Flashcards in Systemic Circulation Deck (53)
What is pulse pressure?
It is the difference between the systolic and diastolic pressures.
What happens to the pulse pressure in vessels further from the heart?
It widens. (the gap increases)
What happens to the mean arterial pressure as you go further out from the heart?
The mean arterial pressure continuously declines.
What is the mean arterial pressure?
Diastolic Pressure + (1/3)*Pulse Pressure
Where does the greatest decrease in arterial pressure occur?
What happens to the compliance of the arteries as you go further from the heart?
What is the BP difference between the right arm and the left arm? Why is this the case?
The right arm will have higher systolic and lower diastolic pressures. This is because the right brachial artery is further from the heart than the left and so the compliance is lower.
Describe pulse pressure profile of the atria.
The pulse pressure of the atria is low as it does not fluctuate much.
Describe pulse pressure profile of the ventricles.
It starts at low pressure and increases to around 120 mmHg before it decreases again for filling. The peaks are sharp as the pressure change is rapid.
Describe pulse pressure profile of the aorta.
The pressure starts around 80 mmHg and increases to 120 before decreasing. There is a dichotic notch due to the elasticity of the aorta.
Describe pulse pressure profile of the arteries.
They have an increased pressure compared to the aorta over 120 mmHg due to their lower compliance. They also have a notch due to elasticity.
Describe pulse pressure profile of the arterioles.
The arterioles show similar profiles to the arteries at lower pressure. Going across the arterioles though, the greatest decrease in arterial pressure occurs.
Describe pulse pressure profile of the veins and capillaries.
They do not have pulse pressure.
Where is elastin found and what function does it serve structurally?
It is found in the tunica intima and media as the Internal Elastic Lamina and External Elastic Lamina respectively. It is not found in veins.
It allows the arteries to flex with increased blood pressures.
Where is smooth muscle found in the vessels and what function does it serve structurally?
It is found in the tunica media of arteries and veins, but the smooth muscle is much more developed in arteries.
Where is collagen found in the vessels and what function does it serve structurally?
Collagen is found in the tunica adventitia of arteries and veins, but it is more developed in veins. Collagen limits the compliance of veins once they reach a certain pressure.
What are the vasa vasorum and where are they found?
They are in the tunica adventitia. They are a network of small blood vessels that supply the walls of large blood vessels, such as elastic arteries (aorta and large veins (vena cava).
How does vessel wall compliance affect the arterial pressure?
Arteries have low compliance due to smooth muscle so they have higher pressures. However, elastin has high compliance, which allows arteries to stretch initially before rebounding due to the smooth muscle and collagen layers. It allows for the maintenance of the diastolic pressure.
Explain the hydraulic filtering properties of the aorta.
The aorta is stretched as blood is pumped into it and is distended. The aortic wall recoils after systole and acts as a secondary pump.
What happens the pressure pulse as it goes further away from the heart?
It increases in velocity
What is the pressure pulse?
It is the wave that travels down the aorta and can be felt as a radial pulse.
What are the physiological factors that determine the mean arterial pulse?
What are the physical factors that determine the mean arterial pulse?
What is the primary determinant of the systolic pressure?
What is the primary determinant of the diastolic pressure?
How does arterial compliance affect the systolic and diastolic pressures?
The arterial compliance determines the amount of systolic pressure that is absorbed into kinetic energy and the amount of diastolic pressure that is propagated.
What are the factors that determine peripheral arterial resistance?
Arteriolar Radius - controlled by local and global control mechanisms from the autonomic system
Viscosity - determined by the hematocrit of the blood
How is mean arterial pressure regulated by the autonomic system?
The sympathetic system controls changes in the heart, veins and arterioles in order to control the mean arterial pressure.
Which part of the autonomic system is the main determinant of the mean arterial pressure?