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30 Cards in this Set
- Front
- Back
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Describe the cardiac cycle. |
1) Deoxygenated blood form the vena cava enters the right atrium from the body 2) The blood then passes through an atrio-ventricular valve into the right ventricle 3) The blood is pumped to the lungs through the semi-lunar valve and into the pulmonary artery 4) The blood then passes through the pulmonary vein into the left atrium 5) The blood passes through the left AV valve and then through a SL valve to the aorta |
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Why is the wall of the left ventricle thicker? |
There are more muscle fibers for a greater contraction force to push the blood around the body |
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What is the role of coronary arteries? |
These branch of form the aorta and supply the heart muscle with blood |
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Why does pressure change in the heart? |
Because of a change in volume and the contractions of the heart muscle |
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Describe what happens when blood enters the atrium. |
1) Blood volume increases pressure 2) Pressure in the atrium is greater than that in the ventricle 3) The AV valve opens 4) The atrium muscles contract 5) Pressure increases further 6) The remaining blood is forced into the ventricle |
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Describe what happens when blood enters the ventricle. |
1) Increased pressure due to the volume of blood 2) The pressure in the ventricle is greater that that in the atrium 3) The AV vlave closes |
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Describe what happens when the ventricle muscle contracts. |
1) Further increases the pressure 2) The pressure is now greater than that in the aorta 3) The SL valve closes 4) Blood enters the aorta |
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Describe what happens when the ventricle relaxes. |
1) The pressure in the ventricle decreases 2) The SL valve closes 3) Blood enters the atrium |
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What is systole? |
Contraction of the heart muscle |
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What is diastole? |
Heart muscle relaxes |
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Why can valves only open one way? |
Tendons anchor the valve |
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Why do valves open and close? |
Due to the pressures |
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How is the activity of the heart measured? |
Cardiac output |
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How is cardiac output defined? |
dm3 per minute |
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What is the formula for cardiac output? |
CO = SV x HR |
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What is stroke volume? |
The volume of blood expelled from the left ventricle in one heart beat |
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What is heart rate? |
the number of cardiac cycles per minute |
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What causes atherosclerosis? |
The lumen of the artery is narrowed due to a build up of fatty deposits and cholesterol underneath the endothelium of the artery (atheroma) |
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How is plaque formed? |
Muscle fibres and calcium salts accumulate forming hard uneven patches |
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What does an atheroma normally lead to? |
- reduced blood flow - partial blockage leads to the muscle cells being deprived of oxygen - These cells respire anaerobically and produce lactic acid - angina |
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What can be a fatal result of an atheroma? |
If the blood vessel is blocked completely the muscle cells get no oxygen and die. This can cause a myocardial infarction. |
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How does thrombosis occur? |
The build up of plaque may rupture and trigger blood clotting over the damaged area. This clot builds up rapidly and causes a blockage. This is known as a thrombus |
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What can be a fatal result of a thrombus? |
The clot may break up and travel into the bloodstream causing blockage elsewhere. This can lead to problems such as a stroke |
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Describe an aneurysm. |
1) The artery becomes blocked and blood flow through the area becomes restricted 2) Blood pressure builds up in front of the blockage and presses on the artery wall 3) The wall will start to weaken and bulge outwards. This is known as an aneurysm. |
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What can an aneurysm result in? |
The vessel may rupture resulting in internal bleeding |
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List 5 known risk factors of heart disease. |
1) Age 2) High lipid/cholestrol diet 3) Genetic factors 4) Smoking 5) Stress |
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Why is age a risk factor in heart disease? |
Gradual deposit over time |
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Why is a high lipid/cholesterol diet a risk factor in heart disease? |
Cholesterol is transported to damaged areas of vessels and cause build up of fatty deposits |
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Why is smoking a risk factor in heart disease? |
- Nicotine is a vaso-constrictor which increases the blood pressure - Smoking can also increase levels of cholesterol |
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Why is stress a risk factor in heart disease? |
Causes increased blood pressure |
