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MBBS > 205 NS - Physiology > Flashcards

205 NS - Physiology Flashcards

1
Q

Describe the formation, circulation, and removal of cerebrospinal fluid (CSF).

A
  1. Formed in the choroid plexus of ventricles (mainly lateral)
  2. Enters the third ventricle through foramen of Monro
  3. Enters the fourth ventricle through the aqueduct of Sylvius
  4. Enters cisterna magna behind medulla & beneath cerebellum
  5. Though midline foramen of Magendie & 2 lateral foramina of Lushka, it enters the subarachnoid space
  6. Removed by arachnoid villi into dural venous sinuses
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2
Q

Broca’s area - location, #, function

A

Location: near the motor cortex, inferior frontal gyrus
#: Area 44
Function: production of speech

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3
Q

Wernicke’s area - location, #, function, lesion

A

Location: posterior 1/3 of lateral superior temporal gyrus; close to the auditory cortex
#: Area 22
Function: for comprehension - receives sensory, auditory & visual info
Lesion: causes difficulty in attributing meaning to words

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4
Q

Wernicke’s aphasia

A

Inability to comprehend speech

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5
Q

Broca’s aphasia

A

Inability to produce speech

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6
Q

Global Aphasia

A

Both Wernicke’s & Broca’s area affected

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7
Q

What happens when there’s a lesion in the angular gyrus?

A

Dyslexia - visual info not processed & transferred to Wernicke’s

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8
Q

4 stages of NREM sleep & its waves

A

Stage 1 - frequency ↓, amplitude ↑
Stage 2 - frequency ↓, amplitude ↑; sleep spindle
Stage 3 - low frequency, high amplitude
Stage 4 - low frequency, high amplitude; delta waves

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9
Q

Physiological changes during sleep

A

During NERM → BMR ↓

During REM → BMR ↑ - w rapid eye movement

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10
Q

Hypothalamic regions modulating sleep

A 
Lateral hypothalamus - secretes orexin/hypocretin - maintain awake state
Ventral preoptic (VLPO) nucleus - activity inhibits brainstem areas - sleep

*balance of 2 determines awake/sleep

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11
Q

What is REM sleep?

A

Low amplitude high-frequency waves, as seen in the awake state

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12
Q

What’s the reward & punishment center of the brain?

A

Ventromedial nucleus

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13
Q

Neural circuits mediating sleep

A

Stimulate RAS → awake

Low-frequency stimulation of thalamus → sleep

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14
Q

Brainstem regions that maintain an awake state & their secretions

A

Raphae nucleus - serotonin
Locus coeruleus - norepinephrine
Tuberomamillary nucleus of hypothalamus - histamine

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15
Q

Signs of LMN lesion (6)

A 
Individual muscles affected
Severe atrophy
Fasciculations seen
Flaccid paralysis - hypotonia
Tendon reflex absent
Normal plantar reflex (flexion)
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16
Q

Signs of UMN lesion (6)

A 
Usually affects groups of muscle
No atrophy
No fasciculations
Spasticity is seen - hypertonia
Tendon reflex exaggerated
Extensor plantar reflex (Babsinki sign)
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17
Q

Parts of Basal ganglia

A

Caudate, Putamen, Globus pallidus - cerebrum
Substantia nigra - midbrain
Subthalamic nucleus - diencephalon

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18
Q

Decorticate rigidity

A

Flexion of UL, extension of LL

by damage to upper midbrain

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19
Q

Decerebrate rigidity

A

Extension of all limbs

by damage to lower midbrain & upper pons

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20
Q

Role of Basal ganglia

A

Planning & programming of voluntary movement

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21
Q

What forms the striatum?

A

Caudate + putamen

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22
Q

What is seen in viral (aseptic) meningitis?

A

Lymphocyte count increases

Glucose levels normal

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23
Q

What is seen in bacterial (pyogenic) meningitis?

A

Protein concentration of CSF increases
Glucose levels decrease
Neutrophil count increases

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24
Q

What cannot pass through BBB?

A

Proteins

Non-lipid soluble substances

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25
Q

What can pass through BBB?

A

Lipid soluble substances: gases, alcohol, anaesthetics

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26
Q

What can pass through blood-CSF barrier?

A

Water, lipid soluble substances & gases

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27
Q

Function of blood-brain barrier

A

Maintains constant electrolyte levels
Prevents entry of toxins into brain
Prevents leak of neurotransmitters into blood
Prevents entry of bilirubin into the brain
Premature babies have leaky barrier

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28
Q

What forms the blood-brain barrier?

A

Foot process of astrocytes around capillaries

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29
Q

Virchow–Robin space

A

Perivascular space, space between artery and brain tissue

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30
Q

Function of thalamus

A

Acts as a relay center, receiving and distributing information between the peripheries and higher centers

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31
Q

Connections of Basal ganglia

A

Cortical neurons → striatal neurons (stimulatory)
Striatal neurons → globus pallidus (inhibitory)
Globus pallidus → thalamus (inhibitory)
Thalamus → cortical neurons (stimulatory)

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32
Q

What are the 2 classifications of senses?

A

Somatic senses

Special senses

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33
Q

3 types of somatic senses

A

Mechanoreceptive
Thermoreceptive
Nociceptive

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34
Q

5 types of special senses

A 
Vision
Hearing
Smell
Taste
Vestibular
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35
Q

7 sense receptors

A 
Free nerve endings
Meissner's corpuscle
Merkel's disc
Hair end organ
Ruffini's endings
Pacinian corpuscles
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36
Q

Free nerve endings

A

Superficial

i.e. thermoreceptor

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37
Q

Meissner’s corpuscles

A 
Superficial
Fingertip, lips
Adapt rapidly
Sense movement over skin
Detect low frequency vibration
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38
Q

Merkel’s disc

A

Superficial
Texture
Adapt slowly

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39
Q

Hair end organ

A 
Superficial
Free nerve ending at base of hair
Adapt rapidly
Sense initial touch
Sense movement of hair
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40
Q

Ruffini’s ending

A

Dermis
Adapt slowly
Joint capsule
Detect pressure/stretch

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41
Q

Pacinian corpuscles

A

Dermis
Adapt rapidly
High-frequency vibrations
Deep pressure

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42
Q

How are mechanical receptors stimulated?

A

By deformation

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43
Q

Adequate stimulus

A

Receptors respond maximally to 1 stimulus

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44
Q

Where & when is action potential generated?

A

1st node of Ranvier when threshold is reached

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45
Q

How do Pacinian corpuscles adapt rapidly?

A

Due to fluid shifts within the corpuscles

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46
Q

Rapidly adapting receptors respond only during ______ of stimuli

A

beginning or end

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47
Q

Slowly adapting receptors respond to ______ stimuli

A

sustained

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48
Q

What type of neuron has highest conduction velocity?

A

A alpha

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49
Q

What type of neuron has lowest conduction velocity?

A

C

  • nonmyelinated
50
Q

Which is the only non-myelinated type of neuron?

A

C

51
Q

Purpose of labeled line principle

A

Helps brain to identify the type of stimulus producing the sensation

52
Q

Sensory unit

A

Each sensory neuron with all its branches and receptors

53
Q

Receptive field

A

Area of skin innervated by each sensory neuron

54
Q

Lateral inhibition

A

Increases contrast of sensory info

Because it spreads to sides of excitatory signal and inhibit adjacent neurons

55
Q

Higher stimulus intensity stimulates ______ sensory neurons & ______ number of ______

A

more; increases; action potential

56
Q

Recruitment of neurons

A

Higher stimulus intensity stimulates more sensory neurons

57
Q

Somatosensory cortex located?

A

Behind central sulcus

58
Q

Primary somatosensory area Brodmann’s area #?

A

3, 1, 2

59
Q

Primary somatosensory area concerned with?

A

Reception & interpreation of sensations

60
Q

Secondary somatosensory area Brodmann’s area #?

A

5, 7

61
Q

Secondary somatosensory area concerned with?

A

Higher order processing of sensory info

62
Q

Larger areas for ______ & ______ in the sensory homunculus.

A

lips; fingers

63
Q

Which layer of somatosensory cortex do ascending nuerons synapse?

A

Layer 4

64
Q

Lesion in primary somatosensory cortex causes?

A

Abnormal tactile localization
2-point discrimination lost
Astereognosis
Graphaesthesia

65
Q

Abnormal tactile localization

A

Inability to localize site of sensation

66
Q

Astereognosis

A

Inability to detect shape or form of objects

67
Q

Graphaesthesia

A

Inability to identify what is written on skin

68
Q

2-point discrimination

A

Ability to identify closely applied touch stimuli as 2 separate stimuli

  • greater in fingertips & lips bc they have smaller receptive fields
  • can distinguish 2 mm
69
Q

Static proprioception

A

Info about position of diff body parts in space

In relation to each other

70
Q

Dynamic proprioception

A

Info on rate of movement (kinesthesia)

71
Q

Vibration sense is due to?

A

Repeated cutaneous stimulation

72
Q

What fiber carries vibration sense?

A

A beta fibres

73
Q

Pain is caused by?

A

Tissue damage

74
Q

Fast pain

A

WIthin seconds
Sharp pain, picking pain, acute pain, electric pain
Superficial

75
Q

Slow pain

A

Seconds to minutes
Burning pain, throbbing pain, aching pain, nauseating pain
Superficial & deep

76
Q

What type of receptors are pain receptors?

A

Free nerve endings

“nociceptors”

77
Q

Why is pain sensation non-adapting?

A

So that we reaact to the pain quickly to prevent further damage

78
Q

Fast pain is carried by?

A

A delta fibres

79
Q

Slow pain is carried by?

A

C fibres

80
Q

How does serotonin suppress pain?

A

Stimulate interneurons that secrete enkephalins

81
Q

Stimulation of tactile ______ fibres can suppress pain

A

A beta

82
Q

Referred pain

A

Pain in viscera referred to surface of body

bc both have same dermatomal segment origin in embryo

83
Q

Where does cardiac pain refer to?

A

Left-arm

84
Q

What may cause visceral pain?

A

Ischemia
Distension
Spasm
Chemical stimuli

85
Q

Visceral pain is carried by ______ fibres.

A

C

86
Q

Visceral inflammation stimulates ______ & ______ pain fibres?

A

visceral; parietal

87
Q

Where does appendicitis pain refer to?

A

Around umbilicus

88
Q

What carries parietal pain?

A

C fibres carried in autonomic neurons

89
Q

What causes parietal pain?

A

Carried by spinal nerves and cause localized pain

90
Q

What fibres carry thermal sensation?

A

A delta & C fibres

91
Q

At what temperature are cold receptors stimulated maximally?

A

24°C

92
Q

Brown Sequard Syndrome

A

Hemi section of spinal cord

Pain, temperature lost on contralateral side
Vibration, light touch, motor lost on ipsilateral side

93
Q

Phantom limb

A

Sensations in amputated area - stimulation of nerve stump

94
Q

Where do dorsal column sensations cross?

A

Medulla

95
Q

Where do spinothalamic pathways cross?

A

Spinal cord

96
Q

Dorsal column sensations

A

Fine touch
Vibration
Position

97
Q

Spinothalamic sensations

A

Pain

Temperature

98
Q

UMN lesion - face

A

Spare upper face - as it has bilateral innervation

99
Q

LMN lesion - face

A

Weakness in lower & upper face

100
Q

Role of premotor cortex

A

Idea for movement from prefrontal cortex

Converted to plan by basal ganglia & lateral cerebeluum

101
Q

UMN vs LMN

A

UMN - CNS - brain + spinal cord

LMN - PNS - others

102
Q

Direct pathway of basal ganglia

A

Facilitates intended movement

103
Q

Indirect pathway of basal ganglia

A

Suppresses non-synergistic & competing movement

104
Q

Lead pipe rigidity

A

Hypertonic state throughout the range of motion

Seen in Parkinson’s disease

105
Q

Cog-wheel rigidity

A

Hypertonic state with superimposed ratchet-like jerkiness and is commonly seen in upper extremity movements

Lead pipe rigidity + tremor

Seen in Parkinson’s disease

106
Q

Oculomotor loop of basal ganglia

A

Saccadic eye movement

107
Q

Prefrontal loop of basal ganglia

A

For cognition - initiating planning

108
Q

Limbic loop of basal ganglia

A

For emotions - switching from one mood to another

109
Q

Cerebellar function

A

Helps in motor agility

Error correction & motor learning

110
Q

How does the cerebellum connect w UMN?

A

Through thalamus

111
Q

Superior cerebellar peduncle

A

Sends output from the cerebellum

112
Q

Inferior cerebellar peduncle

A

Receives input for cerebellum from spinal cord & brainstem

Also sends out impulses

113
Q

Middle cerebellar peduncle

A

Largest

Gets inputs for cerebellum through pontine nuclei from cortex

114
Q

Vermis of cerebellum

A

Co-ordinates movements of proximal muscles

115
Q

Major afferents to cerebellum

A

Pontine nuclei
Vestibular nuclei
Spinocerebellar & cuneocerebellar tract
Inferior olive

116
Q

Inferior olive concerned w

A

Motor learning & error correction

117
Q

Climbing fibres

A

Can modulate synaptic connection between parallel fibres & Purkinje cells
Weaken the parallel fibre synapse w Purkinje cells by LTD (long-term depression)

118
Q

Signs of cerebellar disease

A 
Dysmetria/Dysdiadochokinesia
Ataxia
Nystagmus
Intension tremor
Scanning speech
Hypotonia
119
Q

Scanning or staccato speech

A

Talking syllable by syllable w gap between every syllable

Seen in cerebellar lesion

120
Q

Why does cerebellar lesions cause ipsilateral problems?

A

bc spinocerebellar pathways are ipsilateral

MBBS (28 decks)

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