1. HOMEOSTASIS “Keeping The Status Quo”

2.  A set of processes used to maintain a balanced body environment  Blood pressure at 120/80  Body temperature at 37 o C  Blood pH at 7.4  Glucose concentration 100 mg per mL  Heartbeat at 50 – 100 beats per minute HOMEOSTASIS

3.  There are TWO kinds of mechanisms used in homeostasis:  NEGATIVE FEEDBACK: a mechanism used to CORRECT change  POSITIVE FEEDBACK: a mechanism used to AMPLIFY change HOMEOSTASIS

4. NEGATIVE FEEDBACK

5. TEMPERATURE CONTROL COLD  Shivering  VASOCONSTRICTION: blood vessels constrict (tighten) and move away from the surface to keep the core organs (heart, brain, liver, etc.) warm  Goosebumps raise the hair up to trap warm air to the surface of the skin HOT  Sweating  VASODILATION: blood vessels in the body dilate (widen) and rise to the surface of the skin to radiate off heat.

6.  When we stop breathing:  Carbon dioxide levels increase  This produces carbonic acid  This lowers the pH of the blood  Receptors detect the change in pH  The brain sends a message to the diaphragm and intercostal muscles to contract  Heart rate also increases to deliver oxygen and remove carbon dioxide quickly BREATHING CONTROL

7. GLUCOSE CONTROL AFTER A MEAL…  Blood glucose levels increase  Specialized receptor cells signal the release of insulin from the pancreas  Insulin is released which promotes the uptake of glucose from blood to restore normal levels WHEN YOU ARE STARVING…  Blood glucose levels decrease  Receptor cells signal the release of glucagon from the pancreas  Glucose is released from energy reserves in the liver

8.  Associated with disease or addiction  EXAMPLE: High Blood Pressure  High blood pressure leads to damage of the walls of the arteries  The arteries develop scar tissue  Cholesterol sticks to the scar tissue with causes the diameter of the artery to shrink  The flow of blood decreases, which increases blood pressure POSITIVE FEEDBACK

9. ENDOCRINE SYSTEM  An organ system comprised of:  HORMONES: chemical messengers  GLANDS: specialized group of cells that deliver hormones

11. ENDOCRINE GLANDS EXOCRINE GLANDS  Hormones are released through DUCTS ENDOCRINE GLANDS  Hormones are released directly into the blood vessels  No ducts

12.  HYPOTHALAMUS: monitors the body and regulates the pituitary gland  PITUITARY: produces hormones to regulate the endocrine system  THYROID: controls metabolism with the hormone THYROXIN  PANCREAS: regulates blood sugar with the hormones INSULIN and GLUCAGON ENDOCRINE ORGANS

13.  ADRENALS: regulates stress  CORTISOL: hormone released during long term stress  ADRENALINE: hormone released during short term stress or the “flight or fight” stress ENDOCRINE ORGANS

14.  OVARIES AND TESTES: produce and use the same hormones FSH and LH ENDOCRINE ORGANS FEMALESMALES LH and FSH are involved in the menstrual cycle LH: involved in testosterone production FSH: involved in sperm production