Endocrine System Anatomy Part A

  1. Endocrinology
    Study of hormones and endocrine organs
  2. What system does the endocrine coordinate with?
    • The nervous system
    • The influences of metabolic activities via hormones; responses of endocrine are much slower but are longer lasting than the nervous system
  3. Endocrine System Overview
    • Controls and integrates:
    • Reproduction
    • Growth and development
    • Maintenance of electrolyte, water, and nutrient balance of blood
    • Regulation of cellular metabolism and energy balance
    • Mobilization of body defenses
  4. Exocrine glands
    • Nonhormonal substances (sweat, saliva)
    • Have ducts to carry secretion to membrane surface
  5. Endocrine glands
    • produce hormones
    • Lack ducts
  6. Specific endocrine glands include:
    • Pituitary gland
    • Thyroid gland
    • Parathyroid gland
    • Adrenal gland
    • Pineal glands
  7. Neuroendocrine organ includes:
  8. Organs that have both exocrine and endocrine functions include:
    • pancreas
    • gonads
    • placenta
  9. Other tissues and organs that produce hormones:
    • Adipose cells
    • Thymus
    • Cells in Walls of small intestine
    • Stomach
    • Kidneys
    • Heart
  10. Hormones
    Long-distance chemical signals that travel in blood or lymph
  11. Autocrines
    Chemicals that exert effects on same cells that secrete them
  12. Paracrines
    Locally acting chemicals that affect cells other than those that secrete them
  13. Autocrines and Paracrines are
    Local chemical messengers and are not considered part of the endocrine system
  14. Two main classes of Hormones
    • 1) Amino acid-based hormones which include amino acid derivatives, peptides, and proteins
    • 2) Steroids which are synthesized from cholesterol and include gonadal and adrenocortical hormones
  15. Mechanisms of Hormone Action
    • Hormones circulate systemically but only cells with the specific receptors for that hormone are affected (target cells = tissues with receptors specific to that hormone)
    • Hormones alter target cell activity
  16. Hormone Action on target cells may be to
    • Alter plasma membrane permeability and/or membrane potential by opening or closing ion channels
    • Stimulate synthesis of enzymes or other proteins
    • Activate or deactivate enzymes
    • Induce secretory activity
    • Stimulate mitosis
  17. The two ways at which hormones act at receptors depend on
    Their chemical nature and receptor location
  18. Water-soluble hormones (all amino acid based hormones except thyroid hormones) mechanisms
    • Act on plasma membrane receptors
    • Act via G protein second messengers
    • Cannot enter cell
  19. Lipid-Soluble hormones (steroid and thyroid hormones) mechanisms
    • Act on intracellular receptors that directly activate genes
    • Can enter cell
  20. CAMP signaling mechanism of plasma membrane receptors and second messenger systems
    • CAMP signaling mechanism can have a huge amplification effect by intracellular enzymatic cascades
    • 1. Hormone (first messenger) binds to receptor
    • 2. Receptor activates G protein
    • 3. G protein activates adenylate cyclase
    • 4. Adenylate cyclist converts ATP to cAMP (second messenger)
    • 5. CAMP activates protein kinases that phosphorylate proteins
  21. What does G protein do in cAMP signaling?
    It activates adenylate cyclase
  22. Adenylate cyclase
    An enzyme that concerts ATP to cAMP second messenger
  23. CAMP activates what?
    Protein kinases that phosphorylate proteins
  24. Phosphodiesterase
    enzyme that rapidly degrades cAMP
  25. Plasma membrane receptors and second-messenger system PIP2-calcium signaling mechanism
    • Involves G protein and membrane bound effect or (phospholipase C)
    • Phospholipase C splits PIP2 into two second messengers (diacylglycerol (DAG) and inositol triphosphate (IP3))
  26. Phospholipase C splits PIP2 into
    Two messengers called diacylglycerol (DAG) and inositol triphosphate (IP3)
  27. Diacylglycerol (DAG)
    Activates protein kinase
  28. Inositol triphosphate (IP3)
    Causes Ca2+ release; the calcium ions then act as second messengers
  29. Calcium ions in Plasma membrane receptors and second messenger systems
    • The calcium alters enzyme activity and channels or binds to regulatory protein calmodulin
    • Calcium-bound calmodulin activates enzymes that amplify cellular response
Card Set
Endocrine System Anatomy Part A
Anatomy and phys II endocrine opt notes part A