The model on test is the 'Sprinter Stick which according to the website is designed to be a 'segmental stretching device' and is the most rigid of the smaller models. The rigidity is still allows some flex without too much pressure and the stick certainly feels strong enough to take a hard rub if needs be.
In most vertebrates oxygen enters the bloodstream  via diffusion at the alveoli of the lungs. This diffusion (a  passive thing) is accomplished because oxygen concentration â¦ in the  lungs is much higher than that of the blood, even than that of   oxygenated blood.es, in a sense the respiratory system removes oxygen from the air and replaces it with carbon dioxide. When the respiratory system takes in air, it reduces the concentration â¦ of oxygen from 21% to 16%. The air is inhaled by the diaphragm into the trachea, which leads into the lungs via the bronchi.
Blood passes through the capillaries. The pulmonary artery carries blood containing carbon dioxide to the air sacs, where the gas moves from the blood to the air, according to the NHLBI. Oxygenated blood goes to the heart through the pulmonary vein, and the heart pumps it throughout the body.The diaphragm, a dome-shaped muscle at the bottom of the lungs, controls breathing and separates the chest cavity from the abdominal cavity, the American Lung Association noted.xygenated blood goes to the heart through the pulmonary vein, and the heart pumps it throughout the body. The diaphragm, a dome-shaped muscle at the bottom of the lungs, controls breathing and separates the chest cavity from the abdominal cavity, the American Lung Association noted.