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.
Venous blood pressure. To keep it moving toward the heart, it relies on: gravity skeletal muscle movements (squeezing vessels keeps blood moving in right direction to heart) respiratory movements-like a bellows-inhalation pushes the diaphragm down, so it pushes on veins and keep blood moving. î î î.hey have a single layer of epithelial cells. Walls are semipermeable, and substances in blood are exchanged for substances in the tissue fluid surrounding the cells. Provide the vital function of exchanging gases, nutrients and metabolic by-products between blood and tissue fluid.