Animal form and function: endocrine

Controls  Animals have 2 systems of control  Nervous: rapid response  Endocrine: slower response. Longer lasting  Reception: hormone binds receptor protein on target cell (or in)  Change receptor protien: initiates transduction  Hormones (steroid): bind protein in cytosol: enter nucleus as transcription factors and turn genes off or on.  Signal transduction: binding triggers events within the cell  Response: change in cells behavior

Types of signals  Endocrine: long distance stim. Carried through blood stream  Paracrine: local. Stim neighboring cells  Neurotransmitters  Growth factors  prostoglandins

Endocrine example: epinephrine  Epinephrine is secreted from the adrenal medulla in response to stress. Receives Neural stimulus from hypothalmus  Epinephrine stimulates the breakdown of glycogen to glucose in the muscle and liver  Sutherland found: in test tube  epinephrine + glycogen phosphorylase + glycogen = no work  Need intact cells and cell membrane  Epinephrine uses G protein-linked receptors: binds on outside of cell: stims change in G protein in cytosol. Makes it active

 FYI: epinephrine stimulates:  Dilation of capillaries in the lungs  Increased heart rate and cardiac output  Smooth muscles of some blood vessels contract, others dilate

Remember cell signaling  Hormones that act inside the cell (steroids)  transcription factors  G-protein linked receptors: on cell membrane: act on protein in the cytosol (change out the guanine) making it active  Tyrosine kinase: catalyze the transfer of a phosphate group from ATP to tyrosine  Ion gated channels: affected by the level of certain ions in the extracellular fluid (Na)

Glands of endocrine  Hypothalamus  Pineal  Pituitary  Thyroid  Thymus  Adrenals  Pancreas  Ovaries/ testes

Hypothalamus  Hypothalamus makes hormones and stores them in:  Posterior pituitary:  oxytocin: uterine contraction  ADH: anti diuretic hormone (decrease urination)  Anterior pituitary: Secretes trophic hormones: control other glands: regulated by hypothalmus  ACTH: adrenal control  FSH/LH: gonad regulation  Growth hormone: growth regulation  Prolactin: milk production  TSH: thyroid stim

Hypothalamus  Hypothalamus: TSH releasing hormone  Stims Anterior Pituitary to release: TSH  Stims Thyroid: release T3 and T4  Negative feedback: T3 and T4 negative feedback to hypothal.  A signal transduction pathway with cAMP as 2 nd messenger

Thyroid  Thyroid  Thyroxine: metabolic rate  Calcitonin: decreases blood calcium  Parathyroid  PTH: when Ca++ is low, PTH stim osteoclasts to breakdown bone and kidneys to retain Ca++ so, raises Blood calcium

Pancreas  Exocrine: digestive enzymes: through DUCT to small intestine  Endocrine: Islets of Langerhan:  Alpha cells: glucagon  Beta cells: insulin  Glucagon: stim breakdown of glycogen  Insulin: increases cells ability to take up glucose. And stim. the storage of glucose as glycogen in liver and muscles

Adrenal glands  Adrenal Medulla  Stim by acetylcholine from sympathetic nerve system  Epinepherine  norepinepherine  Adrenal Cortex  Glucocorticoids: aldosterone

Blood Pressure  Blood volume low:  Kidneys secrete renin  Stims angiotensin from liver:  constricts blood vessels  Stims aldosterone from adrenal cortex  Kidney tubules increase reabsorbtion of water  Antiduiretic hormone works in same situation

Ovaries & testes  Ovaries  Estrogen  progesterone  Testes  Testosterone

Pineal gland  Melatonin: involved in light/dark cycles