15.1 The principles of homeostasis

Question 1

define homeostasis

Answer 1

the process of making the kidney go through osmoregulation (body maintains a dynamic equilibrium with small fluctuations over a narrow range of conditions )

Question 2

explain how receptors and effectors work

Answer 2

• sensory receptors detect changes in the internal/external environment of an organism
• info is transmitted to the brain and impulses are sent along motor neurones to the effectors
• effectors are muscles/ glands that react to motor stimulus to bring about a change

Question 3

how do negative feedback systems work

Answer 3

• small change in one direction is detected by sensory receptors
• effectors work to reverse the change and restore conditions to their base level

Question 4

why are negative feedback systems important

Answer 4

• control blood sugar levels
• temperature control
• water balance

Question 5

how do positive feedback systems work

Answer 5

• change in internal environment detected by sensory receptors
• effectors are stimulated to reinforce the chance and increase the response

Question 6

describe how positive feedback works in the blood closing cascade

Answer 6

• platelets stick to the damaged region and release factors to initiate clotting and attract more platelets
• platelets add to the cycle until clot forms

Question 7

describe how positive feedback works in childbirth

Answer 7

• baby’s head presses against the cervix, stimulating production of oxytocin
• oxytocin stimulates uterus to contract and pushes the head of the baby even harder against the cervix
• triggers release of more oxytocin
• continues until baby is born