chapter 15

What is the mechanism behind myogenic autoregulation in vascular smooth muscle?

• Increased blood flow through an arteriole delivers more oxygen and glucose, making the smooth muscle cells more likely to contract

• Stretch causes depolarization of local neurons, which in turn depolarize the smooth muscle cells in the area

• When cells stretch, mechanically gated cation channels open, depolarizing the cell, resulting in contraction.

• Increased blood flow stimulates the release of paracrine factors that vasodilate local vessels.

Under what circumstance would the heart produce significant levels of adenosine?

• bradycardia

• myocardial hypoxia

• increased heart rate

• myocardial hyperoxia

Which of the following involves an increase in parasympathetic activity, leading to widespread vasodilation and fainting?

• hypertension

• parasympathetic hyperactivity

• sympathetic hypotension

• vasovagal syncope

Why is the velocity of blood lowest in the capillaries as compared with all other types of vessels

• The capillaries have a relatively large amount of smooth muscle for their diameter.

• The capillaries have the lowest blood volume.

• The capillaries have a larger diameter than the arterioles that feed them

• The capillaries have the largest cross-sectional area

fainting is also known as

• reactive hyperemia

• vasovagal syncope

• infarction

• eclampsia

________ are also known as the pressure reservoir of the cardiovascular system.

• arteries

• capillaries

• veins

• venules

Smooth muscle is present in the walls of

• veins only

• all vessel types

• arteries only

• all vessel types except capillaries and venules

The mean arterial pressure (MAP) is important because

• it represents the driving pressure for blood flow

• it reflects the difference in time that systole lasts compared to diastole

• it forces the practitioner to do math, thus they must pay attention to the values obtained.

• it represents the driving pressure for blood flow and it reflects the difference in time that systole lasts compared to diastole.

Blood flow to a tissue will increase if the

• level of oxygen at the tissue increases

• level of carbon dioxide at the tissue increases

• pH increases

• vessels constrict

The difference between the systolic and diastolic pressures is called the

• pulse pressure

• blood pressure

• circulatory pressure

• systemic pressure