Transcript Chapter 18
The Endocrine System Chapter 18 Comparison of NS and ES, table 18.1 Nervous & Endocrine Systems coordinate functions of all body systems: the neuroendocrine system ________________________ nerve impulses conducted along axons of neurons at synapse nerve impulses trigger release of mediator molecules = _____________________ _______________________ releases mediator molecules = ________________ molecules leave glands blood circulating blood delivers hormones to virtually all cells hormones affect only cells with the proper receptor Comparison of control by NS & ES Nervous system Neurotransmitters Act close to release site Muscles, glands, neurons Onset of action within milliseconds Duration of action is generally brief Lasting milliseconds Endocrine system Hormones Act far from release site Cells throughout body Onset of action: seconds to hours, to days Duration of action is generally longer Lasting second to days Exocrine vs. Endocrine ______________________ Exocrine glands secrete products into ducts that carry secretions into: Body cavities Into the lumen of an organ Outer surface of the body Sweat, oil, mucous, digestive ______________________ Endocrine glands secrete products (hormones) into interstitial fluid surrounding secretory cells rather than ducts From interstitial fluid blood(or directly to) target cells Fig.18.01 Functions of hormones Help ________________: fig 18.1 Chemical composition & volume of internal environment (interstitial fluid) Metabolism and energy balance Contraction of smooth & cardiac muscle fibers Glandular secretions Some immune system functions ____________________________ Regulate reproductive system Help establish ____________________ Hormones ___________- secretion of endocrine cells, alters physiological activity of ______________ approximately 50 hormones Hormones travel through body in the blood each affects only a few cell types cell will only respond if has specific receptor for hormone have powerful effects in low concentrations bind receptors on target cell various target cells respond differently to same hormone If excess hormone present, receptors may = _______________________ Circulating vs. local hormones _____________________- most endocrine are this type, circulate in the blood From secretory cells interstitial fluid blood _______________- act on neighbor or same cell that secreted it, without entering blood ________________- beside or near ________________- self Fig.18.02 Response to hormone Various target cells– ______________________________________ Ex.) insulin: stimulates synthesis of glycogen in liver cells stimulates synthesis of triglycerides in adipose cells Responses are: _____________________ _______________________________ _______________________________ in or out _________________________ _________________________ Chemical classes of hormones, table 18.2 ____________________ Steroid hormones- derived from cholesterol Thyroid hormones- T3 and T4 Nitric oxide (NO)- hormone and neurotransmitter ____________________ Amine hormones- catecholamines, histamine, seratonin, melatonin Peptide hormones- some have carb glycoprotein hormones Eicosanoid hormones- important local, may circ prostaglandins leucotrienes Lipid soluble fig. 18.3 Water soluble Figure 18.4 Control of secretion Release usually in ________________ Regulation __________________ production Hormone secretion regulated by: ______________________________ ______________________________ ______________________________ Most regulation works by feedback loops Negative feedback loop, 18.17 Positive feedback loop, 1.4 Negative feedback Ex.) Glucocorticoids Positive feedback Ex.) Oxytocin Hypothalamus & pituitary gland, 18.5 ___________________- “master” endocrine gland secretes hormones that control other endocrine glands __________________- major link between NS & ES important regulatory center in NS- can control pituitary crucial endocrine gland Cells of hypothalamus synthesize 9 different hormones 2 of these are stored and secreted from the posterior pit. Anterior pituitary secretes 7 hormones Together these16 hormones play important roles in ______________________________________________ Hypothalamus endocrine function At least 9 hormones synthesized by hypothalamus 5 releasing & 2 inhibiting hormones produced affect _____________________ (___________________) produced by hypothalamic neurosecretory cells transported within axon & released from axon terminals diffuse hypophyseal portal system 1° 2° plexus target cells of anterior pituitary GHRH, GHIH, TRH, GnRH, PRH, PIH, CRH Hypothalamic function (2) Neurosecretory cells w/cell body in hypothalamus synthesize the 2 hormones that __________________ ______________ (___________________) where the axon terminals lie package into secretory vesicles travel to axon terminal and stored released from posterior pituitary due to nerve impulse triggering exocytosis capillary plexus Oxytocin and Anti-diuretic hormone (ADH) Regions of the pituitary gland Anterior pituitary -75% of total wgt of gland Posterior pituitary – only oxytocin and ADH Pars distalis, pars tuberalis- sheath around infundibulum Adeno= ________, hypophysis = __________________ Secretes hormones that reg. wide range release _______________________ & suppressed ______________________________________ controlled by negative feedback loops Contains axons & axon terminals of >10,000 neurons from nuclei in hypothalamus Terminals associated w/ pituicytes- specialized neuroglia Pars nervosa, infundibulum ________________________________________________ Pars media = atrophies during fetal development Hypophyseal portal system _______________________- blood flows from one capillary network into portal vein & then to 2nd capillary network without passing thru heart Hypophyseal portal system- blood flows from capillaries in hypothalamus into portal vein that carries blood to capillaries of adenohypophysis Neurosecretory cells synthesize releasing & inhibiting hormones in cell bodies vesicles axons 1° plexus Act immediately on anterior pituitary before diluted or destroyed in general circulation 5 releasing hormones of hypothalamus table 18.3 Growth hormone releasing hormone (GHRH) = somatocrinin Thyrotropin releasing hormone (TRH) Stimulates gonadotrophs Prolactin releasing hormone (PRH) Stimulates thryotrophs AND lactotrophs Gonadotrophic-releasing hormone (GnRH) Stimulates somatotrophs Stimulates lactotrophs Corticotropin-releasing hormone (CRH) Stimulates corticotrophs 2 inhibiting hormones of hypothalmus table 18.3 Growth hormone Inhibiting hormone (GHIH) = Somatostatin released from hypothalamus inhibits activity of somatotrophs Prolactin Inhibiting hormone (PIH) = dopamine inhibits activity of lactotrophs Cells of the Anterior Pituitary ____________________ – “somato” = body, “tropin” = change secrete ___________________________ (hGH) or somatotropin Stimulates several tissues to secrete insulin-like growth factors general body growth regulate metabolism ___________________ - secrete thyroid stimulating hormone (TSH) or thyrotropin controls secretions & activities of thyroid gland Cells of the anterior pituitary (2) _______________-- “gonado” = seed Secretes _________________________ (FSH) Stimulates estrogen production in ovaries Initiates oocyte development Sperm production Secretes _________________________ (LH) Stimulates secretion of progesterone & estrogen in ovaries Stimulates ovulation, formation of CL Stimulates secretion of testosterone in testes Stimulates interstitial cell development in testes Cells of the anterior pituitary (3) __________________- “lacto” = milk Secrete prolactin (PRL) initiating milk production in mammary glands __________________ - “cortico” = rind or bark Secrete adrenocorticotropic hormone (ACTH) or corticotropin Stimulates the adrenal cortex to secrete glucocorticoids Ex.) cortisol Some corticotrophs - remnants of pars intermedia secrete melanocyte stimulating hormone (MSH) Role unclear May affect brain activity levels cause skin darkening Negative feedback – corticotrophs 7 Anterior pituitary hormones & what they stimulate hGH- stimulates liver, muscle, cartilage, bone, & others to synthesize & secrete IGFs IGF - promote body cell growth, protein synthesis, tissue repair, lipolysis & blood glucose TSH- stimulates synthesis & secretion of thyroid hormones by thyroid gland T3 and T4 - BMR, stimulate protein synthesis, use of glu & f.a. for ATP syn, lipolysis, cholesterol secretion, body growth, development of NS Anterior pituitary hormones (2) FSH- follicle stimulating hormone: ♀- initiate _____________________, induce ovarian secretion of ________________ ♂- stimulates testes to ____________________ LH- luteinizing hormone ♀- stimulates secretion of _______________ & __________________, ______________, & ___________________________________ ♂ stimulates ___________________ production Anterior pituitary hormones (3) PRL - promotes milk secretion by mammary glands ACTH – stimulates secretion of ___________________ (for glucose metabolism) by adrenal cortex ____________________ MSH- exact role unknown, may influence brain activity, when present in excess can cause darkening of skin 2 Posterior pituitary hormones, table 18.5 ____________________ (OT) stimulates uterine smooth muscle contraction during childbirth stimulates contraction of myoepithelial cells in mammary glands milk ejection Pitocin is synthetic form _______________________ (ADH) or vasopressin Anti = against, dia= throughput, ouresis = urination conserves body water by decreasing urine volume decrease water loss thru perspiration raises bp by constricting arterioles Thyroid hormones, table 18.6 & fig 18.10 T3 (_________________) and T4 (____________) BMR Stimulate synthesis of Na+/K+ pump ↑ lipolysis & enhance cholesterol excretion in bile Enhance actions of catecholamines (NE and E) ↑ ATP production ↑ more heat ↑ body temp: calorigenic Stim protein synthesis & glucose & fa use to make ATP ↑ O2 consumption, metabolism of carbs, fats, protein ↑ ↑ heart rate, ↑ b.p. Accelerate body growth (w/ hGH & insulin) contribute to development of nervous & skeletal systems Also a hormone produced in the thyroid: __________________ (CT)- parafollicular C cells of the thyroid produce it lowers blood levels of calcium & phosphates Inhibits bone reabsorption by osteoclasts & accelerating uptake of calcium & phosphates into bone matrix High blood calcium levels stimulate secretion (low blood calcium levels inhibit secretion) Formation, storage & release of T3 & T4, figures 18.11 and 18.12 Thyroid = only gland that stores large quantities of its secretory product 100 day supply in colloid Figure 18.11 shows synthesis Figure 18.12 shows control of secretion: TRH from hypothalamus anterior pituitary causes releases TSH thyroid gland causes release of T3 & T4 negative feedback inhibition of both TRH & TSH Thyroid problems Deficiencies in thyroid hormones during fetal development, infancy or childhood causes: ______________________ symptoms include: Severe mental retardation Stunted bone growth ↑ heart rate, ↑b.p., force of heart beats Removal of thyroid- __________________ _____________________ because cannot utilize calorigenic effect Parathyroid gland hormones _______________________ (PTH) Specifically works by # & activity of _____________ bone resorption, releasing ionic Ca2+ & phosphates In the _________________: Slows Ca2+ & Mg2+ loss to urine phosphate loss from blood to urine promotes formation of calcitriol by kidneys Calcitriol = active form Vitamin D absorption rate of dietary Ca2+ , Mg2+ ,& phosphates Blood Ca2+ directly controls _______________ (from thyroid gland) & PTH secretion via negative feedback Adrenal glands = suprarenal glands CT capsule cover, highly vascularized (like thyroid) Adrenal ___________ – 80-90% of gland, peripheral Produces steroid hormones essential for life Loss would lead to death due to dehydration & electrolyte imbalance (few days to week) unless HRT Adrenal ____________ – centrally located Produces 3 _____________________ Norepinephrine Epinephrine Dopamine (small amount) Modified sympathetic ganglion of the ANS Adrenal cortex hormones ______________ (mainly aldosterone) - affect mineral homeostasis, in zonula glomerulosa ↑ blood levels of Na+ & water decrease blood levels of K+ _______________________ promotes excretion of H+ in urine Removing acids preventing acidosis Adrenal cortex hormones __________________ -95% _____________ = hydrocortisone, corticosterone, & cortisone, zona fasciulata affect glucose homeostasis, Regulate metabolism & resistance to stress ↑ protein breakdown (except in liver) stimulate gluconeogenesis in liver & lipolysis provides resistance to stress Glucose at liver provides source of ATP to combat stresses: Exercise, fasting, Symp NS, temp∆, high altitude, bleeding, infection, surgery, trauma, disease Raise bp- advantageous during blood loss inflammation & depress immune responses Sex hormones from adrenal cortex ________________-(mainly dehydropiandrosterone or DHEA), small amounts of weak androgens that have masculinizing effects, in zona reticularis assist in early growth of axillary & pubic hair in both sexes Contributes to pre-pubertal growth spurt After puberty in males androgen- testosterone is released in greater quantities by testes in females, contribute to libido & are converted to estrogens by other tissues after menopause all estrogens come from this source Adrenal medulla hormones Adrenal medulla develops just as other sympathetic ganglia but the cells secrete hormones- called chromaffin cells Innervated by symp preganglionic neurons that release Ach Both hormones are not essential for life but intensify ________________ responses in other parts of body ____________ = adrenaline, 80% of medullary cells secrete Cortisol induces secretion of an enzyme to convert NE to E _________________ = noradrenaline, 20% of medullary cells secrete because they lack converting enzyme Pancreatic Islet hormones _____________ – pan = “all,” creas = “flesh” Endocrine and exocrine 99% of cells arranged in acini- clusters that produce digestive enzymes that flow thru ducts to the GI tract Scattered among acini are clusters of endocrine tissue- _______________________ or islets of Langerhans Abundant capillary supply Islet cell types Alpha cells = A cells - 17% of islets cells Secrete _________________ – blood glucose by accelerating breakdown of glycogen in liver Converts other nutrients into glucose at liver Releases glucose into blood Beta cells = B cells – 70% of islet cells Secrete _______________- ↓ blood glucose by accelerating transport of glucose into cells Converts glucose into glycogen Decreasing glycogenolysis & gluconeogenesis Increases lipogenesis & stimulates protein synthesis Islet cell types (2) Delta cells = D cells – 7% of islet cells Secrete ________________ = growth hormone inhibiting hormone paracrine effect to inhibit insulin & glucagon release slow absorption of nutrients from GI tract F cells – remainder of pancreatic islets Secrete ____________________- inhibits somatostatin secretion Inhibits gall bladder contraction Inhibits digestive enzyme secretion by pancreas Regulation of insulin and glucagon ____________________ - most important regulator but several hormones & NT regulate too ________________ secretion stimulated by: hGH and ACTH Ach stimulates insulin secretion Amino acids: arginine & leucine GIP- glucose dependent insulinotropic peptide- released when glucose in GI tract ________________ secretion stimulated by: Symp NS activity Rise in blood aa if glucose low (mainly protein meal) Ovaries table 18.10 Produce gametes Produce steroid hormones (work with FSH & LH): __________________ - β-estrodiol, estrone, and estriol ___________________ – prepare endometrium of uterus for implantation mammary glands- milk production ___________________ – flexibility of pubic symphysis during pregnancy Dilate cervix during labor & delivery ___________________ – inhibits secretion of FSH development of oocytes maintain repro structures appearance of 2° sex characteristics Testes table 18.10 Produce gametes Produce steroid hormones _________________ – descent of testes spermatogenesis controls growth of development of male repro organs appearance of 2° sex characteristics body growth _________________ – inhibits secretion of FSH Diseases and disorders Pituitary Gland disorders: hGH disorders: figure 18.22 Hyposecretion: _____________________________ - during growth years slows bone growth & epiphyseal plates close before normal height, body proportions remain childlike Treatment- administer hGH during childhood Hypersecretion: _______________________ – during childhood, abnormal ↑ long bone length, tall but proportions normal ________________________ – during adulthood, hGH cannot lengthen long bones but hands, feet, cheeks, jaws thicken and enlarge; eyelids, lips, tongue, & nose enlarge; skin thickens & develops furrows Disease and disorders (2) _____________________ – most common abnormality assoc w/ the posterior pituitary Due to defects with ADH receptors or inability to secrete ADH Common symptom – excretion of large volumes of urine resulting with dehydration and thrist Bed wetting common in children Person may die of dehydration if deprived from water for a day or more Treatment – HRT for _____________, ________________ may involve diet restrictions (restriction of salt) depending upon details and specifics of kidney dysfunction Thyroid gland disorders: Hyposecretion: _________________________ (previously cretinism) present at birth, devastating if not prompt treatment Severe mental retardation Stunted bone growth Treatment- oral thyroid hormone treatment- birth thru life ______________ – in adulthood, 5x more common in ♀ Edema causes facial tissue to swell and look puffy Slow h.r., body temp, sensitivity to cold, dry hair & skin Muscular weakness and general lethargy Tendency to gain wgt easily Brain has matured no retardation, but might be less alert Treatment = oral thyroid hormones to symptoms Thyroid gland disorders (2): Hypersecretion: _____________ –most common, 7-10X more ♀ < 40 yrs Autoimmune disorder, Ab mimic TSH Enlarged thyroid (2-3x normal size) Peculiar edema behind eyes = exophthalmus Treatment – partial or full thyroidectomy, radioactive iodine to destroy thyroid tissue, antithyroid drugs _____________ – enlarged thyroid gland Assoc w/ hyperthyroidism, hypothyroidism, or euthyroidism (“good,” normal secretion) Dietary intake of iodine may be inadequate thyroid hormone in blood stimulates TSH enlarge Parathyroid gland disorders: ___________________ – too little PTH Deficiency of blood Ca2+ neurons & muscle fibers to depolarize and produce spontaneous AP Twitches, spasms, tetany Leading cause: damage to parathyroid glands or their blood supply during thyroidectomy ____________________– elevated PTH Often due to tumor on one of the glands Excessive reabsorption of bone matrix Raises blood calcium and phosphates, bone soft and easily fractured. ↑ blood Ca2+ promotes kidney stones Fatigue, personality changes, lethargy Adrenal gland disorders: Hypersecretion of cortisol: ______________________ adrenal gland tumor or tumor where ACTH is secreted stimulating excess cortisol Breakdown of muscle protein, redistribute body fat Moon face, buffalo hump, hanging abdomen ↑ cortisol hyperglycemia, osteoporosis, weakness, hypertension, ↑ risk of infection, stress resistance, mood swings Hyposecretion of glucocorticoids & aldosterone: ___________________________ (leads to ↑ K+, Na+) most cases = autoimmune disorders: Ab block or destroy binding of ACTH to its receptors, bacteria. symptoms: appear usually after 90% of adrenal cortex is destroyed– mental lethargy, anorexia, nausea, vomitting, wgt loss, hypoglycemia & muscle weakness Treatment – replace glucocorticoids, mineralocorticoids, Na+ Pancreatic Islet disorders: _____________________- most common endocrine disorder, inability to produce insulin 4th leading cause of death in US cardio damage Unavailable insulin ↑ glucose in blood spills into urine _________– person’s immune system destroys beta cells, AKA insulin dependent diabetes mellitus (IDDM) Usually people under 20, persists thru life Time of symptoms- 80-90% beta cells destroyed Cardio problems, vision loss-cataracts, kidney problems _________ – target cells less sensitive to insulin due to down regulation of receptors > 90% of cases, obese & over 35 Control by diet, exercise, weight loss, drug stim insulin Pancreatic Islet disorders (2): _____________– diabetic injects too much insulin Symptom – _______________- blood glucose level due to excess insulin causing uptake Results in secretion of epinephrine, glucagon, hGH Anxiety, sweating, tremor, ↑ h.r., hunger, weakness Brain cell deprived of glucose mental disorientation, convulsions, unconsciousness, and shock Death can result if glucose level is not raised