Endocrine System I Flashcards
Define glands
Organs derived from epithelial cells, specialised in synthesis/secretion
Define exocrine glands
Secrete products into ducts which lead into external environment eg skin/lumen
Define endocrine glands
Secrete hormones into interstitial fluid, diffuse into blood
What are the 2 major systems regulating cell communication?
Nervous system - Autonomic NS, Somatic NS
Endocrine system
Describe the endocrine system
Consists of endocrine glands that secrete hormones, vital adaptation to changes in internal/external environment
Define hormone
Chemical substance secreted into blood in very small amounts from specialised cells/organs
Define target cells
Cell respond to specific hormone
Define receptor
Certain proteins in target cells that specifically recognise/bind to messenger
Describe hormones in the endocrine system
Release from endocrine gland into blood, transported in blood to target
Describe neurohormones in the endocrine system
Released from neuron into blood, transported in blood to target, acts similar to hormones
Define autocrine
Act through diffusion onto same cells which produce it
Define paracrine
Move by diffusion, act on adjacent cells
Describe the journey through the organs of the endocrine system
Primary: Pineal, hypothalamus, pituitary, thyroid, parathyroid, thymus, adrenal, pancreas, ovaries/testes
Secondary: Heart, stomach, liver, kidneys, small intestines, skin
Describe the secreted products from each primary endocrine organ
Pineal - Melatonin Hypo - Peptide Hs Thyroid - T3, T4 Parathyroid - PTH Thymus - Thymopoietins, thymosins Adrenal > Cortex, medulla Pancreas - Glucagon, insulin Gonads - Oestrogen, progesterone, testosterone
Describe the secreted products from each secondary endocrine glands
Heart - ANP (red blood volume, pressure, Na) GI - Gastrin, serotonin Liver - Somatomedins Kidneys - Eryhtropoietin Skin - Calcitriol, Vit D
What are the different types of hormones in the endocrine system?
Amine (hydrophillic), peptide (hydrophollic), steroid (lipophillic)
Describe amine hormones
Simplest, small molecules, similar structure to AA Eg catecholamine (dop), thyroid hormones (T3), both derived from AA tyrosine
Describe peptide hormones
Peptides/proteins hormones
Eg Pancreas’ insulin
Describe steroid hormones
Lipids from cholesterol
Eg aldosterone from adrenal cortex
Describe the secretion and transport in the blood
Peptides/Catecholamine (hydrophillic) - Secretion by exocytosis free in plasma
Steroids/thyroid hormones - Secretion by simple diffusion, protein-bound in plasma
Describe the action of hydrophillic hormones
Binds to receptors on plasma membrane at:
Channel-linked receptors (LG ion channels)
Enzyme-linked receptors
G-protein-linked receptors (slow LG channels, G-protein-regulated enzymes, second messengers)
Describe the lipophillic hormones
Binds to receptors intracellular at:
Receptors located in cytosol/nucleus
Synthesis of specific proteins is altered
Describe ADH in terms of posterior pituitary
Dec water loss from kidney
Constriction of peripheral blood vessel
Secretion stimulated by: Water deficit, Dec BP
Describe oxytocin in terms of posterior pituitary
Acts on smooth muscle cells in breast/uterus
Stimulated by suckling and uterine contractions
