BLOOD VESSELS -
- Some vessles supply blood to wall of large vessels these are vessel of vessels or vasa vasorum.
- Mainly artery and vein, 2 types of vessels present.
- Third one is capillary - discovered by Marcillo Malpighi, thin, present in organ, only inner layer in wall present.
- In man 10 billion capillaries present.
- They may form 150,000 miles rope.
- In vein blood flows mainly by contraction of body muscles & suction created by diastole of heart.
- In wall of blood vessels 3 layers present.
1. Tunica Externa - Made up of connective tissue, collagen fibres present.
2. Tunica media - Thick, made up of smooth muscles arranged in circular way.
3. Tunica interna - Inner most layer. Outerly made up of yellow elastin fibre. Inner layer is of endothelial cells.
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S.NO.
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ARTERY
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VEIN
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1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
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Carry blood away from heart
Pure blood flows
(in pulmonary artery impure blood flows)
Blood flows with jerk
Blood flows with more pressure
Walls are thick
Lumen is narrow
Not collapse after death
Deeply placed
Valve absent
Wall firm
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Towards heart
Impure blood flows
(In pulmonary vein pure blood flows)
Steady
Less pressure
Thin
Broad
Collapse
Superficially placed
Present to check back flow
Elastic
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