Lecture 8 Flashcards
Arteries can be described as __________ tubes
multilayered tubes
Arteries and arterioles both have ____________
endothelium
Arteries have more ________ __________ whereas arterioles have more _______ ________
elastic tissue
smooth muscle
How is the smooth muscle arranged in an arteriole?
It wraps around the endothelium
What are the two main functions of aorta and large arteries?
- distribute blood
- act as a pressure reservoir
What does it mean when the aorta and large arteries act as a pressure reservoir?
They reduce fluctuations in pressure and flow and maintain flow throughout the cardiac cycle
When the blood is ejected, it travels through the aorta. Describe how the structure of them helps with its function
The aorta has lots of elastic tissue so it can change its shape which helps its function of being a pressure reservoir. Some of the blood stretches the walls of the artery which means it stores potential energy so then during diastole it springs back
Why does the blood go to the periphery and not back into the heart during diastole?
because the semilunar valves are shut
During systole, the aorta ______ potential energy
stores
During diastole, the aorta __________ the energy
releases
What does compliance mean?
stretchiness
What is the equation for compliance?
ΔV/ΔP
What is the opposite of compliance?
stiffness
What is the equation for stiffness?
1/compliance
How does the structure of the aorta/artery change with age and how does this affect its compliance?
A young artery is very compliant whereas an old artery has more collagen and muscle wall which makes it less compliant. This changes its ability to recoil which means that less blood can flow around the capillary
Describe the structure of the aterioles
They have smooth muscle wrapper around the lumen
What is the purpose of the smooth muscle that wraps around the lumen of the arterioles?
It can contract and relax to alter the diameter of the arterioles
What is vasoconstriction and what causes it?
this is when the smooth muscle wrapped around the lumen of the arterioles contracts which reduces the diameter of the arteriole
What is vasodilation and what causes it?
this is when the smooth muscle wrapped around the lumen of the arterioles relaxes which increases the diameter of the arteriole
What is the purpose of vasodilation and vasoconstriction?
to control resistance and therefore control local flow
We have pulsatile blood pressure across the ________ and then this drops in the _________
arteries
arterioles
What is diastolic pressure?
This is the minimum pressure just before ventricle contraction