BIOL 4376 Lecture Notes - Lecture 51: Phosphodiesterase, Negative Feedback, Endocrine System
28 Jul 2020
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Document Summary
3 structural groups of hormones: amino acid derivatives - small, water soluble, dopamine, norepinephrine, epinephrine, thyroid hormones, melatonin, peptide hormones (chains of amino acids) - large, water soluble, synthesized as inactive prohormones, secreted by. Pancreas: lipid derivatives, steroids, derived from cholesterol. Protein bound in the plasma: eicosanoids, derived from arachidonic acid. Homeostasis is maintained via hormonal and neuronal signaling. Both re uire the messenger to pass through the cell, bind to a specific receptor, and trigger a change in activity in the 2nd cell. Neuronal system is wired: specific structural arrangement between neurons and target cells. Major function: coordination of rapid, precise responses. Endocrine system is wireless: endocrine glands widely dispersed and not structurally related to one another and their target cell. Major function: control activities that require long duration. Negative feedback loops/other mechanisms to weaken response. Same cell type can have different combinations of receptors. Receptors for the same hormone can have different signalling mechanism depending on the tissue.
