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MBChB 4 > Neurology > Flashcards

Neurology Flashcards

1
Q

What is Nissl substance and where is it located?

A

Located in the Perkaryion (cell body) Combination of ribosomes and endoplasmic reticulum

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2
Q

What part of the neurone mediates “all or nothing” principal?

A

Axon hillock Highest concentration of voltage gate ion receptors

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3
Q

How is strength of action potential conveyed?

A

Frequency of signals NOT MAGNITUDE

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4
Q

What is a golgi type 1 neurone?

A

Neurone with a long axon

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5
Q

What is a golgi type 2 neurone ?

A

Neurone with short axon

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6
Q

What pathology occurs through retrograde axonal transport?

A

Viruses e.g. policyelitis, herpes and rabies

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7
Q

What type of neurones are lower motor neurones?

A

Multipolar cell ( three or more synapses) Lower motor neurones are the most common type of neurone

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8
Q

What is an example of a unipolar neurone?

A

Peripheral autonomic neurones

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9
Q

If a neurone is in the ventral horn of the spinal cord, what is its function?

A

Motor

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10
Q

If a neurone is in the dorsal horn of the spinal cord, what is its function?

A

Sensory

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11
Q

Where are interneurones located and what are their function?

A

CNS Connection between neurones in the CNS

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12
Q

What is the role of a projection neurone?

A

Conveys action potential to higher brain structures Located in dorsal horn

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13
Q

What does the peripheral nervous system comprise of?

A

31 Spinal nerves

Rami (sensory + motor) –> Spinal nerve (sensory+motor) –> root (seperated sensory and motor)

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14
Q

Describe the events of how an aciton potential arrises?

A

At rest: Voltaged gated channels are closed but responsive

Depolarisation: Na+ channels open, K+ channels remain closed

Maximum depolarisation: Na+ channels inactivate, K+ channels open

Depolarisation: K+ channels remain open, channels remain inactivated

At rest again

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15
Q

What is the resting membrane potential of a neurone and how is this maintained?

A

-70 mV

Efflux of potassium ions

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16
Q

What is the gradient of Potassium and Sodium in a neurone?

A

Potassium high intracellular
Sodium high extracellular

Na/K pump transports 3 Na+ out of cell fo 2 K+ to entre cell

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17
Q

What is the refractory period of a neurone?

A

Absolute Refractory Period

Interval of inactivation, due to voltage gated sodium channels

Another action potential cannot overcome this or triggera second action potential

This occurs over the overshootto the beginning of the undershoot

Relative Refractory Period

Interval in which a second action potential can be generated

Due to undershootbypotassium effluxfrom downstroke

A large enough action potentialcan overcome this

This occurs on the downstroke to the resting potential

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18
Q

Describe the polarity of the extracellular and intracellular membranes of a neurone when an action potential moves along the neurone?

A

As the action potential moves, the polarity is reversed from + outside to - outside and from - Inside to + inside

Each action potential is associated with a influx of positively charged sodium ions

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19
Q

What disease is caused by demyelination of CNS cells?

A

Multiple sclerosis

Central demyelination (olgiodendrocytes)

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20
Q

What disease is caused by peripheral demyelination?

A

Guillain Barre Syndrome (Schwann cells)

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21
Q

What are the features of an excitatory neurone synapse?

A

Neuotransmitter: Glutamate

Glutamate acts on postsynpatic cation selective inotropic glutamate receptors

Depolarisation induced from Na+ influx

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22
Q

What are the features of an inhibitory synapse?

A

Neurotransmitter: GABA / Glycine

Acts on postsynaptic anion inotropic GABA/Glycine receptors

Influx of Chloride ions (Hyperpolarisation)

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23
Q

What effect does influx of anions have on a neurone?

A

Hyperpolarisation (Neurone becomes more negative)

Inhibitory effect

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24
Q

Describe how a synapse works?

A
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25
Q

What neurone transmitters are present in cells and do not require synthesis?

A

Glutamate

Glycine

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26
Q

What neurontransmitter requires synthesis from cells?

A

GABA

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27
Q

With regards to ion movement, how may depolarisation of a neurone occur?

A

Influx of: Na+ K+ Ca2+

Efflux of : Cl-

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28
Q

What regards to ion movement how may hyperpolarisation of a neurone occur?

A

Influx of: Cl-

Efflux of: Na+, K+, Ca2+

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29
Q

What are the excitatory neurotransmitters?

A

Acetylcholine (most widespread)

Noradrenaline

Adrenaline

5HT (Serotonin)

Dopamine

Glutamate

Aspartate

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30
Q

What are the inhibitory neurotransmitters?

A

GABA

Glycine
Histamine

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31
Q

What are excitatory and inhibitory neurotransmitters?

A

Neuropeptides:

Vasopressin

ACTH (adenocorticotrophic hormone)

Substance P

Opioids peptides

ATP

AMP

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32
Q

What is the unite for measuring neurotransmitter?

A

Quanta

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33
Q

What types of cells are pyramidal cells and what is their function?

A

Excitatory CNS Neurones
Located in:

Cerebellum (Cortex)

Hippocampus

Amygdala

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34
Q

What types of cells are purkinje cells and where are they located?

A

Inhibitory effect

Located in cerebellum (middle layer of cerebellum)

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35
Q

What two types of receptors are on the post synpatic neurone

A

Ionotropic ion receptors: Fast

Metabotropic ion receptors: Slow

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36
Q

What are the features of a ionotropic receptor?

A

Ligand gated channels

Fast transmision

Associated with glutamate/ GABA Neurotransmitters

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37
Q

What neurotransmitters are associated with ionotropic receptors?

A

Glutamate (Excitatory)

GABA (Inhibitory)

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38
Q

What neurotransmitters work on pentameric ligand gated channels?

A

GABA (Inhibitory)

Glycine (Inhibitory)

ACH (Excitatory)

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39
Q

What neurotransmitter works on tetrameric ionotropic receptors?

A

Glutamate (Excitatory)

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40
Q

What are the features of a metabotropic receptor?

A

Slow tranmission

Transmission through indirect gating

G protein coupled receptors (Release of GTP to activate respective ionotropic channel)

Function: Long term neuromodulation

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41
Q

What are the two types of ionotropic glutamate receptors?

A

(Classified according to response to N-Methyl- D- aspartate )

  1. AMPA / Non-NMDA Receptors
  2. NMDA receptors
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42
Q

What are the features of AMPA/Non-NMDA receptors?

A

Mediates fast excitatory synaptic transmission

Permeable to sodium and leads to depolarisation

They are impermeable to calcium

Tetramer receptor

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43
Q

What are the features of NMDA receptors?

A

Excitatory

Mediates long term neuromodulation(neuroplasticity)

Influx of Na+/Ca+

Efflux of K+

Inhibited by Mg+ ions

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44
Q

What is the function of metabotropic glutamate receptors?

A

Presynaptic inhibition

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45
Q

How do glutamate receptors work at the retina?

A

Glutamate receptors of the retina are important for the bipolar cells, in switching on and off

Inotropic glutamatereceptors switch on

Metoptropic glutmatereceptors switch off

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46
Q

What are the two major types of GABA receptors?

A

GABAa - Ionotropic receptor - influx of Cl- (Fast)

GABAb - Metabotropic receptor - K+ efflux (Slow)

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47
Q

How does BZD’s work?

A

Modulate GABAa receptor (inotropic GABA receptor)

Enhance Cl- entry, leading to hyper polarisation

Enhances inhibitionin the presence of GABA

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48
Q

How does Baclofen work?

A

Agonist of GABAb receptor (potassium channel agonist)

Enhances potassium efflux

Increases inhibition

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49
Q

What is a excitatory post-synaptic potential ?

A

A depolarising change in the resting membrane potential caused by excitation

Multiple EPSPS/Large EPSPS can cause the resting membrane potential to cross over threshold and result in an action potential

50
Q

What is an inhibitory postsynaptic potential?

A

Negative change in resting membrane potential causes by inhibitory action

Inhibits crossing of threshold and inhibits action potential

51
Q

What are the sensation modalities of the somatosensory system?

A

Exteroceptive - Cutaneous senses

Proprioceptive

Visceral sensation

Deep sensation (muscle fascia bone)

52
Q

How does mechanosensation work?

A

Greater the sensation, the greater the receptor potential is observed

Increased receptor potential elicits a greater frequency of action potentials

53
Q

What is neural adaption?

A

Adaption is a feature of primary sensory neurone that allows them to change the firing rate

54
Q

What are examples of slow adapting receptors?

A

Receptors that convey continuous information to the CNS e.g. Stretch receptors

55
Q

What are examples of rapidly adapting receptors?

A

Receptors that detect changes in stimulus strength

e.g. muscle spindle afferents

Hair follicle afferents

56
Q

What are examples of rapidly adapting receptors?

A

Pacinian capsules

57
Q

What are the four types of sensory neurones?

A

A alpha fibres

A beta fibres

Adelta fibres

C fibres

58
Q

What are the featrues of a A alpha fibre?

A

Thick fibres

Fast conducting

Purpose: Proprioception

59
Q

What are the features of A beta fibres?

A

Medium fibre

Mechanoreceptors of skin: (touch, pressure, vibration)

60
Q

What are the features of A delta fibres?

A

Thin

Purpose : Pain and temperature

Myelinated

61
Q

What are the features of a C fibre?

A

Thin unmyelinated fibres

Purpose: Pain and temperature

62
Q

What do meissner corpuscles detect?

A

Mechanosensation - light touch, stroking, flutter (vibration)

Rapidly adapting receptors

High frequencyin regions with a large two point discrimination

Not present in hairy skin

A beta fibres

63
Q

What do merkle cells detect?

A

Detect Pressure

Slow adapting receptors

Grouped in Iggo domes

High frequency in region with large two point discrimination

Present in hairy skin

A beta fibres used

64
Q

What do Krause end bulbs detect?

A

Receptors found at the border ofdry skin and mucous membrane

Detects cold

65
Q

What do ruffini endings detect?

A

Located within dermis and joint capsules

Detects warmth

66
Q

What do C mechanoreceptors detect?

A

Erotic touch

Stroking

67
Q

What is the dermatomal level of the shoulder?

A

C4

68
Q

What is the dermatomal level of the nipple?

A

T4

69
Q

What is the dermatomal level of the xiphisternum?

A

T6

70
Q

What is the dermatomal level of the umbilicus?

A

T 10

71
Q

What is the dermatomal level of the thumb?

A

C6

72
Q

What is the dermatomal level of the knee?

A

L4

73
Q

What is the dermatomal leve of the dorsum of the foot?

A

L5

74
Q

How is the grey matter organised?

A

Laminae of Rexxed

(10 raminae in total)

75
Q

Where do Nociceptors insert into the laminae of rexxed?

A

Laminae I and Laminae II

Used : A delta and C fibres

76
Q

Where do mechanoreceptors insert into the laminae of rexxed?

A

Laminae III - VI

Fibres A beta

77
Q

Where do proprioceptors insert into the laminae of rexxed?

A

Laminae VII - IX

78
Q

What happens to white matter as you move up the spinal cord?

A

White matter incrases as you move up

79
Q

What is the termination of the spinal cord called?

A

Connus medularis

80
Q

What holds the spinal cord in the subarachnoid space?

A

Denticulate ligament

Fillum terminale

81
Q

What is the blood supply of the spinal cord?

A

3 longitudinal vessels:

2 posterior arteris - supplies dorsal third

1 anterior artery - supplie ventral thid

Reinforced by segmental arteries ( e.g. the artery of adamkiewicz)

82
Q

Describe how the spinal cord is organised?

A
83
Q

What are the features of the dorsal collum medial lemniscus pathway?

A

Dorsal Columns

(fasiculus gracilus+ fasiculus cunetatus)

 Mode: fine touch, vibration and proprioception

 Cell body in dorsal root ganglion

 Decussation: in medulla forming medial lemniscus

84
Q

What are the functions of the fasiculus gascilis and the fasiculus cuneatus?

A

FG: carries sensory firbes of lower limbs

FC: carries sensory fibres of upper limb

85
Q

What are the features of the lateral spinaothalamic tract?

A

Lateral Spinothalamic Tract

 Mode: pain and temperature

 Cell body in dorsal root ganglion

 Decussation: in cord, at entry leve

86
Q

What are the features of the lateral corticospinal tract?

A

Lateral Corticospinal Tract

 Mode: motor (body)

 Cell body: Primary motor cortex

 Decussation: pyramidal decussation in ventral medulla

87
Q

What are the different types of thalamic nuclei?

A

 Ventro posterolateral - reciveves somatosensory body information

Ventro posteromedial - recieves somatosensory head information

 Lateral geniculate nucleus - recieves visual information

Medial geniculate nucleus - recieves auditory

88
Q

What is the function of the basal ganglia?

A

Regulation of posture, locomotion, coordination and movement

89
Q

How do the basal ganglia send output action potentials?

A

Via the thalamus –> cortex

90
Q

What is the functional of the internal capsule?

A

White matter carrying axonal fibres from motor cortex to pyramids of medulla.

91
Q

What is the function of the frontal lobe?

A

 Cognition and memory

 Executive function

 Motor cortex

 Dominant hemisphere: motor speech (Broca’s area)

92
Q

What is the function of the parietal lobe?

A

 Sensory cortex

 Body orientation

93
Q

What is the function of the temporal lobe?

A

 Memory

 Dom hemisphere: receptive language (Wernicke’s)

94
Q

What is the function of the occpital cortex?

A

Visual cortex

95
Q

Describe the route of the motor tracts?

A
  1. Pre central gyrus
  2. Internal capsule
  3. Cerebral peduncle (midbrain)
  4. Basis pontis (pons)
  5. Decussation at pyramids of medulla

6 . Spinal cord

96
Q

Describe the route of dorsal column?

A
  1. Dorsal column (FG or FC)
  2. Straight up cord to medulla
  3. Nucleus gracillus or nucleus cunteatus (medulla)
  4. Decussation at medulla via the medial lemniscus
  5. Medial lemniscus through pons
  6. Medial lemniscus through midbrain
  7. Ventro posteriolateral nucleus of thalmus
  8. Thalmus to post central gyrus

(S for sensory)

97
Q

Describe the route of the spinothalamic tract?

A
  1. Decussation immediately at cord entry level
  2. Entry into spinothalamic tract all the way to thalamus
  3. Synapse at ventro posterolateral nucleus of the thalamus
  4. VPL to post central gryus
98
Q

Describe the nuclei of the craial nerves at the brainstem?

A

 Midbrain: 3, 4, (5)

 Pons: 5, 6, 7, 8

 Medulla: (5), 9, 10, 11, 12

99
Q

What is the role of the mesencephalic nucleus of the trigmeninal nerve?

A

Proprioception of jaw

Motor to muscles of mastication (masseter, temporalis, ptyergoid)

100
Q

What is the role of the spinal nucleus of the trigeminal nerve?

A

Senosry input: deep/crude touch, pain, and temperature from the ipsilateral face.

101
Q

What is the function of the tactus solitarius?

A

Recieves stretch and chemoreceptor information from CVS and respiratory system

Taste sensation from: VII, IX, X

102
Q

What cranial nerve nuclei are in charge of salivation?

A

Cranial nerves: VII + IX

103
Q

What is the function of the nucleus ambiguus?

A

Motor nucleus

Stylopharyngeus via CN: IX

Muscles of the palate, pharynx, upper esophagus, and larynx via the vagus nerve (CN X)

104
Q

Describe transmission of the action potential at the neuromuscular junction?

A
  1. Presynaptic voltage-gated Ca2+ channels open → Ca2+ influx
  2. ACh vesicles released from presynaptic terminal
  3. ACh diffuses across cleft
  4. ACh binds to nicotinic receptors on post-synaptic terminal
  5. Na+ influx → depolarisation → Ca2+ release from SR → muscle contraction
  6. ACh is degraded by acetylcholinesterase and choline is taken up into presynaptic terminal.
105
Q

How may ACH action at the NMJ be blocked?

A

Blockade

1. Block presynaptic choline uptake: hemicholinium

2. Block ACh vesicle fusion: botulinum, Lambert eaton myasthenic syndrome (LEMS)

3. Block nicotinic ACh receptors

  • Non-depolarising: atracurium, vecuronium
  • Depolarising: suxamethonium
106
Q

What are the dopaminergic pathways?

A

 Mesocorticolimbic

 Nigrostriatal:

 Tuberoinfundibular:

107
Q

What dopamine pathway is affected in schizophrenia?

A

Mesocorticolimbic

108
Q

What dopamine pathway is affected in parkinsonism?

A

Nigrostriatal

109
Q

What dopaminergic pathway is affected in hyperprolactinaemia?

A

Tuberoinfundibular

110
Q

Describe the route of sympathetic neurones?

A

Cell bodies located in T1-L2

General visceral afferent synapse at:

 Paravertebral ganglia

 Prevertebral ganglia

 Chromaffin cells of adrenal medulla

111
Q

What is the NT in postganglionic and pregangionlic neurones in the sympathic nervous system?

A

Preganglionic neurones: NT = Ach, acts on nicotinic receptors

Postganglionic: NT= Noradrenaline, acts on adrenoergic receptors

Preganglionic neurones are myelinated

Postganglionic neurones are unmyelinated

112
Q

What cranial nerves are parasympathetic?

A

3

7

9

10

113
Q

What is the NT in preganglionic and postganglionic neurones in the parasympathetic nervous system?

A

Both ACh

114
Q

What are the parasympathetic ganglia and their function?

A

 Ciliary: ciliary muscle and sphincter pupillae

 Pterygopalatine: mucus mems of nose and palate, lacrimal gland

 Submandibular: submandibular and sublingual glands

 Otic: parotid gland

 Vagus supplies thoracic and abdo viscera

Sacral: pelvic splanchnic nerves (S2-4) innervate pelvic viscera

115
Q

Does cranial nerves innervate the ipsilateral or contralateral side?

A

All cranial nerves exceptor CN IV (Trochlear) innervate ipsilateral side

Trochlea deccusates at level of the pyramids in the medulla

116
Q

Describes the nerves invovled in the vestibulo-occular reflex?

A

Axons of the vestibular nerve project via the medial longitudinal fasiculus (MLF)

Reflex: Head turns L → eyes turn R

117
Q

How can the vestibulo-ccular nerve be tested?

A

Caloric Testing

Warm and cold water is irrigated into the external auditory meatus

Warm → ↑ firing of vestibular N. → eyes turn to contralateral side c¯ nystagmus to ipsilateral side

Remember fast direction of nystagmus – COWS

 Cold: Opposite  Warm: Same

Absence of eye movements = brainstem damage on side being tested

118
Q

Describe visual field defects caused by lesions affecting the optic nerve?

A

Optic nerve: Complete blindness in eye

Optic chiasm: Bitemporal hemianopia

Optic tract: Homonymous hemianopia

Lower optic radiation: upper quadrantanopia

Upper optic radiaiton: Lower quadrantanopia

Occipital cortex: Hemianopia with macula sparing

119
Q

Describe the pupillary light reflex?

A

Affect: Sensory part of optic nerve

Efferent: Oculomotor nerve

Occulomotor will also cause vasoconstrction due to Edinger - Westphall nucleus)

120
Q
A

MBChB 4 (9 decks)

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