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PLE Physiology > Neurophysiology > Flashcards

Neurophysiology Flashcards

1
Q

Free nerve endings contain receptors for what sensations?

A

Pain, temperature, crude touch

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2
Q

Anomic aphasia is usually caused by damage to which area of the brain?

A

Angular Gyrus

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3
Q

Nonfluent aphasia such as in Pick’s Disease is caused by a lesion in which brain area?

A

Broca’s area

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4
Q

Fluent aphasia is caused by a lesion in which brain area?

A

Wernicke’s Area

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5
Q

Memory loss can be a result of a lesion in which brain area?

A

Hippocampus

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6
Q

Concentration of glucose and protein in CSF is higher, lower, or same as plasma

A

Lower (both glucose and protein)

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7
Q

Part of the cerebellum connected to the vestibular nuclei, and is associated with central vertigo

A

Flocculonodular Lobe

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8
Q

What frequencies of sound produce vibration of the basilar membrane at the base of the cochlea (near oval and round window)

A

High frequency

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9
Q

What frequencies of sound produce vibration of the basilar membrane at the apex of the cochlea (near helicotrema)

A

Low frequency

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10
Q

What percentage of the human genome is involved in the formation and function of the nervous system?

A

40%

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11
Q

Electrical vs chemical synapse

A

Electrical - by gap junctions, two way

Chemical - neurotransmitter and receptor at synapse, one way only

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12
Q

Two internal structures in the presynaptic terminal and their function

A

Transmitter vesicles - contain neurotransmitter

mitochondria - provide ATP for neurotransmitter generation

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13
Q

Events that lead to neurotransmitter release from presynaptic terminals

A
  1. Action potential depolarizess presynaptic terminal
  2. Voltage Gated Calcium channel opens,making calcium enter terminal
  3. Calcium causes release of neurotransmitters from vessels by binding to release sites
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14
Q

Two actions of neurotransmitter in the postsynaptic neuron

A
  1. Gating Ion Channels

2. Activating second messengers

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15
Q

Logic behind ion channels

Differentiate cation channel and anion channel

A

Neurotransmitter opens ion channel, (diameter large enough for ions to pass) closes when substance is no longer present

Cation channels are lined with negative charge, which attracts + carge sodium, potassum etc,

Anion channels are lined with positive charge, attracting negative charge (chloride, etc)

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16
Q

Ion channels provide rapid or prolonged neuronal control?

A

Rapid

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17
Q

Second messengers provide rapid or prolonged control

A

Prolonged

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18
Q

Components of the inactive G protein

A

GDP, alpha beta and gamma component

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19
Q

Which component of the G protein is the activator

A

Alpha

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20
Q

Mechanism of acivation of G protein

A
  1. Neurotransmitter activates receptor
  2. Conformational change exposes G protein binding site
  3. G protein binds
  4. Alpha subunit releases GDP and binds GTP
  5. A-GTP complex dissociates from beta and gamma
  6. A-GTP performs its function
  7. GTP is hydrolyzed to GDP, releasing it from target protein and binding it back to B and Y
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21
Q

Role of sodium, potassium, and chloride channels in postsynaptic membrane

A

Sodium channels allow Na entry to postsynaptic cell, increasing membrane potential - excitation

Potassium channels allow exit of K on postsynaptic cell, decreasing membrane potential - inhibition

Chloride channels allow chloride entry into the cell, decreasing membrane potential - inhibition

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22
Q

Rapidly acting neurotransmitters vs neuropeptide

A

Rapidly acting is small, vesicles reusable

Neuropeptides are large and long acting, vesicles unreusable, autolyzed after release

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23
Q

Mechanism of recycling of vesicles in presynaptic cells

A
  1. Vesicle fuses with membrane to release neurotransmitter
  2. Vesicle invaginates back to the terminal, forming new vesicle
  3. New vesicle synthesizes new transmitters
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24
Q

Enzyme responsible for synthesizing acetylcholine

A

Choline acetyltransferase

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25
Q

Components of acetylcholine

A

AcetylCoA + choline

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26
Q

Enzyme which splits acetylcholine in the synaptic cleft

A

Cholinesterase

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27
Q

What happens to choline at the synaptic cleft

A

Actively transported back to presynaptic terminal to be used for synthesis of new acetylcholine

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28
Q

Which of the ff are inhibitory, excitatory, or both?

Acetylcholine, Norepinephrine, Dopamine, Glycine, GABA,Glutamate, Serotonin

A

Inhibitory - dopamine, glycine, gaba, serotonin (pain and higher cortex)

Excitatory - glutamate

Both - acetylcholine (excitatory except in vagus), norepinephrine,

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29
Q

Neurotransmitter not stored in vesicles in the presynaptic terminal and freely diffuses from presynaptic to postsynaptic cell

A

Nitric oxide

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30
Q

Mechasnism of neuropeptide release

A

Synthesis in ribosome, transport to ER and Golgi,packaged into transmitter vesicle, action potential releases transmitter and autolyzes vesicles

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31
Q

What is excitatory post synaptic potential and inhibnitory post synaptic potential and principle behind it

A

increase or decrease in resting membrane potential after synaptic excitation

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32
Q

What is the principle of summation in excitation of neurons

A

Sucessive excitation of synapses increase EPSP to the threshold potential, thus eliciting action potential in the postsynaptic neuron

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33
Q

In which part of the postsynaptic neuron is action potential first generated

A

Beggining part of axon (higher concentration of sodium channels than soma)

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34
Q

Neurotransmitter involved in presynaptic inhibition and mechanism

A

GABA - opens anion channels, causing chloride influx which cancels excitatory effect of sodium

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35
Q

Mechanics of spatial and temporal summation

A

Spatial summation - multiple synapses in a soma are charged simultaneously
Temporal summation - one synapse charged consecutively, before effect of previous impulse fades

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36
Q

Mechanics of decremental conduction and its implications in location of synapses along a dendrite?

A

Membrane potential decreases as it moves along the dendrite due to leaky membranes

Synapses closer to soma have more effect in excitation or inhibition

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37
Q

TRUE OR FALSE - Excitatory synapses can infinitely be stimulated

A

FALSE. Principle of fatigue of synaptic transmission as a protective factor for overexcitation, such as seizure (ubos neurotransmitter, activate inhibitors, ion concentration changes, etc)

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38
Q

Effect of acidosis and alkalosis on synaptic transmission

A

Acidosis - depresses neuronal activity
Alkalosis excites activity
(Think H+ makes outside more positive, potential decrease, similar to K+ exit)
(bicarb is negative, does opposite)

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39
Q

Effect of hypoxia on synaptic transmission

A

Inhibitory. Synaptic transmission is highly dependent on O2, which is why HIE happens if panget sats

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40
Q

Effect of strychnine on neuron excitability and mechanism of action

A

Excitatory by inhibiting inhibitory neurotransmitters

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41
Q

5 basic types of sensory receptors

A 
Mechanoreceptors - compression and stretch
Thermoreceptors
Nociceptors - pain
Electromagnetic  receptors - retina
Chemoreceptors
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42
Q

What is differential sensitivity

A

Each receptor is highly sensitive to what it is designed to perceive, and almost unresponsive to other stimuli

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43
Q

What is the Labeled Line principle regarding modalities of sensation

A

Each nerve fiber follows a specific tract and terminates at the center (ex, pain center, vision center), thus only one modality of sensation is transmitted by electical impule of nerve fiber

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44
Q

Mechanism of tonic receptors and give examples

A

Slowly adapting receptors,

ex muscle spindle, vestibular system,pain receptor, arterial baroreceptors, chemoreceptor of carotid

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45
Q

Mechanism of phasic receptors and give examples

A

Rapid reaction to change in stimulus strength, but quickly adapts

ex: pacinian corpuscle - when sitting down, no impulse even if may pressure sa pwet

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46
Q

Type A vs Type C fibers

A

A - large and medium sized myelinated fibers of spinal nerves
C fibers - small unmyelinated low velocity sensory fibers and postganglionic autonomic fibers

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47
Q

The A-alpha fibers are divided into Group 1a and 1b. Differentiate the two

A

1a -a annulospiral ending of muscle spindle

1b - golgi tendon organ fibers

48
Q

What are A-beta and A-gamma fibers, also known as Group II?

A

Fibers from most discrete cutaneous tactile receptors and flower-spray ending of muscle spindle

49
Q

What are A-delta fibers, also known as Group III?

A

Fibers carrying temperature, crude touch, and prickling pain

50
Q

What are C fibers, also known as Group IV

A

Unmyelinated fibers carrying pain, itch, temperature, and crude touch

51
Q

Meissner’s corpuscle is an elongated encapsulated nerve ending of type ____ fiber

A

A-beta

52
Q

Function of Meissner’s corpuscle

A

Sensitive to movement of objects and low frequency vibration - rapidly adapting

53
Q

Function of Merkel’s disc

A

Continuous touch sensation

54
Q

Hair contains touch receptors? TRUE OR FALSE?

A

TRUE - the hair end organ

55
Q

Function of ruffini endings

A

Slowly adapting - for signaling deformation like heavy prolonged touch and pressure

56
Q

Function of pacinian corpuscle

A

Detection of pressure and vibration

57
Q

What fiber transmits tactile signals in peripheral nerves?

A

A-beta - most specialized receptors - for rapid transmission and localization/sensitivity
A-delta and C fiber - free nerve endings - cruder signals, poorly localized

58
Q

Pruritus is sensed by the brain through stimulation of what fiber

A

C fiber

59
Q

Logic behind scratching when itchy?

A

Removes irritant,or causes pain which supresses itch signals by lateral inhibition

60
Q

Stimuli which excite pain receptors

A

Mechanical, thermal, and chemical

61
Q

Chemicals which excite chemical pain receptors

A

Bradykinin, serotonin, histamine, K, acids, acetylcholine, proteolytic enzymes

62
Q

Chemicals which enhance sensitivity of pain endings but do not directly excite them.

A

Prostaglandin, Substance P

63
Q

TRUE OR FALSE - Pain receptors exhibit adaptibility?

A

FALSE. Isipin mo pain is warning taht something is wrong. correct first

64
Q

TRUE OR FALSE - Pain intensity is associated with rate of damage of tissue and total damage done to tissue?

A

FALSE. Think burns

65
Q

Temperature at which tissues begin to be damaged by heat, also temp when average person begins to perceive pain?

A

45 deg C

66
Q

Fast vs Slow pain fibers in terms of
A. Fiber used
B.eliciting factor

A

Fast pain is transmitted by A-delta fibers from mechanoreceptors and thermoreceptors

Slow pain is transmitted by C fibers, usually from chemoreceptors

67
Q

Neurotransmitter secreted by A-delta nerve fiber endings in the spinal cord

A

Glutamate

68
Q

Termination of C fibers in the spinal cord

A

Substantia gelatinosa (Laminae II and III)

69
Q

Termination of A-delta fiber in the spinal cord

A

Lamina I

70
Q

Neurotransmitter secreted by C nerve fiber ending involved in slow chronic pain

A

Substance P

71
Q

Neurotransmitters involved in analgesia system of brain

A

Enkephalin and serotonin

72
Q

Nerve fiber which transmits visceral pain?

A

C fibers

73
Q

Parietal pain vs Visceral pain

A

Visceral pain is dull, aching, poorly localized

Parietal pain is sharp, localizing

74
Q

Special spinal cord tract where thermal signals enter in the spinal cord

A

Tract of Lissauer

75
Q

Definiton of diopter

A

1 meter / focal length of lens

76
Q

Arrange by increasing index of refraction

Air, Cornea, aqueous, Lens, Vitreous

A 
Air 1
Aqueous humor 1.33
Vitreous hunor 1.34
Cornea 1.38
Lens 1.4(ave)
77
Q

Two thirds of refractive power of eye is supplied by what?

A

Cornea

78
Q

Muscle responsible for accomodation

A

Ciliary Muscle

79
Q

Layers of the Retina

A

Outside to inside

  1. Pigmented layer
  2. Rods and cones
  3. Outer nuclear layer (of rods and cones)
  4. Outer plexiform layer
  5. Inner nuclear layer
  6. Inner plexiform layer
  7. Ganglionic layer
  8. Layer of optic nerve fibers
  9. Inner limiting membrane
80
Q

Central fovea is composed almost entirely of (rods/cones/both)?

A

Cones

81
Q

Light sensitive photochemical in rods and cones

A

Rods - rhodopsin

Cones - “color pigments”

82
Q

Histology of outer segment of rod and cone vs inner segment

A

Large number of discs, infolded cell membrane with pigment proteins as transmembrane proteins.

Inner segmebt - organelles

83
Q

Pigment contained in pigment layer of retina and function

A

Melanin - black pigment which prevents light reflection in globe, allowing contrast

84
Q

Storage location of vitamin A in retina

A

Pigment layer

85
Q

Rhodopsin is a combination of which two molecules

A

Scotopsin and 11-cis retinal

86
Q

What happens when light energy is absorbed by rhodopsin

A

11-cis retinal changes to all-trans retinal, which is unstable and splits from scotopsin

Pathway: rhodopsin - bathorhodopsin - lumirhodopsin - metarhodopsin I - metarhodopsin II - all trans retinal & scotopsin

87
Q

It is also called activated rhodopsin. This molecule excites electrical changes in rods and transmit visual image

A

Metarhodopsin II

88
Q

Reconversion of rhodopsin from all-trans to cis is catalyzed by what enzyme

A

Retinal isomerase

89
Q

Form of vitamin A which can be used to replenish 11-cis retinal and pathway involved

A

All-trans retinol

All trans retinal – all trans retinol (isomerase) – 11-cis retinol – 11cis retinal

90
Q

Severe vitamin A deficiency can cause what opthalmologic problem and pathophysio

A

Nyctalopia (night blindness)

Decreased retinal and rhodopsin

91
Q

Most sensory receptors are depolarized when exposed to stimulus. Which receptor is hyperpolarized when exposed?

A

Rods

92
Q

Sodium channel in outer surface of rod is gated by?

A

cGMP

93
Q

G protein stimulated by activated rhodopsin which is involved in hyperpolarization

A

Transducin

94
Q

Physiology of ions in the rod at the dark state

A

Inner membrane Na K pump pumps Na out and K in
Inner membrane K leaks out in nongated K channels
Outer membrane Na leaks in cGMP gated channel
Normal electronegativity in cell is -40mV

95
Q

How does light hyperpolarize the rod?

A
  1. Rhodopsin is activated by light forming metarhodopsin II
  2. Activated rhodopsin stimulates transducin, a g protein
  3. Transducin activates cGMP phosphodiesterase, which catalyzes breakdown of cGMP
  4. Reduced cGMP closes Na channels
  5. Continued Na K pump pumping makes inside of cell lose Na, hyperpolarizing it
  6. Rhodopsin kinase inactivates the activated rhodopsin and ion flow reverts to normal
96
Q

Enzyme which inactivates the activated rhodopsin

A

Rhodopsin kinase

97
Q

Difference in structure of pigment in cones vs rods

A

In cones, retinal is the same as in rods, but scotopsin structure is different depending on pigment. (Photopsins)

98
Q

How many color pigments are present in a cone?

A

1

99
Q

Wavelength of peak light sensitivity for RGB

A

Blue - 445 nm
Green - 535 nm
Red - 570 nm

100
Q

Wavelength of peak light sensitivity for rhodopsin

A

505 nm

101
Q

Rods vs cones in dark adaptation

A

Cones adapt faster, rods are more sensitive

102
Q

Loss of red cones is called

A

Protanopia

103
Q

Loss of green cones is called

A

Deuteranope

104
Q

Retinal cells which transmit signals horizontally in the outer plexiform layer from rods/cones to bipolar cells

A

Horizontal cells

105
Q

Retinal cells which transmit signals vertically from rods cones and horizontal cells to the inner plexiform layer

A

Bipolar cells

106
Q

Cells which transmit signals from bipolar cells to ganglion cells

A

Amacrine cells

107
Q

Cells which transmit output signals from retina to the brain

A

Ganglion cells

108
Q

Retinal cell which transmits inhibitory signals retrograde from inner plexiform to outer plexiform

A

Interplexiform cell

109
Q

Retinal cells which transmit signals horizontally

A

Horizontal and amacrine cells

110
Q

Direct visual pathway in rod vs cone

A

Rod - bipolar - amacrine - ganglion

Cone - bipolar - ganglion

111
Q

Neurotransmitter in synapse bet rod or cone and bipolar cell

A

Glutamate

112
Q

TRUE OR FALSE Transmission of most signals in the retina is by action potentials

A

FALSE. Electronic conduction since stimulus hyperpolarizes. This allows graded conduction depending on light intensity

113
Q

Cells involved in lateral inhibition and purpose?

A

Horizontal cells - allows contrast

114
Q

Attenuation reflex in middle ear mechanism

A

Tensor tynpani pulls malleus inward
Stapedius pulls stapes outward

Reduces intensity to protect cochlea

115
Q

Nicotinic receptor blocker at the ganglia but not at the NMJ

A

Hexamethonium

PLE Physiology (7 decks)

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