N542 Physiology Of The Central Nervous System Ii

Front 1

What is the function of microglial cells?

Back 1

Immune cells of the CNS

Front 2

How can damage to microglial cells impact the brain?

Back 2

They can release cytotoxic substances and cause a lot of damage

Front 3

What role do microglial cells play in TBI recovery?

Back 3

They phagocytize the dead tissue

Front 4

What type of cells produce CSF?

Back 4

Specialized ependymal cells

Front 5

What cells in the PNS are analogous to astrocytes?

Back 5

Satellite cells

Front 6

What role do oligodendrocytes play?

Back 6

Myelination of axons within the CNS

Front 7

What do dendrites do?

Back 7

Receive signals

Front 8

What part of the neuron contains the biosynthetic (protein synthesis) mechanisms?

Back 8

Cell body/soma

Front 9

What area of the neuron is most rich in voltage-gated sodium channels?

Back 9

Axon hillock

Front 10

What causes the one-way movement of the action potential?

Back 10

The refractory period prevents the action potential from moving backwards to the area of the membrane that just depolarized/repolarized.

Front 11

What % of synapses are on the dendrites vs. the soma?

Back 11

80-90% are on the dendrites

Front 12

Where do inhibitory synapses tend to be - dendrites or soma?

Back 12

Soma, though that's not a hard and fast rule, just a tendency

Front 13

How many synapses are possible on one neuron?

Back 13

200,000

Front 14

What organisms tend to have unipolar neurons?

Back 14

Invertebrates

Front 15

What type of nerves have pseudounipolar neurons?

Back 15

Sensory

Front 16

What type of nerves have bipolar neurons?

Back 16

Special sensory and interneurons

Front 17

What type of nerves have multipolar neurons?

Back 17

Classic motor neurons

Front 18

What two types of neuronal cells are in the cerebral cortex and what are their relative % distributions?

Back 18

Pyramidal cells: 75%

Stellate/granule interneuron cells: 25%

Front 19

What type of neurotransmitters do pyramidal cells use? Are they excitatory or inhibitory?

Back 19

Glutamate or aspartate; excitatory

Front 20

What type of neurotransmitters do stellate cells use? Are they excitatory or inhibitory?

Back 20

Can be either excitatory or inhibitory (most are the latter)

Excitatory: glutamate or aspartate

Inhibitory: GABA

Front 21

What type of structures act as a transportation guidewire within the axon?

Back 21

Microtubules

Front 22

What substances does the neuron use a great deal of in order to transport substances down the axon?

Back 22

Glucose

Calcium

ATP (to reestablish Ca++ gradient)

Front 23

How fast do substances travel out from the cell body down the axon?

Back 23

400mm/day

Front 24

What protein moves substances from the cell body to the axon terminal?

Back 24

Kinesin

Front 25

What protein moves substances from the axon terminal back to the cell body?

Back 25

Dynein

Front 26

What quality of the action potential is variable/not fixed and therefore can be used to communicate information?

Back 26

Frequency; amplitude is fixed (all-or-none firing)

Front 27

What membrane inclusion is found in great quantity in the nodes of Ranvier?

Back 27

Voltage-gated Na+ channels

Front 28

How does myelination change the axon's electrical qualities?

Back 28

Increases the resistance

Decreases the capacitance

Front 29

What are the functional benefits of myelination?

Back 29

Speed - fast reflexes

Enables complex mental processing

Offers a metabolic advantage

Front 30

Which nerve fibers - A, B, or C fibers - are the biggest?

Back 30

A fibers

Front 31

Which nerve fibers - A, B, and/or C fibers - are myelinated?

Back 31

A and B fibers

Front 32

Name the A fibers and whether they are motor, sensory, or both:

Back 32

Aα (motor and sensory)

Aβ (sensory)

Aγ (motor)

Aδ (sensory)

Front 33

Name the sensory nerve fiber types:

Back 33

Aα

Aβ

Aδ

C

Front 34

Name the motor nerve fiber types:

Back 34

Aα

Aγ

B

C

Front 35

How do nerve size and conduction velocity relate?

Back 35

Larger nerves have faster conduction

Front 36

What structures do Aα sensory fibers supply?

Back 36

Primary muscle spindles

Golgi tendon organs

Front 37

What structures do Aβ sensory fibers supply?

Back 37

Secondary muscle spindles

Skin mechanoreceptors

Front 38

What structures do Aδ sensory fibers supply?

Back 38

Skin mechanoreceptors

Thermal receptors

Nociceptors

Front 39

What structures do C sensory fibers supply?

Back 39

Skin mechanoreceptors

Thermal receptors

Nociceptors

Front 40

What structures do Aα motor fibers supply?

Back 40

Extrafusal skeletal muscle fibers

Front 41

What structures do Aγ motor fibers supply?

Back 41

Intrafusal muscle fibers

Front 42

What structures do B motor fibers supply?

Back 42

Preganglionic autonomic fibers

Front 43

What structures do C motor fibers supply?

Back 43

Postganglionic autonomic fibers

Front 44

What type of sensory information do Aα fibers provide?

Back 44

Proprioceptive

Front 45

What type of sensory information do Aδ fibers provide?

Back 45

Pain/temperature/touch

Front 46

How can we assess if sharp pain signals have been blocked without using painful stimulus?

Back 46

Temperature stimulus instead; the two are both carried by Aδ fibers

Front 47

What type of sensory information do C fibers provide?

Back 47

Slow, dull, aching, chronic type pain

Front 48

What is extra-synaptic signaling?

Back 48

Neurotransmitters diffuse out of the synapse and affect nearby structures

Front 49

What are the three forms of synaptic signalling?

Back 49

Neuron-neuron

Neuron-glial

Extra-synaptic

Front 50

What two ways do gap junctions allow communication between cells?

Back 50

Electrical coupling

Flow of small ions

Front 51

Gap junctions: unidirectional or bidirectional?

Back 51

Bidirectional

Front 52

What are the gap junction channels called?

Back 52

Connexon channels

Front 53

When a drug acts upon a receptor, what is it doing to the receptor?

Back 53

Stabilizing the receptor in one of its conformations that it otherwise fluctuates between

Front 54

What type of receptors involve secondary signalling inside the cell?

Back 54

G-protein coupled receptors

Front 55

What two ways are neurotransmitters cleared from the synapse?

Back 55

Reuptake and degradation

Front 56

How does neostigmine work in the synapse?

Back 56

Blocks ACh-ase and increases ACh availability

Front 57

What are the three types of neurotransmitters?

Back 57

Small molecule transmitters

Neuropeptides

Gaseous neurotransmitters

Front 58

What four criteria define a neurotransmitter?

Back 58

1. Present in the presynaptic terminal
2. Synthesized by the cell
3. Released when the presynaptic membrane depolarizes
4. Has a specific receptor on the postsynaptic membrane

Front 59

Classic & peptide neurotransmitters: where is each synthetized?

Back 59

Classic: in the axon terminal

Peptide: in the cell body, then transported

Front 60

Classic & peptide neurotransmitters: in what form is each synthesized?

Back 60

Classic: already in active form

Peptide: active form must be cleaved from larger polypeptide

Front 61

Classic & peptide neurotransmitters: what container is each usually present in?

Back 61

Classic: small, clear vesicles

Peptide: large, e- dense vesicles

Front 62

Classic & peptide neurotransmitters: where is each released?

Back 62

Classic: into the synaptic cleft

Peptide: possibly extrasynaptically

Front 63

Classic & peptide neurotransmitters: how does the action of each terminate?

Back 63

Classic: reuptake via Na+ powered active transport

Peptide: proteolysis or diffusion

Front 64

Classic & peptide neurotransmitters: what is the latency and duration of action of each?

Back 64

Classic: short latency and short duration (msec)

Peptide: long latency, can last long (seconds)

Front 65

What is an example of a class I small molecule neurotransmitter?

Back 65

Acetylcholine

Front 66

What are some examples of class II small molecule neurotransmitters and what type of molecule are they?

Back 66

• Epinephrine
• Norepinephrine
• Dopamine
• Serotonin
• Histamine

Biogenic amines

Front 67

What are some examples of class III small molecule neurotransmitters and what type of molecule are they?

Back 67

• GABA
• Glycine
• Glutamate
• Aspartate

Amino acids

Front 68

What are two excitatory amino acid neurotransmitters?

Back 68

Glutamate

Aspartate

Front 69

What are two inhibitory amino acid neurotransmitters?

Back 69

GABA

Glycine

Front 70

What do opioid peptides do?

Back 70

Inhibit pain perception

Front 71

What does Substance P do?

Back 71

Enhances transmission of pain signals to brain; excitatory transmitter for nociceptive nerves

Front 72

What are some examples of gaseous neurotransmitters?

Back 72

Nitric oxide

Carbon monoxide

Front 73

How does NO function as a neurotransmitter?

Back 73

Ca++ increase in the cell leads to eNOS, which cleaves NO from arginine, after which the NO diffuses across the membrane and activates second messengers (cGMP)

Front 74

At what point(s) on the membrane do neurotransmitter vesicles fuse?

Back 74

"Active zones" - specific sites rich in calcium channels

Front 75

What are the proteins called that assist in vesicle fusion?

Back 75

SNARE proteins

Front 76

What three proteins 'zip together' to bring the vesicle membrane and presynaptic cell membrane together?

Back 76

Synaptobrevin

Syntaxin

SNAP-25

Front 77

What are three models for vesicular recycling?

Back 77

Classical

Kiss and run

Bulk endocytosis

Front 78

What is the biological advantage of the "kiss and run" model for vesicular recycling?

Back 78

Less energy intensive

Front 79

What is the classical model for vesicular recycling?

Back 79

Pits in the plasma membrane pinch off to form coated vesicles in the cytoplasm; then, they lose the coating and transform into final form

Front 80

What is the "kiss and run" model for vesicular recycling?

Back 80

The vesicle fuses with the plasma membrane just enough to form a pore, and then detaches and reseals

Front 81

What are the four ways Ca++ enters/exits the cell?

Back 81

Ca++ pump (active transport)

Ligand-gated Ca++ channel

Voltage-gated Ca++ channel

Na+/Ca++ exchanger

Front 82

What non-neuron cells also have glutamate receptors?

Back 82

Glial cells

Front 83

What roles do glial cells play in glutamate recycling?

Back 83

They convert glutamate back to glutamine, its inactive form, so it diffuse back into the axon terminal without effect

Front 84

What are the "fast" and "slow" postsynaptic transmission pathways?

Back 84

Fast: ligand-gated ion channel

Slow: g-protein coupled receptor

Front 85

Is glutamate a fast or slow neurotransmitter?

Back 85

Fast; activates Na+ and Ca++ channels

Front 86

How do postsynaptic g-protein coupled receptors work?

Back 86

G-protein has three units; the alpha unit will break off and influence another protein

Protein can be ion channel; K+ will hyperpolarize and be inhibitory; Na+ will depolarize and be excitatory

Can also activate an enzyme or affect gene transcription

Front 87

Define the terms in Ix = gx * (Vm - Ex)

Back 87

Ix = current

gx = conductance

Vm = membrane voltage

Ex = equilibrium potential

Front 88

What does MEPP stand for? What is it?

Back 88

Miniature end plate potential; the 0.5mV depolarization from a single vesicle

Front 89

What ion movements cause an EPSP?

Back 89

Increased Na+ in

Decreased Cl- in

Decreased K+ out

Front 90

What ion movements cause an IPSP?

Back 90

Increased Cl- influx

Increased K+ in

Front 91

What three ways can a neurotransmitter cause an inhibitory response?

Back 91

1. The neurotransmitter inhibits further release
2. A synapse on the axon before the synapse in question can release a neurotransmitter that inhibits further release
3. The neurotransmitter can be circulating and bind/inhibit further release

Front 92

What are two types of potential summation?

Back 92

Spatial (multiple synapses firing)

Temporal (increased frequency from one synapse)

Front 93

If a neuron excites an inhibitory neuron, what is the end result?

Back 93

Inhibition

Front 94

Are the majority of synapses dendritic or somatic?

Back 94

Dendritic

Front 95

How does a change in the pH of the interstitial fluids affect neuronal excitability?

Back 95

Alkalosis greatly increases neuronal excitability

Acidosis greatly decreases neuronal excitability

Front 96

How does hypoxia affect neuronal excitability?

Back 96

Hypoxia severely decreases neuronal excitability