HISTOLOGY
BLOOD VESSELS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Roughly the same thickness of a hair
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One cell thick
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1 Micrometres
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5 Micrometres
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Detailed explanation-1: -Most capillaries are only about 8 to 10 micrometers in diameter (a micrometer is 0.001 mm). They’re so tiny that red blood cells have to pass through in a single file line. Capillaries contain two layers of cells: Endothelial cells are inside the capillary.
Detailed explanation-2: -The capillary walls are one cell thick. Capillaries allow molecules to pass through across the capillary walls. This exchange of materials is not possible across the walls of other types of blood vessels because the walls are too thick.
Detailed explanation-3: -The walls of capillaries are just one cell thick. Capillaries therefore allow molecules to diffuse across the capillary walls. This exchange of molecules is not possible across the walls of other types of blood vessel because the walls are too thick.