1
The muscular wall that separates the left and right sides of the heart is called the
Septum
Which part of the heart pumps blood to the lungs?
A. Left atrium
B. Right atrium
C. Left ventricle
D. Right ventricle
D. Right ventricle
Which type of blood cell has no nucleus and functions mainly to transport oxygen?
A. Erythrocyte
B. Leucocyte
C. Platelet
D. Lymphocyte
A. Erythrocyte
The heart muscle is __________, meaning it can contract and relax without stimulation by nerve impulses.
Myogenic.
Which structure acts as the primary pacemaker of the heart?
A. AV node
B. SA node
C. Purkinje fibres
D. Bundle of His
B. SA node
The __________ valve prevents the backflow of blood into the left atrium when the left ventricle contracts.
Bicuspid valve
Which of the following statements about arteries is correct?
A. They have valves to prevent backflow.
B. They have thick, muscular walls to withstand high pressure.
C. They carry only deoxygenated blood.
D. Their walls are one cell thick.
B. They have thick, muscular walls to withstand high pressure.
__________ are the smallest blood vessels where the exchange of gases, nutrients, and wastes between blood and body cells occurs.
Capillaries
Which sound (“lub” or “dub”) is produced when the semilunar valves close?
A. Lub
B. Dub
C. Both
D. Neither
B. Dub
The electrical impulses from the SA node are transmitted to the ventricles via the __________ node.
Atrioventricular (AV)
State two structural differences between veins and arteries.
Arteries: Thick, muscular, elastic walls; small lumen; no valves; high pressure.
Veins: Thin, less muscular, less elastic walls; large lumen; valves present; very low pressure.
Which of the following correctly matches the number of heart chambers with the organism?
A. Amphibians – two atria and two ventricles
B. Humans – one atrium and one ventricle
C. Fish – one atrium and one ventricle
D. Insects – two atria and one ventricle
C. Fish – one atrium and one ventricle
In amphibians, oxygenated and deoxygenated blood mix partially in the __________.
Ventricle.
Which of the following correctly matches the heart structure with its function in electrical conduction?
A. Purkinje fibres – initiate heartbeat
B. Bundle of His – transmit impulses from AV node to ventricles
C. SA node – slow down impulse conduction
D. AV node – pump blood into aorta
B. Bundle of His – transmit impulses from AV node to ventricles
Explain why skeletal muscle contraction is important for returning blood to the heart through veins.
Skeletal muscle contraction squeezes veins, opening valves to push blood toward the heart and preventing backflow, especially against gravity.
Which sequence correctly describes the path of deoxygenated blood from the body to the lungs?
A. Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs
B. Vena cava → Right ventricle → Right atrium → Pulmonary vein → Lungs
C. Vena cava → Left atrium → Left ventricle → Pulmonary artery → Lungs
D. Vena cava → Left ventricle → Right atrium → Pulmonary artery → Lungs
A. Vena cava → Right atrium → Right ventricle → Pulmonary artery → Lungs
State two similarities between the circulatory systems of fish and amphibians.
Both have a closed circulatory system.
Both have a heart with at least one atrium and one ventricle.
Which sequence correctly describes blood flow in the pulmonary circulation of humans?
A. Right atrium → Right ventricle → Pulmonary veins → Lungs
B. Right ventricle → Pulmonary arteries → Lungs → Pulmonary veins → Left atrium
C. Left atrium → Left ventricle → Pulmonary arteries → Lungs
D. Right ventricle → Aorta → Lungs → Pulmonary veins
B. Right ventricle → Pulmonary arteries → Lungs → Pulmonary veins → Left atrium
Which sequence correctly describes the spread of electrical impulses in the heart?
A. SA node → AV node → Bundle of His → Purkinje fibres → Ventricles
B. SA node → Bundle of His → AV node → Purkinje fibres → Ventricles
C. AV node → SA node → Purkinje fibres → Bundle of His → Ventricles
D. Bundle of His → SA node → AV node → Ventricles → Purkinje fibres
A. SA node → AV node → Bundle of His → Purkinje fibres → Ventricles
The “lub” sound is caused by the closing of the __________ and __________ valves.
Tricuspid, bicuspid (mitral)
Explain why the left ventricle wall is thicker than the right ventricle wall.
The left ventricle needs to generate high pressure to pump blood to the entire body, so it has a thicker muscular wall than the right ventricle, which only pumps blood to the lungs.
Discuss the structural features of arteries, veins, and capillaries, and explain how each structure is related to its function.
Arteries: Thick muscular walls, small lumen, no valves → withstand and maintain high blood pressure.
Veins: Thin walls, large lumen, valves present → prevent backflow and help return blood at low pressure.
Capillaries: One-cell thick walls, narrow lumen → allow efficient diffusion of gases, nutrients, and waste.
Explain one advantage of a complete double circulatory system over a single circulatory system.
It maintains higher blood pressure in the systemic circulation, ensuring faster delivery of oxygen and nutrients to tissues and more efficient removal of wastes.
Why does damage to the AV node disrupt the coordination between atrial and ventricular contractions?
The AV node delays and transmits impulses from the atria to the ventricles. Damage blocks or delays signals, causing uncoordinated contractions and inefficient blood pumping.
Discuss the role of the
1) SA node,
2) AV node,
3) Bundle of His, and
4) Purkinje fibres
in the regulation of heartbeat, and explain how valve closure produces the characteristic heart sounds.
SA node: Initiates heartbeat, sets pace.
AV node: Delays impulse to allow atrial contraction before ventricles.
Bundle of His: Transmits impulse from AV node to ventricles.
Purkinje fibres: Distribute impulses through ventricular walls for coordinated contraction.
Heart sounds: “Lub” from closure of tricuspid and bicuspid valves; “Dub” from closure of semilunar valves.