The pressure in the arteries is created due to the pumping of the cardiac output through the vascular resistance. Cardiac output is the blood pumped by the heart. The vascular resistance in action here is commonly termed as the total peripheral resistance by many researchers and physicians.
Natural Fluctuation -
The pulsatile nature of the cardiac output, is the reason of the up and down (fluctuation) in the arterial blood pressure. The reason can also be the interaction of the stroke volume versus the volume and elasticity of the major arteries.
The endothelium lines all blood-contacting surfaces. This may include the arterioles, venules, arteries, veins, capillaries and the heart chambers. The production of nitric oxide in ample quantities by the endothelium decides over the healthy being along with several other biochemical complexes like polyphenols, enzymes like nitric oxide synthase and L-arginine.
A pathogen may also result in constricting the flow of the blood causing stenosis. This will help in increasing the total peripheral resistance, leading to hypertension.
Medication -
Drugs that are engaged to lower the blood pressure called the antihypertensives. They target at the muscular contraction of arterioles. Example – the drug dihydropyridines (nifedipine and nicardipine) can block the calcium conductance in the arterioles at their muscular layer. This the causes relaxation. The medications decreases the resistance to the blood flow into peripheral vascular beds, lowering their overall systemic pressure.
In hypotension, the renal blood flow is reduced and the macula densa releases prostaglandins. This helps in releasing the renin from the juxtaglomerular cells lining of the afferent arterioles which activates the renin-angiotensin-aldosterone system to increase the blood pressure.
