THE CONTROL OF HEART RATE

Gap-fill exercise

Fill in all the gaps, then press "Check" to check your answer
Heart rate is regulated by the found in the
of the brain. The cardiac control centre is controlled by the nervous system. This system consists of and motor nerves from either the sympathetic or nervous system. Sympathetic nerves heart rate and parasympathetic nerves heart rate. The cardiac control centre initiates either sympathetic or parasympathetic nerves to stimulate the node to increase or decrease heart rate.

There are three main factors which affect the activity of the cardiac control centre. They are , hormonal and .

Neural control
During exercise sensory receptors stimulate the cardiac control centre. These receptors include:-
which sense that movement has increased.
which sense changes in chemicals in the muscles and blood. These changes include increased levels of and lactic acid and increased in the blood.
which are sensitive to stretch within within the blood vessel walls. These detect increased blood pressure.
The cardiac control centre responds to this information by stimulating the sino-atrial node via the sympathetic cardiac nerve to increase heart rate.

Hormonal control
Before and during exercise is released in the blood.
This stimulates the sino-atrial node to increase heart rate

Intrinsic control
During exercise increases which increases the speed of nerve impulses which in turn increases hear rate
Venous return increases heart rate which directly increases EDV and therefore (Starlings Law).