Heart rate response to exercise Cardiac control centre Understand how exercise effects the heart rate Know what the cardiovascular drift is. Understand how the heart is controlled.

Cardiac control centre SA Sympathetic nervous system Increases heart rate and SV Via accelerator nerve Cardiac control centre Parasympathetic nervous system Decreases the heart rate. Via Vagus nerve

Heart regulation during exercise Rule of three two one. 3 Neural factors 2 Intrinsic factors 1 Hormonal

1 Hormonal Adrenalin From adrenal glands Stimulates the SA node directly via blood. This increases the heart rate as well as the stroke volume.

2 Intrinsic Temperature Increase in temperature which speeds up the nerve impulse, which in turn speeds up the heart rate. Venous return Increase in SV (staling’s law) Increase in HR and SV

3 Neural Baroreceptors Baro = pressure Increase in blood pressure = decrease in HR but is neutralised due to demand of 02. Chemoreceptors Chemo = Chemical In muscle aorta and carotid arteries Decrease in PH Increase in pp Co2 Decrease in pp O2 Proprioceptors Muscle spindles, joint receptors Increase in motor activity = increase in HR and SV