The Body's Negative Feedback Loop

What is positive feedback?

The opposite of negative feedback. It makes a small change even bigger.

e.g. release of oxytocin, which increases number of contractions during childbirth.

When does negative feedback occur?

If internal condition changes and is no longer optimal, this stimulus is detected and the body works to return conditions to optimum.

What happens when humans exercise intensely?

Anaerobic respiration occurs when insufficient oxygen is supplied to the muscles.

During anaerobic respiration glucose is broken down into lactic acid.

Lactic acid can cause muscle fatigue and soreness.

How can our bodies increase oxygen supply to muscles?

• Increasing breath volume.

• Increase heart rate.

Why is exercise dangerous for someone with anhidrosis that cannot sweat?

Their body may overheat as they cannot sweat. Sweating releases heat.

How would our control systems respond to an increase in body temperature?

• Receptor cells detect the change in temperature.

• Coordination centres receive and process information arriving from receptor cells.

• This message is sent to effectors, which are muscles or glands.

• Effectors carry out responses to stimuli which help to restore optimum levels.

How is enzyme function affected if the internal body temperature is too high?

• If the temperature increases, enzymes can denature.

• As a result, this reduces the enzyme’s ability to catalyse metabolic reactions.