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Y3 NEUROLOGY > Hormuzdi Physiology > Flashcards

Hormuzdi Physiology Flashcards

1
Q

Which ions have an excitatory effect (depolarizing) on a cell when they influx?

A

Na+
Ca+
(increase positive charge)

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2
Q

Which ion has an inhibitory effect (hyperpolarizing) on a cell with influx?

A

Cl-

increase negative charge

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3
Q

Which ion has an inhibitory effect (hyperpolarizing) on a cell with efflux?

A

K+

increase negative charge

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4
Q

What would be the effect of an Na channel antagonist on neurotransmission? Give an example of a drug that works like this

A

Closes Na channel, stops Na influx, hyperpolarizing (inhibitory) effect, cell relaxes
e.g. lidocaine in anaesthesia

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5
Q

Influx of which ion, in response to depolarization, causes exocytosis of neurotransmitter at the synaptic cleft?

A

Ca

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6
Q

What are the 2 main types of receptor neurotransmitter can act on in the postsynaptic cell?

A 
Ionotropic receptor (direct)
Metabotropic receptor (indirect)
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7
Q

What is the structural/mechanical differences between ionotropic and metabotropic receptors?

A 
Ionotropic = channel molecule 
Metabotropic = signalling molecule
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8
Q

The action of a metabotropic receptor is sufficient to illicit an action potential. True/False?

A

False

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9
Q

Which receptor does ACh act on in autonomic ganglia - ionotropic or metabotropic?

A

Both!

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10
Q

ACh acting on ionotropic receptors illicits a fast/slow epsp

What type of channels are associated with it?

A

ACh acting on ionotropic receptors illicits a fast epsp

Na+ and K+ channels

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11
Q

ACh acting on metabotropic receptors illicits a fast/slow epsp
What type of channels are associated with it?

A

ACh acting on metabotropic receptors illicits a slow epsp

K+ channel

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12
Q

Out of ACh, GABA, glycine and glutamine, which are excitatory and which are inhibitory neurotransmitters?

A

Excitatory: ACh, glutamine
Inhibitory: GABA, glycine

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13
Q

GABAa is the ionotropic/metabotropic receptor and GABAb is the ionotropic/metabotropic receptor

A

GABAa is the ionotropic receptor and GABAb is the metabotropic receptor

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14
Q

How do benzodiazepines and barbiturates work in terms of GABA inhibition?

A

Positively modulate GABAa receptor to enhance GABA neuro-inhibition

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15
Q

What is the normal frequency range for sound that humans can hear?

A

20-20,000 Hz

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16
Q

Which ossicle converts rhythmic sound energy to mechanical energy in the middle ear?

A

Stapes at oval window

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17
Q

What is impedance matching of sound?

A

Ossicles overcome loss of sound pressure caused by fluid by amplifying stimulus by 30dB

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18
Q

What are the 3 fluid-filled cavities of the cochlea?

A

Scala vestibuli, tympani and media

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19
Q

Which membrane separates the scala vestibuli and media?

A

Reissner’s membrane

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20
Q

Which membrane separates the scala media and tympani?

A

Basilar membrane

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21
Q

Which fluid - endolymph or perilymph - is present in the scala media?

A

Endolymph

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22
Q

Which fluid - endolymph or perilymph - is present in the scala vestibuli?

A

Perilymph

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23
Q

Which fluid - endolymph or perilymph - is present in the scala tympani?

A

Perilymph

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24
Q

The basilar membrane is flexible and vibrates with fluid motion. Which end of the membrane is wider and how does this relate to pitch?

A

Wide at apex of cochlea, narrow at base

High pitch/frequency received at base

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25
Q

Stereocilia transduction is caused by K efflux. True/False?

A

False!

K influx causes depolarisation in this case

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26
Q

The auditory system has two types of hair cell - describe their function

A

Inner hair cells perceive sound (CN VIII)

Outer hair cells regulate sound (superior olivary complex)

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27
Q

What are the two methods by which the auditory nerve codes frequency of sound?

A 
Place code (area of basilar membrane)
Temporal code (no. of action potential peaks)
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28
Q

Which vestibular structures aid head rotation?

A

Semicircular canals

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29
Q

Which vestibular structures aid translational (linear) head movement?

A

Utricle
Saccule
(otolith organs)

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30
Q

What displaces hair cells in the vestibular labyrinth?

A

Acceleration/gravity

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31
Q

List the 3 main vestibular reflexes

A

Vestibulo-ocular reflex (keep eyes still in space when head moves)
Vestibulo-colic reflex (keeps head still in space)
Vestibulo-spinal reflex (adjusts posture for rapid changes in position)

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32
Q

At rest, photoreceptors are depolarised. True/False?

A

True

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33
Q

What causes depolarisation in photoreceptors?

A

Dark current at rest involving Na influx through cGMP channel

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34
Q

What causes hyperpolarisation in photoreceptors?

A

Light causes less Na influx so Vm is closer to Ek which causes K efflux

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35
Q

Which cells - ganglion, bipolar or photoreceptors - generate action potentials?

A

Ganglion cells

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36
Q

What are the two possible end routes for neurotransmitters?

A

Return to terminal fro reuse

Pass onto glial cells

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37
Q

What technique do metabotropic receptors have to use to help stimulate the release of neurotransmitters?

A

Modulatory synaptic actions

38
Q

What types of ionotropic receptors exist in glutamate?

A

NON-NMDA: permeable to Na, K

NMDA: permeable to Na, K, Ca

39
Q

What part of glutamate reception is targeted by anaestheisa?

A

NMDA receptor, focusing on Ca influx

40
Q

The GABAa inotropic receptor is associated with what type of ion channel?

A

Cl- channel

41
Q

The GABAb metabotropic receptor is associated with what type of ion channel?

A

K+ channel

42
Q

Baclofen targets what receptor used by GABA neurotransmitters?

A

GABAb receptor

43
Q

What type of receptor and channel does glycine act on?

A

Ionotropic receptor

Cl channel

44
Q

What is an epsp. and ipsp.?

A 
Excitatory postsynaptic potential (depolarizing rmp) and creates an AP if threshold is reached
Inhibitory PSP (hyperpolarizing rmp) which inhibits APs
45
Q

What is meant by ‘interneurone’?

A

Locally acting neurone that releases neurotransmitter (typically GABA, glycine) to cause an ipsp.

46
Q

What is meant by ‘projection neurone’?

A

Convey signals to other parts of brain, usually glutamate to cause an epsp.

47
Q

An excitatory neurone releases a depolarising/ hyperpolarising neurotransmitter e.g. glutamate/ GABA

A

Depolarising

Glutamate

48
Q

An inhibitory neurone releases a depolarising/ hyperpolarising neurotransmitter e.g. glutamate/ GABA

A

Hyperpolarising

GABA

49
Q

Neurotransmitters are released in single vesicles called…

A

Quanta

50
Q

What is meant by the term ‘synaptic integration’?

A

Summation of psp allows multiple synaptic inputs to be integrated

51
Q

What is the difference between spatial and temporal summation?

A

SPATIAL: summation of epsps and ipsps are spatially distributed but timed together
TEMPORAL: epsps occur in temporal sequence such that the threshold is triggered

52
Q

Which neurotransmitter is involved in regulating the responsive cation entry of ions by hair cells?

A

Glutamate - excitatory signal

53
Q

The otilith organs are involved in what type of movement?

A

Tilt and acceleration

54
Q

How are sound vibrations transmitted to the auditory cortex?

A 
Vibrates eardrum and otilith organs
Spreads to cochlea
Vibration of air converted to fluid
Captured by hair cells
Transduction (conversion to neural energy)
---> Auditory cortex
55
Q

What are the three mechanisms which cause amplification in the middle ear?

A

Area ration of ear drum to stapes
Lever action of ossicles
Buckling of ear drum

56
Q

Where do scala vestibuli and scala tympani connect?

A

At helicotremia

57
Q

Which protein in outer hair cells can change the length of the cell, and increase transduction?

A

Prestin

58
Q

Outline the central auditory pathway

A 
(Right and left cochlear impulses cros)
Eighth CN
Cochlear nucleus
Superior olivary nuclei
Lateral lemniscus
Inferior colliculus
(MGN ---> auditory cortex)
59
Q

What are the three cochlear nuclei, branches of CNVIII?

A

Dorsal cochlear nucleus
Posteroventral cochlear nucleus
Anteroventral cochlear nucleus

60
Q

Where does locating sound occur?

A

Medial and lateral olive

61
Q

What type of fluid is contained within SCC?

A

Endolymph

62
Q

How many SCC are there?

A

3 push-pull pairs of fluid-filled canals (right angles to each other)

63
Q

Hair cells in the macula are divided by _____ into two populations with opposing polarities
What is it’s function?

A

Striola

Allow all organs to have multidirectional sensitivity

64
Q

What type of crystals respond to tilt and are on the otilithic membrane?

A

CaCO3

65
Q

Give examples of agents that can be ‘ototoxic’ and contribute to vestibular system dysfunction

A

Aminoglycoside antibiotics
Chemo agents
Alcohol

66
Q

List the stages of the direct pathway for signal transmission in the retina. Is this the same as light?

A 
Photoreceptors
----> Horizontal cells
Bipolar cells
----> Amacrine cells
Ganglion cells
CNII (ganglion cell axons)

Light travels in opposite direction: ganglion cells, bipolar cells, photoreceptors

67
Q

What chemical is composed of opsin and 11-cis retinal? What is the activated form of 11-cis retinal?

A

Rhodopsin

Trans-retinol

68
Q

Rod cells have less acuity than cone cells. True/ False? Why?

A

True
Used in dim light, cells have increased convergence and therefore increased sensitivity and reduced acuity. The opposite is true in cones.

69
Q

Ionotropic bipolar cells respond negatively to glutamate. True/ False?

A

False

Metabotropic bipolar cells respond negatively, and ionotropic respond positively.

70
Q

What is the role of lateral inhibition in vision?

A

Exaggerates the difference in stimulus intensity detected by adjacent neurones, via inhibitory interneurones, and aids with localization

71
Q

What type of retinal cells interconnect a group of surround neurones?

A

Horizontal cells

72
Q

An on-center cell is stimulated when the center of its receptive field is exposed to light/dark, and is inhibited when the ______ is exposed to light/dark. Off-center cells have just the opposite reaction.

A

Light
Surround
Light

73
Q

Which neurotransmitter is involved in inhibiting on and off-centre cells? What does this do?

A

GABA

Increase the response of the centre on bipolar cells

74
Q

What is the function of central surround organization?

A

Sharpens boundary between objects of different luminance

75
Q

Which process is important in modifying receptive fields of ganglion cells to have a centre surround organisation?

A

Lateral inhibition

76
Q

List the three types of retinal ganglion cells which give information about different receptive fields.

A

M (movement)
P (form and colour)
Non M and P (colour)

77
Q

What type of ganglion cells is involved in giving information about light and dark?

A

On and off centre ganglion cells

78
Q

What type of ganglion cell is involved in giving information about colour?

A

Opponent ganglion cells

79
Q

What type of hemiretina - nasal or temporal - crosses at chiasm to form optic tracts?

A

Nasal

80
Q

Which part of the retina occupies the largest area of the visual cortex?

A

Centre of retina - the FOVEA

81
Q

An injury to CNII in the visual pathway would cause what visual defect?

A

Monocular blindness

82
Q

An injury to the optic chiasm in the visual pathway would cause what visual defect?

A

Bitemporal haemanopia

83
Q

An injury to the optic tract in the visual pathway would cause what visual defect?

A

Contralateral haemanopia

84
Q

An injury to the optic radiation in the visual pathway would cause what visual defect?

A

Quadrantic haemanopia

85
Q

An injury to the striate cortex in the visual pathway would cause what visual defect?

A

Foveal sparing

86
Q

What layer are the first binocular neurones found in in the striate cortex?

A

Layer 3

87
Q

What is the purpose of the ocular dominance columns?

A

Neurones coming from the eye only act on a particular area of cortex on contralateral side

88
Q

The peak frequency of the cortical receptive fields of the striate cortex depends on…

A

The particular orientation

89
Q

What is the ‘competition hypothesis’?

A

Connection from two eyes compete in cortex and affect the ocular dominance columns

90
Q

What is the effect of monocular deprivation during development?

A

Active afferents in one eye remain and reduce in the other which affects the structure of the cerebral cortex

Y3 NEUROLOGY (22 decks)

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