Control of Arterial Pressure

Control of Arterial Pressure - CONTROL OF ARTERIAL PRESSURE...

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CV-30 CONTROL OF ARTERIAL PRESSURE Pages 397-402 Behavioral Objectives 1. Identify the major cardiovascular variable that is being regulated in the systemic circulation. 2. Write an equation that can be used to calculate mean arterial pressure. 3. Describe the operation of the baroreceptor system. Indicate the meaning of the term “adaptation” in this context. 4. Identify the mechanism by which blood pressure is controlled in the long term. Control of blood pressure The major cardiovascular variable being regulated is the mean arterial pressure in the systemic circulation. This ensures adequate blood flow to all organs of the body. Mean arterial pressure = Cardiac output x Total peripheral resistance MAP = CO x TPR All changes in mean arterial pressure must be the result of changes in cardiac output and/or total peripheral resistance, or both. The baroreceptor reflex The baroreceptor reflex , along with changes in hormonal secretions, provides a means of controlling mean arterial pressure over the time span of seconds to hours . The baroreceptors are specialized collections of nerve endings located bilaterally in the carotid sinuses and in the arch of the aorta . (See Figure 12-53 in text) The baroreceptors are stretch receptors whose rate of firing is directly proportional to the pressures present in the large blood vessels where they are located. Afferent neurons from the baroreceptors travel to the cardiovascular control centers in the brainstem. The medullary cardiovascular center is the primary integrating center for the control of blood pressure. The input to this center comes from the arterial baroreceptors and the output goes to the heart, arterioles, and veins. Remember that the baroreceptor reflex is adequate for the short-term control of blood pressure. Adaptation of the stretch receptors to prolonged increases or decreases in blood pressure limits the ability of this system to deal with sustained increases or decreases in arterial pressure. Long-term regulation of blood pressure Long-term regulation of blood pressure is accomplished mainly through regulation of blood volume by the kidneys.
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CV-31 CARDIOVASCULAR TBL TERMS AND DEFINITIONS Aortic Stenosis Aortic stenosis results when the aortic valve does not open properly. The generic term “stenosis” indicates a narrowing of any opening. A valve that is labeled as being stenotic is one that does not open properly, which causes an abnormally high resistance to blood flow across it. Stenotic valves typically cause the blood flow across them to become turbulent, rather than the laminar flow that normally exists. This turbulent flow sets up vibrations in the vascular system that can be heard with a stethoscope placed on the chest wall. The sound that is produced is called a murmur, and in the case of aortic stenosis, the murmur is heard during systole when blood is moving across the stenotic aortic valve. Aortic Insufficiency
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This note was uploaded on 10/01/2011 for the course PSYO 5016 taught by Professor Staff during the Fall '11 term at The University of Oklahoma.

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Control of Arterial Pressure - CONTROL OF ARTERIAL PRESSURE...

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