1. The importance of homeostasis

Question 1

what is the hypothalamus?

Answer 1

part of the brain next to the pituitary gland, it is the control centre for ANS

Question 2

define vasoconstriction

Answer 2

narrowing the diameter of arterioles near the surface of the skin, retaining heat

Question 3

define vasodilation

Answer 3

widening the diameter of arterioles near the surface of the skin, so that warm blood passes close to its surface through the capillaries

Question 4

outline the two systems your body uses to maintain a constant internal environment

Answer 4

1. nervous system: uses action potentials in neurones to transfer electrical signals from receptor to brain and spinal cord
2. Endocrine system: uses hormones released from specialised tissue, to travel to effector organs via the bloodstream

Question 5

what is pilorelaxation?

Answer 5

when you are too hot:
where sweat glands release more sweat and body heat, vasodilation occurs, allowing more heat loss, causing nerve impulses to be sent to hair erector muscles, which causes hairs to lie flat on the skin

Question 6

what is piloerection

Answer 6

when you are too cold:
skeletal muscles contract rapidly, shivering, they need energy from respiration
vasoconstriction takes place, allowing warm blood near the skin,
when we are still too cold, nervous impulses are sent to the hair erector muscles, which contracts, causing hairs on skin to raise.

Question 7

Blood-glucose concentration is controlled through ——– ———–

Answer 7

negative feedback

Question 8

blood-glucose concentration must be controlled to maintain ________

Answer 8

water potential

Question 9

give an example of positive feedback

Answer 9

• oxytocin is released is released during contractions to lower pain, therefore more is released for each contraction until childbirth