Lab 10 - Homeostasis in the Cardiovascular System

" What changes will be expected in peripheral resistance, blood pressure, and cardiac output if a vasodilatory drug were to be infused?"

decreased TPR, decreased BP, increased CO

Flow chart for increased cardiac output

inc. CO = inc. BP = baroreceptors respond by dec. R

Flow chart for decreased cardiac output

dec CO = dec BP = baroreceptors respond by inc. R

Flow chart for increased resistance

inc R = inc. BP = baroreceptors respond by dec. CO

Flow chart - alpha antagonist decreases resistance by dialating blood vessels (vasodialation)

dec. R = dec. BP = baroreceptors respond by inc. CO

Flow chart - a postural change causes a decrease in blood pressure

dec. BP = baroreceptors respond by inc. R and inc. CO

Two drugs—one for the heart and one for the vascular system— are used to treat low blood pressure (hypotension). How might they work?

One will cause vasoconstriction and the other will increase heart rate

When standing on your head, blood pressure rises. The body would respond to this increase in blood pressure with which of the following?

A decrease in cardiac output and a decrease in peripheral resistance

An increase in heart rate without directly affecting blood pressure would cause which of the following?

Increased CO and decreased TPR

The angiotension II Infusion has which of the following effects?

Peripheral resistance is increased (powerful vasoconstriction drug)

What change in cardiac output is expected after an increase in resistance?

Decrease in cardiac output

"Identify the following components of the homeostatic control mechanism for blood pressure:

-The receptors (that monitor blood pressure) ="

baroreceptors

"Identify the following components of the homeostatic control mechanism for blood pressure:

-The control center ="

hypothalamus and medulla oblongata

"Identify the following components of the homeostatic control mechanism for blood pressure:

-The effectors ="

Sympathetic NS and Parasympathetic NS

What two cardiovascular parameters determine blood pressure?

Cardiac output and resistance (TPR)

Why would there be a decrease in resistance after a drug which increases cardiac output is administered?

Increasing cardiac output means the blood pressure will increase. If blood pressure increases, then the resistance will decrease (vasodilation) in order to bring the blood pressure down (or maintain homeostatic levels).

"Describe the body's normal homeostatic response to a sudden increase in blood pressure.

"

An increase in blood pressure would be detected by the baroreceptors which would communicate a signal to the hypothalamus. As a consequence, cardiac output and resistance would be decreased in an effort to bring the blood pressure back down to normal.

Describe the body's normal homeostatic response to a sudden decrease in blood pressure.

A decrease in blood pressure would be detected by the baroreceptors which would communicate a signal to the hypothalamus. As a consequence, cardiac output and resistance would be increased in an effort to bring the blood pressure back up to normal.

How would a decrease in cardiac output affect blood pressure?

A decrease in cardiac output would cause a decrease in blood pressure.

How would an increase in peripheral resistance affect blood pressure?

An increase in resistance would increase blood pressure.

How is the fact that an artificial heart is being used important in series one and two?

In Series One and Two the artificial heart allows the experimenter to alter the cardiac output.

What changes would be expected in peripheral resistance, blood pressure, and cardiac output if a vasodilatory drug that has no direct affect on the heart were infused?

"A vasodilatory drug would decrease resistance which would cause a decrease in blood pressure. The baroreceptor mediated response to the decrease in blood pressure would be an increase in cardiac output (in an effort to bring the blood pressure back up).

Decreased Resistance => Decreased Blood Pressure -> Increased Cardiac Output"

If a magical drug that increases heart rate without directly affecting any other cardiovascular parameters was injected, what changes in cardiac output, blood pressure, and resistance would be expected?

"Because cardiac output is a function of both heart rate and stroke volume, increasing heart rate would cause an increase in cardiac output. As cardiac output and resistance determine the blood pressure, the increase in cardiac output would cause an increase in blood pressure. The baroreceptor mediated response to the increase in blood pressure would be a decrease in resistance (in an effort to bring the blood pressure back down).

Increased Heart Rate => Increased Cardiac Output -> Increased Blood Pressure -> Decreased Resistance "