Lower chamber
- Ventricle
- Pump the blood out of the heart
Upper chamber
- Atria
- Receive the blood that is returning to the heart and transfer it to the ventricles
Arteries
The vessels that take blood away from the heart
Veins
Vessels that return blood to the heart
Flow of blood through the body - Step 1
Oxygen rich blood is pumped from the left ventricle into the aorta
Flow of blood through the body - Step 2
Oxygen rich blood is delivered to various tissues and organs
Flow of blood through the body - Step 3
At the tissues and organs, oxygen and other nutrients are removed from the blood while carbon dioxide and other waste products are added to the blood
Flow of blood through the body - Step 4
- Blood is now oxygen-poor
- It circulates the veins and then returns to the right atria via the venae cavae
Flow of blood through the body - Step 5
- Blood is then pumped into the right ventricle
- Then pumped again through the pulmonary artery, taking the blood to the lungs
Flow of blood through the body - Step 6
In the lungs, carbon dioxide is removed and oxygen is added again to the blood
Flow of blood through the body - Step 7
The oxygen rich blood flows through the pulmonary vein into the left atria where it is pumped into the left ventricle to start the circuit again
Why is blood flow unidirectional and how is it maintained in the heart?
- Blood flows in one direction to ensure constant oxygen delivery
- Four pressure-operated valves open when pressure is high to let blood pass and close when pressure drops to prevent backflow
Valve is open
When the pressure is greater behind the valve, it opens
Valve is closed
When the pressure is greater in front of the valve, it closes
Two types of valves in the heart
- Atrioventricular valve
- Semilunar valves
Atrioventricular valve
- Located between the atria and ventricles
- When pressure inside atria is greater than in the ventricles, these valves open and the blood flows from the atria into the ventricles
- When ventricle pressure is greater than atria pressure, the valves close
- Valves are connected to papillary muscles of the ventricle walls via chordae tendineae to prevent them from everting
Right AV valve
- Called the tricuspid valve
- Has three cusps or leaflets
Left AV valve
- Called the bicuspid valve/mitral valve
- has two leaflets
Semilunar valves
- Valves between the ventricles and the arteries leaving them
- Contain tree leaflets
- Do not have chordae tendineae
- Shape of valve prevents them from inverting when arterial pressure is greater then ventricular pressure
Pulmonary valve
Lies between right ventricle and pulmonary artery
Aortic valve
Lies between left ventricle and the aorta
What is valvular heart disease (VHD)?
The dysfunction of one or more heart valves, disrupting normal one-way blood flow and potentially leading to heart failure
What are the two main types of valvular heart disease?
- Regurgitation
- Stenosis
Regurgitation
- Occurs when a valve does not close properly which causes blood to flow back into the compartment from which it came
- Can occur in any of the 4 valves
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Module 1: Section 1 + 256
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Module 1: Section 316
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Module 1: Section 413
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Module 1: Section 531
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Module 2: Section 120
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Module 2: Section 216
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Module 2: Section 332
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Module 2: Section 451
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Module 2: Section 511
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Module 4: Section 127
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Module 4: Section 235
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Module 4: Section 333
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Module 4: Section 426
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Module 4: Section 59
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Module 4: Section 628
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Module 5: Section 115
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Module 5: Section 234
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Module 5: Section 352
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Module 5: Section 47
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Module 5: Section 533
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Module 5: Section 67
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Module 6: Section 121
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Module 6: Section 223
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Module 6: Section 344
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Module 6: Section 428
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Module 6: Section 512
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Module 6: Section 613
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Module 6: Section 743
