Assignment | Unit 4C.1 | The Heart | Bio 20

The type of muscle found only in the heart is (a)   .

• Skeletal muscle
• Smooth muscle
• Cardiac muscle
• Voluntary muscle

Answer explanation

Cardiac muscle is the type of muscle found only in the heart. It is involuntary and striated, distinct from skeletal muscle, which is voluntary, and smooth muscle, which is found in organs. Thus, the correct answer is cardiac muscle.

Match the following muscle types with their control type.

• Involuntary control in the heart

• Cardiac muscle

• Involuntary control in organs

• Skeletal muscle

• Involuntary control in the heart

• Smooth muscle

• Voluntary control in the body

• Myocardial muscle

Answer explanation

Skeletal muscle is the only muscle type under voluntary control, allowing conscious movement. In contrast, cardiac and smooth muscles operate involuntarily, and 'myocardial muscle' is another term for cardiac muscle.

Which chamber of the heart receives deoxygenated blood from the superior and inferior vena cavae?

• Left atrium

• Right atrium

• Left ventricle

• Right ventricle

Answer explanation

The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava, making it the correct answer. The left atrium receives oxygenated blood, while the ventricles pump blood out.

Match the following heart components with their functions.

• Lungs

• Oxygenate the blood

• Atrium

• Pump blood out of the heart

• Kidney

• Receive blood from veins

• Ventricle

• Filter the blood

Answer explanation

The ventricles are responsible for pumping blood out of the heart. The right ventricle pumps deoxygenated blood to the lungs, while the left ventricle pumps oxygenated blood to the rest of the body.

Which blood vessel carries oxygenated blood away from the heart to the body?

• Pulmonary vein

• Superior vena cava

• Inferior vena cava

• Aorta

Answer explanation

The aorta is the main artery that carries oxygenated blood from the heart to the rest of the body. In contrast, the pulmonary vein carries oxygenated blood from the lungs to the heart, while the superior and inferior vena cavae return deoxygenated blood.

Match the following parts of the body with the blood vessels that return blood from them:

• Superior vena cava

• The upper body

• Inferior vena cava

• The heart muscle itself

• Coronary sinus

• The lungs

• Pulmonary veins

• The lower body

Answer explanation

The superior vena cava is responsible for returning deoxygenated blood from the upper body, including the head, neck, and arms, back to the heart. It does not return blood from the lungs, lower body, or heart muscle.

The inferior vena cava delivers blood into the (a)   of the heart.

• Left atrium
• Right atrium
• Right ventricle
• Left ventricle

Answer explanation

The inferior vena cava carries deoxygenated blood from the body and delivers it into the right atrium of the heart, which then pumps it to the lungs for oxygenation.

Match the following heart functions with their corresponding atrioventricular valve actions.

• Prevents blood from flowing backward into the atria

• Blood from flowing backward into the atria

• Prevents blood from entering the aorta

• Blood from entering the aorta

• Prevents blood from exiting the heart too quickly

• Blood from exiting the heart too quickly

• Prevents blood from mixing between ventricles

• Blood from mixing between ventricles

Answer explanation

Atrioventricular valves prevent blood from flowing backward into the atria when the ventricles contract, ensuring efficient blood flow through the heart.

Which of the following is an example of a semilunar valve?

• Mitral valve

• Tricuspid valve

• Aortic valve

• AV valve

Answer explanation

The aortic valve is a semilunar valve located between the left ventricle and the aorta, allowing blood to flow out of the heart. In contrast, the mitral and tricuspid valves are atrioventricular (AV) valves.

What acts as the natural pacemaker of the heart?

• AV node

• Purkinje fibres

• SA node

• Bundle of His

Answer explanation

The SA node, or sinoatrial node, is the heart's natural pacemaker. It generates electrical impulses that initiate each heartbeat, regulating the heart's rhythm, unlike the AV node, Purkinje fibres, or Bundle of His.