Unit 1 Section 5.2
- Created by: stephloupoole
- Created on: 18-04-14 13:35
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- Heart Basics
- External and Internal Structure of the Heart
- Heart Valves
- the atrioventricular valves
- link the atria to the ventricles
- Semi lunar Valves
- link the ventricles to the pulmonary artery and aorta
- stop blood flowing the wrong way
- the atrioventricular valves
- link the atria to the ventricles
- the atrioventricular valves
- the valves only open one way - whether they're open or closed depends on the relative pressure of the heart chambers.
- If There's higher pressure behind a valve, its forced open. if pressure is higher in front of the valve its forced shut
- the atrioventricular valves
- Heart Valves
- Thickness of heart Chamber walls
- the heart is mainly cardiac muscle. when its contracts it creates high pressure - enough to force blood all the way around the body
- each of the four chambers of the heart has a different function
- the more work that a heart chamber has to do, the more muscle it needs - so the thicker the wall is
- the left ventricle of the heart has thicker, more muscular walls than the right ventricle
- because it needs to contract powerfully to pump blood all the way round the body
- the right side only needs to get blood to the lungs which are nearby.
- because it needs to contract powerfully to pump blood all the way round the body
- the ventricles have thicker walls than the atria, because they have to push blood out of the heart whereas the atria just need to push blood a short distance into the ventricles
- The Cardiac Cycle
- is an ongoing sequence of contraction and relaxation of the atria and ventricles that keeps blood continuously circulating round the body
- the volume of the atria and ventricles changes as they contract and relax, altering the pressure in each chamber
- this causes valves to open and close which directs the blood flow through the heart. the cardiac cycle can be simplified into 3 stages
- 1. VENTRICLES RELAX AND ATRIA CONTRACTS
- 2. VENTRICLES CONTRACT AND THE ATRIA RELAX
- 3. VENTRICLES RELAX AND THE ATRIA RELAX
- External and Internal Structure of the Heart
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