feedback loops

hormones and feedback

• hormones are secreted by an endocrine gland

• they travel by the bloodstream

• target cells have receptors for the hormones

• homeostasis is like being in balance or a teeter totter

• once homeostasis is achieved, the brain turns off production of the hormone. this is called negative feedback.

  pituitary → human growth hormone → growth

• without feedback a person would continue to grow.

• once the hormone has it effect, the brain would stop making it

• if negative feedback does not occur, the body would not be able to maintain homeostasis and it would be over produced

adrenaline and stress

• adrenaline gets the body ready for stress.

  effects

• increase heartrate

• increase blood pressure

• increase muscle strength

• increase breathing rate

melatonin and sleep

• melatonin production is high when its dark

• it is secreted by the pineal gland

• they do not remain constant during the night

blood sugar levels

• causes cells to take in sugar and therefore decreases blood sugar levels

• glucagon causes the liver to release sugar and cause an increase in blood sugar levels