CENTRAL NERVOUS SYSTEM

TRUE/FALSE in C.N.S
1.cerebral blood flow:(CBF)

a).is subject to autoregulation over a mean arterial pressure (MAP) range of 50-150 mmHg
b)is critical for maintaining the intracranial pressure(ICP) at around a normal of 10-15mmHg.
c)is adjusted to keep a cerebral perfusion pressure(CPP) of about 70mmHg in normal people.
d)hypoxia is a more potent stimulus for increased CBF than a similar fall in the PaCO2.
e)overall CBF and oxygen consumption in the brain varies widely throughout a normal 24 hours.
f)sympathetic vasoconstriction of cerebral vessels is often seen in acute brain damage.

g)cerebral steal means that blood is diverted to the brain from extra cranial regions.

h)increases during sleep.

2.The intracranial pressure (ICP)
a)increases during sleep(irrespective of position)

b)almost all volatile anaesthetics increase the ICP.

3.Cerebral cortex,EEG,CVA
a) the EEG is due to firing of cortical neurons (AP generations)

b)in an alert adult with closed eyes,alpha waves predominates

c)irregular small waves are characteristic of mental activity

d)during seizures the brain ECF K+ often rises dramatically.

e)a transient ischaemic attack( TIA) usually lasts less than 10 mts.

The thalamus:
f)plays an essential role in arousal.

g)has each half of the body represented topographically.

4.subcortical areas
Regarding reticular formationRF and limbic system

a)the only proven function of RF are associated with wakefulness,arousal,and posture control.

b)the amygdaloid nucleus is mainly concerned with memory

c)the hippocampus is important in behavioural disorders

d)some striatalnigral fibres release serotonin

e)some nigrostriatal fibres secrete acetylcholine

f)the tremor in parkinsonism PD is exacerbated by alcohol

g)the tremor in PD is present even when the subject is asleep

h)GABA agonists worsen parkinsonism

5.pain
a)pain receptors are polymodal in nature

b)anaesthetization of stump gives only temporary relief in phantom pain

c)pain pathways are not fully developed in the newborn

6.memory
a)working memory is located mainly in the frontal lobes

b)one cannot transfer information from primary to secondary memory in anterograde amnesia.

7.Sleep

a)in REMsleep there is a general rise in skeletal muscle tone

b)REM generating neurons lie in the pons

c)normally REMsleep occurs within 10 min of falling sleep

d)at birth REM accounts for about 50% of sleep

e)sleep-walking occurs in deep stage 3-4 NREM sleep

f)hypnic jerks,bruxism(teeth grinding)and head-banging occur in REM sleep

g)daytime sleepiness,per-sleep dreams,sleep paralysis,cataplexy confirm the diagnosis of narcolepsy.

h)obstructive sleep apnea and obesity often go together

i)polycythemia is common in subjects who suffer from sleep apnea

j)the sleep-wake cycle is retained in coma


TRUE/FALSE in CNS (ANSWERS)
1.a)true b)true c)true d)false.(the PaCO2 must fall below 50 mmHg before there is a significant rise in the CBF.)
e)false.(CBF and o2 consumption are fairly constant over a period of 24 hrs(3ml/100gm/mt)
f)true g)false( diversion of blood to an area of the brain that is relatively vasodilated from other normally perfused areas of the brain)
h)true
ed
2.a)true b)true

3.a)false (EEG is due to changes in EPSP and IPSP in cortical neurons.)
b)true c)true d)true e)true f)false(arousal is possible even if the thalamus is grossly damaged
g)true

4.a)false(RF also modulates muscle tone ,maintains vegetative functions and has a role in affective emotions(pain,pleasure,aggression )
b)false(aggression ,restlessness,and instinctual drives)
c)false(short term memory)
d)false(some nigrostriatal fibers release serotonin)
e)true
f)false(lessened by alcohol)
g)false(disappears in sleep)
h)true

5.a)true b)false(central in origin.,gives no relief)
c)false(pain receptors have been demonstrated from 7th week of fetus.thalamocortical connections are complete by 20-24 weeks of gestations)

6.a)true b)true

7)a)false(atonia)
b)true c)false(begins about 40 mts after sleep onset)
d)true e) true f)false(occurs in stage 1-2 of NREM sleep
g)true h) true i) true j) false(however it is retained in persistent vegetative states)