BIO 3347 Lecture 1: Endocrine System
Document Summary
1800s - time period when endocrine system was discovered. Endocrine system - internam milieu - homeostasis, internal secretions - hormones. Classic - blood stream, distant target, lack of control (longer time to reach target) Neuro endocrine - goes through nerve, and goes into the blood. Intracrine - endocrine cell produces hormonal signal inside cell, it never leaves, and then binds itself to an intracellular receptor. Paracrine - endocrine cell produces hormonal product, which acts with local surrounding cells. Autocrine - endocrine cell releases hormone, and then absorbs the hormone back to receptors on the outside of the cell. 2,000 - 100,000 receptors - number of receptors correlates to type of response in a given cell. Excess hormone produces a decrease in number of receptors to avoid hyper- stimulation. Up-regulation = more receptors {decrease in sensitivity of target cell} Target tissue is more sensitive as a result. Change route of hormone in body - binding proteins in blood.
