Dow University MDCAT / Entry Test Biology Circulation — Set 2

Dow University MDCAT / Entry Test Biology Circulation — Set 2

1. Question 1

   Q1. A patient with severe anemia has an increased cardiac output. Which mechanism is primarily responsible for this compensation?

   • A) Increased sympathetic tone
   • B) Decreased peripheral resistance
   • C) Increased stroke volume
   • D) Increased venous return

   Answer: Increased sympathetic tone

   Explanation: Increased sympathetic tone increases heart rate and contractility. Decreased peripheral resistance is not the primary cause.

2. Question 2

   Q2. During strenuous exercise, a person's heart rate increases significantly. What is the primary nervous control for this increase?

   • A) Vagus nerve stimulation
   • B) Sympathetic nerve stimulation
   • C) Parasympathetic withdrawal
   • D) Baroreceptor reflex

   Answer: Sympathetic nerve stimulation

   Explanation: Sympathetic nerves increase heart rate. Vagus nerve stimulation decreases heart rate.

3. Question 3

   Q3. A 45-year-old hypertensive patient is prescribed a beta-blocker. How does this medication lower blood pressure?

   • A) By increasing cardiac output
   • B) By decreasing peripheral resistance
   • C) By reducing heart rate and contractility
   • D) By increasing venous capacitance

   Answer: By reducing heart rate and contractility

   Explanation: Beta-blockers reduce heart rate and contractility, lowering cardiac output. They do not directly decrease peripheral resistance.

4. Question 4

   Q4. In a patient with left-sided heart failure, which symptom is directly related to decreased cardiac output?

   • A) Orthopnea
   • B) Paroxysmal nocturnal dyspnea
   • C) Fatigue
   • D) Pulmonary edema

   Answer: Fatigue

   Explanation: Fatigue results from decreased cardiac output and reduced perfusion of muscles. Orthopnea and PND are related to pulmonary congestion.

5. Question 5

   Q5. A person's electrocardiogram (ECG) shows a prolonged PR interval. What does this indicate?

   • A) First-degree AV block
   • B) Second-degree AV block
   • C) Bundle branch block
   • D) Ventricular tachycardia

   Answer: First-degree AV block

   Explanation: Prolonged PR interval indicates delayed AV conduction, characteristic of first-degree AV block.

6. Question 6

   Q6. During a coronary artery occlusion, the area of heart muscle most vulnerable to ischemia is the?

   • A) Subepicardium
   • B) Subendocardium
   • C) Myocardium
   • D) Epicardium

   Answer: Subendocardium

   Explanation: Subendocardium is most vulnerable due to higher metabolic demand and lower perfusion pressure.

7. Question 7

   Q7. A patient is diagnosed with atherosclerosis. What is the primary pathophysiological process involved?

   • A) Inflammation of the arterial wall
   • B) Thrombosis formation
   • C) Lipid accumulation in the arterial wall
   • D) Smooth muscle cell proliferation

   Answer: Lipid accumulation in the arterial wall

   Explanation: Atherosclerosis involves lipid accumulation, which triggers an inflammatory response. Lipid accumulation is the primary process.

8. Question 8

   Q8. In a capillary bed, what is the primary factor controlling blood flow?

   • A) Precapillary sphincter tone
   • B) Arteriolar diameter
   • C) Venous pressure
   • D) Cardiac output

   Answer: Precapillary sphincter tone

   Explanation: Precapillary sphincters regulate blood flow into capillary beds. Arteriolar diameter affects overall resistance.

9. Question 9

   Q9. A 60-year-old man has varicose veins. Which factor contributes most to their development?

   • A) Increased venous tone
   • B) Valvular incompetence
   • C) Decreased venous pressure
   • D) Increased cardiac output

   Answer: Valvular incompetence

   Explanation: Valvular incompetence leads to backflow and venous distension, causing varicose veins.

10. Question 10

    Q10. During hemorrhage, which compensatory mechanism helps maintain blood pressure?

    • A) Vasodilation
    • B) Decreased heart rate
    • C) Vasoconstriction
    • D) Increased venous capacitance

    Answer: Vasoconstriction

    Explanation: Vasoconstriction increases peripheral resistance, helping maintain blood pressure. Vasodilation would decrease blood pressure.

11. Question 11

    Q11. In a healthy individual, what is the primary mechanism for regulating blood flow to skeletal muscles during exercise?

    • A) Sympathetic vasoconstriction
    • B) Local metabolic vasodilation
    • C) Increased venous return
    • D) Baroreceptor reflex

    Answer: Local metabolic vasodilation

    Explanation: Local metabolic vasodilation increases blood flow to exercising muscles. Sympathetic vasoconstriction occurs in other vascular beds.

12. Question 12

    Q12. A patient with heart failure has an ejection fraction of 40%. What does this indicate?

    • A) Normal contractility
    • B) Mildly reduced contractility
    • C) Moderately reduced contractility
    • D) Severely reduced contractility

    Answer: Moderately reduced contractility

    Explanation: Ejection fraction of 40% indicates moderately reduced contractility. Normal EF is above 55%.

13. Question 13

    Q13. In the lymphatic system, what is the primary function of lymph nodes?

    • A) To filter lymph
    • B) To produce lymphocytes
    • C) To store lymphocytes
    • D) To return lymph to the bloodstream

    Answer: To filter lymph

    Explanation: Lymph nodes filter lymph, trapping pathogens and activating immune responses. They also contain lymphocytes.

14. Question 14

    Q14. A person with deep vein thrombosis (DVT) is at risk for developing which complication?

    • A) Pulmonary embolism
    • B) Myocardial infarction
    • C) Stroke
    • D) Cardiac arrest

    Answer: Pulmonary embolism

    Explanation: DVT can lead to pulmonary embolism if the thrombus dislodges and travels to the lungs.

15. Question 15

    Q15. In the hepatic sinusoids, what is the primary function of Kupffer cells?

    • A) To produce bile
    • B) To store glycogen
    • C) To phagocytose foreign particles
    • D) To produce clotting factors

    Answer: To phagocytose foreign particles

    Explanation: Kupffer cells are macrophages that phagocytose foreign particles and cellular debris.

16. Question 16

    Q16. A patient has a condition that leads to decreased production of von Willebrand factor. What is the primary effect?

    • A) Impaired platelet adhesion
    • B) Increased bleeding time
    • C) Decreased platelet count
    • D) Prolonged prothrombin time

    Answer: Impaired platelet adhesion

    Explanation: Von Willebrand factor is crucial for platelet adhesion to damaged endothelium. Its deficiency impairs platelet adhesion.

17. Question 17

    Q17. During a stress response, which hormone increases cardiac contractility?

    • A) Insulin
    • B) Adrenaline
    • C) Thyroxine
    • D) Cortisol

    Answer: Adrenaline

    Explanation: Adrenaline (epinephrine) increases cardiac contractility by stimulating beta-1 adrenergic receptors.

18. Question 18

    Q18. A 30-year-old woman has Raynaud's phenomenon. What is the primary pathophysiological mechanism?

    • A) Vasodilation
    • B) Vasoconstriction
    • C) Increased cardiac output
    • D) Decreased blood viscosity

    Answer: Vasoconstriction

    Explanation: Raynaud's phenomenon involves exaggerated vasoconstriction in response to cold or stress, reducing blood flow to digits.

19. Question 19

    Q19. In the fetal circulation, what is the primary function of the ductus arteriosus?

    • A) To bypass the lungs
    • B) To increase pulmonary blood flow
    • C) To supply oxygenated blood to the brain
    • D) To regulate systemic blood pressure

    Answer: To bypass the lungs

    Explanation: The ductus arteriosus bypasses the lungs by shunting blood from the pulmonary artery to the aorta.

20. Question 20

    Q20. A patient has a condition leading to increased blood viscosity. What is the primary effect on blood flow?

    • A) Increased flow
    • B) Decreased flow
    • C) No change in flow
    • D) Variable flow

    Answer: Decreased flow

    Explanation: Increased blood viscosity increases resistance to flow, decreasing blood flow according to Poiseuille's law.