Homeostasis

Question 1

What is a sensor in the feedback system?

Answer 1

Part of the feedback system that monitors a physiological value which is reported to the control centre

Question 2

What is a control system in the feedback system?

Answer 2

Part of the feedback system that compares value to the normal range (set point) and if it deviates from the normal range the effector is activated

Question 3

What is the effector in the feedback system?

Answer 3

Part of the feedback system that causes change to reverse the situation/return to the normal range

Question 4

What is an example of a negative feedback loop?

Answer 4

Control of blood glucose levels
- the cells in the pancreas detect excess glucose in the blood
- this increases the hormone insulin in the bloodstream
- skeletal muscle fibres, fat cells, and liver cells take up the excess glucose/removes it from the bloodstream
- decreased concentration of glucose is detected and the release of insulin stops

Question 5

What is a positive feedback loop?

Answer 5

A positive feedback loop intensifies the body’s physiological condition rather than reversing it
- a deviation from normal results in more changes/going further and further away from normal
- it has a definite end point

Question 6

What is an example of a feedback loop?

Answer 6

Child birth or blood loss
- head of baby pushes on cervix
- impulses from the cervix to the brain are sent
- the pituitary gland secretes oxytocin
- oxytocin is carried to the uterus
- oxytocin stimulates contractions and pushes the baby toward the cervix
This cycle continues until the baby is born