropin-releasing hormone (TRH), which stimulates the anterior pituitary to release TSH, which then stimulates the thyroid gland to release T3 and T4. |
| What are the primary effects of growth hormone (GH)? | GH promotes tissue growth by directly affecting mitosis and cellular differentiation, and it indirectly stimulates the liver to produce insulin-like growth factors (IGF-I and IGF-II). |
| what is GH also called and what is it secreted by? | somatotropin, somatotropes of ant. pit. |
| what is the most-secreted anterior pituitary hormone? | GH |
| what does GH do? | ↑tissue growth (bone, cartilage, muscle); in adulthood ↑osteoblastic activity & appositional growth affecting bone thickening and remodeling; directly affecting mitosis and cellular differentiation; also indirectly stimulates liver to produce IGF-I & –II |
| true or false, levels of GH are higher during first 2 hours of deep sleep, after high protein meals, after vigorous exercise | true |
| true or false, levels of GH are lower after high carb meals | true |
| what are IGF-I & –II somatomedins? | peptide hormones that promote cell growth, multiplication, and differentiation, act as vital mediators of growth hormone (GH) and regulate cellular metabolism similarly to insulin |
| what are the 4 functions of GH-IGF? | protein synthesis (↑AA transport into cells), lipid metabolism (↑FFA+glycerol release from adipocytes, protein sparing), carb metabolism (glucose sparing), electrolyte balance (↑Na+, K+, Cl- retention by kidney, Ca2+ abs. by small intestine) |
| What happens to blood concentrations of growth hormone as we age? | By age 75, blood concentrations of growth hormone decrease to one-quarter of the levels seen in adolescence (At 30, the average body is 10% bone, 30% muscle, 20% fat; At 75, 8% bone, 15% muscle, 40% fat. |
| what is the other name for ACTH and what is it secreted by? | corticotropin, secreted by corticotropes |
| what does ACTH do? | regulates response to stress, stimulates adrenal cortex to secrete corticosteroids that regulate glucose, fat & protein metabolism |
| prolactin is secreted by lactotropes. what does it do? | in females, PRL induces milk synthesis after delivery. in males, PRL stimulates LH sensitivity, thus indirectly stimulates testosterone secretion |
| what does oxytocin do? | induces labor contractions, milk ejection/let-down, possible role in sperm transport in males and emotional bonding in both genders |
| what controls the anterior pituitary and what controls the posterior pituitary? | anterior is controlled by releasing hormones (ex. GHRH) and inhibiting hormones (ex. PIH) of hypothalamus, while posterior lobe is controled by neuroendocrine reflexes |
| what are 2 examples of the neuroendocrine reflexes that control the posterior pituitary? | hormone release due to signals such as suckling infant-> stimulates nerve endings -> hypothalamus -> neurohypophysis -> release OT -> milk ejection; 2) hormone release due to higher brain centers: milk ejection reflex can be triggered by a baby's cry |
| what positive and negative feedback from target organs control the pituitary? | Negative feedback: ↑target organ hormone levels inhibits release of tropic hormones; Positive feedback: stretching of uterus → ↑oxytocin release → contraction of smooth muscle of uterus, → further stretching of uterus → ↑OT release, until delivery |
| What does the pineal gland produce? | |
| what other body processes or responses may the pineal gland regulate? | May regulate timing of puberty in humans; note that melatonin levels are high in SAD & PMS, decreased by phototherapy, also associated with depression, sleepiness, irritability and carbohydrate craving |
| which gland requires melanopsin found in the ganglion cells of the retina? | pineal |
| Where is the thymus located and what happens to it after puberty? | The thymus is located in the mediastinum superior to the heart, and it undergoes involution after puberty. |
| what hormones does the thymus secrete that regulate development and later activation of T-lymphocytes? | thymopoietin and thymosins |
| what is the largest endocrine gland with high rate of blood flow? (hint: it's on anterior and lateral sides of trachea, with 2 large lobes connected by its isthmus) | thyroid gland |
| what is the histology of thyroid follicles (thyrocytes - refer to a diagram)? | filled with colloid and lined with simple cuboidal epithelium (follicular cells) that secrete two hormones, T3 & T4 |
| What do the follicular cells of the thyroid gland secrete? | T3 and T4 |
| what does thyroid hormone do? (6 items) | increase body's metabolic rate, increase oxygen consumption, increase heat production (calorigenic effect), stimulates heart rate and contraction strength, increases respiratory rate, stimulates appetite and breaks down carbs, lipids & proteins |
| What do the C cells (parafollicular cells) of the thyroid gland produce? | C cells produce calcitonin, which lowers blood calcium levels by promoting calcium deposition and bone formation esp. in children |
| How does parathyroid hormone (PTH) respond to hypocalcemia? raise or lower Ca2+ levels? (4 assoc. items) | PTH raises blood calcium levels by promoting the synthesis of calcitriol, increasing calcium absorption, decreasing urinary excretion, and stimulating bone resorption. |
| What stimulates the adrenal medulla to release epinephrine and norepinephrine? what cells are involved? | The adrenal medulla is innervated by sympathetic preganglionic fibers that stimulate its chromaffin cells during a fight-or-flight response. |
| what causes adrenal medulla cells to stimulate adrenal cortex? | stress |
| the adrenal cortex is known for its corticosteroids. Which layer of the adrenal cortex produces mineralocorticoids? | The outer layer, known as the zona glomerulosa, produces mineralocorticoids like aldosterone to control electrolyte balance. |
| the adrenal cortex is known for its corticosteroids. Which layer of the adrenal cortex produces glucocorticoids? | zona fasciculata: especially cortisol, stimulates fat & protein catabolism, gluconeogenesis (from a.a.’s & FA’s) and release of fatty acids and glucose into blood; anti-inflammatory effect causes immune suppression with long-term use |
| the adrenal cortex is known for its corticosteroids. Which layer of the adrenal cortex produces sex steroids? | zona reticularis: dehydroepiandrosterone; weak androgens (including DHEA which other tissues convert to testosterone) and smaller amounts of estrogens (important after menopause |
| what are the 3 layers of the adrenal cortex from outer to inner? | (outer) zona glomerulosa, (middle) zona fasciculata, (inner) zona reticularis |
| which organ is retroperitoneal, and inferior to/dorsal to stomach? | pancreas |
| how many million pancreatic islets produce hormones | 1-2 million; the other 98% of organ produces digestive enzymes (exocrine) |
| What does insulin do and where is it secreted from? | Insulin is secreted by the beta cells of the pancreatic islets after a carbohydrate-rich meal, and it lowers blood glucose by stimulating glucose and amino acid uptake into cells. |
| what is the action of insulin and how to describe its uptake? where does it occur? | Insulin binds to receptors on target cells. Vesicles with GLUT4 carrier proteins bind to membrane. Glucose diffuses through GLUT4 channels by facilitated diffusion; occurs in adipose tissue, skeletal muscle, and the liver |
| When is glucagon secreted and what is its function? | Glucagon is secreted by the alpha cells of the pancreas during fasting or very low carbohydrate diets to increase blood glucose levels by stimulating glycogenolysis and gluconeogenesis. |
| when is somatostatin secreted and what is its paracrine characteristic? | secreted with rise in blood glucose and amino acids after a meal; paracrine secretion = inhibits secretion of alpha and beta cells |
| what are the hyperglycemic hormones that raise blood glucose? | glucagon, epinephrine, norepinephrine, cortisol & corticosterone |
| what is the hypoglycemic hormone that lowers blood glucose? | insulin |
| what is the name for an egg surrounded by granulosa cells? | follicle |
| what does the granulosa cells in wall of ovarian follicle do? | produces estradiol, first half of menstrual cycle |
| what is the term for the follicle after ovulation? | corpus luteum |
| what does the corpus lutem produce and when? | produces estradiol (an estrogen) and progesterone for 12 days or 8-12 weeks with pregnancy (refer to Reproduction chapter) |
| What hormones are produced by the corpus luteum in the ovary? | The corpus luteum produces estradiol and progesterone, which regulate the menstrual cycle, sustain pregnancy, and prepare mammary glands for lactation |
| what do the follicle and corpus luteum both secrete that suppreses FSH secretion (negative feedback of adenohypophysis)? | inhibin |
| what produces sperm at the testis? | seminiferous tubules |
| what cells are between the seminiferous tubules? | interstitial cells of Leydig, that produce testosterone, weaker androgens, and estrogen |
| what are the 2 functions of the testis? | development of male reproductive system and physique; sustains sperm production and sex drive |
| what are the male cells that secrete inhibin which suppresses FSH secretion, which stabilizes sperm production rates? | sustentacular (Sertoli) cells (aka sustencocytes, nurse cells) |
| What is the endocrine function of the heart? | The heart releases atrial natriuretic peptide in response to increased blood pressure, which lowers blood volume and pressure by increasing sodium and water loss by the kidneys. |
| what is the endocrine function of the skin? | keratinocytes help produce D3, first step in synthesis of calcitriol |
| what are the 5 endocrine functions of the liver? | converts vitamin D3 (aka cholecalciferol) to calcidiol, source of IGF-I that works with GH, secretes about 15% of erythropoietin (RBC-producing hormone), secretes angiotensinogen (prohormone) which is a precursor of angiotensin II, a vasoconstrictor |
| what are the 6 endocrine functions of the kidneys? | calcidiol→calcitriol (active form of vitamin D), ↑Ca2+ absorption by intestine and inhibits its loss in the urine, ↑Ca2+ available for bone deposition, produces 85% of erythropoietin, ↑bone marrow to produce RBC’s, angiotensinogen→angiotensin I via renin |
| what is the endocrine function of the stomach and small intestine? | 10 enteric hormones, coordinate digestive motility and secretion |
| what is the endocrine function of the placenta? | secretes estrogen, progesterone and others which help regulate pregnancy, stimulate development of fetus and mammary gland |
| How do the kidneys contribute to calcium homeostasis and red blood cell production? | The kidneys convert calcidiol to active calcitriol to increase calcium absorption, and they produce 85% of the body's erythropoietin to stimulate red blood cell production. |
| what are the 2 ways to cartilage grows? | Appositional growth and interstitial growth |
| describe appositional of cartilage | cartilage increases in width or diameter: Appositional growth expands cartilage from the outside by adding new layers of extracellular matrix to the tissue's outer surface. |
| describe interstitial growth of cartilage | Interstitial growth expands cartilage from the inside out as existing, dividing cells secrete new matrix that pushes them apart. |
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