A&P 2 Chapter 20 HW
An action potential in cardiac contractile cells is the same as an action potential in skeletal muscle cells EXCEPT for
the presence of a plateau phase in cardiac contractile cells
The long plateau phase of the cardiac muscle action potential is due to
calcium channels remaining open
In cardiac muscle, the fast depolarization phase of the action potential is the result of
increased membrane permeability to sodium ions
Rupture of the papillary muscles in the left ventricle may result in
mitral valve prolapse
Each of the following factors will increase cardiac output except increased
parasympathetic stimulation
Coronary veins empty into the
right atrium
What feature allows the blood supply to the heart muscle to remain relatively constant regardless of the pressure changes in the coronary arteries due to heartbeats?
arterial anastomoses
The property of heart muscle to contract in the absence of neural or hormonal stimulation is called
automaticity
Activation of which kind of receptor causes heart rate to increase?
beta-one
Part complete The amount of blood pumped by the left ventricle in one minute during the cardiac cycle is called the
cardiac output
The cusps (leaflets) of atrioventricular valves attach directly to
chordae tendinae
As blood leaves the right ventricle, it passes through the ________ and then into the pulmonary trunk.
conus arteriosus
A procedure in which a length of the patient's vein or artery is used to create a detour around an obstruction in a coronary artery is called
coronary artery bypass graft
When a blood clot forms on a ruptured plaque in a coronary artery, the condition is referred to as a(n)
coronary thrombosis
The amount of blood remaining in the ventricle when the semilunar valve closes is the
end-systolic volume
Blood returning to the heart from the pulmonary circuit first enters the
left atrium
An MI that affects the ________ side of the heart is more severe because it has to pump blood with ________ force.
left;more
Contractions of the papillary muscles
prevent the atrioventricular valves from reversing into the atria.
Blood leaves the right ventricle by passing through the
pulmonary valve
Stroke volume depends on all of the following factors except
respiratory rate
Blood returning to the heart from the systemic circuit first enters the
right atrium
The phase in the cardiac cycle when the mitral valve is closed and the aortic valve is open is the
systolic ejection phase
Blood is supplied to the myocardium by
the coronary arteries
If the connection between the SA node and AV node becomes blocked,
the ventricles will beat more slowly
Muscular ridges on the inner surface of the ventricles are calledt
trabeculae carneae
________ is when the heart can't maintain adequate cardiac output.
Heart failure
If the force of ventricular contraction increases, what will happen to the end-systolic volume?
decrease
Part complete Which of the following describes what is directly measured by an ECG?
electrical conduction
The ________ is the volume of blood in a ventricle at the beginning of systole.
end-diastole volume
The ________ is the amount of blood in a ventricle after it has contracted and before it begins to refill.
end-systolic volume
Tetanic muscle contractions don't occur in a normal cardiac muscle because
the refractory period lasts until the muscle relaxes
The normal pacemaker of the heart is located in
the sinoatrial node
Cardiac cells damaged by infarction will show all of the following except
an increase in metabolic activity
