Endocrine Principles Lecture Notes PDF

Endocrine Principles Helen Miliotis, PhD [email protected]  Endocrine Principles Lecture outline Homeostasis Negative and Positive Feedback Mechanisms Cell-Cell Communication Short and Long Reflexes Features and Location of Hormones Identifying Hormones Textbook readi...

Endocrine Principles Helen Miliotis, PhD [email protected]  Endocrine Principles Lecture outline Homeostasis Negative and Positive Feedback Mechanisms Cell-Cell Communication Short and Long Reflexes Features and Location of Hormones Identifying Hormones Textbook reading: 8th ed: 13-18, 165-167, 181-190, 195-196 7th ed. 13-18, 166-168, 182-191, 197-198 (6th ed. 14-19, 175- 177, 192-200, 207-21); (5th ed. 179-181, 196-205, 216-220);  What is homeostasis? = The process of maintaining a constant internal environment despite changing conditions “the constancy of the internal environment” “homeostasis”, regulation of the internal environment Claude Bernard, 1880’s Walter B. Cannon, 1929 How does the internal environment stay stable? Deviation from set point Homeostasis: The tendency towards a relatively constant internal environment  Homeostasis isn’t equilibrium! T Dynamic steady state Figs 1.5 & 1.7 Feedback control setpoint Oscillation around a setpoint Fig 1.11  Negative feedback for homeostasis Positive feedback for change Negative Feedback Positive Feedback Initial Initial Stimulus Stimulus Response Response can be turned off by Outside Feedback factor Stimulus Stimulus Stabilizing Reinforcing back to opposite of - homeostasis  Negative feedback e.g. Regulation of cortisol - Negative secretion feedback action of cortisol - suppresses CRH release and ACTH release Once there is enough Positive feedback rare e.g. oxytocin and the control of uterine contractions Note: This is NOT homeostatic  Review question Imagine a hormone that is released in response to low - blood pressure and acts to reduce blood pressure. - What is this an example of? a) O Positive feedback NOT GETING BODY TO SET UP it is b) Negative feedback Reinforcing idea c) Feed forward control Of Law Blood PRESSURE d) Neutral feedback  Maintaining homeostasis and other body functions requires intercellular communication Local control Autocrine Gap junctions Contact-dependent Small ions Membrane protein Molecules same all or and molecules binds to move through others move through membrane protein interstitial fluid; really gap junctions short distance close connecting cells by Fig 6.1 Long-distance communication MIX Neuroendocrine Fig 6.1  Simple and Complex Reflexes – Simple are mediated either by the nervous or the - endocrine system – Complex reflexes are mediated by both systems and - go through several integrating systems Compare neural and endocrine reflexes © 2016 Pearson Education, Inc. Figure 1.9 A comparison of local control and reflex control BIG SYSTEMIC CHANCE Locac it fix © 2016 Pearson Education, Inc. Homeostatic reflex pathways SENSOR can be Specialized cells or structures that convert various stimuli into electrical signals Modified Figs 6.16 & 6.17 Reflex pathway patterns – Nervous system Fig 6.19 Simple endocrine reflex Receptor Endocrine cell Hormone Target cell (effector) Modified Fig 6.19 Why do you need different control systems?  What are hormones & the endocrine system? Epithelium Connective tissue proliferation Exocrine: Exocrine Endocrine Endocrine: Exo = outside Endo = inside krinein = to secrete krinein = to secrete * sweat Where hormones ; digestive ceme in enzymes Into a duct* Into the bloodstream^ * Substances secreted to environment ^ Hormones secreted into the external to self bloodstream  Take ONE minute and map as many hormones to their respective organs as you can! hormones Hypothalamus canease ↓ Pineal gland Pituitary gland Primary Thyroid gland Endocrine Heart Organs Parathyroid gland (main function is Liver to release hormone) of Secondary Pancreas > - on top Adrenal glands Endocrine Kidneys Organs Kidneys (release hormones - & do something else) Stomach & small intestine Placenta Adipose Tissue Testes (male) Skin  What are some features of hormones? can be made in different places in the body chemicals made by cells in specific endocrine glands or other tissues transported in the blood to distant targets bind to specific receptors may act on multiple tissues alter activity of target cells action must be terminated to return to homeostasis maintain homeostasis or precipitate change in many physiological processes  How were hormones identified? Remove gland & observe results Replace gland…. Replace extract from gland…. Give excess gland (or extract)…… Purify extract & test in biological 2 assay DIABETES after insulin Based on an 1849 experiment by the German physiologist AA Berthold  Key points Homeostasis is a core concept in physiology that requires cell-cell communication Cell-cell communication often involves the nervous system or the endocrine system The endocrine system communicates via messengers known as hormones Hormones produced in endocrine glands have various effects on target cells