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Nervous System Flashcards

1
Q

What is the function of a neuron?

A

Transmit electrical impulse and translate impulse into a chemical signal

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2
Q

What is another name for a neuron’s cell body?

A

Soma

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3
Q

What is another name for a neuron’s soma?

A

Cell body

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4
Q

Where is the nucleus of a neuron found?

A

Cell body / Soma

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5
Q

Where is the endoplasmic reticulum and ribosomes of the neuron found?

A

Cell body / Soma

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6
Q

What emanates directly from the cell body?

A

Dendrites

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7
Q

What do dendrites do?

A

Receive incoming messages from other cells

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8
Q

Where does a cell signal go from the dendrite?

A

Cell body to the axon hillock

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9
Q

What does the axon hillock do?

A

Integrates incoming signals and plays an important role in action potentials

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10
Q

What is the axon?

A

Long appendage from the cell body that terminates in close proximity to a target structure

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11
Q

What is myelin?

A

Fatty membrane covering mammalian nerve fibers (insulation to prevent loss of signals)

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12
Q

Does myelin increase or decrease the speed of conduction of an axon?

A

Increases

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13
Q

Where is myelin produced in the CNS?

A

Oligodendrocytes

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14
Q

Where is myelin produced in the PNS?

A

Schwann cells

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15
Q

What are nodes of Ranvier?

A

Small breaks in the myelin sheath that leads to exposed areas of axon membrane

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16
Q

Besides myelin, what increases the speed of a nerve impulse?

A

Nodes of Ranvier

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17
Q

What is another name for the nerve terminal?

A

Synaptic bouton

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18
Q

What is another name for the synaptic bouton?

A

Nerve terminal

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19
Q

Are neurons connected?

A

No

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20
Q

Synaptic cleft

A

Space between one nerve terminal and another nerve’s dendrites into which neurotransmitters are released

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21
Q

Synapse is composed of?

A

Nerve terminal
Synaptic Cleft
Postsynaptic membrane

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22
Q

What are ganglia?

A

Cell bodies of neurons of the same type

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23
Q

How many types of information does one tract carry?

A

One

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24
Q

What are the cell bodies of a neuron in a tract known as?

A

Nuclei

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25
What is the function of glial cells?
Provide structure and support
26
What do astrocytes do?
Nourish neurons | Form the blood-brain barrier
27
What do ependymal cells do?
Line ventricles Produce CSF Shock absorber
28
What cells form the blood-brain barrier?
Astrocytes
29
What cells produce CSF?
Ependymal cells
30
What cells line the ventricles?
Ependymal cells
31
What do microglia do?
Pahgocytic cells that ingest and break down pathogens and waste in CNS
32
What cells are phagocytic in the CNS?
Microglia
33
Neuron resting membrane potential? Where do the negative ions lie?
-70 mV | Negative inside
34
Is there more potassium inside or outside the cell?
Inside (140mM to 4mM)
35
Potassium leak channels
Slow, favorable leak of potassium out of the cell
36
Equilibrium potential of potassium
Concentration gradient pulls K out of the cell but negative charge pulls the cation back in = no net movement -90mV
37
Is there more sodium inside or outside the cell?
Outside (12mM to 145mM)
38
Sodium leak channels
Slow, favorable leak of sodium into the cell
39
Equilibrium potential of sodium
60mV
40
Na+/K+ ATPase
Continually pumps potassium into the cell and sodium out of the cell
41
Does excitatory input cause de- or hyper-polarization and what does that mean?
Depolarization - raises the membrane potential and causes an action potential
42
Does inhibitory input cause de- or hyper-polarization and what does that mean?
Hyperpolarization - lowers the membrane potential and lessens the chance of an action potential
43
What is the threshold for an action potential?
-55 to -40mV
44
What happens to the ions when the membrane reaches the threshold?
Migration of sodium into the cell due to electrochemical gradient leading to rapid depolarization
45
What happens to the ions during repolarization?
Potassium leaves the cell
46
Absolute refractory period
No amount of stimulation can cause another action potential to occur
47
Relative refractory period
Greater than normal stimulation is required to generate an action potential because the cell is more negative than usual
48
What is the functional purpose of the refractory period?
Information can only flow in one direction
49
How does length and cross-sectional area of the axon affect the speed of action potentials?
Increased length - higher resistance and slower conduction Increased area - lower resistance and faster propagatiom
50
Does length or area contribute more to action potential speed?
Area
51
What does saltatory conduction mean?
Action potential signals hop from one node of Ranvier to another - ions can only move into and out of the cell at these nodes due to insulation caused by myelin
52
Effector
Name for the post-synaptic cell if it is a muscle or gland rather than another neuron
53
Differentiate between electrical and chemical transmission during an action potential
Electrical signals are passed down the length of an axon Chemical (neurotransmitter) signals are used to pass the signal from one neuron to the next
54
What is the first chemical step of an action potential at the nerve terminal?
Voltage-gated ion channels open and cause an influx of calcium into the neuron
55
What does the increase in intracellular calcium during an action potential cause?
Fusion of membrane-bound vesicles with the membrane leading to exocytosis of the neurotransmitter
56
What are the three ways that neurotransmitters can be removed from the synaptic cleft and what is a classic example of each?
1. Breakdown by an enzyme - acetylcholine 2. Reuptake carriers bring the neurotransmitter back to the presynaptic neuron - serotonin, dopamine, norepi 3. Simple diffusion out of the synaptic cleft - NO gas
57
Inactivation during an action potential
When the membrane potential reaches +35, the sodium gates close and potassium channels open
58
Monosynaptic reflex arc
Sensory neuron fires directly onto the motor neuron
59
Polysynaptic reflex arc
Sensory neuron fires onto motor neurons as well as interneurons that then fire onto motor neurons
60
Are motor neurons afferent or efferent?
Efferent
61
Are sensory neurons afferent or efferent?
Afferent
62
Are motor neurons presynaptic or post-synaptic?
Post
63
Are sensory neurons presynaptic or post-synaptic?
Pre

MCAT (31 decks)

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