The Endocrine System

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  1. What is an Endocrine System?
    A set of hormone secreting glands within the body of an animal
  2. What is the function of the Endocrine System?
    Homeostasis, communication and response to stimuli
  3. What is a hormone?
    A hormone is a chemical messenger (protein) secreted by an endocrine gland into the bloodstream and carried to a target organ where it causes a response
  4. What is an endocrine gland?
    An endocrine gland is a ductless gland, produces & secretes hormones directly into the bloodstream, eg thryoid - thyroxine 
  5. What is an exocrine gland?
    An exocrine gland has ducts, secretes directly to site of action eg salivary glands- saliva- salivary ducts-mouth
  6. Differences between Nervous System and Endocrine System?
    • 1. Nervous is faster
    • 2. Nervous shorter in duration
    • 3. Nervous stops quicker
    • 4.Nervous response is much more local
    • 5.Nerve 'messages' are conducted electrically, endocrine chemically
  7. Pituitary (master) gland?
    • 1. Growth hormone - stimulates growth
    • 2. Prolactin- stimulates milk formation in mammary glands
    • 3. Pituitary- muscle contractions at birth, milk ejection
  8. Pineal gland?
    Melatonin - natural sleep, enhances immunity
  9. Hypothalmus?
    GHRF- stimulates pituitary to produce growth hormone
  10. Thryoid?
    Thryoxine- controls metabolism
  11. Adrenals?
    Adrenaline- emergency response
  12. Islets of Langerhans (pancreas)?
    Insulin- stimulates the uptake of glucose from blood, maintains blood sugar level
  13. Ovary?
    • Oestrogen- female 2ndary characteristics, graafian follicle formation, control menstrual cycle.
    • Progesterone- maturation of uterine lining, prep for pregnancy
  14. Testes?
    Testosterone- male 2ndary characteristics, sperm
  15. Thryoid Gland in detail?
    • 1. Thryoxine
    • 2. Regulation of metabolic rate, growth and development
    • 3. Iodine is needed for thryoxine formation
    • 4. Iodine is absorbed from blood by active transport
  16. Thryoxine Deficiency? HYPOthryoidism
    • Underactivity of thyroid gland. Insufficient thyroxine. Cretinism in kids-poor, stunted growth/dwarfism & poor brain development.
    • Myxoedema in adults- fatique, low energy, reduced resistence to disease, sluggishness, reduced metabolic rate-weight gain. Lack of iodine can cause this
  17. Thryoxine EXCESS? HYPERthyroidism
    • Overactivity of thyroid gland. Overproduction of thyroxine. Raised metabolism, greater appetite, weight loss, restlessness, protruding eye- Graves Disease
    • Drugs suppress thyroid gland, or surgically remove part of the gland, radioactive iodine to destroy part of gland
  18. Regulation of Thyroid action?
    • TSH ( thyroid stimulating hormone)
    • Released in blood, causes gland to produce thyroxine.
    • If thyroxine level is correct- tsh not produced-no more thyroxine produced. Correct level of thyroxine has a NEGATIVE effect- Negative feedback
    • Below normal thyroxine level-tsh made- more thyroxine produced-thryoxine level correct it switches off
  19. Hormone supplements?
    • Insulin for diabetes-under-secretion of insulin- allows glucose to enter cells from the blood
    • Growth hormone for potential cretinism?
Card Set:
The Endocrine System
2013-12-12 20:22:49
Biology definitios
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