click below
click below
Normal Size Small Size show me how
endocrine hormones
chapter 16
Question | Answer |
---|---|
Anterior Pituitary hormones list | Growth hormone (GH) Thyroid-stimulating hormone (TSH) or thyrotropin Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Prolactin (PRL) |
Anterior pituitary hormones info | All are proteins All except GH activate cyclic AMP second-messenger systems at their targets TSH, ACTH, FSH, and LH are all tropic hormones (regulate the secretory action of other endocrine glands) |
oxytocin | released by: paraventricular nuclei of hypothalamus target: uterus and mammary glands action: stimulates labor contractions and milk production releasing signal: stretching of uterus and suckling Inhibition: lack of stimuli |
Antidiuretic Hormone (ADH) | released by: supraoptic nuclei of hypot. target organs: kidneys action: increases water retention, reduces urine vol. releasing signal: osmoreceptors stimulate hypot, to release ADH Inhibition: (-) feedback, normal/low osmolarity of blood |
Growth Hormone (GH) | Target organ: bone, muscle, cartilage, liver, fat, systemic Action: anabolic, (stim. mitosis + cell differentation) liver produces IGF: (prolongs action of GH) |
Thyroid Secreting Hormone (TSH) | target organ: thyroid action: stimulates secretion of thyroid hormone releasing signal: Thyrotropin Releasing H (TRH) Inhibition: (-) feedback from high levels of thyroid hormone T3 and T4 |
Adrenocorticotropic Hormone (ACTH) | Target Organ: Adrenal cortex action: Release glucocorticoid -> cortisol to overcome stress releasing signal: Corticotropin-Releasing Hormone (CRH) Inhibition: (-) feedback from high levels of glucocorticoids |
Gonadotropins – FSH & LH | Target Organ: gonads FSH action: stimulates secretion of ovarian sex hormones development of ovarian follicles (sperm collection) LH action: stimulates ovulation, corpus luteum secretes progesterone, stimulates testes to secrete testosterone |
Gonadotropins – FSH & LH continued | Releasing signal: Gonadotropin Releasing Hormone (GnRH) Inhibition: Negative feedback from high levels of FSH and LH |
Prolactin Hormone (PRL) | target organ: mammary gland Action: Women: PRL + and - with estrogen within cycle -> breast tenderness Pregnant: PRL levels + -> stimulate mammary glands to make milk Releasing signal: estrogen and suckling Inhibition: prolactin inhibiting Hormone |
Hormone functions and effects | Regulate the metabolic function of other cells Have lag times ranging from seconds to hours Tend to have prolonged effects |
Eicosanoids | biologically active lipids with local hormone–like activity leukotrienes (autocrine) and prostaglandins (paracrine) have highly localized function. Hormone like behavior |
classes of hormones | amino acid based steroid based |
Amino acid based hormones | Amines, thyroxine, peptide, and protein hormones |
steroid based hormones | Synthesized from cholesterol gonadal and adrenocortical hormones |
where are the receptors for hormones found? | on the cell membrane , cytoplasm, nucleus |
what do receptors do? | turn on metabolic pathways when hormones bind to them |
hormone action on target cells | Alter plasma membrane permeability of membrane potential by opening or closing ion channels Stimulate synthesis of proteins or regulatory molecules Activate or deactivate enzyme systems Induce secretory activity Stimulate mitosis |
Hormone chemistry | Non steroidal Hormones Steroidal hormones |
Non steroid Hormones | made of amino acids water soluble (can't cross phospholipid bilayer) vary in structure and size monamine, peptides, glycoproteins |
Steroid Hormones | made of cholesterol lipid soluble permeable through plasma membrane estrogen, testosterone, adrenocortical Hormone |
Water soluble hormones | all amino acid-based H except thyroid H - cannot enter the target cells - act on receptors in the plasma membrane - Coupled by G proteins to intracellular second messengers that mediate the target cell’s response |
Lipid soluble hormones | - steroid H and thyroid H - act on intracellular receptors - directly activate genes |
Second messenger systems | amino acid based hormones (EXCEPT THYROID HORMONE) exert efforts through second messenger systems |
types of second messenger systems | Cyclic AMP PIP2-calcium |
cAMP signaling mechanism (cyclic AMP) | H (1st mes.) binds to receptor Recep. activates G protein G protein activates adenylate cyclase Adenylate cyclase: ATP -> cAMP (2nd mes.) cAMP activates protein kinases Protein kinase: activates enzymes, stimulates cellular secretion opens ion chan. |
hormone release | controlled by negative feedback mechanism |
what stimulates hormonal secretion | 1. humoral mechanism 2. neural mechanism 3. hormonal mechanism |
humoral secretion | Secretion of a hormone directly related to a molecule or ion in the blood Ex. Calcitonin is secreted by the presence of Ca ions in the blood |
Neural secretion | Secretion of a hormone directly related to stimulation of the nervous system Ex. Sympathetic NS -> stimulate adrenal medulla |
Hormonal secretion | Hormonal secretion is directly related to another hormone secreted by another organ or gland |
Nervous system modification | The nervous system modifies the stimulation of endocrine glands and their negative feedback mechanisms |
up regulation | target cells form more receptors in response to the hormone |
down regulation | target cells lose receptors in response to the hormone |
target cell specificity | Hormones circulate to all tissues but only activate cells referred to as target cells Target cells must have specific receptors for hormone to bind to These receptors may be intracellular or located on the plasma membrane |
paraventricular nuclei of hypothalamus | produces oxytocin (transported to posterior pituitary) |
supraoptic nuclei of hypothalamus | produces ADH (transported to posterior pituitary) |
posterior lobe of pituitary gland | down growth of hypothalamic neural tissue has a neural connection with hypothalamus bc of hypothalamic-hypophyseal tract |
how many hormones does the pituitary gland secrete? | 9 hormones |
Adenohypophysis | anterior lobe of pituitary made up of glandular tissue Synthesizes and secretes a number of hormones |
Neurohypophysis | posterior lobe (neural tissue) of pituitary AND the infundibulum Pituicytes (glial-like supporting cells) and nerve fibers Receives, stores, and releases hormones from the hypothalamus |
isthmus | median mass that connects the two lateral lobes of the thyroid |
thyroid gland | Composed of follicles that produce the glycoprotein -thyroglobulin |
thyroid hormone | produced by: follicular cells -> T4 and T3 (T4 converted to T3) target organ: most cells releasing signal: TSH and TRH (hormonal mech.) Inhibition: negative feedback |
thyroid hormone actions | increase basal metabolic rate, O2 consumption heat production appetite GH secretion alertness quick reflexes increase the heart rate reg. tissue growth and development reproductive system development |
homeostatic imbalances of TH | Hyposecretion in adults—myxedema; endemic goiter if due to lack of iodine Hyposecretion in infants—cretinism Hypersecretion—Graves’ disease |
Calcitonin Hormone | produced by: thyroid target organ: bone and kidney action: deposit calcium in bone and stimulates osteoblast activity and bone formation releasing signal: high conc. of Ca in blood (humoral mechanism) inhibition: (-) feedback – normal Ca in blood |
parathyroid hormone (PTH) | produced by: parathyroid glands target organs: bone, kidney, intestines action: demineralize bone, stimulates osteoclast activity releasing signal: low concentration of Ca in blood (humoral mech.) inhibition: negative feedback- normal Ca in blood |
Adrenal glands (suprarenal) | paired pyramid shaped glands on top of kidneys two glands in one: adrenal cortex adrenal medulla |
adrenal medulla | nervous tissue; part of the sympathetic nervous system |
adrenal cortex | three layers of glandular tissue that synthesize and secrete corticosteroids |
adrenal cortex layers and corticosteroids produced | Zona glomerulosa—mineralocorticoids Zona fasciculata—glucocorticoids Zona reticularis—sex hormones, or gonadocorticoids |
Zona glomerulosa | Outer most layer mineralocorticoids – chiefly aldosteron control the balance of minerals and water |
zona fasciculata | middle layer glucocorticoids - chiefly cortisol cells arranged in cords, metabolic hormone |
zona reticularis | inner most layer gonadocorticoids - chiefly androgens cells have a net like arrangement produces small amount of sex hormones |
Aldosterone Hormone | produced by: glomerulosa cells target organ: kidney action: retains Na -> reduces Na excreted (water comes with it) releasing signal: Low concentration of Na in blood High K+ in blood Low blood pressure/blood volume inhibition: opposites |
Aldosterone mechanisms to regulate secretion | 1. Renin-Angiotensin 2. Plasma Concentration of K+ and Na+ ions 3. Atrial Natiuretic Peptide (ANP) |
Cortisol Hormone | produced by: fasiculata cells target cells: most cells releasing signal: CRH from hypothalamus -> ACTH from anterior pituitary inhibiton: negative feedback from cortisol |
cortisol hormone action | stimulates fat and protein catabolism gluconeogenesis – Formation of glucose from amino acids and fatty acids Helps body adapt to stress and repair tissues Anti-inflammatory effect |
hypersecretion of Glucocorticoids | Cushing's syndrome Depresses cartilage and bone formation Inhibits inflammation Depresses the immune system Promotes changes in cardiovascular, neural, and gastrointestinal function |
hyposecretion of Glucocorticoids | Addison's disease Also involves deficits in mineralocorticoids Decrease in glucose and Na+ levels Weight loss, severe dehydration, and hypotension |
Gonadocorticoids (Sex Hormones) | Most are androgens (male sex hormones) that are converted to testosterone in tissue cells or estrogens in females |
Pineal gland | secretes melatonin which effects: sleep cycle, timing of sexual maturity, physiological processes |
Pancreatic gland | Exocrine and endocrine functions Acinar cells – exocrine - produces digestive juices Islets of Langerhan – endocrine – produce hormones Alpha cells -> glucagon H Beta cells -> insulin H |
Glucagon | secreted by: alpha cells of Pancreatic Islets target cell: liver action: increase blood sugar Gluconeogenesis Glycogenolysis: Release of glucose to blood Hyperglycemic agent releasing signal: low blood glucose inhibition: (-) feeback, high g |
insulin | secreted by: beta cells of pancreatic Islets target cells: liver action: decrease blood glucose Increase the uptake of glucose into cells Inhibit glycogen breakdown Hypoglycemic agent releasing signal: high blood glucose inhibition: low glucose |
ovaries | produce oocytes hormones: estrogen and progesterone |
testes | Microscopic seminiferous tubules produce sperm Leydig cells (interstitial cells) lie in clusters between tubules produce Testosterone |
heart | Atrial natriuretic peptide (ANP) reduces blood pressure, blood volume, and blood Na+ concentration |
Gastrointestinal tract enteroendocrine cells | Gastrin stimulates release of HCl Secretin stimulates liver and pancreas Cholecystokinin stimulates pancreas, gallbladder, and hepatopancreatic sphincter |
Kidneys | Erythropoietin signals production of red blood cells Renin initiates the renin-angiotensin mechanism |
Skin | Cholecalciferol, the precursor of vitamin D |
Thymus | Thymulin, thymopoietins, and thymosins are involved in normal the development of the T lymphocytes in the immune response |