CH 20. The Heart
Blood is supplied to the myocardium by
the coronary arteries
Activation of which kind of receptor causes heart rate to increase?
beta-one
When a blood clot forms on a ruptured plaque in a coronary artery, the condition is referred to as a(n)
coronary thrombosis
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 True: -force of contraction. -heart rate. -sympathetic stimulation. -venous return.
Stroke volume depends on all of the following factors except
respiratory rate. True: -venous return of blood to the heart. -the pressure required to pump blood into the aorta. -end diastolic volume -the contractility of the ventricle.
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
The long plateau phase of the cardiac muscle action potential is due to
calcium channels remaining open.
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 tendineae
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
The amount of blood remaining in the ventricle when the semilunar valve closes is the
end-systolic volume.
________ is when the heart can't maintain adequate cardiac output.
heart failure
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
Abnormal heart sounds caused by turbulent flow through faulty valves are called
murmurs
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
Blood returning to the heart from the systemic circuit first enters the
right atrium
Coronary veins empty into 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.
The normal pacemaker of the heart is located in
the sinoatrial node.
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 called
trabeculae carneae
If the force of ventricular contraction increases, what will happen to the end-systolic volume?
decrease (ventricle won't have chance to fill as much)
John encounters a bear while hiking. His heart will respond in all of the following ways except
decreasing heart rate and contractility. True: -increasing venous return. -increasing contractility. -increasing preload. -increasing heart rate.
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
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 True: -the movement of potassium ions out of the cell during repolarization -at threshold, voltage-gated sodium channels open, and there is a massive influx of sodium ions -as the membrane potential approaches +30mV, the voltage-gated sodium channels close, and sodium begins to be actively transported out of the cell
Tetanic muscle contractions don't occur in a normal cardiac muscle because
the refractory period lasts until the muscle relaxes.
Cardiac cells damaged by infarction will show all of the following except
an increase in metabolic activity True: -release of enzymes into the circulation. -a switch to anaerobic metabolism -release of CK-MB into the circulation. -release of troponin T and I into the circulation.
