Unit 1 The Endocrine System 1 How do hypothalamic hormones travel to the adenohypophysis Hypothalamic hormones travel to the adenohypophysis anterior pituitary by means of the Hypophyseal portal system It is a vascular connection to the anterior pituitary containing the primary capillary plexus Hypophyseal portal vein and secondary capillary plexus 2 Why must endocrine glands be highly vascularized Hormones are released into the ECF diffuse through capillary walls and travel in the blood stream to the target organ High vascularization is the mode of transportation for hormones 3 What is a tropic hormone What does it regulate Tropic hormones are hormones that have other endocrine glands as their target they release hormones that stimulate other hormone releasing producing glands Tropic hormones are produced and secreted by the anterior pituitary they include ACTH corticotropes TSH thyrotropes FSH and LH gonadotropes 4 How does the thyroid gland differ from other glands The Thyroid gland is the largest endocrine gland and it is the only gland that stores hormones in large quantity 3 4 months worth Major metabolic involvement 5 What do T3 T4 Norepinephrine and Epinephrine have in common While Norepinephrine and Epinephrine help to prepare for physical activity the Thyroid Hormones correlate T3 T4 by increasing heart rate respiratory rate and the strength of the heartbeat many metabolic rates Both hormones increase alertness and reflexes TH breaks down carbs fats and protein for fuel while the epinephrines mobilize these fuels Essentially these hormones work together 6 Compare Calcitonin and Parathyroid hormone and their actions on bone the gut and the kidney Bone Calcitonin is a hormone secreted from C clear cells parafollicular cells when there is a high calcium level in the blood Calcitonin reduces osteoclast activity to receive less calcium Then it stimulates osteoblast activity connecting the calcium with new bone formation Calcitonin is an antagonist to the Parathyroid hormone PTH PTH raises blood calcium levels when the body is experiencing hypocalcemia Gut PTH promotes intestinal reabsorption Calcitonin permits calcium reabsorption by the intestines Kidney PTH inhibits urinary excretion promotes calcium conservation and reabsorption of phosphate in kidneys Calcitonin resists the reabsorption of phosphate and calcium leading to increased rates of the loss of urine PTH absorbs raises calcium levels Calcitonin permits lowers calcium levels 7 What are hormones produced by the adrenal cortex and adrenal medulla AC produces over 25 steriod hormones Adrenal Cortex Mineralocorticoids Zona glomerosa Aldosterone electrolyte and water balance Na and water retention plus K excretion Glucocorticoids Zona fasciculata Cortisol and Corticosterone aids in chronic stress prolonged events makes sure theres enough energy ATP fat and protein metabolism tissue repair anti inflammatory gluconeogenesis Gonadocorticoids Zona reticularis Androgens or Dehydroepiandrosterone sex hormones mainly precursor for male testosterone indirectly aiding in puberty and bone growth Female androgen Estradiol adrenal estrogen Adrenal Medulla Epinephrine Norepinephrine and Dopamine promote alertness raise metabolic rates respiration and circulation increase blood glucose inhibit insulin secretion in order to save glucose for the brain mobilize organic fuels 8 What are the endocrine functions of the pancreas The pancreas is mainly an exocrine digestive gland In the exocrine gland contains cells called pancreatic islets or islets of Langerhans which are of vital importance to regulate the blood glucose concentration the regulation of glycemia Alpha A cells secrete glucagon between meals when the blood glucose level drops They also stimulate fat catabolism for the release of fatty acids and promote amino acid absorption Beta B cells secrete insulin after a meal when blood nutrient levels are rising they lowering the level of blood glucose and nutrients Insulin stimulates cells to absorb glucose amino acids and fatty acids in order to store or metabolize them Delta D cells secrete somatosatin or growth hormone inhibiting hormone when B cells secrete insulin Somatosatin inhibits some digestive enzyme secretion and neutrient absorption 9 Endocrine functions of the gonads The endocrine function of the gonads is to produce sex hormones 10 What are the water soluble and lipid soluble biogenic amines Water soluble Peptide protein and catecholamines Hydrophilic or Lipophobic Free hormones can diffuse through capillary walls without assistance Once bonded to receptor at target cell receptor on membrane initiates Second Messenger Activation Lipid Soluble Steriods Eicosanoids Hydrophobic Bound hormones need to attach to hydrophilic transport proteins in order to travel through the blood mostly water they must disassociate from transport to diffuse out of capillary and into target cell Once in target cell heads to receptor in nucleus acts on genes mRNA 11 What is the precursor for lipid based hormones Cholesterol 12 What hormone is responsible for regulating sodium What triggers its release Aldosterone regulates sodium retaining sodium and releasing potassium into urine water is retained into cells with sodium via osmosis Aldosterone helps to maintain blood volume and pressure Aldosterone release is triggered by Renin release from the kidneys regulates body s arterial blood pressure In this case Angiotensin II constricts blood vessels and raises BP triggering the release of Renin to lower BP triggering the release of Aldosterone 13 What hormone is released during long term stress Acute stress Long Term stress Cortisol Acute Stress Epinephrine Norepinephrine Adrenalin