Endocrine System

     A.   Two major systems for maintaining homeostasis
          1.   nervous
               a.   sympathetic
               b.   parasympathetic
          2.   hormonal
     B.   Hormonal systems
               a.   work by different types of negative feedback
               b.   are released from "ductless" endocrine glands
               c.   secrete directly into the blood or lymph
               d.   hormones are specific (tropic)
                    (1)  targets
                         (a)  cell
                         (b)  tissue
                         (c)  organ
               e.   different effects
                    (1)  activate enxyme systems
                    (2)  alter cell membrane permeability
                    (3)  cause muscular contraction or relaxation
                    (4)  stimulate protein systhesis
                    (5)  cause cellular secretion
               f.   mechanisms
                    (1)  cause cyclic AMP to be produced
                         (a)  is the most common method
                         (b)  causes the above 5 actions to occur
                    (2)  can also cause other intracellular
                         hormones to be produced
                         (a)  prostaglandins
                         (b)  cyclic guanosine monophosphate
     C.   Hormone glands
          1.   Pituitary Gland  (hypophysis)
               a.   general
                    (1)  located at the base of the brain
                    (2)  is very small
                    (3)  is connected to the hypothalamus
                    (4)  releases many hormones
               b.   posterior lobe   (neurophysis)
                    (1)  secretes ADH - antidiueretic hormone
                         (vasopressin)
                         (a)  promotes water absorbtion from the
                              kidneys
               c.   anterior lobe  (adenohyphysis)
                    (1)  secretes
                         (a)  GH (growth hormone - "somatatropin")
                         (b)  thyroid stimulating hormone
                              i)   which stimulates the production
                                   and release of thyroid hormones
                         (c)  adrenocorticotropin hormone
                              (corticotropin)
                              i)   stimulates the release of the
                                   glucocorticoid hormones from
                                   the adrenal cortex
                         (d)  follicle stimulating hormone 
                              i)   which produces growht of the
                                   ovarian follicle of
                                   spermatogenesis
                         (e)  leutinizing hormone
                              i)   stimulates various sex related
                                   things
                         (f)  prolactin
                              i)   responsible for milk secretion
                                   and ENDORPHINS
     D.   Specific Hormones
          1.   ADH - antidiueretic hormone
               a.   promotes water absorbtion from the kidneys by
                    acting on the collecting tubules only
                    (1)  see aldosterone, renin, and angiotensin's
                         I and II
               b.   works with aldosterone (from the adrenal
                    cortex) to control water regulation
          2.   Pancreatic hormones
               a.   Insulin 
                    (1)  causes a increase in cellular uptade of
                         glucose resulting in a lower blood
                         glucose level
               b.   Glucagon 
                    (1)  does the opposite of insulin, causes the
                         release of glucose
          3.   Thyroid hormones
                    (1)  increase significantly with exercise
                    (2)  increase the metabolism
                    (3)  remain elevated for days after the
                         exercise
               a.   Thyroxin and triiodothyronine are the main
                    hormones released