the heart

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  • Created by: mariam
  • Created on: 22-12-09 23:17

Structure of the heart


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  • The left ventricle has a thicker wall so it can withstand the high pressures and pump blood out of the aorta so oxygen can be recieved to all parts of the body.
  • The pressure on the right side of the heart must be kept low to prevent the capillaries in the lungs from bursting.
  • right side oxygenated blood
  • left side deoxygenated blood
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Flow of blood

  • vena cava carries the blood with very little oxygen from the body tissues
  • right atrium
  • tricuspid valve
  • right ventricle
  • pulmonary artery carries the blood to the lungs to collect oxygen
  • lungs
  • pulmonary veins carry oxygenated blood back to the heart
  • left ventricle
  • bicuspid valve
  • left atrium
  • aorta then carries the blood with a lot of oxygen to the body
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Atrioventricular valves

Atrioventricular valves

  • ventricle walls relax and recoil after contracting
  • The pressure in the atria is higher than the ventricles causing the atrioventricular valves to open
  • blood flows straight through the atria into the ventricles
  • ventricles contract pressure of blood increases in the ventricles
  • when the pressure of blood is higher in the atria than the ventricles blood moves up and valves snap shut
  • this prevents back flow
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Semilunar Valves

  • Ventricles contract when the pressure in the major arteries is higher than the pressure in the ventricles SEMILUNAR VALVES CLOSED.
  • Pressure builds up in the ventricles as the semilunar valves - closed
  • once the pressure in the ventricles is higher than the aorta and pulmonary artery the SEMI LUNAR VALVES OPEN and blood is pushed out in a high pressure
  • elastic fibres in the ventricle walls recoil and go back into shape. pressure drops below the major arteries.
  • As blood leaves the semilunar valves they shut so blood will not return to the ventricles
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Cardiac cycle

Filling phase

  • Atrium and ventricle relax, internal volume increases and blood flows into the heart from the major veins.
  • Blood flows into the atria through the open atrioventricular valves into the ventricles
  • This cycle is called Diastole

Atrial contraction

  • Atrium contracts small increase in pressure helps to push blood into the ventricles. This stretches the walls of the ventricles so they are full of blood
  • contraction of atria is called Atrial Systole
  • Blood fills the atrioventricular valve causing them to snap shut preventing backflow
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Cardiac cycle continued

Ventricular contraction

  • Wall of the ventricle contracts - Ventricular systole
  • contraction starts apex of the heart upwards towards the arteries
  • Semi-lunar valves open and blood is pushed out of the heart.


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control of cardiac cycle


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control of the cardiac cycle

  • Cardiac muscle is MYOGENIC initates its own heart beat
  • muscles contract and relax in sync
  • FIBRILLATION are contractions which are not in a sychronised way in all four chambers
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P- wave of excitation sweeping over the atria

QRS- wave of excitation in ventricalar walls

T- recovery of ventricle walls


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abnormal ecg's



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fanks 4 the notes... rely helpful!!

Natalie Beard


This is great. Seriously great. Perfect infact :P My only suggestion is that you make the font bigger, on slides where info is sparse, theres no need for it to be that small, but excellant resource! :)

Natalie Beard


Just clicked printable PDF, and it said the file is damaged, i don't know how this happens, i spent three days once creating a set of 20 cards and it did that to me :P I'd msg admin about it :) maybe try a little copy and paste?



Great thanks. This helped me loads :) With my AS Revision cards :)

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