Heart Control

• Cardiac muscle is myogenic, but can be controlled by electrical impulse
• Sinoatrial nodes release a wave of depolarisation across the atria to contract, which is called the atrial systole
• Atrioventricular Node releases a delayed wave of depolarisation once the first wave has reached, this travels down the bundle of His and into the purkyne fibres, causing the ventricle muscles to contract, called Ventricular Systole
• The Medulla Oblongata controls cardiac muscle contraction via the autonomic nervous system
• Chemoreceptors detect changes in blood pH, pH decreases due to high respiratory rates creating CO2 or lactic acid; this sends an impulse via the sympathetic nervous system to the SAN to increase heart rate
• Baroreceptors detect changes in blood pressure, if pressure is too high, it can damage capillary walls, sends impulse via parasympathetic nervous system to SAN to decrease heart rate
• Baroreceptors are located in the aortic arch and carotid sinuses
• Chemoreceptors are located in the brain stem, cerebellum, hypothalamus and midbrain