lab questions

The phases of the cardiac cycle are shown in the diagram above: atrial contraction, isovolumetric contraction, ejection, isovolumetric relaxation and rapid filling. When do the AV valves close?

At the start of isovolumetric contraction.

What is the approximate conduction velocity of motor nerves?

50 m/s

The QRS complex in the ECG occurs:

Before the first heart sound is heard.

The valve located between the left atrium and left ventricle is known as the:

Bicuspid (mitral) valve

Which of the following is responsible for generating the first heart sound, then the second heart sound?

Closing of the AV valves, then closing of the semilunar valves.

What does EMG record?

Electrical activity of the innervated muscle fibers.

Every organ or tissue that has a sympathetic innervation also has a parasympathetic innervation.

False

Opening of the semilunar valves is associated with the second heart sound.

False

The first heart sound from valves in the right side of the heart is best heard over the second intercostal space, just to the right of the sternal edge.

False

The mitral valve separates the right ventricle from the pulmonary artery.

False

The pulmonary valve separates the right atrium from the right ventricle.

False

The tricuspid valve opens at the end of ventricular systole.

False

The tricuspid valve separates the left atrium from the left ventricle.

False

During exercise, the heart rate is most affected by which of the following?

Increased sympathetic nervous innervation.

Systole consists of which two stages of the cardiac cycle?

Isovolumetric contraction and ejection.

In assessing the autonomic nervous system, which of the following is true for skin potentials recorded over the palm and sole of the foot?

It assesses sympathetic activity in peripheral nerves.

Which describes the phenomenon of "coactivation"?

It is the weaker contraction of the antagonist muscle during the contraction of the agonist muscle.

In assessing autonomic nervous system function, which of the following is true for heart rate variability (HRV)?

It's determined by both vagal and sympathetic innervation of the heart.

Which of the following factors have been suggested as contributing to muscle fatigue?

Loss of "central drive". Reduction in calcium release in excitation-contraction coupling. Reduction in muscle blood flow owing to compression of blood vessels. All of the above.

What would you expect the measured systolic blood pressure to be with the arm raised above the head?

Lower than that measured with the arm in its normal position.

What would you expect if a sphygmomanometer cuff designed to be used on a small child's arm was used on an adult's arm?

Measured systolic and diastolic pressures would both be higher than the true pressures.

Which if the following is true for the parasympathetic system?

Norepinephrine is never involved as a postganglionic neurotransmitter.

Together with a sphygmomanometer, what is a finger pulse transducer capable of determining?

Only systolic pressure. Systolic pressure is indicated by the first detection of a finger pulse, whereas diastolic pressure can only be determined using the auscultation method.

At rest, the heart rate is most affected by which of the following?

Parasympathetic (vagal) nervous innervation

In the ECG of a normal cardiac cycle, the T wave corresponds to:

Repolarization of the ventricles.

How many muscle fibers may a single motor neuron innervate?

Several muscle fibers

During exercise, there is a large increase in blood flow to which of the following?

Skeletal muscles

In measuring the autonomic nervous system skin potentials, which of the following is true for stimulation of the median nerve?

Stimulation can be on either side.

Which statement correctly describes the cardiac cycle's two phases?

Systole - ventricles contract; diastole - ventricles relax.

Which of the following is altered the most in conditions where heart rate is increased?

TP interval

In the auscultation method for blood pressure measurement, what is diastolic pressure indicated by?

The disappearance of the sounds.

How is acetylcholine removed from the synaptic cleft?

The enzyme acetylcholinesterase hydrolyzes the acetylcholine within the synaptic cleft.

In the auscultation method for blood pressure measurement, what is systolic pressure indicated by?

The first detection of the sounds.

lub dub sound

The lower-pitched "lub" sound occurs during the early phase of ventricular contraction. This is produced by the closure of the atrioventricular (mitral and tricuspid) valves, and prevents blood from flowing back into the atria. When the ventricles relax, the blood pressure drops below that in the artery, and the semilunar valves (aortic and pulmonary) close, producing the higher-pitched "dub" sound.

Which statement regarding evoked EMG is true?

There is synchronous excitation of the muscle fibers innervated by the stimulated nerve.

Closure of the aortic valve contributes to the second heart sound.

True

Closure of the atrioventricular valves is associated with the first heart sound.

True

The aortic valve opens relatively early in ventricular systole.

True

The aortic valve separates the left ventricle from the aorta.

True

The first heart sound from valves in the left side of the heart is best heard over the apex of the heart.

True

The mitral valve closes at the beginning of ventricular systole.

True

What is the basis for the sounds referred to as Korotkoff sounds?

Turbulent blood flow

During exercise, cardiac output increases. Which of the factors below does not contribute to this increase?

Vasoconstriction in the exercising muscles.

In assessing autonomic nervous system function in a healthy person, which of the following may the Valsalva maneuver result in?

an appreciable increase in heart rate

The terms systole and diastole usually refer to the _______ and _______, respectively, of the _______.

contraction; relaxation; ventricles

In the parasympathetic system, which of the following is the preganglionic neurotransmitter?

it is always acetylcholine

In assessing autonomic nervous system function in a healthy person, which of the following may occur with a change from a supine to a standing posture?

little change in systolic blood pressure after 3 minutes

The action potential causes the release of calcium ions from ________________ in the muscle cell.

the sarcoplasmic reticulum

EMGs may be obtained from needle or surface electrode recordings.

true