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Describe Capillaries.
Capillaries
- They are the smallest vessels, their avarage diameter is ` 8 µm.
- Referred as exchange vessels , because they are involved in exchange of gases nutrients and metabolites between blood and tissues.
- Their walls consist of endothelial cells and basement membrane.
What are the Different Types of Capillaries?
There are two types of capillaries:
Continuous capillaries
- These are the commenest type of capillaries.
- Endothelial cells form continuous lining.
- They are present in connective tissue, muscle , brain, lung, exocrine glands
Fenestrated capillaries
- These capillaries have tiny pores in the endothelial cells.
- The pores closed by thin diaphragm.
- They are found in endocrine glands, small intestine and renal glomeruli.
What are sinusoids?
Sinusoids are wide capillaries which have a fenestrated or discontinuous endothelium.There are gaps between endothelial cells (basement membrane is incomplete).
- Their diameter is about 30-40 µm.
- Phagocytic cells may be seen in the wall.
- They are present in liver, spleen, adrenal medulla and bone marrow.
Name the Sites Where Sinusoids are Found.
Sites where sinusoids are found are:
• Liver
• Spleen
• Bone marrow
• Anterior pituitary gland
What are the Differences Between Capillaries and Sinusoids?
Following are the differences between capillaries and sinusoids
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