BIOL 1412 Lecture Notes - Osteoblast, Bone Resorption, Parathyroid Gland
Document Summary
Regulates growth, reproduction, metabolism (long-term events) (fig. Glands & tissues secrete hormones which travel in blood to target cells ( = cells w/ Bind to receptors + change cell activity specific receptors for that hormone) Peptides, proteins, catecholamines ( = 1st messenger) steps: a) hormone binds to cell membrane receptors b) hormone-receptor complex activates membrane proteins eg. a g-protein c) g-proteins then activates 2nd messenger systems. [camp] to alter their activity changes cell activity blood eg. epinephrine on liver cells (activates camp) causes breakdown of glycogen to glucose - released to. Why use 2nd messenger systems: hormone can"t enter cell (h2o soluble, rapid acting (enzymes already present - just activate, 1 hormone mol. Many enzyme mol. s activated multiple signal: limited - messenger broken down or removed. Camp broken down by phosphodiesterase: lipid soluble hormones: (fig. Take time slow, but long lasting response. Regulation of hormone secretion into blood: (fig 16. 3) * stim. acting on endocrine gland may be: