Explain the mechanisms for regulating ventilation and pulse rates.

Ventilation and pulse rates are controlled by the nervous system . The nervous system consists of the brain and the spinal cord. Electrical impulses are transmitted around the body by neurones to enable the body to deal with certain situations.There are two sides to the nervous system known as the sympathetic nervous system(which speeds things up) and the parasympathetic nervous system(which slows things down).

This process can be seen during times of fear and stress, and is often referred to as 'Fight or Flight'.This means that when the brain senses danger, the sympathetic nervous system, will send electrical impulses down the spinal cord and along neurones which will : Dilate the pupils (for better vision) , inhibit saliva flow, Dilate the bronchi (to allow for maximum amount of oxygen to enter the body), inhibit peristalsis and secretion, Convert glycogen to glucose, secrete adrenaline (which increases heart rate and breathing) and inhibits bladder contraction.

When the danger has passed then the para-sympathetic nervous system takes over and all the reactions above return to normal.

Ref: Image from www.drstandley.com/images/nervous5.bmp