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Satia's MRCS copied decks > Neuro Physiology > Flashcards

Neuro Physiology Flashcards

1
Q

Autoregulation of CBF

A

Myogenic
Local
Neural

Costant between CPP of 60- 160 mmHg

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2
Q

Hyperbaric oxygen and cerebral blood flow

A

Although PaO2 has a far lesser effect on CBF vs PCO2

Hyperbaric oxygen can reduce cerebral blood flow by ~20%

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3
Q

Total volume CSF

A

130 -150 ml

100ml spinal cord
40ml in ventricles

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4
Q

Normal CSF pressure

A

0.5-1 kPa

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5
Q

Production of CSF

A

Choroid plexus in lateral, third and fourth ventricles

L, 3rd and 4th

~500ml / day

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6
Q

Foramin of Luschka

A

Lateral

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7
Q

Foramin of Magendie

A

Medial

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8
Q

Areas in which blood-brian barrier is permeable - fenestrated endothelium

A

Third and fourth ventricles
-Chemoreceptor trigger zone at floor of fourth ventricle
-Angiotensin II passes to the vasomotor centre in this region to increase sympathetic outflow and causes vasoconstriction of peripheral vessels

Posterior pituitary
-Allows production of ADH and oxytocin into circulation

Hypothalamus
-this allows the release of releasing or inhibitory hormones into the portal– hypophyseal tract (to anterior pituitary)

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9
Q

Consequences of rising ICP

A

Hydrocephalus
-Seen in posterior fossa lesions due to ocmpression of aqueduct

Ischaemia
-Rising ICP reduces CPP and therefore CBF

Herniation
-Compression of brain via herniation

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10
Q

Pupilly dilatation and raised ICP

A

–> oculomotor nerve compression

= Transtentorial herniation

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11
Q

Cortical blindess and raised ICP

A

= Transtentorial herniation

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12
Q

Resting membrane potential of axon

A

negative 70mV

-70mV

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13
Q

Depolarisation

A

Axon membrane potential goes form -70 –> +50mV

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14
Q

Absolute and relative refractory

A

During action potential = absolute refraction

During repolarisation = relative refraction, larger stimulus can cause another action potential

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15
Q

Mechanism of depolarisation and repolarisation

A

The Na+ channel activates much faster than the K+
channel.

This explains the rapid influx of Na+; the
channel also closes much faster; the K+ channel
remains open over a longer period than the Na+
channel and is responsible for repolarisation as K+
is released and the membrane potential falls back
to its negative value

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16
Q

Nodes of Ranvier

A

Gaps in between myelinated axons

Points of depolarisation

Increases speed of transmission as between nodes the axon depolarises quickly and entriely

= saltatory conduction

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17
Q

Aα axons

A

Motor

Propioception

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18
Q

Aβ axons

A

Touch

Pressure

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19
Q

Aγ axons

A

Muscle spindles

20
Q

Aδ axons

A

Pain

(myelinated version of pain fibres)

21
Q

C-fbres axons

A

Unmyelinated pain neurons

22
Q

B axons

23
Q

Breakdown of amine neurotransmitters

A

Monoamine oxidase: breaks down neurotransmitter taken up at PRE-synaptic neuron

Catechol-O-methyl transferase breaks down catecholamine in post-synaptic neuron

24
Q

Glutamate + Aspartate

A

Excitatory

25
Glycerol
Inhibitory
26
Substance P
Pain transmission
27
Kehr’s sign
Referred pain Left-sided diaphragmatic irritation and left shoulder tip pain
28
Gate control theory Modulation of pain
Descending Periaqueductal grey matter and raphe magnus --> releasing serotonin Locus coeruleus --> noradrenaline Local Naturally occurring enkephalins and endorphins at point of tansmission synpase in spinal cord
29
Proteins on actin filament
Actin: double strand helix Tropomyosin: lies in groove between double-stranded helix of actin Troponin: regular arrangement along actin filament -Attached ot both actin nad tropomysin -Has binding sites for Ca2+ and is involved in the regulation of contraction. -Troponin and tropomyosin block the myosin-binding site on actin. Rise in calcium allows removal and binding of myosin
30
Proteins on mysosin
Head section has binding site for ATP --> allows release of head from actin filament Structure: had + long tail
31
Troponin
-Attached to both actin and tropomyosin -Has binding sites for Ca2+ and is involved in the regulation of contraction. -Troponin and tropomyosin block the myosin-binding site on actin. Rise in calcium allows removal and binding of myosin
32
Tropomyosin
Tropomyosin: lies in groove between double-stranded helix of actin Rise in calcium allows removal and binding of myosin
33
Type I muscle fibre
Slow / postural
34
Type IIa muscle fibre
Type IIa or fast oxidative fibres e.g. calf muscles They rely on aerobic metabolism and contain myoglobin; they have moderate resistance to fatigue
35
Type IIb muscle fibre
Type IIb or fast glycolytic fibres e.g. extraocular muscle Do not contain myoglobin and thus appear white They contain a large amount of glycogen and rely on anaerobic metabolism.
36
Intrafusal muscle fibres
Respond to stretch "stretch sensory" receptor for stretch-contraction reflex arc
37
Precentral gyrus
Motor cortex Frontal lobe immediately anterior to central sulcus
38
Corticobulbar tracts
Motor supply to cranial nerve
39
Corticospinal tracts
Supply spinal motor neurons --> voluntary movement
40
Four descending motor inputs from brainstem
Rubrospinal tract: red nucleus Tectospinal tract: superior colliculus of midbrain Vestibulospinal tract: bestibular nuclei Reticulospinal tracts: pons and medulla
41
Rubrospinal tract
Descending motor input from the brainstem - Red nucleus -Primarily innervates distal limb muscles
42
Tectospinal tract
Descnding motor input from brianstem -Superior colliculus of midbrain -Receives inputs from the visual cortex a -Controls reflex activity in response to visual stimuli
43
Vestibulospinal tract
Descending motor input form brainstem -Vestibular nuclei -Supplies muscles of the ipsilateral side of the body. -Innervates muscles concerned with balance and posture in response to inputs from the vestibular apparatus
44
Reticulospinal tract
Desnding motor input form brainstem -Arises from pons and medulla -Supply muscles on the ipsilateral side of the body and are important in maintaining posture and muscle tone
45
Cerebellum
No descending tracts Modulation of motor coordination directly into motor cortex in precentral gyrus Receives information from: -Vestibular apparatus -Visual system -Corticospinal tracts -Peripheral proprioceptors

Satia's MRCS copied decks (32 decks)

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