NBDHE NBDHE Scientific Basis of Practice 5 — Questions and Answers
Question 1: Which cranial nerve is responsible for motor innervation of the muscles of mastication?
- Cranial nerve V1 (ophthalmic)
- Cranial nerve V3 (mandibular) (Correct answer)
- Cranial nerve VII (facial)
- Cranial nerve XII (hypoglossal)
Correct answer: Cranial nerve V3 (mandibular)
The mandibular division (V3) of the trigeminal nerve carries the motor fibers that innervate the masseter, temporalis, medial and lateral pterygoid muscles.
Question 2: A biopsy of an oral ulcer shows acantholysis and loss of intercellular bridges between keratinocytes. Which autoimmune condition does this suggest?
- Mucous membrane pemphigoid
- Pemphigus vulgaris (Correct answer)
- Lichen planus
- Erythema multiforme
Correct answer: Pemphigus vulgaris
Pemphigus vulgaris is caused by autoantibodies against desmoglein, resulting in acantholysis (separation of keratinocytes) and intraepithelial vesicle formation.
Question 3: Which metabolic pathway produces ATP most efficiently under aerobic conditions?
- Glycolysis alone
- Pentose phosphate pathway
- Oxidative phosphorylation via the electron transport chain (Correct answer)
- Beta-oxidation of fatty acids only
Correct answer: Oxidative phosphorylation via the electron transport chain
Oxidative phosphorylation in the mitochondria generates approximately 30–32 ATP per glucose molecule, far exceeding the 2 ATP from anaerobic glycolysis.
Question 4: Which organism is the primary causative agent of acute necrotizing ulcerative gingivitis (ANUG)?
- Streptococcus mutans and Lactobacillus
- Porphyromonas gingivalis only
- Fusobacterium nucleatum and Treponema species (Correct answer)
- Actinomyces israelii
Correct answer: Fusobacterium nucleatum and Treponema species
ANUG is associated with a fusospirochetal complex, primarily Fusobacterium nucleatum and Treponema species, in a setting of stress and immune compromise.
Question 5: Aspirin irreversibly inhibits cyclooxygenase in platelets. How long does it take for platelet function to fully recover after aspirin discontinuation?
- 24–48 hours
- 3–4 days
- 7–10 days (Correct answer)
- 14–21 days
Correct answer: 7–10 days
Since platelets are anucleate and cannot synthesize new COX, platelet function recovers only as new platelets are produced over 7–10 days (the platelet lifespan).
Question 6: Which salivary gland produces the most serous (watery, enzyme-rich) secretion and contributes the largest volume of saliva?
- Sublingual gland
- Submandibular gland
- Parotid gland (Correct answer)
- Minor mucous glands
Correct answer: Parotid gland
The parotid gland produces purely serous saliva and contributes about 60–65% of total salivary volume when stimulated.
Question 7: During the inflammatory process, which chemical mediator causes vasodilation and increased vascular permeability by acting on H1 receptors?
- Bradykinin
- Histamine (Correct answer)
- Serotonin
- Prostaglandin E2
Correct answer: Histamine
Histamine, released from mast cells and basophils, binds H1 receptors to cause vasodilation and increase vascular permeability in early acute inflammation.
NBDHE NBDHE Scientific Basis of Practice 5
Which cranial nerve is responsible for motor innervation of the muscles of mastication?