During the depolarization phase of cardiac muscle ______________.

voltage-gated sodium channels open

voltage-gated calcium channels open

ligand-gated sodium channels open

voltage-gated potassium channels open

ligand-gated potassium channels open

What are the individual ion contributions to the resting membrane potential of the cardiac pacemaker cells? Select all that apply.

Greater concentration of sodium outside the cell

Greater concentration of potassium inside the cell

Calcium gradient with more calcium outside the cell

Greater concentration of anionic proteins outside the cell.

Arteries always take blood away from the heart.

Anatomy always take blood towards the heart.

Arteries always carry deoxygenated blood.

Arteries always carry oxygenated blood.

Arteries are thin vessels that allow for the exchange of nutrients.

Oxygenated blood enters the left atrium.

The right ventricle pumps deoxygenated blood to the lungs.

Pulmonary veins pass blood into the left atrium whereas the pulmonary arteries carry blood away from the right ventricle.

Oxygenated blood enters the right atrium.

The left ventricle pumps deoxygenated blood to the lungs.

the number of QRS-complexes present within a specific unit of time

the number of PT intervals present within a specific unit of time

the number of P-waves present within a specific unit of time

the number of PQRS intervals present within a specific unit of time

the number of T-waves within a specific unit of time

The semilunar valves open to allow blood to flow into the large arteries.

The AV valves close to prevent backflow of blood into the atria.

All valves in the heart close in order to complete relaxation.

The semilunar valves remain closed throughout systole to prevent backflow of blood into the ventricles.

The AV valves open to allow blood to enter the ventricles from the atria.

contraction of the ventricles and the resulting rise in ventricular pressure.

contraction of the atria and the resulting rise in atrial pressure.

contraction of the ventricles and the resulting drop in ventricular pressure.

contraction of the atria and resulting drop in atrial pressure.

Becoming anxious before an exam

Receiving an injection of epinephrine