MYOGENIC - The heart produces its own electrical impulses involuntary.
PATHWAY OF CARDIAC IMPULSES
- SA NODE (Sinoatrial node)
- AV NODE (Atrioventricular node)
- HIS FIBRES
- PURKINJE FIBRES
- THEN AROUND THE HARD TO CONTRACT.
- AV and SA valves are both closed.
- The atriums begin to fill with blood coming from the pulmonary vein.
- Increase filling of blood increases the pressure placed against the AV valves.
- AV valves open due to an increase pressure in the atriums.
- Blood begins to enter the ventricles.
- Increase filling of blood increases pressure paced against the SA valves.
- The AV valves cloe whilst the SA valves open
- Blood begins to leave from the left ventricle via the pulmonary artery
- Blood is then taken away to the rest of the body.
CONTROL OF THE HEART RATE
- Cardiac control centre located in the medulla oblongata
- Consists of the sympathetic nerve, which increases heart rate and the parasymathetic nerve, which decreases heart rate.
- Adrenaline and Noradrenaline which are released by the adrenal gland, this increases heart rate and helps to vasoconstrict blood vessels.
- Acetylcholine, released by parasympathetic nerves, reduces heart rate.
- PROPRIOCEPTORS: Detects movement in the muscles and the joints, which increases the heart rate.
- CHEMORECEPTORS: Detects an increase in blood pH levels, for example, an increase in lactic acid or carbon dioxide.
- BARORECPTORS: Detects a change in blood pressure, increase blood pressure increases the heart rate.
- The volume of blood that is ejected from the left ventricle per beat.
- linearly increases as intentsity of exercise increases.
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