Q.5
Burning pain is carried by which type of fibres :-
A. A alpha
B. A delta
C. A beta
D. C
Explanation :
Pain is transmitted via two fiber types.
Thinly myelinated A-delta fibers (2-5m in diameter) which conduct at rates of 12-30 m/s.
Unmyelinated C fibers (0.4-1.2m in diameter)which conduct at low rates of 0.5-2 m/s.
Thermoreceptors also span these two fiber types. Cold receptors are on dendritic endings of A-delta fibers and C fibers, whereas warmth (heat) receptors are on C fibers.
Q.7
Slow IPSP in autonomic ganglia is generated by
a) Nicotinic cholinergic
b) Muscarinic cholinergic
c) Dopamine
d) GnRH
e) Adrenaline
A. BC
B. ABC
C. CD
D. AB
Explanation :
Fast EPSP in autonomic ganglia are generated by Acetylcholine on nicotinic cholinergic receptors.
Slow EPSP in autonomic ganglia are generated by Acetylcholine on M1 muscarinic receptors.
Slow IPSP in autonomic ganglia are generated by Catecholamines (Dopamine, noradrenaline) on dopaminergic, α- adrenergic and M2 muscarinic receptors.
Q.9
Arterial PO2 is decreased in hypoxia due to :-
A. Cyanide poisoning
B. CO poisoning
C. COPD
D. Shock
Explanation :
COPD presents with Hypoxic Hypoxia. Hypoxic hypoxia is the most common form of hypoxia seen clinically.
The diseases that cause it can be roughly divided into those in which the gas exchange apparatus fails, those such as congenital heart disease in which large amounts of blood are shunted from the venous to the arterial side of the circulation, and those in which the respiratory pump fails.
Lung failure occurs when conditions such as pulmonary fibrosis produce alveolar-capillary block, or there is ventilation-perfusion imbalance.
Pump failure can be due to fatigue of the respiratory muscles in conditions in which the work of breathing is increased or to a variety of mechanical defects such as pneumothorax or bronchial obstruction that limit ventilation.
It can also be caused by abnormalities of the neural mechanisms that control ventilation, such as depression of the respiratory neurons in the medulla by morphine and other drugs.
Q.10
Surfactant secreted by :-
A. Type 1 pneumocytes
B. Type 2 pneumocytes
C. Epithelial cells
D. Macrophage
Explanation :
A surfactant is produced by type II alveolar epithelial cells.
Typical lamellar bodies, membrane-bound organelles containing whorls of phospholipid, are formed in these cells and secreted into the alveolar lumen by exocytosis.
Tubes of lipid called tubular myelin form from the extruded bodies, and the tubular myelin, in turn, forms the phospholipid film.
Following secretion, the phospholipids of surfactant line up in the alveoli with their hydrophobic fatty acid tails facing the alveolar lumen.
Surface tension is inversely proportional to their concentration per unit area.
The surfactant molecules move further apart as the alveoli enlarge during inspiration, and surface tension increases, whereas it decreases when they move closer together during expiration.
Some of the protein-lipid complexes in surfactant are taken up by endocytosis in type II alveolar cells and recycled.
Q.11
Vibration sensation is mediated by :-
A. Merkel's disc
B. Ruffini's end organ
C. Paccinian corpuscle
D. Meissner's corpuscle
Explanation :
Touch receptors
- For superficial touch- Meissner’s corpuscles & Merkel’s disc (Rapidly adapting)
- For pressure (Deep touch)- Ruffini’s end organ (slowly adapting)
- For vibrations- Pacinian corpuscle (rapidly adapting)
Q.14
Conscious proprioception is carried by :-
A. Dorsal column fibres
B. Anterior spinothalamic tract
C. Lateral spinothalamic tract
D. Vestibular tract
Explanation :
Sensations carried by posterior column
- Proprioception, Vibration, kinesthesia, fine touch.
Sensations carried by anterolateral column
- Temperature, pain (lateral) and crude touch (anterior)
Q.15
Pain and temperature are carried by :-
A. Anterior spinothalamic tract
B. Lateral spinothalamic tract
C. Dorsal column
D. None
Explanation :
Sensations carried by the posterior column
- Proprioception, Vibration, kinesthesia, fine touch.
Sensations carried by anterolateral column
- Temperature, pain (lateral) and crude touch (anterior)
Q.16
True about brown sequard syndrome :-
A. Ipsilateral loss of joint sensation
B. Contralateral loss of joint sensation
C. Ipsilateral loss of pain & temperature
D. Segmental sign are bilateral
Explanation :
In Brown sequard syndrome, a hemisection of the spinal cord results in
- Sensory
- Loss of Ipsilateral dorsal column sensations- Proprioception, vibration, fine touch, Kinesthesia.
- Loss of contralateral lateral column sensations- Pain, temperature
- Motor
- Loss of ipsilateral corticospinal action- results in UMNL- Weakness, spasticity, Extensor plantar response.
Q.17
Brown - sequard syndrome -
A. Pain loss in the opposite side of lesion
B. Fine touch lost in opposite side of lesion
C. UMN paralysis in opposite side of lesion
D. LMN paralysis in opposite side of lesion
Explanation :
In Brown sequard syndrome, a hemisection of the spinal cord results in
- Sensory
- Loss of Ipsilateral dorsal column sensations- Proprioception, vibration, fine touch, Kinesthesia.
- Loss of contralateral lateral column sensations- Pain, temperature
- Motor
- Loss of ipsilateral corticospinal action- results in UMNL- Weakness, spasticity, Extensor plantar response.
Q.18
Stereoanesthesia is due to lesion of
a) Nucleus Gracilis
b) Nucleus cuneatus
c) Cerebral cortex
d) Spinothalamic tract
A. ABC
B. AB
C. AC
D. AD
Explanation :
Astereognosis/Stereoanaesthesia- Loss of ability to recognize size and shape of an object.
Seen in- lesion of somatosensory cortex, lesion of tractus cuneatus, lesion of tractus gracilis.
Somatosensory cortex lesion- proprioception and tactile sensations are lost while pain and temperature sensations are preserved.
Tractus cuneatus- formed by fasciculus cuneatus (spinal cord) and nucleus cuneatus (medulla). Pass through lateral portion of dorsal column. Carries sensations of dorsal column- proprioception and tactile sensations from upper part of the body.
Tractus gracilis- formed by fasciculus gracilis (spinal cord) and nucleus gracilis (medulla). Pass through medial portion of dorsal column. Carries sensations of dorsal column- proprioception and tactile sensations from lower part of the body.
