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28 Cards in this Set
- Front
- Back
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What are the key features of the atrium and the ventricle? |
Atrium Elastic so it stretches as it collects blood Thin-walled because it only has to pump blood a short distance
Ventricle Thick muscular wall because it has to pump blood some distance |
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Which side of the heart deals with oxygenated blood? |
Left |
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Why does the heart have two separate pumps? |
Blood has to pass through tiny capillaries in the lungs in order to present a large surface area for the exchange of gases This would cause large drop in pressure so blood flow would be slowed |
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Why does the right ventricle have a thinner muscular wall compared to the left ventricle? |
The right ventricle only has to pump deoxygenated blood to the lungs which is a short distance away |
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What are the valves called between the atrium and the ventricle? Why are they there? |
Atrioventricular valves Prevent the backflow of blood |
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What is the role of the aorta? |
Connected to left ventricle and carries oxygenated blood to all parts of the body except the lungs |
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What is the role of the vena cava? |
Connected to right atrium and brings deoxygenated blood back from the tissues of the body |
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What is the role of the pulmonary artery? |
Connected to the right ventricle and carries deoxygenated blood to the lungs |
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What is the role of the pulmonary vein? |
Connected to the left atrium and brings oxygenated blood back from the lungs |
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What vessels supply the heart with its own blood supply? |
Coronary arteries |
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Blockages of the coronary arteries could lead to what? |
Myocardial infarction |
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What are the two stages of the cardiac cycle? |
Contraction/Systole Relaxation/Diastole |
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What happens when the heart relaxes? |
Blood enters the atria through the pulmonary vein and the vena cava As the atria fills the pressure rises, pushing open the atrioventricular valves, allowing blood to pass to the ventricles Ventricle walls relaxed, reducing the pressure Pressure is now lower in ventricles than in aorta and pulmonary artery so semi-lunar valve closes
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What happens when the atria contracts? |
Forces the blood into the ventricles The increase in blood in the atria means the pressure is higher in the atria than in the ventricles, allowing the atrioventricular valves to open |
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What happens when the ventricles contract? |
Once the atria have contracted there is a short delay before the ventricles do the same to allow them to fill with blood The atrioventricular valves close before the contraction due to the pressure being higher in the ventricles than in the atria The pressure increases further once the AV valve is closed, causing the semi lunar valves to open, pushing blood into the pulmonary artery and the aorta |
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What are pocket valves? |
Found in veins Ensure that when veins are squeezed the blood flows back to the heart rather than away from it |
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How do you calculate cardiac output? What is the stroke volume? |
Cardiac Output= Heart Rate x Stroke Volume How much blood is pumped out each beat |
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What does it mean by the cardiac muscle is myogenic? |
Its contraction is initiated from within the muscle itself |
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What causes the atria to contract? |
Sinoatrial node causes a wave of excitation to spread across the atria |
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What prevents the wave of excitation from passing to the ventricles? |
A layer of non-conductive tissue called the atrioventricular septum |
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What is the pathway of the electrical energy created by the atrioventricular node? |
It travels along muscle fibres called the Bundle of His The Bundle of His conducts the wave to the base of the ventricles where the Bundle branches into smaller fibres called the apex This causes the ventricles to contract from the base upwards, expelling all blood |
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What is an atheroma? |
1. A fatty deposit that forms within the wal of an artery 2. Begins as a fatty streak made of white blood cells that have taken up low-density lipoproteins 3. Streaks enlarge to form atheromatous plaque made of cholesterol, fibres and dead muscle cells 4. Plaque bulges in lumen of artery, narrowing blood pathway so flow is restricted |
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What can an atheroma increase the risk of? |
A thrombus (dissociated blood clot) An aneurysm |
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How is a thrombus formed? |
1. Atheroma breaks through lining of the blood vessel 2. Rough surface interrupts flow of blood, leading to a blood clot |
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Why are thrombus' dangerous? |
It can block tissues further on from their blood flow, deprieving them of oxygen, glucose and other nutrients- tissue dies
Thrombus may be carried from place of origin and lodges an artery, resulting in a myocardial infarction |
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What is an aneurysm? |
Balloon-like, blood filled structure in the arteries |
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What causes an aneurysm? |
The atheroma weakens the artery walls The weakened points swell to from a balloon-like, blood-filled structure |
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Why are aneurysms dangerous? |
They can burst, leading to haemorrhage and therefore blood loss to the region of the body served by that artery Brain aneurysm is known as a stroke |
