Increasing evidence supports the importance of hemodynamic forces that are directly related to the work of the heart as the primary triggering event of atherosclerosis and atherothrombosis. The factors that primarily determine the work of the heart include systolic blood pressure (BP), blood viscosity, and the volume of blood the myocardium has to pump.
The relationship between BP and viscosity is such that, given a constant systolic BP, if blood viscosity increases, then the total peripheral resistance (TPR) will necessarily increase, thereby reducing blood flow. Conversely, when viscosity decreases, blood flow and perfusion will increase. Because of the dependence of systemic arterial BP on cardiac output and TPR, if blood viscosity and TPR rise, systolic BP must then increase for cardiac output to be maintained. Consequently, blood viscosity has been established as a major determinant of the work of the heart and tissue perfusion [1]. Since increased viscosity requires a higher BP to ensure the same circulating volume of blood, both the burden on the heart and the forces acting on the vessel wall are directly modulated by changes in blood viscosity.
Three important studies helped establish the relationship between blood pressure and blood viscosity. The earliest study observed 49 normal subjects and 49 patients with untreated essential hypertension, showing a direct correlation between BP and blood viscosity among both normotensive and hypertensive subjects (p<0.001). Systolic blood viscosity was 8 to 10% higher in hypertensive patients compared with normotensive controls, and diastolic blood viscosity was 16 to 28% higher in hypertensive patients. Subgroups each comprised of 25 subjects having matched hematocrits were also compared, and viscosity remained significantly higher in hypertensive subjects (p<0.05). [2]
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Answer:
1: (The arteries carry blood away from the heart; the veins carry it back to the heart.)
2: (In the systemic circulation, the left ventricle pumps oxygen-rich blood into the aorta.)
4: (Blood, which is low in oxygen, is collected in veins and travels to the right atrium and into the right ventricle.)
Explanation:
The blood circulatory system (cardiovascular system) delivers nutrients and oxygen to all cells in the body. It consists of the heart and the blood vessels running through the entire body. ... In the systemic circulation, the left ventricle pumps oxygen-rich blood into the main artery (aorta).
The arteries carry blood away from the heart; the veins carry it back to the heart. ... The blood travels from the main artery to larger and smaller arteries and into the capillary network. There the blood drops off oxygen, nutrients and other important substances and picks up carbon dioxide and waste products.
The inferior and superior vena cava bring oxygen-poor blood from the body into the right atrium. The pulmonary artery channels oxygen-poor blood from the right ventricle into the lungs, where oxygen enters the bloodstream. The pulmonary veins bring oxygen-rich blood to the left atrium.
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The part of the nervous system that is used to help you think through situations is called the central.
Answer: Option C
<u>Explanation:</u>
The central nervous system comprises of the spinal cord and the brain. It is given the name as Central nervous system as it accelerates thinking and passes information. There are some important reflexes that mainly involve the spinal cord and central nervous system like thinking through the situations.
It controls our movements, thinking and acting. The central nervous system send signal from one cell to another cell. It gathers information from all over the body and transmits it to the other parts.
Answer:agriclture agriculture hope it helps (:
Explanation:
Answer:
Always include the steps and/or background required to get to the final answer. Let’s help other people understand and solve future problems on their own. Explanation:
