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CAPS 301 T1 > Neurophysiology Facts > Flashcards

Neurophysiology Facts Flashcards

1
Q

Location of hair cells in vestibular apparatus

A

On cupulla (ridge in ampulla - widening at end of loops), with base anchored to bone beneath; in cochlea (hearing), utricle, saccule

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3
Q

parasympathetic system pre- and post-ganglionic nerve length

A

preganglionic: long postganglionic: short (synapse at terminal ganglion, which may be in target organ)

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3
Q

2 requirements for an excitable cell

A

selectively permeable membrane, differential charged ion distribution

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4
Q

E_Na+

A

+60mV, goes down concentration gradient (towards inside), down electric gradient from K+ (towards inside)

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4
Q

soma location: PNS sensory neurons

A

dorsal root ganglion (just outside spinal cord)

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4
Q

Mechanism: mechanoreceptors

A

open stretch-sensitive ion channels

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5
Q

[Na+] inside cell at rest

A

15mM

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6
Q

Factor(s) contributing to membrane resistivity to electrotonic propagation

A

Number of leak channels in membrane, amount of myelin

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6
Q

Which spinal nerve does NOT carry both sensory & motor neurons?

A

C1 (uppermost; cervical 1) - only motor

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7
Q

Why is RMP closer to E_K than E_Na?

A

More potassium leak channels -> higher permeability of K+ (permeability 1:50 Na+:K+ at rest)

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7
Q

Use & meaning of I, II, III, IV classification system

A

SENSORY neuron type - based on fiber diameter I > II > III > IV

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8
Q

Semi-circular canal function

A

detect head rotation/angular acceleration of head

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8
Q

Where do hair cells in the vestibular apparatus project into?

A

Endolymph (fluid inside membrane)

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9
Q

parasympathetic neuron origin in spinal cord

A

cranial nerves and sacral region (top & bottom)

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10
Q

neuromuscular junction neurotransmitter

A

Acetylcholine

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11
Q

What is special about the fluid in the utricle & saccule vs. vestibular apparatus?

A

Topped by otolith - layer with density (and inertia) increased by CaCO3 crystals

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12
Q

State of membrane ion channel gates in stage 1 (resting) of AP propagation

A

Na+ activation: closed Na+ inactivation: open K+ activation: closed

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12
Q

reason for absolute refractory period

A

most Na+ channels have inactivation gate closed, so they are unavailable -> can’t get to threshold no matter how big the stimulus

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13
Q

What sends signals to the Medial vestibular nucleus, and where do they go from there?

A

utricle & saccule; passed on to trunk & neck for posture correction

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14
Q

type of signal propagation at nodes of Ranvier

A

active, via voltage-gated ion channels; SLOW (high membrane capacitance)

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16
Q

[K+] inside cell at rest

A

150mM

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17
Q

Threshold to open voltage-gated ion channels

A

-40mV

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17
Q

CNS excitatory neurotransmitter & receptors

A

Glutamate AMPA receptor: g_Na=g_K -> V=0mV NMDA receptor: uses Na+, K+, Ca++ (long-term changes)

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18
Q

Use & meaning of ABC classification system

A

neuron type - based on conduction velocity A(alpha>beta>gamma>delta)>B>C considers myelination, neuron diameter e.g. alpha motor neuron

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20
Q

[Na+] outside cell at rest

A

150mM

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21
Q

State of membrane ion channel gates in stage 5 (recovery from inactivation) of AP propagation

A

Na+ activation: closed Na+ inactivation: open(ing) K+ activation: closed

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21
Q

Benefits of post-synaptic membrane organization in NMJ

A
  • ACh receptors very close to ion channels -> EPP doesn’t have to travel far - lots of Na+ channels ensures V_m reaches threshold - reliable & safe
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22
Q

Are hair cells aligned in the utricle & saccule?

A

no; go all directions

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23
Q

Mechanism: nociceptors, chemoreceptors, photoreceptors

A

G-protein coupled, indirectly open channels

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24
Q

[K+] outside cell at rest

A

5mM

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24
Q

sympathetic neuron origin in spinal cord

A

thoracolumbar region (middle)

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24
Q

Generator Potential: refractory period? graded/all-or-nothing? passive/active propagation?

A

no, graded, passive

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26
Q

Describe +ve feedback in depolarization

A

Initial depolarization increases V_m -> opens some Na+ channels -> further depol -> open more Na+ channels -> … -> all Na+ channels open

27
Q

Are hair cells aligned on the cupulla?

A

yes

28
Q

directions sensed by saccule

A

position/movement relative to gravity: front/back, up/down

29
Q

How is RMP established?

A

RMP: resting membrane potential -Na+/K+ ATPase constitutively moves ions to maintain supply -leak channels change permeability to establish RMP

31
Q

State of membrane ion channel gates in stage 4 (AHP - After HyperPolarization) of AP propagation

A

Na+ activation: closed Na+ inactivation: closed K+ activation: open (closing slowly)

32
Q

Formula for (electrotonic) length constant

A

lambda = sqrt(R_m/R_a), R_m = membrane resistivity, R_a = axial resistivity

33
Q

Why is active propagation effective/efficient?

A

-Don’t have to depolarize entire membrane -Depolarization of one segment causes electrotonic propagation, depolarizing segment further down enough to reach threshold -Individual ions don’t have to travel the length of the axon

34
Q

Where do signals from the vestibular apparatus go?

A

Vestibular nuclei, in brain stem

35
Q

What sends signals to the Inferior vestibular nucleus, and where do they go from there?

A

all parts of vestibular apparatus; passed on to cerebellum for movement coordination

36
Q

Structure of pre-synaptic membrane in NMJ

A
  • vesicles of neurotransmitter (ACh) in rows (active zone); transported from soma - vesicle movement controlled by Ca++ & snare proteins
37
Q

Structure on hair cells used to generate signal, and mechanism

A

kinocilium -pushed by linked stereocilia (smaller so sway easier, together move stiffer kinocilium) -opens/closes Na+/K+ gated ion channels -ion diffusion to bottom of cell opens/closes V-gated Ca++ channels -incr/decr glutamate release on Cranial Nerve VIII

37
Q

What sends signals to the Superior vestibular nucleus, and where do they go from there?

A

canals of the vestibular apparatus; passed on to MLF (medial longitudinal fasciculus for eye movement coordination)

38
Q

accessory myelin cells

A

Peripheral Nervous System: Schmann cells Central Nervous System: oligodendrocytes

40
Q

How do graded (generator & other) potentials create an action potential?

A

Temporal or spatial summation

41
Q

nerves used for special senses

A

cranial nerves

42
Q

sympathetic system pre- and post-ganglionic nerve length

A

preganglionic: short postganglionic: long (synapse in ganglion just outside spinal cord)

42
Q

State of membrane ion channel gates in stage 3 (falling) of AP propagation

A

Na+ activation: open Na+ inactivation: closed -> Na+ UNAVAILABLE K+ activation: open

43
Q

steps of synaptic transmission

A
  1. Na+ AP reaches terminal button 2. depolarization opens V-gated Ca++ channels -> Ca++ influx stimulates vesicle mov’t to membrane 3. exocytosis of neurotransmitter 4. NT diffuses across synaptic cleft & binds receptors 5. Opens ligand-gated ion channels on post-synaptic membrane, changing V_m (PSP); PSP attenuates via electrotonus to soma (ONLY place AP can start)
45
Q

Structure of post-synaptic membrane in NMJ

A
  • folded to increase surface area - ACh receptors on top of folds (close to where ACh is released) - Na+ channels (V-gated) in bottoms of folds (perijunctional zones) - ACh esterase held near here for ACh breakdown (accurate control)
46
Q

Gate(s) on Na+, K+ channels

A

Na+: activation, inactivation K+: activation only

47
Q

autonomic system neurotransmitter (between neurons)

A

Acetylcholine

48
Q

Factor(s) contributing to axial resistivity to electrotonic propagation

A

Diameter of axon

50
Q

systems that exert control over autonomic nervous system

A

spinal cord, medulla, hypothalamus, prefrontal cortex

51
Q

Relation between signal strength from vestibular apparatuses on opposite sides of head

A

one increases while the other decreases, since the fluid goes the same way but the hairs are oppositely oriented (“forward” hair movement gives same change in signal, but one side moves forward & other back)

52
Q

afferents of autonomic nervous system detect…

A

pressure, osmolarity, temperature, sexual stimuli, pain & stretch in viscera

53
Q

State of membrane ion channel gates in stage 2 (rising) of AP propagation

A

Na+ activation: open Na+ inactivation: open K+ activation: closed (opening v. slowly)

54
Q

Type of receptors & neurons used to sense pain & temperature

A

free nerve endings in skin, unmyelinated neurons (slow)

55
Q

CNS inhibitory neurotransmitter & receptors & effect

A

GABA GABA_A receptors: increase Cl- permeability; E_Cl = -70mV (voltage clamp) GABA_B receptors: increase K+ permeability; E_K = -90mV (hyperpolarization) -prevents unwanted motion

58
Q

reason for relative refractory period

A

some Na+ channels still inactivated (unavailable), but enough available that a large stimulus (depolarization) can open enough of them to get to threshold

59
Q

Shape & location of vestibular apparatus

A

labyrinth of (3) membrane-lined loops in temporal bone, connected to cranial nerve VIII

60
Q

location of AP (after sensor) in myelinated sensory neurons

A

1st node of Ranvier, NOT the soma

61
Q

Mechanism of phasic mechanoreceptors

A

Pacinian corpuscule (accessory; layered & fluid-filled) wrapped around sensory nerve ending; on first pressure, puts pressure on sensory nerve (signal) b/c fluid incompressible, but fluid quickly moves away, releasing pressure (stops firing)

63
Q

Requirement for sensory neuron to generate AP

A

generator potential reaches threshold

64
Q

Into which structure do the loops of the vestibular apparatus open?

A

Utricle, then saccule (chambers)

65
Q

role of sensors

A

signal transduction (stimulus to AP)

67
Q

E_K+

A

-90mV, concentration gradient (towards outside) balances with charge gradient (towards inside)

68
Q

steps of signal transmission through NMJ

A
  1. Na+ AP reaches terminal button 2. depolarization opens V-gated Ca++ channels -> Ca++ influx stimulates vesicle mov’t to membrane 3. exocytosis of ACh into synaptic cleft 4. ACh diffuses across cleft to ACh receptors 5. opens ligand-gated ion channels on motor end plate, depolarizing muscle (EPP); ACh esterase degrades ACh in synaptic cleft
69
Q

State of membrane ion channels at rest

A

available

70
Q

Acetylcholine esterase function

A

removes Acetylcholine from NMJ to stop signal

71
Q

soma location: PNS motor neurons

A

CNS (spinal cord)

72
Q

type of signal propagation beneath myelin layer

A

electrotonus (passive, FAST (low membrane capacitance))

73
Q

Info from hair cells in utricle

A

head position with respect to gravity, linear side-to-side and front-to-back head movement

74
Q

What sends signals to the Lateral vestibular nucleus, and where do they go from there?

A

utricle & saccule; passed on to limbs for posture correction

75
Q

nerves used for general senses

A

SOMATIC: cranial V, spinal nerves except C1

76
Q

Direction of graded potential movement

A

bi-directional (both ways along membrane)

78
Q

of axon terminals per muscle fiber & result

A

1; must be reliable

79
Q

What coordinates eye movement with head movement?

A

Vestibulo-ocular reflex (CVIII - audiovestibular, CIII - oculomotor (medial), CVI - abducens (lateral))

80
Q

directions sensed by utricle

A

position/movement relative to gravity: front/back, left/right

CAPS 301 T1 (10 decks)

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