Chapter 17 My Labs Homework
A patient has a heart rate of 70 beats per minute, an EDV of 110 ml, and an ESV of 70 ml. What is the patient's cardiac output?
2.8 L/min
How much blood is pumped from each ventricle during the ventricular ejection phase?
70 mL
Calculate the stroke volume (SV) of a patient whose EDV is 140 milliliters and whose ESV is 60 milliliters.
80 mL
Which of the following would happen to cardiac output if sympathetic nervous system stimulation of the heart had positive chronotropic effects only?
Heart rate would increase, and cardiac output would decrease.
How will the cardiac output change if you double the heart rate but reduce the stroke volume by one-half?
It will not change.
The main pacemaker of the heart is the __________.
SA node
What best describes the Frank-Starling law?
The Frank-Starling law states that the more the ventricular muscle cells are stretched, the more forcefully they contract.
Which of the following happens immediately after the P wave?
The atria contract.
Determine the impact if the connection between the sinoatrial (SA) node and the atrioventricular (AV) node becomes blocked.
The ventricles will contract more slowly.
What activity is occurring in the heart during the Q-T interval on an electrocardiogram (ECG)?
The ventricular cells are undergoing action potentials.
According to the Frank-Starling law, a bigger preload will result in __________.
a stronger contraction
The cusps of the atrioventricular valves attach to the papillary muscles via the __________.
chordae tendineae
Part complete Which of the following is not an effect of the sympathetic nervous system?
decrease in heart rate
Digoxin is a positive inotropic agent derived from the foxglove family of plants. Which of the following is an effect of digoxin?
decreased ESV
Hemorrhage would lead to a __________ preload and therefore __________ cardiac output.
decreased; decreased
The electrical impulse is __________ as it passes through the AV node, which permits the atria to contract __________ ventricles.
delayed; before
The maximum amount of blood in the ventricles at the end of the ventricular filling phase is called __________.
end-diastolic volume
Coronary circulation involves the delivery of oxygenated blood to the:
heart
The drug digoxin increases the concentration of intracellular calcium ions in cardiac muscle cells. Select what effect you would see.
increase in stroke volume
What ion movement changes the membrane potential in a contractile cell from negative to positive during the rapid depolarization phase?
influx of sodium ions
Ventricular systole begins during the __________ phase of the cardiac cycle.
isovolumetric contraction
As ventricular systole begins, all four heart valves are closed during the:
isovolumetric contraction phase
The heart is situated in the middle of the thoracic cavity in a region known as the:
mediastinum
The AV valves close when __________.
pressure in the ventricles increases
Blood that leaves the right ventricle enters the __________.
pulmonary trunk
What two values are needed in order to calculate cardiac output (CO) for a ventricle?
stroke volume (SV) and heart rate (HR)
The aortic valve closes when __________.
the pressure in the left ventricle falls below aortic pressure
Blood from the systemic circuit returns to the heart via the __________.
venae cavae
The chambers that have just emptied when the second heart sound is heard are the __________.
ventricles
The T wave of an ECG corresponds to __________.
ventricular repolarization
