Capillaries?

Question

Functiion of capillaries

Answer 1

They connect arteries and veins, and most closely interact with tissues.

Answer 2

Capillaries, the smallest and most numerous of the blood vessels, form the connection between the vessels that carry blood away from the heart (arteries) and the vessels that return blood to the heart (veins). The primary function of capillaries is the exchange of materials between the blood and tissue cells.

Capillary distribution varies with the metabolic activity of body tissues. Tissues such as skeletal muscle, liver, and kidney have extensive capillary networks because they are metabolically active and require an abundant supply of oxygen and nutrients. Other tissues, such as connective tissue, have a less abundant supply of capillaries. The epidermis of the skin and the lens and cornea of the eye completely lack a capillary network. About 5 percent of the total blood volume is in the systemic capillaries at any given time. Another 10 percent is in the lungs.

Smooth muscle cells in the arterioles where they branch to form capillaries regulate blood flow from the arterioles into the capillaries.

Role of the Capillaries

In addition to forming the connection between the arteries and veins, capillaries have a vital role in the exchange of gases, nutrients, and metabolic waste products between the blood and the tissue cells. Substances pass through the capillaries wall by diffusion, filtration, and osmosis. Oxygen and carbon dioxide move across the capillary wall by diffusion. Fluid movement across a capillary wall is determined by a combination of hydrostatic and osmotic pressure. The net result of the capillary microcirculation created by hydrostatic and osmotic pressure is that substances leave the blood at one end of the capillary and return at the other end.

Answer 3

They connect arteries and veins, and most closely interact with tissues. Capillaries have walls composed of a single layer of cells, the endothelium. This layer is so thin that molecules such as oxygen, water and lipids can pass through them by diffusion and enter the tissues. Waste products such as carbon dioxide and urea can diffuse back into the blood to be carried away for removal from the body. Capillary permeability can be increased by the release of certain cytokines.

The endothelium also actively transports nutrients, messengers and other substances. Large molecules may be too big to diffuse across endothelial cells. In some cases, vesicles contained in the capillary membrane use endocytosis and exocytosis to transport material between blood and the tissues.

In an immune response, the endothelial cells of the capillary will upregulate receptor molecules, thus "catching" immune cells as they pass by the site of infection and aiding extravasation of these cells into the tissue.

The "capillary bed" is the network of capillaries supplying an organ. The more metabolically active the cells, the more capillaries it will require to supply nutrients. The capillary bed usually carries no more than 25% of the amount of blood it could contain, although this amount can be increased through autoregulation (e.g. active muscle cells) by inducing relaxation of smooth muscle. Note that the capillaries do not possess this smooth muscle in their own walls, and so any change in their diameter is passive. Any signalling molecules they release (such as endothelin for constriction and Nitric oxide for dilation) act on the smooth muscle cells in the walls of nearby, larger vessels, e.g. arterioles.

Answer 4

The primary function of capillaries is the exchange of materials between the blood and tissue cells.

Answer 5

well capillaries are like the things through which all the essentials carried by the blood move from the blood stream to the tissues......blood itself really dosent move........its just the medium

Answer 6

delivery of blood
they are smaller blood vessels which are branches of big blood vessels that Cary blood

for example when you cut your self that blood is coming from the capillaries in the skin

Answer 7

They feed the tributaries.

Answer 8

eat, eat, eat, make cacoon, sleep , break out become butterfly, mate, lay eggs, die no wait thats a catapillar

Answer 9

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