PHSI2006 Study Guide - Midterm Guide: Lipophobicity, Signal Transduction, Blood Sugar

• School: University of Sydney
• Department: Physiology
• Course: PHSI2006
• Professor: phsi2006

Document Summary

But ectohormones are secreted into the external environment (a sub class is pheromone which attract other organisms of opposite sex): trace amount: the concentration of hormone in the blood is very low- micro or pico molar. Hormones exert their effect at very low concentrations (nanomolar -9 to picomolar range -12: hormone action must be terminated: they must be of limited duration (half-life) so the body can respond to changes in its internal state. E. g. you need insulin to do its job then go away, otherwise blood glucose levels would fall very low. Hormones in bloodstream are degreated into inactive metabolites by enzymes. Hypothalamus, pituitary, pancreas, parathyroid, gut: steroid hormones (made of cholesterol), synthesised on demand from precursors, released by simple diffusion, long half life, takes longer to have effect. Body temperature is lowest when you wake up and highest when you go to bed.