How can blood diff use into and out capillaries?
the air goes into your lungs. In your lungs there are billions of tiny air sacs. Surrounding each air sac is a network of blood capillaries. The air sacs and the blood capillaries are separated by a thin membrane. Across this membrane the air sacs give the blood capillaries oxygen and they blood capillaries give the air sacs carbon dioxide. We breathe out this carbon dioxide!
Because if blood pressure in lung capillaries was as high as it is in body capillaries, the hydrostatic pressure caused by this blood pressure would force blood plasma out of the capillaries into intracellular spaces (as is done in body capillaries) or into the alveoli. This would reduce the efficiency of gas exchange.
Well, the capillaries are the smallest blood vessels that diverge from/to arteries and veins. The blood diffuses between them and the muscle (oxygenated blood leaving the capillaries to the muscle and de-oxygenated blood leaving the muscle to the capillaries) The diffusion happens quickly because the capillaries have one cell-thick walls so the blood can easily pass through them. So, the capillaries allow the oxygenated blood (from the arteries) to enter the muscle whilst also removing…
The epidermal layer has blood capillaries, which have looped out from the vascular system circulating the blood. These blood capillaries are so close to the skin that the gases can diffuse from the surroundings into and out of the blood through the skin and the capillary walls. The blood contains haemoglobin in solution which circulates the gases through the body.