Pneumococcal infections are caused by Streptococcus pneumoniae, a gram-positive, catalase-negative organism commonly referred to as pneumococcus.
Blood pressure is a measure of the changing fluid pressure within the circulatory system. It varies. from a peak pressure produced by contraction of the left ventricle, to a low pressure, which is. maintained by closure of the aortic valve and elastic recoil of the arterial system. The peak.
Blood pressure reflects the force of blood as it hits the walls of the arteries. When the heart squeezes and pushes the blood out, the blood pushes against the walls of the blood vessels. People are born with very elastic vessels that can expand easily, and bounce back when the pressure on them is low.