A4 Heart Flashcards
What are the risk factors for coronary heart disease?
- High salt diet leads to an increase in blood pressure
- Higher blood pressure famages the endothelium which lowers water potential in cells
- High fat diet and a sedentary lifestyle leads to increased blood fat levels
- Nicotine and caffeine increases heart rate
Explain, in terms of pressure, why the semilunar valves open?
Pressure in the ventricle rather then the artery
Explain how the heart muscle and the
heart valves maintain a one-way flow of
blood from the left atrium to the aorta?
Atrium has higher pressure than ventricle (due to filling/contraction); 2. Atrioventricular valve opens; 3. Ventricle has higher pressure than atrium (due to filling/contraction); 4. Atrioventricular valve closes; 5. Ventricle has higher pressure than aorta; 6. Semilunar valve opens; 7. Higher pressure in aorta than the left ventricle 8. Semi-Lunar valve close.
The maximum pressure in the ventricle is
much higher than that in the atrium.
Explain what causes this.
- (Ventricle has) thick wall / more muscle; 2. So contractions are stronger / harder;
What is the equation for Cardiac output?
Heart rate x Stroke volume
What is the definition of cardiac output?
It is the volume of blood pumped by the left ventricle in one minute.
What is heart rate?
The contractions of the heart in one minute
What is stroke volume?
It is the volume of blood that leaves the left ventricle per contraction
What happens during Diastole in the Cardiac Cycle?
- All muscles relax
-AV valve opens
-SL valve closes and blood flows into the ventricles as the pressure is highest in the atria
What happens during Atrial Systole in the Cardiac Cycle?
- Atrial muscles contract
- AV valve opens
- SL valve closes and blood flows into the ventricle as the pressure is highest in the atrium
What happens during Ventricular Systole?
- Ventricular muscles contract
- AV valve closes
- SL valve opens and blood flows into the arteries as the pressure is highest in the ventricle
What is the bundle of his?
A bundle (group) of specialised fibres that transmit the electrical impulses from the AV node to the ventricles
What are Purkinje fibres
They are located in the walls of the ventricles , they are fibres that conduct the electrical impulse to the muscle cells of the ventricle, causing them to contract
Describe the structure and function of the Arteries?
They carry blood away from the heart at high pressure, they have a thick muscular wall with thick elastic tissue.
They have a small lumen, no valves and arteries also carry deoxygenated blood.
Describe the structure and function of the Capillaries?
The capillaries are where gas exchange occurs, they have a one cell thick endothelium wall (short diffusion distance) and has the smallest lumen.
They carry blood at low pressure and they carry oxygenated blood but the blood loses oxygen along the length of the capillary.
