19. The Blood Vessels

Compare the effects of the cardioacceleratory and cardioinhibitory centers on cardiac output and blood pressure.

Bob is sitting outside on a warm day and is sweating profusely. Mary wants to practice taking blood pressures, and he agrees to play the patient. Mary finds that Bob's blood pressure is elevated, even though he is resting and has lost fluid from sweating. (She reasons that fluid loss should lower blood volume and, thus, blood pressure.) Why is Bob's blood pressure high instead of low?

Blood is transported through the venous system by means of:

(a) Skeletal muscle contractions

(b) Decreasing blood pressure

(c) The respiratory pump

(d) A and C

The most important factor in vascular resistance is:

(a) The viscosity of the blood

(b) The diameter of the lumen of blood vessels

(c) Turbulence due to irregular surfaces of blood vessels

(d) The length of the blood vessels

Which of the following conditions would have the greatest effect on peripheral resistance?

(a) Doubling the length of a vessel

(b) Doubling the diameter of a vessel

(c) Doubling the viscosity of the blood

(d) Doubling the turbulence of the blood

(e) Doubling the number of white cells in the blood

How do pressure and resistance affect cardiac output and peripheral blood flow?

More than one choice may apply.

Using the figure, determine which vessels have the most resistance.

a. Arteries

b. Veins

c. Capillaries

d. Arterioles

e. Venules

How does the control of blood flow to the skin for the purpose of regulating body temperature differ from the control of nutrient blood flow to skin cells?

Which of the following factors would increase peripheral resistance?

a. Increased blood viscosity

b. Shorter vessel

c. Vasodilation

d. An increase in vessel radius

Explain the mechanisms that assist in the return of venous blood to the heart.

You are babysitting two children who are having a contest to see who can hang upside-down for the longest time. At the end of the contest, both children feel dizzy and are worried they are sick. Explain to them why they feel this way and why the effect is only temporary. (Hint: Consider how the baroreceptor reflex responds when a person hangs upside-down.)

The Agawam High School band is playing some lively marches while the coaches are giving pep talks to their respective football squads. Although it is September, it is unseasonably hot (88°F/31°C) and the band uniforms are wool. Suddenly Ryan, the tuba player, becomes light-headed and faints. Explain his fainting in terms of vascular events.

a. Define blood pressure. Differentiate between systolic and diastolic blood pressure.

b. What is the normal blood pressure value for an adult?

Arterial blood pressure increases in response to:

a. increasing stroke volume

b. increasing heart rate

c. atherosclerosis

d. rising blood volume

e. all of these