Body Fluids and Circulation
Test 5

Correct answer Carries: 4.

Wrong Answer Carries: -1.

Which blood cells are responsible for antibody production?

T-lymphocytes
B-lymphocytes
Monocytes
Eosinophils
2

B-lymphocytes produce antibodies that play a key role in the immune response.

Which structure initiates the contraction of the heart?

AV node
Purkinje fibers
Sinoatrial (SA) node
Bundle of His
3

The SA node, also called the pacemaker of the heart, initiates the heartbeat by generating electrical impulses.

Which of the following is correct about the function of the atrioventricular (AV) valves?

They prevent backflow of blood into the atria during ventricular contraction.
They allow blood to flow from ventricles to the atria.
They close during atrial contraction.
They are present only in the right side of the heart.
1

The **AV valves (tricuspid and bicuspid)** prevent backflow into the atria when the **ventricles contract**.

Which of the following statements about red blood cells (RBCs) is incorrect?

RBCs lack a nucleus in their mature form.
RBCs contain hemoglobin for oxygen transport.
RBCs have a lifespan of about 60 days.
RBCs are produced in the bone marrow.
3

RBCs have a lifespan of **about 120 days**, not 60 days.

Which of the following statements about heart valves is incorrect?

The bicuspid valve is located between the left atrium and left ventricle.
The tricuspid valve prevents backflow into the right atrium.
The pulmonary valve prevents backflow into the left ventricle.
The aortic valve prevents backflow into the left ventricle.
3

The **pulmonary valve prevents backflow into the right ventricle**, not the left ventricle.

Which of the following is correct about cardiac output?

Cardiac output is the amount of blood pumped per beat.
Cardiac output is calculated as heart rate × stroke volume.
Cardiac output remains constant at all times.
Exercise has no effect on cardiac output.
2

**Cardiac output = stroke volume × heart rate**, and it varies based on activity level.

Which of the following blood components is involved in antigen-antibody reactions?

Platelets
Erythrocytes
Globulins
Fibrinogen
3

Globulins are plasma proteins that function in immune responses, including antigen-antibody reactions.

Which type of WBCs produces histamine during allergic reactions?

Neutrophils
Basophils
Eosinophils
Monocytes
2

Basophils release histamine, which plays a role in allergic responses and inflammation.

Which of the following is responsible for maintaining the pH of blood?

Hemoglobin
Bicarbonate buffer system
Fibrinogen
Platelets
2

The bicarbonate buffer system helps maintain blood pH by regulating hydrogen ion concentration.

Which of the following statements about erythropoiesis is correct?

Erythropoiesis occurs in the liver of adults.
Erythropoietin is a hormone that stimulates RBC production.
Iron plays no role in erythropoiesis.
RBCs are produced in lymph nodes.
2

Erythropoietin is a hormone released by the **kidneys** that stimulates RBC production in bone marrow.

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