Neurophysiology Flashcards
1
Q
Free nerve endings contain receptors for what sensations?
A
Pain, temperature, crude touch
2
Q
Anomic aphasia is usually caused by damage to which area of the brain?
A
Angular Gyrus
3
Q
Nonfluent aphasia such as in Pick’s Disease is caused by a lesion in which brain area?
A
Broca’s area
4
Q
Fluent aphasia is caused by a lesion in which brain area?
A
Wernicke’s Area
5
Q
Memory loss can be a result of a lesion in which brain area?
A
Hippocampus
6
Q
Concentration of glucose and protein in CSF is higher, lower, or same as plasma
A
Lower (both glucose and protein)
7
Q
Part of the cerebellum connected to the vestibular nuclei, and is associated with central vertigo
A
Flocculonodular Lobe
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
9
Q
What frequencies of sound produce vibration of the basilar membrane at the apex of the cochlea (near helicotrema)
A
Low frequency
10
Q
What percentage of the human genome is involved in the formation and function of the nervous system?
A
40%
11
Q
Electrical vs chemical synapse
A
Electrical - by gap junctions, two way
Chemical - neurotransmitter and receptor at synapse, one way only
12
Q
Two internal structures in the presynaptic terminal and their function
A
Transmitter vesicles - contain neurotransmitter
mitochondria - provide ATP for neurotransmitter generation
13
Q
Events that lead to neurotransmitter release from presynaptic terminals
A
- Action potential depolarizess presynaptic terminal
- Voltage Gated Calcium channel opens,making calcium enter terminal
- Calcium causes release of neurotransmitters from vessels by binding to release sites
14
Q
Two actions of neurotransmitter in the postsynaptic neuron
A
- Gating Ion Channels
2. Activating second messengers
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)
16
Q
Ion channels provide rapid or prolonged neuronal control?
A
Rapid
17
Q
Second messengers provide rapid or prolonged control
A
Prolonged
18
Q
Components of the inactive G protein
A
GDP, alpha beta and gamma component
19
Q
Which component of the G protein is the activator
A
Alpha
20
Q
Mechanism of acivation of G protein
A
- Neurotransmitter activates receptor
- Conformational change exposes G protein binding site
- G protein binds
- Alpha subunit releases GDP and binds GTP
- A-GTP complex dissociates from beta and gamma
- A-GTP performs its function
- GTP is hydrolyzed to GDP, releasing it from target protein and binding it back to B and Y
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
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
23
Q
Mechanism of recycling of vesicles in presynaptic cells
A
- Vesicle fuses with membrane to release neurotransmitter
- Vesicle invaginates back to the terminal, forming new vesicle
- New vesicle synthesizes new transmitters
24
Q
Enzyme responsible for synthesizing acetylcholine
A
Choline acetyltransferase
25
Components of acetylcholine
AcetylCoA + choline
26
Enzyme which splits acetylcholine in the synaptic cleft
Cholinesterase
27
What happens to choline at the synaptic cleft
Actively transported back to presynaptic terminal to be used for synthesis of new acetylcholine
28
Which of the ff are inhibitory, excitatory, or both?
| Acetylcholine, Norepinephrine, Dopamine, Glycine, GABA,Glutamate, Serotonin
Inhibitory - dopamine, glycine, gaba, serotonin (pain and higher cortex)
Excitatory - glutamate
Both - acetylcholine (excitatory except in vagus), norepinephrine,
29
Neurotransmitter not stored in vesicles in the presynaptic terminal and freely diffuses from presynaptic to postsynaptic cell
Nitric oxide
30
Mechasnism of neuropeptide release
Synthesis in ribosome, transport to ER and Golgi,packaged into transmitter vesicle, action potential releases transmitter and autolyzes vesicles
31
What is excitatory post synaptic potential and inhibnitory post synaptic potential and principle behind it
increase or decrease in resting membrane potential after synaptic excitation
32
What is the principle of summation in excitation of neurons
Sucessive excitation of synapses increase EPSP to the threshold potential, thus eliciting action potential in the postsynaptic neuron
33
In which part of the postsynaptic neuron is action potential first generated
Beggining part of axon (higher concentration of sodium channels than soma)
34
Neurotransmitter involved in presynaptic inhibition and mechanism
GABA - opens anion channels, causing chloride influx which cancels excitatory effect of sodium
35
Mechanics of spatial and temporal summation
Spatial summation - multiple synapses in a soma are charged simultaneously
Temporal summation - one synapse charged consecutively, before effect of previous impulse fades
36
Mechanics of decremental conduction and its implications in location of synapses along a dendrite?
Membrane potential decreases as it moves along the dendrite due to leaky membranes
Synapses closer to soma have more effect in excitation or inhibition
37
TRUE OR FALSE - Excitatory synapses can infinitely be stimulated
FALSE. Principle of fatigue of synaptic transmission as a protective factor for overexcitation, such as seizure (ubos neurotransmitter, activate inhibitors, ion concentration changes, etc)
38
Effect of acidosis and alkalosis on synaptic transmission
Acidosis - depresses neuronal activity
Alkalosis excites activity
(Think H+ makes outside more positive, potential decrease, similar to K+ exit)
(bicarb is negative, does opposite)
39
Effect of hypoxia on synaptic transmission
Inhibitory. Synaptic transmission is highly dependent on O2, which is why HIE happens if panget sats
40
Effect of strychnine on neuron excitability and mechanism of action
Excitatory by inhibiting inhibitory neurotransmitters
41
5 basic types of sensory receptors
```
Mechanoreceptors - compression and stretch
Thermoreceptors
Nociceptors - pain
Electromagnetic receptors - retina
Chemoreceptors
```
42
What is differential sensitivity
Each receptor is highly sensitive to what it is designed to perceive, and almost unresponsive to other stimuli
43
What is the Labeled Line principle regarding modalities of sensation
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
44
Mechanism of tonic receptors and give examples
Slowly adapting receptors,
| ex muscle spindle, vestibular system,pain receptor, arterial baroreceptors, chemoreceptor of carotid
45
Mechanism of phasic receptors and give examples
Rapid reaction to change in stimulus strength, but quickly adapts
ex: pacinian corpuscle - when sitting down, no impulse even if may pressure sa pwet
46
Type A vs Type C fibers
A - large and medium sized myelinated fibers of spinal nerves
C fibers - small unmyelinated low velocity sensory fibers and postganglionic autonomic fibers
47
The A-alpha fibers are divided into Group 1a and 1b. Differentiate the two
1a -a annulospiral ending of muscle spindle
| 1b - golgi tendon organ fibers
48
What are A-beta and A-gamma fibers, also known as Group II?
Fibers from most discrete cutaneous tactile receptors and flower-spray ending of muscle spindle
49
What are A-delta fibers, also known as Group III?
Fibers carrying temperature, crude touch, and prickling pain
50
What are C fibers, also known as Group IV
Unmyelinated fibers carrying pain, itch, temperature, and crude touch
51
Meissner's corpuscle is an elongated encapsulated nerve ending of type ____ fiber
A-beta
52
Function of Meissner's corpuscle
Sensitive to movement of objects and low frequency vibration - rapidly adapting
53
Function of Merkel's disc
Continuous touch sensation
54
Hair contains touch receptors? TRUE OR FALSE?
TRUE - the hair end organ
55
Function of ruffini endings
Slowly adapting - for signaling deformation like heavy prolonged touch and pressure
56
Function of pacinian corpuscle
Detection of pressure and vibration
57
What fiber transmits tactile signals in peripheral nerves?
A-beta - most specialized receptors - for rapid transmission and localization/sensitivity
A-delta and C fiber - free nerve endings - cruder signals, poorly localized
58
Pruritus is sensed by the brain through stimulation of what fiber
C fiber
59
Logic behind scratching when itchy?
Removes irritant,or causes pain which supresses itch signals by lateral inhibition
60
Stimuli which excite pain receptors
Mechanical, thermal, and chemical
61
Chemicals which excite chemical pain receptors
Bradykinin, serotonin, histamine, K, acids, acetylcholine, proteolytic enzymes
62
Chemicals which enhance sensitivity of pain endings but do not directly excite them.
Prostaglandin, Substance P
63
TRUE OR FALSE - Pain receptors exhibit adaptibility?
FALSE. Isipin mo pain is warning taht something is wrong. correct first
64
TRUE OR FALSE - Pain intensity is associated with rate of damage of tissue and total damage done to tissue?
FALSE. Think burns
65
Temperature at which tissues begin to be damaged by heat, also temp when average person begins to perceive pain?
45 deg C
66
Fast vs Slow pain fibers in terms of
A. Fiber used
B.eliciting factor
Fast pain is transmitted by A-delta fibers from mechanoreceptors and thermoreceptors
Slow pain is transmitted by C fibers, usually from chemoreceptors
67
Neurotransmitter secreted by A-delta nerve fiber endings in the spinal cord
Glutamate
68
Termination of C fibers in the spinal cord
Substantia gelatinosa (Laminae II and III)
69
Termination of A-delta fiber in the spinal cord
Lamina I
70
Neurotransmitter secreted by C nerve fiber ending involved in slow chronic pain
Substance P
71
Neurotransmitters involved in analgesia system of brain
Enkephalin and serotonin
72
Nerve fiber which transmits visceral pain?
C fibers
73
Parietal pain vs Visceral pain
Visceral pain is dull, aching, poorly localized
| Parietal pain is sharp, localizing
74
Special spinal cord tract where thermal signals enter in the spinal cord
Tract of Lissauer
75
Definiton of diopter
1 meter / focal length of lens
76
Arrange by increasing index of refraction
| Air, Cornea, aqueous, Lens, Vitreous
```
Air 1
Aqueous humor 1.33
Vitreous hunor 1.34
Cornea 1.38
Lens 1.4(ave)
```
77
Two thirds of refractive power of eye is supplied by what?
Cornea
78
Muscle responsible for accomodation
Ciliary Muscle
79
Layers of the Retina
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
Central fovea is composed almost entirely of (rods/cones/both)?
Cones
81
Light sensitive photochemical in rods and cones
Rods - rhodopsin
| Cones - "color pigments"
82
Histology of outer segment of rod and cone vs inner segment
Large number of discs, infolded cell membrane with pigment proteins as transmembrane proteins.
Inner segmebt - organelles
83
Pigment contained in pigment layer of retina and function
Melanin - black pigment which prevents light reflection in globe, allowing contrast
84
Storage location of vitamin A in retina
Pigment layer
85
Rhodopsin is a combination of which two molecules
Scotopsin and 11-cis retinal
86
What happens when light energy is absorbed by rhodopsin
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
It is also called activated rhodopsin. This molecule excites electrical changes in rods and transmit visual image
Metarhodopsin II
88
Reconversion of rhodopsin from all-trans to cis is catalyzed by what enzyme
Retinal isomerase
89
Form of vitamin A which can be used to replenish 11-cis retinal and pathway involved
All-trans retinol
All trans retinal -- all trans retinol (isomerase) -- 11-cis retinol -- 11cis retinal
90
Severe vitamin A deficiency can cause what opthalmologic problem and pathophysio
Nyctalopia (night blindness)
| Decreased retinal and rhodopsin
91
Most sensory receptors are depolarized when exposed to stimulus. Which receptor is hyperpolarized when exposed?
Rods
92
Sodium channel in outer surface of rod is gated by?
cGMP
93
G protein stimulated by activated rhodopsin which is involved in hyperpolarization
Transducin
94
Physiology of ions in the rod at the dark state
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
How does light hyperpolarize the rod?
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
Enzyme which inactivates the activated rhodopsin
Rhodopsin kinase
97
Difference in structure of pigment in cones vs rods
In cones, retinal is the same as in rods, but scotopsin structure is different depending on pigment. (Photopsins)
98
How many color pigments are present in a cone?
1
99
Wavelength of peak light sensitivity for RGB
Blue - 445 nm
Green - 535 nm
Red - 570 nm
100
Wavelength of peak light sensitivity for rhodopsin
505 nm
101
Rods vs cones in dark adaptation
Cones adapt faster, rods are more sensitive
102
Loss of red cones is called
Protanopia
103
Loss of green cones is called
Deuteranope
104
Retinal cells which transmit signals horizontally in the outer plexiform layer from rods/cones to bipolar cells
Horizontal cells
105
Retinal cells which transmit signals vertically from rods cones and horizontal cells to the inner plexiform layer
Bipolar cells
106
Cells which transmit signals from bipolar cells to ganglion cells
Amacrine cells
107
Cells which transmit output signals from retina to the brain
Ganglion cells
108
Retinal cell which transmits inhibitory signals retrograde from inner plexiform to outer plexiform
Interplexiform cell
109
Retinal cells which transmit signals horizontally
Horizontal and amacrine cells
110
Direct visual pathway in rod vs cone
Rod - bipolar - amacrine - ganglion
| Cone - bipolar - ganglion
111
Neurotransmitter in synapse bet rod or cone and bipolar cell
Glutamate
112
TRUE OR FALSE Transmission of most signals in the retina is by action potentials
FALSE. Electronic conduction since stimulus hyperpolarizes. This allows graded conduction depending on light intensity
113
Cells involved in lateral inhibition and purpose?
Horizontal cells - allows contrast
114
Attenuation reflex in middle ear mechanism
Tensor tynpani pulls malleus inward
Stapedius pulls stapes outward
Reduces intensity to protect cochlea
115
Nicotinic receptor blocker at the ganglia but not at the NMJ
Hexamethonium
