PE AQA PHED 1 CARDIOVASCULAR SYSTEM

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  • Created by: mylie101
  • Created on: 13-05-16 21:29

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.

CARDIAC CYCLE

DIASTOLE

  • 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.

ATRIAL SYSTOLE

  • 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.

VENTRICULAR SYSTOLE

  • 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.

HORMONAL CONTROLS

  • 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.

NEURAL CONTROLS

  • 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.

STROKE VOLUME

  • The volume of blood that is ejected from the left ventricle per beat.
  • linearly increases as intentsity of exercise increases.
  • Plateaus

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