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 capillary also allows waste from the metabolizing cell to diffuse from the tissue spaces into the capillaries for transport by the blood to the organs of excretion. The capillaries are called exchange vessels because they allow for an exchange of nutrients and waste.