cappillaries
Capillary
Capillaries.
it has three kinds of blood vessels because they each have a special job and it helps your body.
The walls of blood vessels have smooth muscle, which allow contraction and dilation (for example, in response to temperature changes.
In hot weather - blood vessels dilate (widen) - to allow the exchange of heat between the blood and sweat glands. The sweat evaporates - cooling the blood.
capillaries
Capillaries are known as exchange vessels. Capillaries are the smallest of vessels and allow nutrients and waste to pass through blood and body.
Capillaries via osmosis
Blood vessels are surrounded by very small circular muscles which contract and relax to allow blood vessels to constrict and dilate. The vessels also contain elastin which allows them to stretch.
Capillaries are the smallest blood vessels, and they allow for gas exchange in the tissues.
capillaries