MCQ 61:
What is the primary function of the lungs in the circulatory system?
A) Pumping blood
B) Gas exchange
C) Filtering blood
D) Storing blood
Answer: B) Gas exchange
Explanation: The lungs are responsible for the exchange of gases (oxygen and carbon dioxide) between the air and the bloodstream.
MCQ 62:
What is the primary role of the immune system?
A) Transport nutrients
B) Regulate body temperature
C) Defend against pathogens
D) Remove waste products
Answer: C) Defend against pathogens
Explanation: The immune system protects the body from infections and diseases by identifying and destroying pathogens.
MCQ 63:
Which part of the brain regulates heart rate?
A) Cerebrum
B) Medulla oblongata
C) Cerebellum
D) Thalamus
Answer: B) Medulla oblongata
Explanation: The medulla oblongata regulates vital functions, including heart rate and blood pressure, as part of the autonomic nervous system.
MCQ 64:
What is the function of the carotid arteries?
A) Supply blood to the heart
B) Supply blood to the brain
C) Carry deoxygenated blood
D) Regulate blood pressure
Answer: B) Supply blood to the brain
Explanation: The carotid arteries carry oxygenated blood from the heart to the brain, supplying essential nutrients and oxygen.
MCQ 65:
Which condition results from a blockage in the coronary arteries?
A) Stroke
B) Heart attack
C) Hypertension
D) Anemia
Answer: B) Heart attack
Explanation: A blockage in the coronary arteries can restrict blood flow to the heart muscle, leading to a heart attack (myocardial infarction).
MCQ 66:
What is the primary function of the lymphatic system?
A) Nutrient transport
B) Fluid balance and immune response
C) Blood clotting
D) Oxygen transport
Answer: B) Fluid balance and immune response
Explanation: The lymphatic system maintains fluid balance by collecting excess tissue fluid and plays a key role in the immune response.
MCQ 67:
Which organ is primarily responsible for filtering blood?
A) Liver
B) Heart
C) Kidneys
D) Spleen
Answer: C) Kidneys
Explanation: The kidneys filter waste products and excess substances from the blood, producing urine for excretion.
MCQ 68:
What is the effect of adrenaline on the heart?
A) Decrease heart rate
B) Increase heart rate and force of contraction
C) Stabilize blood pressure
D) Decrease oxygen consumption
Answer: B) Increase heart rate and force of contraction
Explanation: Adrenaline (epinephrine) stimulates the heart, increasing heart rate and the force of each contraction, especially during stress or exercise.
MCQ 69:
Which of the following is a characteristic of a stroke?
A) Decreased blood flow to the heart
B) Sudden loss of brain function
C) High blood pressure
D) Increased heart rate
Answer: B) Sudden loss of brain function
Explanation: A stroke occurs when blood flow to a part of the brain is interrupted, leading to sudden loss of brain function, such as speech or movement.
MCQ 70:
Which type of blood vessel regulates blood flow and pressure?
A) Capillaries
B) Arteries
C) Veins
D) All of the above
Answer: B) Arteries
Explanation: Arteries have muscular walls that can constrict or dilate to regulate blood flow and maintain blood pressure.
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