Why Is Capillaries Important
Capillaries exchange fluids, gasses, heat, nutrients and wastes to the tissues through diffusion. Capillary walls contain small pores that are selectively permeable allowing only certain molecules to pass in and out. This exchange is controlled by blood pressure through hydrostatic pressure and osmotic pressure. Osmotic pressure is produced by high levels and salts and proteins in the blood. As blood enters the capillary by the arteriole end the blood pressure is higher than the osmotic pressure. When it reaches the middle of the capillary the blood of the vessels equals out to the pressure of the osmotic pressure. At this point the gases and nutrients exchange at this point. Once it reaches the venule end the blood pressure becomes less than
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This is because it is a semipermeable layer that is only one cell thick allowing exchange between the blood and tissue fluid through slits separating endothelial cells. Capillaries are very small and measure 5-10 micrometres in width although the cross-sectional area of the capillary in an average size muscle would be bigger than the aorta. There are three types of capillaries:
Continuous- The cells that form the capillary provide a continuous lining. The lining is very small due to the tight junctions which only allow the smallest of partials to get through. This type is found in the central nervous system, skeletal muscles, and skin.
Fenestrated- This capillary contains small pours, openings. This vessel allows small particles as well as a limited amount of nutrients to pass through the walls. It is most commonly found in the endocrine system as it helps growth and reproduction and other organs such as the kidneys. It also includes the pituitary and thyroid glands.
Discontinuous- This is found in the liver, bone marrow and in lymphoid tissue that lacks pours which permits some fluid exchange between adjoining endothelial cells. They often have irregular, broad
This is because it is a semipermeable layer that is only one cell thick allowing exchange between the blood and tissue fluid through slits separating endothelial cells. Capillaries are very small and measure 5-10 micrometres in width although the cross-sectional area of the capillary in an average size muscle would be bigger than the aorta. There are three types of capillaries:
Continuous- The cells that form the capillary provide a continuous lining. The lining is very small due to the tight junctions which only allow the smallest of partials to get through. This type is found in the central nervous system, skeletal muscles, and skin.
Fenestrated- This capillary contains small pours, openings. This vessel allows small particles as well as a limited amount of nutrients to pass through the walls. It is most commonly found in the endocrine system as it helps growth and reproduction and other organs such as the kidneys. It also includes the pituitary and thyroid glands.
Discontinuous- This is found in the liver, bone marrow and in lymphoid tissue that lacks pours which permits some fluid exchange between adjoining endothelial cells. They often have irregular, broad