Exercise Physio CH09

Atrial repolarization occurs during which phase of the cardiac cycle as observed on an ECG?

the QRS complex

In most subjects, stroke volume continues to increase during incremental exercise up to approximately _________

40% of VO2 max

The arterial-venous oxygen difference _________

increases as a function of exercise intensity

Skeletal and cardiac muscle are similar in which of the following ways?

-both muscles contain fibers that are branched

-both muscles are composed of striated fibers containing actin and myosin

-both muscles contain type I, IIa, and IIx fibers

-both muscles are under voluntary control

both muscles are composed of striated fibers containing actin and myosin

Which factor has the greatest influence on blood flow to a skeletal muscle during exercise?

diameter of the arterial blood vessels leading to the muscle

In order to meet the increased oxygen demands of muscle during exercise, two major adjustments in blood flow must be made _________

an increase in cardiac output and a redistribution of blood flow from inactive tissues to skeletal muscles

What is the correct order of events pertaining to contraction of the left ventricle?

The bundle branches depolarize, the ventricle contracts, the ventricular pressure increases, and blood exits the ventricle.

The _________ represents ventricular repolarization during a recording of the electrical activity (i.e., ECG) of the heart.

T wave

Which of the following statements about heart rate variability (HRV) is NOT true?

-HRV decreases in response to regular aerobic exercise training

-Epidemiological studies suggest that a low HRV is an excellent predictor of mortality in some patient populations

-HRV is influenced by the balance between the parasympathetic nervous system and the sympathetic nervous system

-HRV refers to the time interval between heart beats

HRV decreases in response to regular aerobic exercise training

According to the Fick equation, if cardiac output doubles during exercise and the arterial-mixed venous oxygen difference remains constant, body oxygen consumption would _________

increase by 100%

What would not result in an increase in stroke volume during exercise?

an increase in afterload

The greatest resistance to blood flow is in the _________

arterioles

If a person with ischemic heart disease experiences chest pain when their double product exceeds 20,000, which of the following combinations will produce angina?

HR = 150, BP = 150/80

Which of the following factors can decrease blood pressure?

-increased parasympathetic nervous system activity

-an increase in stroke volume

-systemic vasodilation

-an increase in blood viscosity

systemic vasodilation

The age-dependent decrease in maximal heart rate can be estimated via the Karvonen formula _________

HR max = 220 - age

The fact that an increase in end-diastolic ventricular volume increases the stroke volume of the heart is an illustration of the _________

Frank-Starling law of the heart

The difference between systolic and diastolic blood pressure is called the _________

pulse pressure

A local increase in the nitric oxide concentration around arterioles results in _________

vasodilation

Which of the following is NOT a mechanism for increasing venous return during exercise?

-skeletal muscle contractions

-rhythmic pattern of breathing provides a mechanical pump to increase venous return

-an increase in stroke volume

-venoconstriction

an increase in stroke volume

The relationship between oxygen uptake, cardiac output, and the arterial-venous oxygen difference is described mathematically by the _________

Fick equation

The increase in cardiac output that occurs during exercise is due to _________

-both an increase in mean arterial pressure and a decrease in vascular resistance.

-a decrease in vascular resistance only.

-an increase in mean arterial blood pressure only.

-an increase in heart rate and a decrease in mean arterial blood pressure.

both an increase in mean arterial pressure and a decrease in vascular resistance

Sympatholysis refers to

local inhibition of sympathetic-induced vasoconstriction.

Which of the following statements about beta-adrenergic blocking medications are true?

-beta-blockade reduces the vigor of ventricular contraction

-beta-blocking drugs reduce heart rate during exercise

-All of these answers are correct

-beta-blocking drugs compete with epinephrine and norepinephrine for beta-adrenergic receptors in the heart

All of these answers are correct

The cardiovascular control center is located in the _________

Medulla oblongata

The central command theory of cardiovascular control proposes that initial signal to the cardiovascular control center comes from _________

higher brain regions

The most important variable that determines resistance to blood flow is _________

the diameter of the blood vessel

n the transition from rest to exercise, what is the distribution of cardiac output to the heart?

the % of cardiac output is unchanged, but the volume of blood increases

Which of the following factors contribute to "fine-tuning" of cardiovascular control during exercise?

-muscle chemoreceptors

-muscle mechanoreceptors

-baroreceptors

-All of these are correct

All of these are correct

Backflow of blood from the arteries into the heart ventricles is prevented by the _________

semilunar valves

Electrical impulses are conducted between heart muscle cells by _________

intercalated discs

What is the correct order of events of the flow of blood after it leaves the left ventricle and before it returns to the right atrium?

Blood flows through the aorta, oxygen moves out of the capillaries, blood flows through the venules, blood enters the veins

The muscle of the heart is referred to as the _________

myocardium

The contraction phase of the heart is called _________

systole

The primary purpose of the cardiovascular system is to _________

deliver adequate levels of oxygen and remove wastes from body tissues.

In a healthy heart, the time spent in systole is generally _________ diastole.

shorter than

Withdrawal of parasympathetic influence on the heart results in _________

in increase in HR

Most of the increase in mean arterial blood pressure that occurs during dynamic (isotonic) incremental exercise is due to _________

the increase in systolic blood pressure

During exercise, the time spent in diastole and systole _________

is decreased, with the greatest decrease occurring in diastole.

Which of the following most accurately describes changes in autonomic control of heart rate during incremental exercise (from rest to VO2 max)?

PNS withdrawal is followed by SNS outflow

All gas exchange between the vascular system and tissues occurs in _________

capillaries

The relationship between cardiac output and metabolic rate is _________

linear and positively correlated

The normal pacemaker of the heart is the _________

sinoatrial (SA) node

The metabolic demand of the heart can be estimated by _________

-multiplying heart rate by systolic blood pressure.

-the double product.

-All of these above are correct

-the rate-pressure product.

All of these above are correct

Autoregulation of blood flow to contracting muscles during exercise is due to _________

locally produced factors such as nitric oxide, prostaglandins, and adenosine