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)
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 2nd 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