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.
Since blood flows from high pressure to low pressure, a continuous _____ in pressure is necessary to keep the blood moving. drop. Smooth muscle and elastic fibers. (tunica media)