MadSci Network: Anatomy

Re: Regarding Diastolic and Systolic blood pressure

Area: Anatomy
Posted By: David Schneider, Faculty Health Sciences
Date: Fri May 23 22:38:39 1997
Area of science: Anatomy
ID: 862057975.An

There are many mechanisms the body uses to control blood pressure. Actually, the heart itself plays only a minor role in regulating the blood pressure. Most of the work is done by the kidneys and the medium sized arteries called arterioles. The heart responds to an increased need for blood flow in two ways:

  1. It increases the number of times it beats (heart rate).
  2. It increases the strength of each contraction as well as the amount of blood pumped out with each contraction (stroke volume).
Keep in mind though, these alterations only come about in response to chemical and physiological changes within the body.

[Admin note: Systolic blood pressure is the (maximal) pressure within the cardiovascular system as the heart pumps blood into the arteries.
Diastolic pressure represents the minimum in pressure, as happens while the heart rests and fills with blood, prior to the next contraction.]

With regards to the change in pressure with exercise, it is not uusual for the systolic pressure to rise 10 to 20 mm of mercury during strenuous exercise. This is the pressure in the system while the heart contracts - the heart pumps faster, and pumps a greater volume of blood during exercise. However, diastolic pressure should not vary more than 5 to 10 mm of mercury as this represents pressure in the system when the heart is not contracting. An extreme rise in diastolic pressure during exercise could indicate a serious malfunction within the cardiovascular system.

Blood pressures average in the area of 120/80 +/- 10mm for children ages 10 to 12.

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