The structure of arteries, veins and capillaries Flashcards
1
Q
What happens to the blood pressure as blood moves away from the heart?
A
it decreases
2
Q
What happens during vasoconstriction?
A
smooth muscle contracts causing constriction of the arteriole, decreasing blood flow.
3
Q
What happens during vasodilation?
A
Smooth muscle relaxes, and the arteriole dilates, increasing blood flow.
4
Q
Describe capillaries:
A
- form dense networks around body tissues
- very thin walls
- allows efficient exchange of materials
5
Q
Describe arteries:
A
- Have an outer layer of connect tissue containing elastic fibres
- middle layer of smooth muscle with more elastic fibres
- The elastic walls stretch and recoil to accommodate the surge of blood after each contraction of the heart
6
Q
Describe veins:
A
- Have an outer layer of connective tissue containing elastic fibres
- much thinner wall than arteries
- contain valves to prevent the back flow of blood
7
Q
what does pressure filtration do?
A
it causes blood plasma to pass through the capillary walls into the tissue fluid surrounding the cells
8
Q
what does tissue fluid supply to cells?
A
- Oxygen
- glucose
- other substances
9
Q
what does blood plasma have that tissue fluid doesn’t?
A
plasma proteins
10
Q
What is the function of the lymphatic vessels?
A
They absorb excess tissue fluid and return it as lymph to the circulatory system.
