Free Circulation MCQs with Answers

• A. atherosclerosis
• B. arthritis
• C. anaemia
• D. haemophilia

Explanation: Plaques of cholesterol and debris narrow and stiffen arteries, raising blood pressure and predisposing to clots that cause heart attacks…

• A. tonsils
• B. spleen
• C. thymus
• D. lymph node

Explanation: The spleen sits in the abdomen and acts on blood the way lymph nodes act on lymph, trapping pathogens and recycling old erythrocytes.

• A. along the spinal cord
• B. in the thorax around the heart
• C. in the throat, guarding the entrances of the respiratory and digestive tracts
• D. inside the bone marrow

Explanation: Their position at the back of the mouth and nose lets them sample inhaled and swallowed material and mount early immune responses.

• A. capillaries of the tissues
• B. aorta
• C. pulmonary vein
• D. subclavian veins near the neck

Explanation: The thoracic duct and right lymphatic duct empty lymph into the subclavian veins, restoring fluid and proteins that leaked from the…

• A. T lymphocytes mature
• B. red blood cells are produced
• C. antibodies are stored
• D. platelets are formed

Explanation: Immature lymphocytes from the bone marrow migrate to the thymus, where they learn to distinguish self from non self.

• A. contains more red blood cells than blood
• B. has no red blood cells and less protein
• C. flows away from the heart through arteries
• D. contains no white blood cells

Explanation: Lymph is essentially filtered tissue fluid, so it lacks erythrocytes and is poorer in plasma proteins, though it carries lymphocytes.

• A. they fill with excess tissue fluid
• B. bacteria dissolve inside them
• C. lymphocytes multiply rapidly inside them to fight the pathogen
• D. their valves close and trap lymph

Explanation: Trapped antigens trigger lymphocyte proliferation within the node, enlarging it and making it tender.

• A. thick muscular walls like arteries
• B. red blood cells
• C. pacemakers
• D. valves that keep the lymph moving in one direction

Explanation: Lymph flows under very low pressure, so valves prevent backflow while surrounding muscle contractions squeeze it onwards.

• A. Lungs
• B. Body
• C. Right atrium
• D. Pulmonary artery

Explanation: The left ventricle pumps oxygenated blood through the aorta to the entire body (systemic circulation).

• A. AV bundle
• B. Pacemaker of the heart
• C. Valve of the heart
• D. Coronary artery

Explanation: The sinoatrial (SA) node in the right atrium is the natural pacemaker, initiating each heartbeat.

• A. Vena cava
• B. Pulmonary vein
• C. Aorta
• D. Capillary

Explanation: The aorta has the thickest wall to withstand the high pressure of blood ejected from the left ventricle.

• A. Vitamin A
• B. Vitamin K
• C. Vitamin C
• D. Vitamin D

Explanation: Vitamin K is required for synthesis of clotting factors II, VII, IX, and X in the liver.

• A. Atrial depolarization
• B. Ventricular depolarization
• C. Atrial repolarization
• D. Ventricular repolarization

Explanation: The QRS complex represents ventricular depolarization (contraction); the P wave is atrial depolarization.

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

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

• A. Active transport
• B. Ultrafiltration from capillaries
• C. Secretion by cells
• D. Osmosis only

Explanation: Tissue fluid forms by ultrafiltration from arterial ends of capillaries due to hydrostatic pressure.

• A. Heart rate + Stroke volume
• B. Heart rate × Stroke volume
• C. Heart rate - Stroke volume
• D. Stroke volume only

Explanation: Cardiac output (mL/min) = Heart rate (beats/min) × Stroke volume (mL/beat).

• 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.

• A. Prothrombin
• B. Thrombin
• C. Calcium
• D. Platelets

Explanation: Thrombin converts soluble fibrinogen to insoluble fibrin, forming the mesh of blood clots.

• 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…

• A. Arteries: Due to thick walls
• B. Capillaries: due to highest overall cross-sectional area
• C. Veins: due to blood flow against the gravity
• D. Capillaries: Due to two-way blood flow in capillaries

Explanation: Although each capillary is tiny, there are so many in parallel that their combined cross sectional area is far greater than that of the…