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Physiology > Last Minute Revision CNS > Flashcards

Last Minute Revision CNS Flashcards

1
Q

Types of intrafusal fibres

A
  1. Nuclear bag fibres - nuclei aggregated as bags in the central portion
  2. Nuclear chain fibres - nuclei are arranged in single row
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2
Q

Sensory nerve supply of muscle spindle

A
  1. Annulospiral endings

2. Flower spray endings

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3
Q

Annulospiral endings

A
  • 1a afferents
  • end as a ring around central portion of nuclear bag and chain fibres
  • both dynamic and static response
  • respond both to changes in length and velocity of change
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4
Q

Flower spray endings

A
  • A beta fibres
  • only from nuclear chain fibres
  • mainly static response
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5
Q

Static response

A

When receptor portion is stretched slowly number of impulses transmitted from both primary and secondary endings increases directly proportional to degree of stretching

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6
Q

Dynamic response

A

When length of receptor increases suddenly primary ending is powerfully stimulated and responds actively to rapid rate of change and spindle length but only while the length is actually increasing

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7
Q

Motor nerve supply

A
  1. Gamma 1 efferents - NBF dynamic

2. Gamma 2 efferents - NCF static

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8
Q

Mechanism of activation of muscle spindle

A
  1. Stretch of muscle causes stretch of spindle activating primary and secondary endings
  2. Activation of Gamma motor efferents
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9
Q

Functions of muscle spindle

A
  1. Participates in stretch reflex
  2. Regulation of muscle tone and posture by alpha gamma co activation
  3. Proprioception
  4. Monitors length of muscle
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10
Q

Alpha Gamma co activation

A

Alpha motor neurones and gamma motor neurones are stimulated simultaneously.
Causes for extrafusal and muscle spindle fibres to contract at same time.
1. Prevents activation of muscle spindle reflex
2. Maintains damping function

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11
Q

Brain areas controlling gamma motor system

A
  1. Reticular activating system

2. Signals from cerebellum, basal ganglia, cerebral cortex

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12
Q

Components of stretch reflex arc

A
  1. Muscle spindle
  2. Afferent sensory nerves
  3. Spinal cord
  4. Motor nerves
  5. Extrafusal fibres
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13
Q

Phasic stretch reflex

A
  • dynamic
  • activating primary endings
  • causes contraction of muscle containing muscle spindle and inhibition of antagonistic muscle
  • helps bring about movement
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14
Q

Tonic stretch reflex

A
  • static
  • activation of both primary and secondary endings
  • causes steady contraction of muscle containing spindle
  • for maintaining tone and posture
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15
Q

Location of Golgi tendon organ

A
  • junction between muscle fibres and tendon

- detect tension in muscle

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16
Q

Functions of Golgi tendon organ

A
  1. Modulates muscle tension during movements
  2. Prevent muscle tear
  3. Inverse stretch reflex and lengthening reaction
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17
Q

Spastic gait

A

Lesion in pyramidal tract

Hemiplegia

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18
Q

Drunken gait

A

Cerebellar ataxia

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19
Q

Festinant gait

A

Parkinsonism

Bent forward moves in rapid shuffling steps

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20
Q

Stamping gait

A

Tabes dorsalis

Due to loss of sensory feedback to brain

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21
Q

High stepping gait

A

Weakness of extensor muscles of feet

Common peroneal nerve palsy

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22
Q

Waddling gait

A

Myopathies and muscular dystrophies

Body tilted back

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23
Q

Scissors gait

A

Congenital spastic paraplegia

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24
Q

Hypotonia seen in

A
  1. Destruction of motor fibres
  2. Destruction of dorsal columns
  3. Stimulation of inhibitory areas of brain
  4. Inhibition of facilitatory areas
  5. Sleep
  6. Thalamic and cerebellar lesions
  7. Barbiturates
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25
Q

Hypertonia seen in

A
  1. Stimulation of facilitatory areas
  2. Destruction of inhibitory areas
  3. Increase Gamma motor neuron activity
  4. Increase Alpha motor neurone activity
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26
Q

Spasticity

A

Lesion of pyramidal tract
Involves only one group of muscles
Clasp knife rigidity
Proportional to stretch

27
Q

Rigidity

A 
Lesion of basal ganglia
Involve both agonists and antagonists
Lead pipe rigidity
No auto inhibition
Resistance is present through passive movements
28
Q

Cerebellar disorders

A
  1. Drunken gait
  2. Hypotonia
  3. Pendular reflexes
  4. Asynergia
  5. Dysmetria
  6. Intention tremors
  7. Asthenia
  8. Rebound phenomenon
  9. Dysdiadochokinesia
  10. Nystagmus
  11. Scanning speech

SIN AAA DDD

29
Q

Functions of semicircular canals

A
  1. Give info about rotational movement of head
  2. Help maintain equilibrium
  3. visual fixation during angular rotation of head
30
Q

Vestibulo ocular reflex

A
  • Form stable image on retina during rapid head rotation
  • producers conjugate movements of eyes in opposite direction of head rotation
  • vestibular apparatus with 3rd, 4th, 6th cranial nuclear through medial longitudinal fasciculus
31
Q

Optokinetic reflex

A
  • Person viewing rapidly moving object from stationary position
  • eyes move along stimulus till it disappears and return to original position rapidly
  • superior colliculus with 3rd, 4th, 6th cranial nerves through medial longitudinal fasciculus
32
Q

Functions of otolith organs

A
  1. Info about static position of head
  2. Respond to linear acceleration
  3. Utricle detect dorsiflexion and ventriflexion
  4. Maintain balance while jumping or walking down stairs
33
Q

Main outlet for efferents of basal ganglia

A

Globus pallidus

34
Q

Afferents of basal ganglia

A

Corticostriatal - ipsi., Frontal and parietal

Thalamostriate - intralaminar and centromedian

35
Q

Internuclear connections of basal ganglia

A

Nigrostriatal
Nigropallidal
Striatonigral
Strialopallidal

36
Q

Efferent connections of basal ganglia

A

Pallidothalamic via ansa fasicularis and ansa lenticularis

Nigrothalamic

37
Q

Food intake hypothalamus

A

VMN - satiety centre

LN - feeding centre

38
Q

Chorea

A

Destruction of GABA ergic neurons in caudate n.
- involuntary jerky mvmts of limbs, orofacial muscles
Sydenhams - in children due to rheumatic fever
Huntington’s - autosomal. Chorea + dememtia

39
Q

Athethosis

A

Inability to fix muscles of fingers toes in one position
Destruction of GABA neurons in putamen
Appear as grasping mvmts

40
Q

Ballism

A

Lesion in subthalamic body

Flinging involuntary mvmts of extremeties on opp. Side

41
Q

Body temperature hypothalamus

A

Preoptic
Ant. Hypothalamus
Post. Hypothalamus

42
Q

Preoptic nucleus receives info by

A

Blood flowing through hypothalamus

Cutaneous receptors of cerebral cortex

43
Q

Anterior hypothalamus

A 
Stimulus:
When temp. Inc. 
Action:
Cutaneous vasodilation
Sweat secretion
44
Q

Posterior hypothalamus

A 
Stimulus:
When temp. Dec.
Action:
Cutaneous vasoconstriction
Rigors
45
Q

Thirst hypothalamus

A 
Preoptic 
LN
Stimulus:
Inc. tonicity
Oral dryness
ECF volume Dec.
46
Q

Functions of hypothalamus

A
  1. Food intake reg.
  2. Body temp. Reg.
  3. Thirst reg.
  4. ECF volume reg.
  5. Endocrine
  6. Reproduction
  7. Reproductive behaviour
  8. Sleep wake cycle
  9. ANS control
  10. Emotion reg.
  11. Stress
  12. Circadian rhythm
  13. Reward punishment
47
Q

Sleep wake cycle hypothalamus

A

Diencephalic sleep zone
Basal forebrain sleep zone
Slow wave sleep

48
Q

Papez circuit

A

Ant. Thalamic nuclei -
Cingulate gyrus
Hippocampus
Mamillary bodies

49
Q

Functions of limbic system

A
  1. Autonomic function
  2. Discriminative feeding
  3. Memory and learning
  4. Emotional behaviour
  5. Sexual behaviour
  6. Olfaction
  7. Reward punishment
  8. Maternal behavior
50
Q

NREM sleep

A 
Hypotonia
Slow delta waves
No rapid eye mvmts
Dreams can't be recalled
No pontogeniculooccipital spikes
Low pulse, bp
Low serotonin
Sensory threshold Inc.
Low brain activity
Low O2 consumption
51
Q

REM sleep

A 
Reduced muscle tone
Fast beta waves
REM saccades
Dreams recalled clearly
Teeth grinding
Pontogeniculooccipital spikes seen
Irregular bp, pulse
Noradrenaline Dec.
Sensory threshold very high
More brain activity
More O2 consumption
52
Q

Significance of evoked potentials

A
  1. Find integrity of pathway
  2. Auditory evoked potential to test hearing in newborn
  3. Understanding sensory connections
  4. Map centres for sensation
  5. Localise site of lesion
53
Q

Focal seizures

A
  • begin in localised region of cortex
  • local to 1 hemisphere
  • promote rapid neuronal discharges
  • called Jacksonian March
  • starts from particular area and spreads to adjacent areas
  • usually by brain tumor
54
Q

Generalized seizures

A
  • cannot be referred to one hemisphere
55
Q

Grand mal seizure

A
  • sudden loss of consciousness followed by convulsions
  • epileptic aura felt
  • starts with tonic contractions followed by clonic
  • EEG spikes
56
Q

Petit mal seizure

A
  • Sudden loss of consciousness
  • no convulsions
  • spike dome EEG
57
Q

Parts involved in short term memory

A 
Hippocampus
Mamillary bodies
Thalamus
Amygdala
Prefrontal cortex
58
Q

Mechanisms of short term memory

A

Reverberating circuits
PTP
Presynaptic facilitation

59
Q

Mechanism of long term memory

A

LTP

60
Q

Physiological changes seen in LTP

A
  1. Change in the expression of postsyn. Neuron
  2. Inc. Synthesis and release of neurotransmitter
  3. Change in receptor response
61
Q

Structural changes in LTP

A
  1. Formation of new connections
  2. Inc. no of releasing sites and receptor sites
  3. Change in neuroglial cells
62
Q

Speech centres

A

Area 42, 18, 19, 39
Wernickes
Brocas

63
Q

Functions of external ear

A
  1. Inc. sound pressure on tympanic membrane
  2. Sound collection, localisation
  3. Humid environment
  4. Prevents entry of foreign bodies
  5. Limits frequencies reaching tympanum

Physiology (9 decks)

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