Endocrine Glands 1 Nervous and endocrine communication a Differences i ii Hormone blood transported chemical message to specific tissues to bind specific receptors Action potential ionic electrical membrane potential that excites tissue systematically conducted by nervous tissues to muscles b Endocrine system Secretes hormones into blood Slower response i ii iii More prolonged response c Nervous system i ii iii Transmits nerve impulses Faster response Less prolonged response 2 Homeostasis a Endocrine and nervous systems work closely together to maintain physiological responses to environmental stimuli b Maintaining variables within a very certain range c Dynamic equilibrium d Negative feedback end product hormones go back to receptors at start of cascade to shut down further production e Positive feedback hormones in previous steps of a cascade stimulate the production of other hormones f Hypothalamic releasing and inhibiting hormones i 5 types of cells in anterior pituitary 1 Somatotrophs GHRH GHIH a Secrete GH 2 Lactotrophs or Mammotrophs PIH a Secrete prolactin 3 Gonadotrophs GnRH a Secrete FSH and LH 4 Thyrotrophs TRH a Secrete TSH 5 Corticotrophs CRH a Secrete ACTH 3 Growth hormone a Somatotropin body change b Protein hormone 191 amino acids c Regulated by GHRH and GHIH i i d Anabolic hormone Simulates somatotropic cells to secrete GH i Metabolic functions non trophic actions Increase fat breakdown lipolysis in adipocytes 1 2 Decrease glucose uptake and utilization 3 In liver increased glycogenolysis breaks down glycogen to individual glucose molecules a Increased blood glucose i Anti insulin or glucose sparing effect 4 Mitosis ii iii Growth promoting functions building biomass for growth and repair Trophic actions 1 Mediated by insulin like growth factors a Produced in response to GH 2 Insulin like growth factors stimulate actions required for growth a Uptake of nutrients b Formation of bone matrix 3 Thyroid gland a Makes thyroid hormones 4 Thyroid glands and hormones a Iodine I is absorbed from the small intestine as iodide I anion of I Iodide moves into follicular cells via sodium iodide symporter i i ii iii iv b Thyroid hormones Amines Lipid soluble Contain iodide Two types 1 T4 thyroxine major forms that consists of two tyrosine molecules with four bound iodine atoms a Circulating form 2 T3 triiodothyronine form that has two tyrosines with three bound iodine atoms a Must be converted from T4 at tissue level b Most active form 1 Thyroid hormones effects a Thyroid hormone effects every cell in body i ii Intracellular receptor Regulates gene expression Increase glucose oxidation c Regulates tissue growth and development b Thyroid hormones increases basal metabolic rate and heat production calorigenic effect Critical for normal skeletal and nervous system development and reproductive capabilities d Maintains blood pressure Increases adrenergic receptors in blood vessels 2 Calcium homeostasis a Calcium is important in i i i i i i i ii iii i ii Signaling 1 Neurons 2 Action potentials ii Muscle contractions iii Structure 1 Bone Coagulation b Parathyroid gland iv c Thyroid gland Calcitonin Parathyroid hormone 1 Produced by parafollicular cells a C cells in thyroid gland 2 Secreted in response to high Ca2 levels 3 Antagonistic to parathyroid hormone PTH d Parathyroid hormone Secreted by parathyroid cells in the parathyroid gland Secreted in response to low blood levels of Ca2 Inhibited by rising levels of Ca2 e Target organs skeleton kidney and intestine Stimulates osteoclasts Enhances reabsorption of Ca2 iii Promote activation of vitamin D by kidneys 3 Adrenal glands stress hormones a Paired organs on top of the kidneys b Two glands in one i Adrenal cortex 1 2 3 layers of glandular tissue a Make different hormones including cortisol the stress hormone From inner touching medulla to outer touching capsule a Zona reticularis b Zona fasciculata i Secretes glucocorticoids 1 Influence cellular metabolic activity a Increase glucose levels 2 3 types a Cortisol hydrocortisone i Most abundant in humans b Corticosterone c Cortisone c Zona glomerulosa Secretes aldosterone a mineralocorticoid 1 Acts primarily in osmoregulation water balance in 3 Secretes corticosteroids steroid hormones kidneys a Glucocorticoids Regulates metabolism b Mineralocorticoids Regulates electrolyte concentration ii Adrenal medulla 1 Nervous tissue a Part of the sympathetic nervous system Another region that secretes neurohormones Sympathetic nervous system is the fight or flight nervous response and secretes norepinephrine Blah 2 Chromaffin cells 3 Secretes catecholamines derived from tyrosine a Epinephrine b Norepinephrine i i i i ii iii i ii iii i ii iii i ii iii iv i ii iii iv c Aldosterone regulation Rising blood K or decreasing blood Na 1 humoral direct stimulus RAAS system 1 Hormonal stimulus ACTH 1 Adrenocorticotropic hormone 2 Hormonal stimulus The body s response to a stimulus Fight or flight response 1 Adrenal medulla 4 Stress a What is stress a Chromaffin cells make catecholamines b Modified postganglionic neuron i ii 80 epinephrine 20 norepinephrine Corticosteroids b Effects of catecholamines Vasoconstriction Increased heart rate Increased blood glucose levels Blood diverted to the brain heart and skeletal muscle c Glucocorticoids i Made in the adrenal cortex ii iii Released in response to stressful stimulus Basal levels d Stressful stimuli Cause release of CRH from hypothalamus 1 Paraventricular nuclei CRH travels through hypophyseal portal vein to AP 1 Stimulates release of ACTH from AP ACTH travels to adrenal gland 1 Stimulates release of GCs from adrenal cortex Rising GCs feedback to turn off stimuli Lower levels of CRH 1 2 Lower levels of ACTH v Most transported in blood bound to protein vi vii Binds to receptor GR inside the cell 1 Regulates gene expression Short term 1 Increase lipolysis a Increases free fatty acids viii Long term 1 Reduced immune function 2 Muscle breakdown 3 Cardiovascular damage Increase protein breakdown Fatty acids and amino acids made into glucose via gluconeogenesis 2 3 4 Anti inflammatory