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.
There are 4 main factors that maintain blood pressure which are: 1:Peripheral resistance: a)blood quantity b)blood flow c)blood vessels contraction 2:Cardiac output: aâ¦)stroke volume/beat b)ratio of heart beat/minute 3:Blood vessels 4:Venous return: a)body position b)gravity force c)muscular contraction d)respiration.