MCQ 121:
Which of the following conditions can result from an embolism?
A) Stroke
B) Heart attack
C) Pulmonary embolism
D) All of the above
Answer: D) All of the above
Explanation: An embolism can block blood flow in any blood vessel, potentially causing a stroke, heart attack, or pulmonary embolism depending on the location.
MCQ 122:
Which component of blood is primarily involved in immune responses?
A) Plasma
B) Erythrocytes
C) Thrombocytes
D) Leukocytes
Answer: D) Leukocytes
Explanation: Leukocytes, or white blood cells, play a key role in the immune system, helping to defend the body against infections.
MCQ 123:
What is the effect of nitric oxide on blood vessels?
A) Constricts blood vessels
B) Dilates blood vessels
C) Increases heart rate
D) Thickens blood
Answer: B) Dilates blood vessels
Explanation: Nitric oxide is a vasodilator, meaning it relaxes the inner muscles of blood vessels, allowing them to widen and improve blood flow.
MCQ 124:
Which part of the circulatory system is responsible for gas exchange?
A) Heart
B) Capillaries
C) Arteries
D) Veins
Answer: B) Capillaries
Explanation: Capillaries are the site of gas exchange, where oxygen is delivered to tissues and carbon dioxide is removed from the blood.
MCQ 125:
What is the role of the femoral artery?
A) Supply blood to the brain
B) Supply blood to the legs
C) Supply blood to the kidneys
D) Return blood to the heart
Answer: B) Supply blood to the legs
Explanation: The femoral artery supplies oxygenated blood to the thigh and leg.
MCQ 126:
Which structure in the heart prevents backflow during contraction?
A) Septum
B) Valves
C) Atria
D) Ventricles
Answer: B) Valves
Explanation: Heart valves prevent the backflow of blood during contraction, ensuring unidirectional blood flow through the heart.
MCQ 127:
What is the primary role of red blood cells?
A) Immune response
B) Blood clotting
C) Oxygen transport
D) Nutrient absorption
Answer: C) Oxygen transport
Explanation: Red blood cells are primarily responsible for transporting oxygen from the lungs to the body tissues.
MCQ 128:
Which type of circulation carries blood to and from the lungs?
A) Systemic circulation
B) Coronary circulation
C) Pulmonary circulation
D) Hepatic circulation
Answer: C) Pulmonary circulation
Explanation: Pulmonary circulation carries deoxygenated blood from the right side of the heart to the lungs for oxygenation and returns oxygenated blood to the left side of the heart.
MCQ 129:
What condition results from the buildup of fatty deposits in arteries?
A) Anemia
B) Atherosclerosis
C) Varicose veins
D) Hypertension
Answer: B) Atherosclerosis
Explanation: Atherosclerosis is a condition characterized by the buildup of fatty deposits (plaques) in arterial walls, leading to reduced blood flow.
MCQ 130:
Which component of blood helps with the immune response by producing antibodies?
A) Erythrocytes
B) Leukocytes
C) Platelets
D) Plasma
Answer: B) Leukocytes
Explanation: Certain types of leukocytes (B cells) produce antibodies that help identify and neutralize pathogens.
MCQ 131:
What is the primary effect of the hormone aldosterone on blood pressure?
A) Decrease blood pressure
B) Increase blood pressure
C) No effect on blood pressure
D) Stabilize blood pressure
Answer: B) Increase blood pressure
Explanation: Aldosterone promotes sodium retention in the kidneys, leading to increased blood volume and, consequently, increased blood pressure.
MCQ 132:
What type of blood vessel is responsible for returning deoxygenated blood to the heart?
A) Artery
B) Capillary
C) Vein
D) Aorta
Answer: C) Vein
Explanation: Veins are blood vessels that return deoxygenated blood back to the heart.
MCQ 133:
What is the main function of the lymphatic system?
A) Pump blood
B) Transport nutrients
C) Drain excess fluid from tissues
D) Produce red blood cells
Answer: C) Drain excess fluid from tissues
Explanation: The lymphatic system drains excess interstitial fluid from tissues, helping to maintain fluid balance and participate in immune responses.
MCQ 134:
What happens during diastole?
A) The heart contracts and pumps blood
B) The heart relaxes and fills with blood
C) Blood is ejected into the lungs
D) Blood pressure decreases
Answer: B) The heart relaxes and fills with blood
Explanation: Diastole is the phase of the cardiac cycle when the heart relaxes and the chambers fill with blood.
MCQ 135:
Which of the following is NOT a function of platelets?
A) Blood clotting
B) Immune response
C) Transporting oxygen
D) Sealing wounds
Answer: C) Transporting oxygen
Explanation: Platelets are involved in blood clotting and sealing wounds but do not transport oxygen; that is the role of red blood cells.
MCQ 136:
Which structure separates the left and right sides of the heart?
A) Valves
B) Septum
C) Atria
D) Ventricles
Answer: B) Septum
Explanation: The septum is a muscular wall that separates the left and right sides of the heart, preventing the mixing of oxygenated and deoxygenated blood.
MCQ 137:
What condition is characterized by low blood oxygen levels?
A) Anemia
B) Hypoxia
C) Hypertension
D) Hypercapnia
Answer: B) Hypoxia
Explanation: Hypoxia refers to low oxygen levels in tissues, which can lead to various health issues if not addressed.
MCQ 138:
Which organ is primarily responsible for filtering blood?
A) Liver
B) Heart
C) Kidneys
D) Spleen
Answer: C) Kidneys
Explanation: The kidneys filter blood to remove waste products and excess substances, producing urine as a byproduct.
MCQ 139:
What is the main function of the aortic valve?
A) Prevent backflow into the left atrium
B) Prevent backflow into the left ventricle
C) Prevent backflow into the right atrium
D) Prevent backflow into the pulmonary artery
Answer: B) Prevent backflow into the left ventricle
Explanation: The aortic valve prevents blood from flowing back into the left ventricle after it has been ejected into the aorta.
MCQ 140:
What is the main purpose of vasodilation?
A) Increase blood pressure
B) Decrease blood flow
C) Increase blood flow to tissues
D) Regulate body temperature
Answer: C) Increase blood flow to tissues
Explanation: Vasodilation widens blood vessels, increasing blood flow to specific tissues and helping to regulate temperature and oxygen delivery.
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