Lecture 12 Flashcards
1
Q
Where is the majority of the blood in the body found? What fraction?
A
Systemic veins- 2/3
2
Q
Why are veins able to store the extra blood in the body?
A
They have thinner and more compliant walls
3
Q
What is the compliance equation?
A
Change in V/ change in P
4
Q
While supine, is venous volume uniform?
A
Yes
5
Q
What helps to counteract venous pooling in legs?
A
- venous valves
- tone of surrounding tissue
6
Q
How can skeletal muscle help to counteract venous pooling?
A
- can alter tensile state
- muscle tome stiffens veins and make them less compliant
- contracted muscle force superior valves to open and inferior valve to close
- this increases venous returns to the heart therefor stroke volume
7
Q
What is a possible explanation for why someone may be prone to fainting?
A
Low muscle tone + therefor excessive venous pooling
8
Q
What is starlings law of the heart?
A
The more stretched muscle fibres are before a contraction, the stronger a contraction will be
