CH 22 Endocrine System

• Endocrine glands

  •ductless

  •secrete hormones into ISF
• Exocrine glands

  •secrete products into ducts or body cavities, to body cavities
• Primary endocrine glands 


  •pituitary

  •pineal

  •thuroid

  •parathyroid

  •adrenal
• Endocrine tissue-

  secretes hormones, but that is not primary fxn
• Endocrine tissue


  -hypothalamus

  -thymus

  -pancreas

  -ovaries/testes

  -kidneys

  -stomach

  -liver

  -small intesting, ski, heart, adipose tissue & placenta
• Fxns of hormones 


  •help regulate volume of ISF, metabolism, immune system, glandular fxn
• Hormones help control


  Growth & development
• Hormones 


  Regulate reproductive system &

  Help establish Circadian Rhythms
• Endocrine glands produce chemicals called

  hormones
• 50 hormones affect 


  Target cell
• Hormones take longer to respond that 


  NT, but results last longer
• Target cells 


  •only affect cells w specific receptors

  •2,000-100,000 receptors for a hormone
• Downregulation: 


  If hormone is present in excess (insulin) > decrease in # of receptors available
• Upregulation:


  If a hormone is deficient>increase in # receptors available to make it more sensitive
• 3 classes of hormones 


  Peptide hormones

  Steroid hormones

  Biogenic amines
• Peptide hormones-


  Lipid insolubl, stays on receptor on PM (ex:growth hormone)
• Steroid hormones-


  Lipid soluble, penetrates PM, receptors in cytoplasm, ie estrogen
• Biogenic amines:


  nitrogenous base, monoaminergic

  require a receptor (dopamine, NE, &. Ep)
• RU486 effect on uterus


  •binds to receptors for progesterone

  •tells the body it is not pregnant

  •stimulated menses (shedding of uterine lining)
• Negative feedback loop


  •Change produced in opposite direction of stimulis

  •most vookon

  •eating a sandwhich raises blood sugars
• Body releases insulin to

  Lower blood sugars
• Positive feedback loop:

  •Change produced in same direction of stimulis

  •rare

  •ie.baby in birth canal
• Upregulation of hormone receptors occurs when there is too much

  Hormone (chronically), so the receptors are pulled back into the cell to keep it from getting overwhelmed (as in Type II diabetes)
• Hypothalamus:


  master gland-hormones control other glands
• Hypothalamus sits on 


  Anteroimferior diencephalon, superior to pituitary gland & is part of nervous & endocrine system
• Hypothalamus receives input from

  •Reticular Activating System (RAS)

  •Limbic sys

  •Cerebral cortex

  •thalamus

  •internal organs

  •eyes (retina)
• Hypothalamus controls ANS


  •body temp

  •thirst & hunger

  •sexual behavior

  •growth & development

  •defense reactions (fear & rage)

  •emotion part of limbic system
• 3 routes of control for hypothalamus

  1.Regulates anterior pituitary hormones via “releasing” hormones to anterior pituitary

  2.Produces oxytocin (OT) & antidiuretic hormone (ADH)-secretes via posterior pituitary

  3.Controls adrenal medulla by sympathetic imput
• Infundibulum-


  Stalk connecting hypothalamus to pituitary gland
• Posterior pituitary


  •secretes 2 hormones
• Anterior pituitary


  Secretes 7 hormones
• Posterior pituitary gland grows down as 


  Neurohypophysis-direct connection via infundibulum
• Anterior pituitary grows 


  Up from the mouth-connected by blood vessels
• Hypothalamus is aka 


  Hypophysis
• Hypothalamus is directly connected to

  Pituitary gland
• Posterior Pituitary Gland is the


  Direct connection w/hypothalamus via hypothalamohypophyseal tract/bundle
• Posterior Pituitary Gland is aka


  Neurohypophysis
• Posterior pituitary gland

  Secretes oxytocin
• Ocytocin-

  uterine contractions, milk secretion, related to orgasm, cuddling
• Axons make

  infundibulum