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MCAT Biology > The Nervous System > Flashcards

The Nervous System Flashcards

(48 cards)

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1
Q

What is the soma in a neuron? What does it contain?

A

Cell body

Nucleus, ER, and ribosomes

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2
Q

What is a collection of cell bodies called in the CNS?

A

Nucleus

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3
Q

What is a collection of cell bodies called in the PNS?

A

Ganglion

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4
Q

What is the role of astrocytes? 3

A
  1. Nourish neurons
  2. Form the blood/brain barrier
  3. Perform the scarring process in the CNS, which reduces the potential for neural regrowth
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5
Q

What is the role of ependymal cells?

A

Produce cerebrospinal fluid

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6
Q

What is the role of oligodendrocytes?

A

Produce myelin in CNS

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7
Q

What is the role of Scwann cells?

A

Produce myelin in PNS

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8
Q

During the action potential, which ion channel opens first?

A

Na+

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9
Q

What is the voltage of the resting membrane potential?

A

-70mV

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10
Q

What enzyme maintains the resting membrane potential?

A

Na+/K+ ATPase

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11
Q

What is the threshold for the first ion channel to open?

A

-50mV

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12
Q

What regulates the Na+ channel to close?

A

Full depolarization at +35mV

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13
Q

During the action potential, which ion channel opens second?

A

The K+ channel

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14
Q

At what voltage does the second channel open?

A

+35mV

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15
Q

What regulates the K+ channel to close?

A

Hyperpolarization to slightly below -70mV

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16
Q

What is the absolute refractory period?

A

When the axon is GETTING depolarizaed and getting hyperpolarized: the cell is unable to fire another action potential –> whenever Na+ and K+ ion channels are open –> think of the bell on the curve, until -70

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17
Q

What is the relative refractory period?

A

When the axon requires a larger than normal stimulus to fire an action potential: from hyperpolarization to resting potential

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18
Q

What are the Nodes of Ranvier?

A

Exposed areas of demyelinated axons

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19
Q

What are the parts of the synapse?

A
  1. Synaptic bouton of one neuron
  2. Synaptic cleft
  3. Membrane of post-synaptic cell
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20
Q

What does the speed of the impulse down the axon depend on? 2 things
Which effect is more significant?

Study These Flashcards
A
  1. Length: decrease length = increase conduction

2. Cross-sectional area: increase = increase conduction –> more significant

21
Q

Which neurons have very little myelin?

Study These Flashcards
A

Sensory neurons

22
Q

What do local anesthetics inhibit?

Study These Flashcards
A

The Na+ ion channel

23
Q

What ion channel opens once the impulse has reached the synaptic bouton? Where do these ions go?

Study These Flashcards
A

Ca+, come inside the cell

24
Q

What is white matter?

Study These Flashcards
A

Myelinated axons

25
What is grey matter?
Unmyelinated cell body and dendrites
26
What is the difference between monosynaptic and polysynaptic reflexes?
The use of interneurons
27
What is the equation to calculate a membrane potential based on the concentrations of only 1 ion?
Nernst: | E = 61.5/z(charge of ion) x log [ion out] / [ion in]
28
What is the equation to calculate a membrane potential based on the concentrations of multiple ions?
Goldman-Hodgkin-Katz: Vm = 61.5 x log (Pion1.[ion out] + Pion2.[ion out]) / (Pion1.[ion in] + Pion2.[ion in]) P = permeability BUT: invert denominator for ions with a different charge
29
Which one is the presynaptic neuron?
The one releasing the NTs
30
Which one is the postsynaptic neuron?
The one receiving the NTs
31
Why do the concentrations of K+ ions play a much larger role than the Na+ concentrations in determining the membrane potential?
Because K+ has a higher permeability than Na+
32
What neuron type is responsible for pilo erection? Sensory or motor?
Motor
33
Inside the cell, are there more Na+ or K+ ions?
K +
34
What is the normal movement of ions to maintain the resting membrane potential?
3 Na+ ions move out for every 2 K+ ions moved in
35
Outside the cell, are there more Na+ or K+ ions?
Na+
36
Inside the cell: negative or positive?
Negative
37
Outside the cell: negative or positive?
Positive
38
What are the 3 statuses for the Na+ ion channel?
Open, closed, or inactivated
39
When does inactivation of Na+ channels occur? What is the purpose?
When the membrane potential is 35, this is the fast closing of the gate, the other one is slow
40
What is the status of the Na+ channel for another action potential to be fired?
Closed
41
What does a higher magnitude action potential change?
The frequency of the action potential
42
Are the Na+ ions going in or out?
In
43
Are the K+ ions going in or out?
Out
44
When K+ blood concentration is low, how will this affect the action potential?
When the K+ blood concentration is low, the drive for the K+ ion to leave the cell is high, which means the membrane potential will reach even lower values during hyperpolarization = will rneed a higher stimulus for an action potential to happen
45
When K+ blood concentration is high, how will this affect the action potential?
The neuron will be more excitable because the resting membrane potential will be higher
46
What happens on the axon at the unmyelinated portions?
+ charges flow down and open Na+ channels as they go --> recharging
47
Does the Ca2+ go in or out at the axon terminal?
In the cell!
48
How to calculate the change in electric potential energy of an ion crossing the membrane?
U = Delta V . q Delta V = difference between outside (0V) and inside (-70mV) q = charge of the ion: each charge = 1.6 x 10^-19 C

MCAT Biology (18 decks)

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