Тест: Blood Composition and Functions — 10 въпроса

1. What is blood primarily composed of?

A. A fluid containing only plasma and water

B. A collection of only red blood cells

C. A combination of lymph and cerebrospinal fluid

D. A mixture of plasma and formed elements

Answer: (D)

Обяснение

Blood is primarily composed of plasma, which is the liquid component, and formed elements, which include red blood cells, white blood cells, and platelets. This mixture allows blood to perform its vital functions such as transportation, regulation, and protection.

2. What percentage of blood volume is composed of plasma, and which of the following best describes its main components?

A. About 55%; water, proteins, electrolytes, nutrients, hormones, and waste products.

B. Approximately 45%; water, lipids, glucose, and immune cells.

C. Around 60%; cells, hemoglobin, and platelets.

D. Approximately 50%; red and white blood cells, along with platelets.

Answer: (A)

Обяснение

Plasma makes up about 55% of blood and contains water, proteins like albumin, electrolytes, nutrients, hormones, and waste products, making it the liquid matrix of blood.

3. Which plasma protein is primarily responsible for maintaining blood osmotic pressure?

A. Globulins

B. Albumin

C. Fibrinogen

D. Hemoglobin

Answer: (B)

Обяснение

Albumin is the main plasma protein responsible for maintaining blood osmotic pressure, which helps keep water within the bloodstream. Globulins are involved in immune responses and transport, fibrinogen is crucial for clotting, and hemoglobin is a protein in red blood cells, not plasma.

4. Which cell type is primarily responsible for oxygen transport, and what structural feature enables this function?

A. Red blood cells; their biconcave shape increases surface area for hemoglobin binding.

B. White blood cells; their nucleus contains hemoglobin for oxygen transport.

C. Platelets; their small size allows easy movement through vessels to deliver oxygen.

D. Lymphocytes; their immune function helps distribute oxygen.

Answer: (A)

Обяснение

Red blood cells are responsible for oxygen transport because their biconcave shape maximizes surface area for hemoglobin, which binds oxygen efficiently.

5. What is the primary role of formed elements in blood?

A. To transport oxygen and nutrients to tissues

B. To defend the body against infections and facilitate clotting

C. To regulate blood pH and body temperature

D. To carry hormones to target organs

Answer: (B)

Обяснение

The main function of formed elements—red blood cells, white blood cells, and platelets—is to protect the body through oxygen transport, immune defense, and clot formation. Red blood cells transport gases, white blood cells defend against pathogens, and platelets are essential for blood clotting. Therefore, their primary purpose is related to protection and defense mechanisms.

6. Which of the following white blood cell types is classified as an agranulocyte?

A. Lymphocytes

B. Neutrophils

C. Eosinophils

D. Basophils

Answer: (A)

Обяснение

Lymphocytes are agranulocytes characterized by a lack of granules in their cytoplasm, unlike neutrophils, eosinophils, and basophils, which are granulocytes.

7. What is the main function of platelets, and from which cell type do they originate?

A. Blood clotting; they originate from megakaryocytes.

B. Immune response; they originate from lymphocytes.

C. Oxygen transport; they originate from erythroblasts.

D. Phagocytosis of pathogens; they originate from monocytes.

Answer: (A)

Обяснение

Platelets facilitate blood clotting and wound healing, and they originate from megakaryocytes in the bone marrow.

8. Which protein in plasma is essential for blood clot formation, and what is its precursor?

A. Fibrinogen; it is the precursor to fibrin.

B. Albumin; it is the precursor to fibrin.

C. Globulins; they are precursors to fibrin.

D. Hemoglobin; it is essential for clot formation.

Answer: (A)

Обяснение

Fibrinogen is a plasma protein that, upon activation during clotting, is converted into fibrin, forming the meshwork necessary for blood clot stability.

9. Which hormone stimulates erythropoiesis, and which organ primarily produces it?

A. Erythropoietin; produced mainly by the kidneys.

B. Hemoglobin; produced by the liver.

C. Thrombopoietin; produced by the bone marrow.

D. Insulin; produced by the pancreas.

Answer: (A)

Обяснение

Erythropoietin stimulates red blood cell production (erythropoiesis) mainly in the kidneys in response to low oxygen levels.

10. Which of the following functions is NOT typically associated with blood?

A. Transporting gases like oxygen and carbon dioxide.

B. Regulating body temperature through heat distribution.

C. Synthesizing hormones directly within blood.

D. Protecting against infections with white blood cells.

Answer: (C)

Обяснение

Blood does not synthesize hormones; instead, it transports hormones produced by endocrine glands, among other functions.