HISTOLOGY
CLINICAL QUESTIONS
DEFINITION
TRUE OR FALSE
IDENTIFICATION
100
3. Parafollicular cells (C cells) of the thyroid gland produce which hormone?
a) Thyroxine
b) Calcitonin
c) Parathyroid hormone (PTH)
d) Thyroid-stimulating hormone (TSH)
e) Triiodothyronine
b) Calcitonin.
100
A 32-year-old woman presents with weight gain, fatigue, cold intolerance, and dry skin. Her TSH is elevated, and T3/T4 are low. What is the most likely diagnosis?
A. Grave’s disease
B. Cushing’s syndrome
C. Addison’s disease
D. Hashimoto’s thyroiditis
D. Hashimoto’s thyroiditis
Explanation:
Hashimoto’s is an autoimmune condition where the body attacks the thyroid, leading to hypothyroidism. The pituitary responds to low thyroid hormone levels by increasing TSH in an attempt to stimulate more production. Common signs: fatigue, weight gain, cold intolerance, constipation, dry skin.
100
"Which of the following best defines this vascular network that connects the hypothalamus and
anterior pituitary
A. It transports hormones from the anterior pituitary to the hypothalamus
B. It connects the hypothalamus directly to the posterior pituitary
C. It allows hypothalamic releasing hormones to reach the anterior pituitary rapidly
D. It supplies blood to the pineal gland for melatonin regulation
C. It allows hypothalamic releasing hormones to reach the anterior pituitary rapidly
100
A normal EKG shows a P wave followed by a QRS complex.
TRUE
EXPLANATION:
The standard presentation of a normal sinus rhythm on an EKG includes a P wave followed by a QRS complex, indicating proper atrial and ventricular depolarization.
100
Identify the cell shown in the image.
A. Monocyte
B. White Blood cells
C. Band Neutrophils
D. Eosinophil
C. Band Neutrophils
200
Which layer of blood vessels is primarily responsible for controlling the vessel's diameter and
regulating blood flow?
a) Tunica intima
b) Tunica media
c) Tunica externa
d) Vasa vasorum
b) Tunica media
200
A 55-year-old male with chest pain is found to have ST-elevation on ECG in leads II, III, and aVF. Which coronary artery is most likely occluded?
A. Left anterior descending (LAD)
B. Right coronary artery (RCA)
C. Left circumflex artery
D. Posterior descending artery
B. Right coronary artery (RCA)
Explanation:
ECG leads II, III, and aVF view the inferior wall of the heart. The RCA usually supplies this region. So ST-elevation in these leads suggests inferior myocardial infarction due to RCA blockage.
200
"Hematocrit, also called packed cell volume (PCV), is best defined as:"
A. The percentage of total blood volume occupied by red blood cells after centrifugation
B. The volume of plasma proteins in the blood
C. The absolute number of erythrocytes per microliter of blood
D. The concentration of hemoglobin within red blood cells
A. The percentage of total blood volume occupied by red blood cells after centrifugation
200
Atrial fibrillation can be identified by regular R-R intervals on an EKG
FALSE
EXPLANATION: Atrial fibrillation is characterized by an irregular rhythm, meaning the R-R intervals are not consistent.
200
"Identify the valve that prevents backflow from the right ventricle into the right atrium.
A. Mitral valve
B. Aortic semilunar valve
C. Pulmonary semilunar valve
D. Tricuspid valve
D. Tricuspid valve
300
Heart valves are primarily composed of an endothelial surface covering:
a) Cardiac muscle fibers
b) Hyaline cartilage
c) Loose areolar connective tissue
d) Fibrocollagenous and fibroelastic connective tissue
d) Fibrocollagenous and fibroelastic connective tissue
300
A 67-year-old woman presents with fatigue, pallor, and glossitis. Labs show macrocytic anemia and hypersegmented neutrophils. What is the most likely cause?
A. Iron deficiency
B. Folic acid deficiency
C. Vitamin B12 deficiency
D. Thalassemia
C. Vitamin B12 deficiency
Explanation:
Vitamin B12 deficiency causes megaloblastic anemia (enlarged RBCs with impaired DNA synthesis). It often presents with neurological symptoms, glossitis, and hypersegmented neutrophils. Common causes: pernicious anemia, malabsorption (e.g. Crohn’s, gastric bypass).
300
“Melatonin secretion from the pineal gland is inhibited when light stimulates which brain
structure is responsible for regulating circadian rhythms?”
A. Thalmamus
B. Optic Nerve
C. Hypothalamus
D. Medulla oblongata
C. Hypothalamus
300
A tall, peaked T wave on an EKG typically indicates hyperkalemia (high potassium levels).
True
Explanation: Tall, peaked T waves are often a sign of hyperkalemia, indicating elevated potassium levels in the blood, which can affect cardiac function.
300
Identify the endocrine gland whose cortex produces
mineralocorticoids, glucocorticoids, and androgens, and whose medulla produces epinephrine
and norepinephrine."
A. Pituitary gland
B. Thyroid gland
C. Adrenal gland
D. Pineal gland
C. Adrenal gland
400
Which of the following is a characteristic feature of Purkinje fibers?
a) They are primarily responsible for oxygen exchange.
b) They contain large amounts of glycogen.
c) They are found only in the atria.
d) They are composed of dense connective tissue.
b) They contain large amounts of glycogen.
400
A 40-year-old man has hypertension, hypokalemia, and metabolic alkalosis. Aldosterone is elevated, but renin is suppressed. Which of the following is most likely?
A. Secondary hyperaldosteronism
B. Conn’s syndrome (Primary hyperaldosteronism)
C. Cushing's disease
D. Liddle syndrome
B. Conn’s syndrome (Primary hyperaldosteronism)
Explanation:
Conn’s syndrome is a tumor of the adrenal cortex (aldosterone-secreting adenoma). It causes excess aldosterone, leading to:
Na+ retention → HTN
K+ loss → hypokalemia
H+ loss → metabolic alkalosis
Suppressed renin confirms it’s primary (not secondary to other causes).
400
“During isovolumetric relaxation, which of the following occurs?"
A. Semilunar valves open as pressure in the aorta and pulmonary trunk exceeds the
pressure in the ventricles.
B. All four valves remain closed until pressure in the ventricles drops below the pressure in
the atria
C. Blood flows from the ventricles into the aorta and pulmonary trunk.
D. None of the responses above is correct
B. All four valves remain closed until pressure in the ventricles drops below the pressure in the atria
400
If the QRS complex is wider than 0.12 seconds, it indicates normal conduction through the ventricles.
False
Explanation: A QRS complex wider than 0.12 seconds typically indicates a bundle branch block or ventricular conduction delay, suggesting abnormal conduction through the ventricles.
400
"Identify the wave labeled 'U' and its clinical significance."
A. Atrial repolarization; normal in all patients
B. Purkinje fiber repolarization; often seen in hypokalemia
C. Ventricular depolarization; seen in bundle branch block
D. Ventricular repolarization: normal part of the T wave
B. Purkinje fiber repolarization; often seen in hypokalemia
500
Which layer of the heart wall is the thickest and responsible for the heart's contractile force?
a) Epicardium
b) Myocardium
c) Endocardium
d) Pericardium
b) Myocardium
500
A 24-year-old male with sickle cell disease presents with chest pain, fever, hypoxia, and pulmonary infiltrates on chest X-ray. What is the most likely diagnosis?
A. Pulmonary embolism
B. Acute chest syndrome
C. Myocardial infarction
D. Bacterial pneumonia
B. Acute chest syndrome
Explanation:
Acute chest syndrome is a serious complication of sickle cell disease. It is triggered by sickling of red cells in pulmonary vessels, leading to infarction, infection, or fat embolism. It’s a medical emergency. Look for:
Chest pain
Fever
Hypoxia
Pulmonary infiltrates on imaging
500
"Positive inotropism best describes which of the following effects on the heart?
A. Increased contractility leading to a higher stroke volume at the same end-diastolic
volume
B. Decreased preload resulting in a lower end-diastolic volume
C. Increased depolarization rate of the sinoatrial (SA) node
D. Decreased afterload allows for easier ventricular ejection
A. Increased contractility leading to a higher stroke volume at the same end-diastolic volume
500
The QT interval represents the time it takes for the ventricles to depolarize and repolarize.
True
Explanation: The QT interval indeed represents the duration of ventricular depolarization and repolarization. It is essential for assessing the heart's electrical stability.
500
“Identify the immature red blood cell shown in the image, which is slightly larger than a mature
erythrocyte and contains residual ribosomal RNA that appears as a bluish mesh or tint when
stained”
A. Mature erythrocyte
B. Reticulocyte
C. Monocyte
D. Band Neutrophil
B. Reticulocyte