Chapter 011 - Endocrine System.pdf

Endocrine System Presenter: Dr. Jim Hurrell  Endocrine System C H A P T E R 11 Copyright © 2016 by Elsevier, Inc.  Hormones CHARACTERISTICS...

Endocrine System Presenter: Dr. Jim Hurrell  Endocrine System C H A P T E R 11 Copyright © 2016 by Elsevier, Inc.  Hormones CHARACTERISTICS H O R M O N E C H E M I S T RY CONTROL OF HORMONE SECRETION Copyright © 2016 by Elsevier, Inc. 3 Endocrine System works together with nervous system to maintain homeostasis Modified from McBride DF: Learning veterinary terminology, ed 2, St Louis, 2002, Mosby. Copyright © 2016 by Elsevier, Inc. 4  Gland Differentiation  endocrine glands  exocrine glands “ductless glands” secrete their secrete tiny products on to amounts of epithelial surfaces hormones directly through tiny ducts into the bloodstream hormones circulate through body and produce effects when they find specific receptors Copyright © 2016 by Elsevier, Inc. 5  Homeostasis Is Maintained  endocrine system  nervous system slow reaction to stimuli fast reaction to stimuli long duration of effects fast duration for effects hormones are neurotransmitters are chemical messengers chemical messengers produced by produced by neurons endocrine gland or short distance across modified neurons synapse to target long distance through muscle cells, other bloodstream to target neurons all cells and tissues in body Copyright © 2016 by Elsevier, Inc. 6  Hormones  chemical messengers produced by endocrine glands and secreted directly into blood vessels  produce effects only when they bind to their specific receptors in or on cells  cell that has receptors for a particular hormone is a target of that hormone Copyright © 2016 by Elsevier, Inc. 7  Animal Hormone Groups  peptide hormones hydrophilic chains of amino acids receptors located on cell membranes of target cells  steroid hormones synthesized from cholesterol hydrophobic so attach to transport protein = bound hormone receptors located within the cell  monoamine hormones derived from amino acids and retain an amino group receptors for catecholamines located on cell membranes receptors for thyroid hormones located in the nucleus Copyright © 2016 by Elsevier, Inc. 8  Control of Hormone Secretion  level of hormone in blood directly or indirectly “feeds back” to the gland that produced it  activity of gland is affected negative feedback activity decreased by rising levels of hormone positive feedback activity increased by falling levels of hormone Copyright © 2016 by Elsevier, Inc. 9  The Major Endocrine Glands THE HYPOTHALAMUS T H E P I T U I TA RY G L A N D THE THYROID GLAND T H E PA R AT H Y R O I D G L A N D S THE ADRENAL GLANDS T H E PA N C R E A S THE GONADS Copyright © 2016 by Elsevier, Inc. 10  The Hypothalamus  part of the diencephalon of the brain  controls activities of the pituitary gland  portal system of blood vessels links to anterior portion of pituitary gland Copyright © 2016 by Elsevier, Inc. 11  The Hypothalamus  modified neurons secrete releasing and inhibiting factors into portal blood vessels each factor is specific for a particular anterior pituitary hormone Copyright © 2016 by Elsevier, Inc. 12  The Hypothalamus  modified neurons also secrete antidiuretic hormone (ADH) and oxytocin  transported to posterior pituitary for storage  released into bloodstream by nerve impulses from hypothalamus Copyright © 2016 by Elsevier, Inc. 13  The Pituitary Gland = Hypophysis  called the master endocrine gland  two separate glands with different embryological origins, different structures, different functions anterior pituitary = adenohypophysis rostral portion produces hormones when stimulated posterior pituitary = neurohypophysis caudal portion stores and releases hormones Copyright © 2016 by Elsevier, Inc. 14  Anterior Pituitary Hormones  growth hormone  prolactin  thyroid-stimulating hormone  adrenocorticotropic hormone  follicle-stimulating hormone  luteinizing hormone  melanocyte-stimulating hormone Copyright © 2016 by Elsevier, Inc. 15  Growth Hormone (GH)  also known as somatotropin and somatotropic hormone  promotes body growth in young animals  helps regulate metabolism of proteins, lipids, and carbohydrates in all body cells encourages anabolism of proteins causes release of lipids in storage and their catabolism discourages cells from using carbohydrates, esp. glucose Copyright © 2016 by Elsevier, Inc. 16  Prolactin  helps trigger and maintain lactation  production and release continues as long as teat continues to be stimulated by nursing or milking  without stimulation from prolactin: milk production stops mammary gland shrinks back to non-lactating size Copyright © 2016 by Elsevier, Inc. 17  Thyroid-Stimulating Hormone (TSH)  also known as thyrotropic hormone  stimulates growth and development of thyroid gland  causes thyroid gland to produce its hormones  secretion regulated: by feedback from thyroid by interaction among hypothalamus, anterior pituitary, and thyroid glands Copyright © 2016 by Elsevier, Inc. 18  Adrenocorticotropic Hormone (ACTH)  stimulates growth and development of adrenal cortex, and release of some of its hormones  production regulated by feedback from hormones of the adrenal cortex  can be released quickly as result of stress Copyright © 2016 by Elsevier, Inc. 19  Follicle-Stimulating Hormone (FSH)  named for effect on females  effects in the female stimulates oogenesis stimulates production and secretion of estrogen  effects in the male stimulates spermatogenesis Copyright © 2016 by Elsevier, Inc. 20  Luteinizing Hormone (LH)  completes process of follicle development in ovary  LH levels reach peak when follicle is fully mature usually causes ovulation causes development of corpus luteum  LH in males stimulates interstitial cells to produce testosterone Copyright © 2016 by Elsevier, Inc. 21  Melanocyte-Stimulating Hormone (MH)  associated with control of color changes in pigment cells of reptiles, fish, and amphibians rapid changes of colors and color patterns  administration of artificially large amounts to higher mammals can cause darkening of skin Copyright © 2016 by Elsevier, Inc. 22  The Posterior Pituitary = Neurohypophysis  stores 2 hormones produced in hypothalamus antidiuretic hormone oxytocin  hormones from hypothalamus are transported along nerve fibers, and stored in nerve endings  hormones released into bloodstream in response to nerve impulses from hypothalamus Copyright © 2016 by Elsevier, Inc. 23  Antidiuretic Hormone (ADH)  helps prevent diuresis  released when hypothalamus detects dehydration more-concentrated urine is produced  ADH deficiency causes diabetes insipidus polydipsia and polyuria Copyright © 2016 by Elsevier, Inc. 24  Oxytocin  effect on uterus induces uterine contractions at breeding and parturition  effect on active mammary glands stimulation of teat by nursing or milking causes oxytocin to be released causes movement of milk down to lower parts of the mammary gland (milk letdown) Copyright © 2016 by Elsevier, Inc. 25 Thyroid Gland 2 lobes on either side of larynx lobes may be connected by isthmus 2 hormones produced in follicles: thyroid hormone Modified from McBride DF: Learning veterinary terminology, ed 2, St Louis, 2002, Mosby. calcitonin Copyright © 2016 by Elsevier, Inc. 26  Thyroid Hormones  T4 = tetraiodothyronine = thyroxine a prohormone, a circulating reservoir  T3 = triiodothyronine the active hormone  hormones are produced when TSH from anterior pituitary stimulates the thyroid gland Copyright © 2016 by Elsevier, Inc. 27  Effects of Thyroid Hormones  regulates metabolic rate of all body’s cells calorigenic effect allows animals to maintain constant internal body temperature  affects metabolism of proteins, carbohydrates, and lipids anabolism or synthesis of proteins, depending on animal’s diet maintains homeostasis of blood glucose level encourages catabolism of lipids Copyright © 2016 by Elsevier, Inc. 28  Effects of Thyroid Hormones Copyright Penn Foster 2015 29  Calcitonin  produced by C cells located between thyroid follicles  helps maintain blood calcium levels  prevents hypercalcemia by encouraging excess calcium to be deposited in bones  parathyroid hormone is the other hormone involved in maintaining blood calcium levels Copyright © 2016 by Elsevier, Inc. 30  Parathyroid Hormone (PTH)  also called parathormone  produced by parathyroid glands small, pale nodules in, on, or near the thyroid glands  helps maintain blood calcium homeostasis causes kidneys to retain calcium causes intestines to absorb calcium from food withdraws calcium from bones  exerts the opposite effect of calcitonin Copyright © 2016 by Elsevier, Inc. 31  The Adrenal Glands  located near cranial ends of kidneys  consist of two glands: adrenal cortex adrenal medulla Copyright © 2016 by Elsevier, Inc. 32  The Adrenal Cortex produces numerous hormones:  glucocorticoids (cortisone, cortisol, corticosterone) cause general hyperglycemic effect help maintain blood pressure help body resist effects of stress  mineralcorticoids (e.g. aldosterone) regulate levels of electrolytes  sex hormones (androgens, estrogens) Copyright © 2016 by Elsevier, Inc. 33  The Adrenal Medulla  the inner gland resembles nervous tissue  2 hormones produced epinephrine and norepinephrine secretion controlled by sympathetic portion of autonomic nervous system fight-or-flight response Copyright © 2016 by Elsevier, Inc. 34 Pancreas long, flat organ located in the abdomen near the duodenum has both exocrine and endocrine functions Modified from McBride DF: Learning veterinary terminology, ed 2, St Louis, 2002, Mosby. Copyright © 2016 by Elsevier, Inc. 35  The Pancreas  endocrine component pancreatic islets, or islets of Langerhans alpha cells – produce glucagon beta cells – produce insulin delta cells – produce somatostatin  exocrine component produces digestive enzymes Copyright © 2016 by Elsevier, Inc. 36  Pancreas Copyright Penn Foster 2015 37  Pancreatic Hormones insulin  lowers blood glucose levels causes glucose, amino acids, and fatty acids in blood to be absorbed into body cells glucagon  raises blood glucose levels stimulates liver cells to convert glycogen to glucose stimulates glycogenesis Copyright © 2016 by Elsevier, Inc. 38 The Gonads the reproductive organs: testes in the male and ovaries in the female they produce reproductive cells and important hormones Copyright © 2016 by Elsevier, Inc. 39  The Testes 2 testes housed in scrotum  seminiferous tubules spermatogenesis  interstitial cells clumps of endocrine cells that produce androgens testosterone Copyright © 2016 by Elsevier, Inc. 40  The Ovaries  produce ova and hormones in cycles  cycles controlled by FSH and LH  hormone groups produced: estrogens estradiol and estrone progestins relaxin Copyright © 2016 by Elsevier, Inc. 41  Estrogens  follicle cells produce and release estrogens FSH stimulates ovarian follicles to develop follicle cells produce and release estrogens follicle grows amount of estrogen produced increases anterior pituitary reduces FSH and increases LH production LH peaks when follicle is fully mature ovulation occurs Copyright © 2016 by Elsevier, Inc. 42  Progestins  group of hormones produced by corpus luteum principal progestin = progesterone  in pregnant female corpus luteum produces progesterone, necessary for pregnancy to be maintained  if no pregnancy occurs lack of hormone causes corpus luteum to shrink and disappear  progestin-related drugs used therapeutically Copyright © 2016 by Elsevier, Inc. 43  Relaxin  effects of hormone relaxation of ligaments surrounding birth canal mammary development Copyright © 2016 by Elsevier, Inc. 44  Other Endocrine Glands THE KIDNEYS THE STOMACH THE SMALL INTESTINE T H E P L A C E N TA THE THYMUS THE PINEAL BODY P R O S TA G L A N D I N S Copyright © 2016 by Elsevier, Inc. 45  The Kidneys  produce erythropoietin stimulated by hypoxia effect is to increase production of red blood cells increased oxygen level slows down production  deficiency of erythropoietin anemia often accompanies kidney disease or failure Copyright © 2016 by Elsevier, Inc. 46  The Stomach gastrin  hormone produced by cells in stomach wall  acts upon the stomach wall also  secretion stimulated by presence of food causes gastric stomach glands to secrete hydrochloric acid and digestive enzymes encourages muscular contractions of stomach wall Copyright © 2016 by Elsevier, Inc. 47  The Small Intestine  secretion in response to presence of chyme in duodenum  cells in lining produce 2 hormones secretin stimulates pancreas to secrete fluid to neutralize acidic chyme cholecystokinin stimulates pancreas to release digestive enzymes  additional effects of both hormones slows movement of chyme stimulates gall bladder to send bile to small intestine Copyright © 2016 by Elsevier, Inc. 48  The Placenta  life-support system surrounds a developing fetus during pregnancy acts as interface with maternal circulation  produces hormones to support and maintain pregnancy estrogen progesterone chorionic gonadotropin (some species) relaxin (some species) Copyright © 2016 by Elsevier, Inc. 49  The Thymus  large organ in young animals atrophies later in life  important part of animal’s cell-mediated immunity thymosin and thymopoietin primitive cells in thymus transformed into T-lymphocytes (T-cells) Copyright © 2016 by Elsevier, Inc. 50  The Pineal Body  a part of the brain  influences the body’s biological clock  produces melatonin affects moods and wake-sleep cycles may also have role in timing of seasonal estrus cycles Copyright © 2016 by Elsevier, Inc. 51  Prostaglandins  hormone-like substances derived from unsaturated fatty acids  tissue hormones produced in variety of body tissues, and travel only short distance skin, intestine, brain, kidneys, lungs, reproductive organs, eyes  9 main groups, based on molecular structure influence blood pressure, blood clotting, and inflammation influence functions of GI tract, kidneys, and reproductive system Copyright © 2016 by Elsevier, Inc. 52  Key Terms acromegaly calcitonin aldostersone calorigenic adrenal cortex catabolism adrenal gland catecholamine adrenal medulla cell-mediated immunity adrenocorticotropic hormone (ACTH) cholecystokinin alopecia chorionic gonadotropin anabolism chyme androgen corpus luteum anterior pituitary gland cortex antidiuretic hormone (ADH) diabetes insipidus atrophy diabetes mellitus Copyright © 2016 by Elsevier, Inc. 53  Key Terms diuresis follicle-stimulating hormone (FSH) duodenum gastrin dysfunction glucagon eclampsia glucocorticoid hormone endocrine gland gluconeogenesis endocrinology glycosuria epinephrine gonad erythropoietin gonadotropin estrogen growth hormone (GH) exocrine gland homeostasis feedback mechanism hormone fight-or-flight response hydrophilic Copyright © 2016 by Elsevier, Inc. 54  Key Terms hydrophobic interstitial cell hyperadrenocorticism interstitial cell-stimulating hormone (ICSH) hypercalcemia lactation hyperglycemia luteinizing hormone (LH) hyperplasia luteolysis hypoadrenocorticism medulla hypocalcemia melanocyte-stimulating hormone (MSH) hypoglycemia melatonin hypothalamus metabolism hypoxia milk fever iatrogenic milk letdown insulin mineralocorticoid hormone Copyright © 2016 by Elsevier, Inc. 55  Key Terms monoamine hormone parathyroid gland myoepithelial cell parathyroid hormone (PTH) myometrium parturition neurotransmitter peptide hormone nonsteroidal antiinflammatory pineal body drugs (NSAIDS) pituitary gland norepinephrine placenta oogenesis polydipsia ovaries polyphagia oxytocin polyuria pancreas portal system pancreatic islet posterior pituitary gland Copyright © 2016 by Elsevier, Inc. 56  Key Terms precursor target progesterone testes progestin testosterone prohormone tetraiodothyronine (T4) prolactin poietin prostaglandin thymosin prostate gland thymus secretin thyroid gland seminal vesicle thyroid hormone sex hormone thyroid stimulating hormone (TSH) spermatogenesis thyroxin steroid hormone Triiodothyronine (T3) superovulation unsaturated fatty acid Copyright © 2016 by Elsevier, Inc. 57