Investigating Factors that Affect Heart Rate and Blood Pressure

709 Words3 Pages
Investigating Factors that Affect Heart Rate and Blood Pressure

Blood pumped through blood vessels is always under pressure. This

pressure is highest in the arteries closest to the heart and gradually

decreases as the blood travels around the body. Blood keeps moving

around the body because there are differences in pressure in the blood

vessels. Blood flows from higher-pressure areas to lower-pressure

areas until it eventually returns to the heart. Blood pressure is

controlled by three things: heart rate, stroke volume and peripheral

resistance. Generally, when heart rate increases, blood pressure

rises, and vice versa. A number of things affect heart rate, such as

body's temperature, nervous system, hormones, medications, and

diseases, etc. The amount of blood pumped out of a ventricle with each

heartbeat is called stroke volume. When you're resting, stroke volume

is about the same as the amount of blood that veins carry back to the

heart. But under stressful conditions, the nervous system can increase

stroke volume by making the heart pump harder. Width of arteries also

affects the blood pressure. Blood traveling in narrower vessels meets

more resistance than blood traveling through a wider vessel. Depending

on what a person is doing, the amount of blood the heart pumps varies

enormously. Yet the blood pressure normally remains pretty stable.

That's mainly because the body adjusts the resistance of the arteries,

either widening or narrowing them as appropriate, to prevent the blood

pressure from swinging wildly. This ability to regulate the width of

the blood vessels is called the peripheral resistance. Most of the

resistance to blood flow in the circulation occurs in the

small-diameter arteries called arterioles. These arterioles are

especially important in the immediate regulation of blood pressure.

Generally, a change in any factor that may cause the blood pressure to

rise is balanced by a change in another factor. This is how the body

keeps blood pressure in a normal range.

The purpose of this lab is to identify the difference between blood

pressure and heart rate, and to analyze the factors that may affect

More about Investigating Factors that Affect Heart Rate and Blood Pressure

Open Document