Body Fluids and Circulation Chapter-Wise Test 15

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which of the following statements is correct about the sinoatrial (SA) node?

It is located in the interventricular septum and delays impulse conduction.
It receives impulses from the atrioventricular (AV) node.
It is located in the left atrium and initiates ventricular contraction.
It is located in the right atrium and acts as the natural pacemaker of the heart.
4

The sinoatrial (SA) node is located in the right atrial wall near the opening of the superior vena cava. It generates rhythmic electrical impulses and acts as the natural pacemaker of the heart. The impulses then pass to the AV node, Bundle of His and Purkinje fibres.

What is the function of Purkinje fibers in the heart?

Generate electrical impulses
Transmit impulses to the ventricles
Regulate heart valve movement
Control blood pressure
2

Purkinje fibres rapidly conduct electrical impulses throughout the ventricular walls, producing a synchronized contraction of both ventricles for efficient pumping of blood.

Which of the following is incorrect about plasma?

Plasma is a non-viscous fluid.
Plasma contains proteins like albumin and fibrinogen.
Plasma helps in the transport of nutrients and waste products.
Plasma constitutes about 55% of blood.
1

The statement is incorrect because plasma is a viscous, straw-coloured fluid. Its viscosity is mainly due to dissolved plasma proteins such as albumin, globulins and fibrinogen. Plasma makes up about 55% of the total blood volume.

Which of the following is incorrect regarding the lymphatic system?

It drains excess interstitial fluid.
It plays a role in immune defense.
It transports oxygen and carbon dioxide.
It absorbs fats from the intestine.
3

The lymphatic system does not transport respiratory gases. Oxygen and carbon dioxide are transported mainly by red blood cells and plasma. The lymphatic system returns excess tissue fluid to blood, absorbs dietary fats through intestinal lacteals and contributes to immunity.

Which of the following is incorrect about the human circulatory system?

Arteries generally carry oxygenated blood.
It is an open circulatory system.
It consists of a four-chambered heart.
It involves double circulation.
2

Humans possess a closed circulatory system, in which blood always remains confined within blood vessels. The human heart is four-chambered and exhibits double circulation, preventing the mixing of oxygenated and deoxygenated blood.

Which of the following is incorrect about systemic circulation?

It involves the pulmonary artery.
It supplies oxygenated blood to the body.
It includes arteries, veins and capillaries.
It starts from the left ventricle and ends at the right atrium.
1

The pulmonary artery belongs to the pulmonary circulation, carrying deoxygenated blood from the right ventricle to the lungs. Systemic circulation begins at the left ventricle, supplies oxygenated blood to body tissues and returns deoxygenated blood to the right atrium.

Which of the following statements about veins is true?

They carry blood under high pressure.
They always carry oxygenated blood.
They have valves to prevent backflow.
They have thick, muscular walls.
3

Veins carry blood under low pressure. Therefore, they possess valves that prevent the backflow of blood and ensure one-way movement towards the heart. Pulmonary veins are an exception as they carry oxygenated blood.

Which type of blood vessel has the thickest walls?

Capillaries
Veins
Lymphatic vessels
Arteries
4

Arteries possess thick, elastic and muscular walls to withstand the high pressure generated by ventricular contraction. In contrast, veins have thinner walls and capillaries are only one cell thick to facilitate exchange of substances.

Which blood disorder is caused by an excessive number of red blood cells?

Leukocytosis
Polycythemia
Anemia
Thrombocytopenia
2

Polycythemia is characterized by an abnormally high number of red blood cells, increasing blood viscosity. Anemia results from reduced RBCs or haemoglobin, leukocytosis is an increase in white blood cells, and thrombocytopenia is a decrease in platelets.

Which heart valve prevents backflow of blood from the right ventricle into the right atrium?

Tricuspid valve
Pulmonary valve
Mitral valve
Aortic valve
1

The tricuspid valve lies between the right atrium and right ventricle. It prevents the backflow of blood into the right atrium during ventricular systole. The mitral valve performs a similar function on the left side of the heart.

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