They are seized by an uncontrollable urge to move their legs. Their legs actually twitch or jerk, while they experience the sensation of something squirming or wiggling under their skin. Consequently, restless legs syndrome can lead to problems associated with sleep deprivation, such as anxiety and depression.
Gas exchange in the lungs takes place between the blood in the capillary network surrounding the alveoli, and the air in the alveoli itself. All of the blood from the right ventricle flows through the pulmonary artery to the capillary network which surrounds the alveoli.as exchange between the air within the alveoli and the pulmonary capillaries occurs by diffusion. The oxygen must first dissolve before passing through the respiratory epithelium.
The arterioles then divide further into capillaries. Capillaries are the smallest blood vessels and their walls are only one cell thick which allows diffusion between the blood and cells to occur. Nutrients and oxygen from the blood diffuses through the capillary walls into the tissues that need it. This is aided by the relatively high blood pressure that also squeezes the oxygen and nutrients through the capillary wall and into the cells of the tissue. At the same time carbon dioxide and other waste products re-enter the capillary in order to be processed and removed from the body.