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.
Contraction of heart ventricles generates blood pressure. It is the hydrostatic pressure that blood exerts against he wall of a vessel. Rigid vessels maintain blood pressure; less rigid vessels deform and blood pressure is lost.