Free Lymphatic System MCQs with Answers

1. Lymph is formed from

• A. tissue fluid that drains into blind ending lymph capillaries
• B. blood plasma filtered by the kidney
• C. the secretion of the lymph nodes
• D. bile leaving the liver

Explanation: Plasma is forced out of the capillaries at their arterial end to become tissue fluid, most of which returns to the blood at the venous end, and the surplus enters lymph capillaries as lymph. It travels in one direction only, through nodes and along the thoracic duct, and is finally returned to the blood at the subclavian veins. Lymph therefore resembles plasma but has far less protein and no red cells.

2. The main function of lymph nodes is to

• A. pump lymph around the body
• B. produce red blood cells
• C. filter lymph and provide a site where lymphocytes multiply
• D. absorb glucose from the small intestine

Explanation: Nodes are packed with macrophages that trap bacteria and debris carried in the lymph, and with lymphocytes that divide there when an antigen is met, which is why nodes in the neck swell during a throat infection. The lymphatic system has no pump of its own and relies on skeletal muscle movement and valves. Red cell formation belongs to red bone marrow.

3. The lacteals of the intestinal villi are part of the lymphatic system and are responsible for absorbing

• A. glucose
• B. amino acids
• C. water and mineral ions
• D. the products of fat digestion

Explanation: Fatty acids and glycerol are reassembled into fats inside the villus cells and packaged into droplets too large for the blood capillaries, so they enter the lacteal instead and reach the blood later at the thoracic duct. Glucose and amino acids are water soluble and pass directly into the blood capillaries of the villus. This is why a lymph sample after a fatty meal looks milky.

4. Blockage of the lymph vessels, as occurs in filariasis, causes swelling of the limb because

• A. blood cannot leave the limb through the veins
• B. excess tissue fluid cannot be drained away and accumulates
• C. the arteries dilate and overfill the tissue
• D. plasma proteins are digested in the tissue spaces

Explanation: The lymphatic system is the only route by which the surplus tissue fluid returns to the blood, so blocking it lets fluid build up in the spaces between cells, and the result is the oedema seen in elephantiasis. Venous return is unaffected in this condition, which is why the swelling is soft and painless at first. The same reasoning explains the oedema of severe protein deficiency, where too little fluid is drawn back osmotically.

5. Which WBC is most abundant?

• A. Lymphocytes
• B. Monocytes
• C. Neutrophils
• D. Eosinophils

Explanation: Neutrophils are the most abundant WBCs (60-70%), functioning as primary phagocytes against bacteria.

6. Which is NOT a function of lymphatic system?

• A. Return tissue fluid to blood
• B. Fat absorption
• C. Immune defense
• D. Oxygen transport

Explanation: Oxygen transport is a function of blood, not lymph. Lymph returns tissue fluid, absorbs fats, and contains immune cells.

7. The first consequence of lymphatic blockage in tissues is:

• A. Deficiency of oxygen
• B. Loss of nerve signals
• C. Drop in blood pressure
• D. Excess fluid accumulation in tissue

Explanation: The lymphatic system is the only route by which surplus tissue fluid returns to the blood, so blocking it lets fluid collect between the cells and the limb swells, which is the oedema of filariasis. Blood flow through the arteries and capillaries continues normally, so oxygen delivery and blood pressure are not affected first. The swelling is soft and painless in the early stages for exactly this reason.

8. Tissue fluid in a lymphatic system is called as:

• A. Plasma
• B. Matrix
• C. Lymph
• D. Blood

Explanation: Surplus tissue fluid that drains into the blind ending lymph capillaries is called lymph, and it travels one way through nodes and along the thoracic duct back to the subclavian veins. Plasma is the fluid part of blood before it leaves the capillary, so the same fluid takes three names depending on where it is. Lymph resembles plasma but carries far less protein and no red cells.