GCSE Biology - Effect of Adrenaline

Why does adrenaline increase the heart rate?

Adrenaline travels to the heart and increases the blood pressure and heart rate to increase the blood flow to muscles.

Why do blood glucose levels increase?

Adrenaline travels to the liver where glucagon is broken down into glucose and released into the blood. This means there is more glucose available for respiration in the muscles.

Why do the smooth muscles in the airways relax?

Adrenaline travels to the airways and causes them to dilate, so that more oxygen can be taken into the lungs and diffused into the blood. This also increases the removal of carbon dioxide in exhalation.

Why does blood flow to muscles increase?

More blood flow carrying oxygen and glucose for respiration. This increases the rate of respiration and release of energy for muscle contraction.

Why does blood flow to the skin and intestines decrease?

Less blood to digestive system allows blood to be diverted to the muscles.

Why do the pupils dilate?

This allows more light to enter the eye and for the organism to see in more detail and increase peripheral vision.

Why do the hairs on the body stand upright?

This allows the organism to appear bigger and more threatening. It also helps retain heat energy and body temperature.

What happens when the threat has passed?

The levels of adrenaline will decrease and the effects will be reversed.