Function Organization of the Endocrine System

  1. Chemical Messengers
    Allow cells to communicate with each other to regulate body activities
  2. secretion
    controlled release of chemicals from a cell
  3. Classes of Chemical Messengers
    • 1. Autocrine
    • 2. Paracrine
    • 3. Neurotransmitter
    • 4. Endocrine
  4. Autrocrine chemical messengers
    • -Stimulates the cell that originally secreted it
    • -secreted by cells in a local area

    • Example: white blood cells during an infection
    • -Eicosanoids (prostaglandins, thromboxanes, prostacyclins, leukotrienes)
  5. Paracrine Chemical Messengers
    • -act locally on nearby cells
    • -secreted by one cell type into the extracellular fluid and affect surrounding cells

    • Example: Histamine stimulates vasodilation in nearby blood vessels during allergic reactions
    • -Somatostatin, histamine, eicosanoids
  6. Neurotransmitters
    • -secreted by neurons that activate an adjacent cell, with it is another neuron, a muscle cell, or a glandular cell. 
    • -secreted into a synaptic cleft (not bloodstream) by presynaptic nerve terminals
    • -travels short distances
    • -influences postsynaptic cells

    Examples: acetylcholine, epinephrine
  7. Endocrine chemical messengers
    • -secreted into the bloodstream by certain cells and glands.
    • -travels some distance to target tissues
    • -results in coordinated regulation of cell function

    Examples: thyroid hormones, growth hormones, insulin, epinephrine, estrogen, progesterone, testosterone, prostaglandins
  8. Endocrine system
    -composed of endocrine glands and specialized endocrine cells located throughout the body

    • -endocrine:
    • endo = within
    • krino = secrete
  9. hormones
    secreted by endocrine glands into bloodstream (circulatory system) to specific sites called target tissues (effectors) where they produce a coordinated response of the target tissues

    • -produced in small quantities
    • -secreted into intercellular space
    • -transported some distance in circulatory system
    • -acts on target tissues elsewhere in body

    -regulates activities of body structures
  10. Exocrine glands
    have ducts that carry their secretions to the outside of the body (i.e. saliva, sweat, breast milk, and digestive enzymes) or into a hollow organ (i.e. stomach or intestines.)
  11. Comparison of Nervous and Endocrine systems - similarities
    1. associated with the brain (hypothalamus: neural functions and hormone production)

    2. May use same chemical messenger as neurotransmitter (i.e. epinephrine into synaptic cleft) and hormone (epinephrine into bloodstream)

    • 3. Two systems work together to regulate critical body processes
    • -Some neurons secrete hormones. Nervous system secretes neuroendocrine peptides (neurohormones), into circulatory system
    • -some parts of endocrine system innervated directly by nervous system
Card Set
Function Organization of the Endocrine System
A&P - Chapter 17