Endocrine System Powerpoint PDF

ENDOCRINE SYSTEM Did you know?  The human body contains 30 hormones, which regulate activities like sleep, body temperature, hunger and stress management  What exactly is the endocrine system? Introduction to the Endocrine System  Yes, you will know ALL of the...

ENDOCRINE SYSTEM Did you know?  The human body contains 30 hormones, which regulate activities like sleep, body temperature, hunger and stress management  What exactly is the endocrine system? Introduction to the Endocrine System  Yes, you will know ALL of these and the hormones with their target organs on the next slide really well, VERY SOON! Figure 18–1 Organs and Tissues of the Endocrine System. Introduction to the Endocrine System Introduction to the Endocrine System  The Endocrine System  Regulates long-term processes  Growth  Development  Reproduction  Uses chemical messengers to relay information and instructions between cells Endocrine System vs. Nervous System Nervous System Uses electricity and chemicals to send a fast message Has a specific effector organ (i.e. certain muscle) Endocrine System Uses hormones Effects many effector organs (i.e. HGH to all muscles) Is slower and longer lasting Endocrine System vs. Nervous System Endocrine System vs. Nervous System  Neurotransmitters are released by neurons  Hormones are released by endocrine glands endocrine gland neurotransmitter axon hormone carried by blood receptor proteins receptor proteins target cell Endocrine System vs. Nervous System Analagy  NS is like whispering from one person to the next, very specific  Endocrine System is like sending a global e-mail that can be read by anyone who understands the language  Still specific, but more widespread to any cell that has the appropriate hormone receptor Endocrine System Maintains Homeostasis Through Negative Feedback! hormone 1 gland lowers body condition high specific body condition low raises gland body condition hormone 2 Negative Feedback Response to changed body condition  if body is high or low from normal level  signal tells body to make changes that will bring body back to normal level  once body is back to normal level, signal is turned off hormone 1 gland lowers body condition high specific body condition Homeostasis And Intercellular Communication  3 Types (this chapter we will discuss endocrine communication)  Direct communication  Paracrine communication  Endocrine communication Homeostasis And Intercellular Communication  Direct Communication  Exchange of ions and molecules between adjacent cells across gap junctions  Occurs between two cells of same type  Where have we seen these before?  Cardiac muscle cells  Homeostasis And Intercellular Communication  Paracrine Communication  Uses chemical signals to transfer information from cell to cell within single tissue  Most common form of intercellular communication  i.e. Prostaglandins  Homeostasis And Intercellular Communication  Endocrine Communication  Endocrine cells release chemicals (hormones) into bloodstream  Alters metabolic activities of many tissues and organs simultaneously  Analogy once again: Bulk mail – in Russian How Endocrine Communication Works Glands - release products to bloodstream directly Hormones - products deliver messages to other body cells Target Cells – have specific receptors for specific hormones Receptors – a protein on or inside the cell that recognizes a specific hormone and can trigger a change in the cell Homeostasis And Intercellular Communication  Target Cells (target tissue)  Are specific cells that possess receptors needed to bind and “read” hormonal messages  Ex. Skeletal muscle is a target tissue for Testosterone (from testes)  Hormones (must understand!)  Stimulate synthesis of enzymes or structural proteins  Increase or decrease rate of synthesis  Turn existing enzyme or membrane channel “on” or “off”  Responding To Hormones  Lock and key system  hormone fits receptor on “target” cell target cell secreting cell can’t non- can’t read signal target read signal cells  Classifying Hormones  Can be divided into three groups  Amino acid derivatives  Peptide hormones  Lipid derivatives  Steroids  Corticosteroids/anabolic steroids side note  All of these either circulate freely in the blood or are bound to transport proteins  Can also be classified as:  1. Lipid soluble ( ex. Estrogen)  2. Water soluble (ex. Insulin) Secretion and Distribution of Hormones  Free Hormones  Remain functional for less than 1 hour  Diffuse out of bloodstream:  bind to receptors on target cells  Are broken down and absorbed:  by cells of liver or kidney  Are broken down by enzymes:  in plasma or interstitial fluids Secretion and Distribution of Hormones  Thyroid and Steroid Hormones  Remain in circulation much longer  Enter bloodstream  More than 99% become attached to special transport proteins  Bloodstream contains substantial reserve of bound hormones  A reserve  Why do thyroid and steroid hormones stay in circulation longer?  Mechanisms Of Hormone Action  Lipid soluble hormones:  Glucocorticoids (cortisol)  Estrogens  Androgens (testosterone)  Thyroid hormone (T3)  Calcitriol (the active form of vitamin D)  Diffuse across the plasma membrane to reach receptor proteins on inner surface of membrane (intracellular receptors)  REMEMBER: Anything that originates from cholesterol is lipid soluble! Mechanisms Of Hormone Action (Lipid Soluble)  Mechanisms Of Hormone Action  Hormones that are NOT lipid soluble, they are WATER SOLUBLE  Prolactin  Adrenocorticotropic Hormone (ACTH)  Human Growth Hormone (hGH)  Antidiuretic Hormone (ADH)  Peptide Hormones (oxytocin, Insulin)  Atrial-natriuretic Peptide (ANP)  Atrial Natriuretic Factor (ANF)  Leptin  Epinephrine  Unable to penetrate plasma membrane  What is the plasma membrane made of?  Bind to receptor proteins at outer surface of plasma membrane (extracellular receptors) Mechanisms Of Hormone Action WATER-SOLUBLE  Hormones and Plasma Membrane Receptors  Bind to receptors in plasma membrane  Cannot have direct effect on activities inside target cell  Use intracellular intermediary to exert effects  First messenger:  leads to second messenger  may act as enzyme activator, inhibitor, or cofactor  results in change in rates of metabolic reactions  Mechanisms Of Hormone Action  Hormone Receptor  Is a protein molecule to which a particular molecule binds strongly  Responds to several different hormones  Different tissues have different combinations of receptors  Presence or absence of specific receptor determines hormonal sensitivity Mechanisms Of Hormone Action  Important Second Messengers  Cyclic-AMP (cAMP)  Derivative of ATP  Cyclic-GMP (cGMP)  Derivative of GTP  Calcium ions Mechanisms Of Hormone Action (Water Soluble) Mechanisms Of Hormone Action  Why use second messenger?  The Process of Amplification  Is the binding of a small number of hormone molecules to membrane receptors  Leads to thousands of second messengers in cell  Magnifies effect of hormone on target cell Second Messenger Amplification  Mechanisms Of Hormone Action WHAT HAPPENS WHEN SOMEONE HAS TOO MUCH OF A PARTICULAR HORMONE?  Down-regulation (Type II Diabetes)  Presence of a hormone triggers decrease in number of hormone receptors  When levels of particular hormone are high, cells become less sensitive  Receptors are all filled up  Some receptors are broken down by the target cell Down-regulation  Mechanisms Of Hormone Action  WHAT HAPPENS WHEN SOMEONE HAS TOO LITTLE OF A PARTICULAR HORMONE?  Up-regulation  Absence of a hormone triggers increase in number of hormone receptors  When levels of particular hormone are low, cells become more sensitive  Receptors are available SUMMARY  Why do physicians want you to give your depression meds time to work?  What about birth control meds for PMS?  What do hormones do  again? Hormones (must understand!)  Stimulate synthesis of enzymes or structural proteins  Increase or decrease rate of synthesis  Turn existing enzyme or membrane channel “on” or “off”  Hormones and Intracellular Receptors  Alter rate of DNA transcription in nucleus  Directly affect metabolic activity and structure of target cell  Includes steroids and thyroid hormones Water-Soluble Hormones  Lipid- Soluble(Steroid)Hormone s Endocrine Reflexes  Endocrine Reflexes (When do Glands know when to secrete their hormones)  Functional counterparts of neural reflexes  In most cases, controlled by negative feedback mechanisms  Stimulus triggers production of hormone whose effects reduce intensity of the stimulus Endocrine Reflexes  Endocrine reflexes can be triggered by  Humoral stimuli  Changes in composition of extracellular fluid  Hormonal stimuli  Arrival or removal of specific hormone  Neural stimuli  Arrival of neurotransmitters at neuroglandular junctions  Organs Of Endocrine System  Hypothalamus  Anterior pituitary gland  Posterior pituitary gland  Thyroid gland (follicular cells and parafollicular cells)  Parathyroid gland  Adrenal gland (layers of the cortex and medulla)  Pancreatic islets We will learn the rest later!  Kidney (in another chapter)  Heart (in another chapter)  Intestine (in another chapter)  Stomach (in another chapter)  Gonads (in another chapter)  Adipose (in another chapter)  Thymus (in another chapter)  Pineal gland (should already know)  Hypothalamus (CEO) Integrates activities of nervous and endocrine systems in 3 ways: 1. Secretes regulatory hormones:  special hormones that control endocrine cells in pituitary gland 2. Acts as an endocrine organ 3. Contains autonomic centers:  exert direct neural control over endocrine cells of adrenal medullae  Hormones of the Hypothalamus Target- ANTERIOR PITUITARY 1. GnRH-targets Anterior Pituitary to release FSH, LH 2. CRH-targets Anterior Pituitary to release ACTH 3. TRH-targets Anterior Pituitary to release TSH 4. GHRH-targets Anterior Pituitary to release GH 5. GHIH-targets Anterior Pituitary to inhibit GH release 6. PRH-targets Anterior Pituitary to release PROLACTIN 7. PIH- targets Anterior Pituitary to inhibit PROLACTIN release Stored- POSTERIOR PITUITARY 8. Oxytocin- Made in hypothalamus and stored and released by the POSTERIOR PITUITARY 9. Antidiuretic Hormone- Made in hypothalamus and stored and released by the POSTERIOR PITUITARY Note: Melanotropin hormones in trace amounts and no known function in humans! Pathology could cause excess pigmentation of the skin. (Snooki could use this!) Hypothalamus control over Anterior Pituitary Hypothalamus, Anterior Pituitary, Target Organs