Respiratory System MCQs Part 1

# Pulmonary surfactant is:
A. Lecithin
B. Dipalmitoyl Phosphatidyl choline
C. Dipalmitoyl Phosphatidine serine
D. Sphingosine

# Heimilch Maneuver is carried out in:
A. Syncope
B. Airway obstruction
C. Carotid blow out
D. Cardiac arrest

Ideal Orthodontic Tooth Movement

# Resorption in case of ideal orthodontic tooth movement should be:
a) Undermining
b) Indirect
c) Frontal
d) Necrotic     

The correct answer is C. Frontal. 

Application of light orthodontic forces will result in frontal/ direct resorption. Frontal resorption occurs only when the forces applied are close to the capillary pressure, i.e. 20 -26 gm/ sq. cm of root surface area. 

Oppenheim and Schwarz have been given credit for discovering the optimum orthodontic force levels usually light continuous forces are recommended for tooth movement.

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Scissor Bite

# Scissor bite is seen in:
a) Anterior cross-bite
b) Complete deep-bite
c) Total maxillary lingual cross-bite
d) Total maxillary buccal cross-bite   

The correct answer is D. Total maxillary buccal cross bite. 

When all the teeth are in scissors bite, the condition is called as Bodie syndrome.

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Charcot Leyden Crystals

# Charcot Leyden crystals are breakdown products of:
A. Basophils
B. Eosinophil granules
C. Bile
D. Cholesterol granules or clefts

The correct answer is B. Eosinophil granules.

Charcot-Leyden crystals are seen in bronchial asthma. They are diamond shaped crystal seen in association with eosinophils. Repeated attacks may induce chronic bronchitis condition which in turn may develop into emphysema. 

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Oxygen in histotoxic hypoxia

# The beneficial effect of oxygen therapy in histotoxic hypoxia is about:
A. 0 %
B. 50 %
C. 100 %
D. 30 %

The correct answer is A. 0%

Histotoxic hypoxia refers to hypoxia secondary to the inability of the cells to utilize oxygen.

In histotoxic hypoxia, oxygen therapy is  not beneficial as tissue oxygenation is itself defective. 

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Transposition of Teeth

# The commonest teeth involved in transposition are:
a) Maxillary central incisor and lateral incisor
b) Maxillary canine and first premolar
c) Maxillary 1st premolar and 2nd premolar
d) Maxillary canine and Lateral incisor   

The correct answer is B. Maxillary canine and first premolar. 

Canine-first premolar transposition is the most common  transposition. 21. 

Canine-lateral incisor is the second most common transposition. 

Transposition is never seen in primary dentition. 

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Average Leeway Space

# The average "Leeway space" available in each half of the maxilla is approximately:
a) 0.9 mm
b) 4.0 mm
c) 2.9 mm
d) 6.9 mm 

The correct answer is A. 0.9 mm.

The combined mesiodistal width of the permanent canines and premolars is usually less than that of deciduous canines and molars and this difference is known as Leeway Space of Nance. This space is used by the permanent lower molars during late mesial shift from end-on occlusion to class-I relation. The amount ot leeway space is about 1.8 mm (0.9 mm on each side of arch) in maxillary arch and about 3.4 mm in mandibular arch (1. 7 mm on each side of arch). 

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