2. Regents Biology 2009-2010 Endocrine System Regulation - How we maintain homeostasis  nervous system nerve signals control body functions electrical (+/- charges) AND chemical (neurotransmitters)  endocrine system hormones (proteins) chemical signals ONLY control body functions

3. Regents Biology Homeostasis  maintaining internal balance in the body- organism must keep internal conditions stable even if environment changes also called “dynamic equilibrium” use feedback mechanisms  example: body temperature – 37 C – monitored by nervous system humans:  too cold = shiver – (muscles contact – R – produce heat)  too warm = sweat

4. Regents Biology Hormones  chemical messages from one body part to cells in other parts of body  travel through bloodstream  hormones are proteins  communication needed to coordinate whole body  maintaining homeostasis  hormones work SLOWER than nerve impulses

5. Regents Biology Endocrine System Endocrine system releases hormones  glands which secrete (release) chemical signals into blood chemicals cause changes in other parts of body  growth hormone (HGH)  sex hormones  response hormones  metabolism hormones  and more….

6. Regents Biology Getting the correct signal hormone fits receptor on “target” cell target tissue/cell non- target cells secreting cell (gland) can’t read signal hormone receptor

7. Regents Biology Review Protein Synthesis Start with DNA (gene) in the nucleus Transfer info to RNA – DNA can’t leave the nucleus RNA moves to ribosome – amino acid chain is made Moves to ER – packaged into a vessicle Then to Golgi – repackaged in to another vessicle Vessicle moves to cell membrane Secretion by exocytosis (active transport)

8. Regents Biology

9. Pituitary  many hormones: master gland  HGH – human growth hormone  TSH – thyroid stimulating hormone  FSH – follicle stimulating hormone; LH – leutinizing hormone Thyroid  thyroxine – regulates metabolism Parathyroid  Parathyroid hormone – regulates Calcium metabolism Adrenal  adrenaline – “fight or “flight” Pancreas  Insulin – lowers blood sugar  Glucagon – raises blood sugar Ovary - estrogen, progesterone Testes - testosterone Glands

10. Regents Biology Negative Feedback Response to changed body condition  if body is high or low from normal level signal tells body to make changes that will bring body back to normal level  once body is back to normal level, signal is turned off high hormone 1 lowers body condition gland specific body condition Like the thermostat in your house

11. Regents Biology Maintaining homeostasis high low hormone 1 lowers body condition hormone 2 gland specific body condition raises body condition gland Feedback

12. Regents Biology liver pancreas liver Regulation of Blood Sugar blood sugar level (90mg/100ml) insulin body cells take up glucose from blood liver stores sugar as glycogen reduces appetite glucagon pancreas liver releases glucose triggers hunger high low After a meal Between meals

13. Regents Biology Feedback: Maintaining Homeostasis Balancing glucose levels in blood pancreas insulin liver takes up glucose for storage cells take up glucose from blood liver releases glucose to blood depress appetite stimulate hunger glucagon