Neither thin nor thick filaments change in size, although the area of overlap between them increases.

Iron and fats bound to actin play a critical role in muscle cell contraction and relaxation.

A typical muscle fiber at rest contains enough ATP for millions of contractions.

Thin filaments stretch, whereas thick filaments stay the same length.

Thick filaments stretch, whereas thin filaments stay the same length.

It directly stimulates ventricular contraction

It delays the electrical impulse to allow ventricular filling

It prevents backflow of blood into the atria

It serves as the primary pacemaker, initiating the heartbeat

Only skeletal muscle uses actin and myosin for contraction

Cardiac muscle contraction is involuntary, while skeletal muscle contraction is voluntary

Skeletal muscle does not require calcium for filament sliding, but cardiac muscle does

The sliding filament mechanism occurs only in cardiac muscle, not in skeletal muscle

Store calcium for muscle contraction

Contract to pump blood through the chambers

Generate and regulate electrical impulses for heartbeats

Deliver oxygen to cardiac muscle tissue

Lack striations

Fatigue quickly during prolonged activity

Do not require oxygen for energy

Can contract without nervous system input

The movement of blood in the veins

The circulation of blood through the lungs only

The electrical activity of the heart only

One complete heartbeat, including contraction and relaxation

The heart relaxes and fills with blood

The atria contract to push blood into the ventricles

The heart stops beating temporarily

The ventricles contract and pump blood out

chest pain due to a partial blockage of the coronary arteries

damage to or death of cardiac muscle tissue due to a blockage in the coronary arteries

lack of oxygen to the brain, leading to a death of nervous tissue there

hardening of the arteries by accumulation of fatty deposits

a failure of blood to clot

right atrium and right ventricle

left atrium and right atrium

left ventricle only

left atrium only

left ventricle and left atrium

It is loaded with carbon dioxide.

Blood in pulmonary arteries is always blue; it is red in all other arteries.

There is no difference; it is the same as blood in other arteries.

It is moving away from the heart.

It is moving toward the heart.