Hormones

Adrenal glands secrete adrenaline, which prepares the body for 'fight or flight'. The pancreas secretes insulin, which regulates blood glucose levels.

The testes secrete testosterone. This hormone is responsible for the development of male secondary sexual characteristics.

The ovaries secrete oestrogen. This hormone is responsible for the development of female secondary sexual characteristics and plays a role in the menstrual cycle.

Adrenaline increases the breathing rate, providing more oxygen to cells. It also increases the heart rate, delivering oxygenated blood faster. Furthermore, it increases pupil diameter, improving vision.

Nervous control is faster because it uses electrical impulses that travel quickly along neurons, but its effects are short-lived. Hormonal control is slower because hormones must travel through the bloodstream, but its effects last longer.

The pancreas also secretes glucagon. Glucagon works antagonistically to insulin in regulating blood glucose levels.

Adrenaline increases blood glucose concentration by stimulating the liver to convert glycogen into glucose. This provides more glucose for energy during 'fight or flight' situations.

Adrenaline increases heart rate, allowing for faster delivery of oxygen and glucose to muscles. This increases the rate of respiration in muscle cells, providing more energy for movement.

The 'fight or flight' response is a physiological reaction that occurs in response to a perceived harmful event, attack, or threat to survival. It is triggered by the release of adrenaline, which prepares the body for rapid action.