The exchange of gases (O2 & CO2) between the alveoli & the blood occurs by simple diffusion: O2 diffusing from the alveoli into the blood & CO2 from the blood into the alveoli. Diffusion requires a concentration gradient. in the alveoli must be kept at a lower lever than in the blood. We do this, of course, by breathing - continuously bringing fresh air (with lots of O2& little CO2) into the lungs & the alveoli. Breathing is an active process - requiring the contraction of skeletal muscles.
Quick Answer. During a rooster injection on a knee, the doctor cleans an injection site near the kneecap, inserts a needle and withdraws any extra fluid from the knee area, and then through the same needle injects a solution containing hyaluronic acid, a substance obtained from rooster combs, into the knee joint, according to WebMD.
A. An anterior cruciate ligament, or ACL, injury is a tear in one of the knee ligaments that joins the upper leg bone with the lower leg bone.The ACL keeps the knee stable.Injuries range from mild, such as a small tear, to severe, such as when the ligament tears completely or when the ligament and part of the bone separate from the rest of the bone.Without treatment, the injured ACL is less able to control knee movement, and the bones are more likely to rub against each other.he ACL keeps the knee stable. Injuries range from mild, such as a small tear, to severe, such as when the ligament tears completely or when the ligament and part of the bone separate from the rest of the bone.