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MCAT > Nervous System > Flashcards

Nervous System Flashcards

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MCAT 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
Q

What is the function of glial cells?

A

Provide structure and support

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26
Q

What do astrocytes do?

A

Nourish neurons

Form the blood-brain barrier

27
Q

What do ependymal cells do?

A

Line ventricles
Produce CSF
Shock absorber

28
Q

What cells form the blood-brain barrier?

A

Astrocytes

29
Q

What cells produce CSF?

A

Ependymal cells

30
Q

What cells line the ventricles?

A

Ependymal cells

31
Q

What do microglia do?

A

Pahgocytic cells that ingest and break down pathogens and waste in CNS

32
Q

What cells are phagocytic in the CNS?

A

Microglia

33
Q

Neuron resting membrane potential? Where do the negative ions lie?

A

-70 mV

Negative inside

34
Q

Is there more potassium inside or outside the cell?

A

Inside (140mM to 4mM)

35
Q

Potassium leak channels

A

Slow, favorable leak of potassium out of the cell

36
Q

Equilibrium potential of potassium

A

Concentration gradient pulls K out of the cell but negative charge pulls the cation back in = no net movement
-90mV

37
Q

Is there more sodium inside or outside the cell?

A

Outside (12mM to 145mM)

38
Q

Sodium leak channels

A

Slow, favorable leak of sodium into the cell

39
Q

Equilibrium potential of sodium

A

60mV

40
Q

Na+/K+ ATPase

A

Continually pumps potassium into the cell and sodium out of the cell

41
Q

Does excitatory input cause de- or hyper-polarization and what does that mean?

A

Depolarization - raises the membrane potential and causes an action potential

42
Q

Does inhibitory input cause de- or hyper-polarization and what does that mean?

A

Hyperpolarization - lowers the membrane potential and lessens the chance of an action potential

43
Q

What is the threshold for an action potential?

A

-55 to -40mV

44
Q

What happens to the ions when the membrane reaches the threshold?

A

Migration of sodium into the cell due to electrochemical gradient leading to rapid depolarization

45
Q

What happens to the ions during repolarization?

A

Potassium leaves the cell

46
Q

Absolute refractory period

A

No amount of stimulation can cause another action potential to occur

47
Q

Relative refractory period

A

Greater than normal stimulation is required to generate an action potential because the cell is more negative than usual

48
Q

What is the functional purpose of the refractory period?

A

Information can only flow in one direction

49
Q

How does length and cross-sectional area of the axon affect the speed of action potentials?

A

Increased length - higher resistance and slower conduction

Increased area - lower resistance and faster propagatiom

50
Q

Does length or area contribute more to action potential speed?

A

Area

51
Q

What does saltatory conduction mean?

A

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
Q

Effector

A

Name for the post-synaptic cell if it is a muscle or gland rather than another neuron

53
Q

Differentiate between electrical and chemical transmission during an action potential

A

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
Q

What is the first chemical step of an action potential at the nerve terminal?

A

Voltage-gated ion channels open and cause an influx of calcium into the neuron

55
Q

What does the increase in intracellular calcium during an action potential cause?

A

Fusion of membrane-bound vesicles with the membrane leading to exocytosis of the neurotransmitter

56
Q

What are the three ways that neurotransmitters can be removed from the synaptic cleft and what is a classic example of each?

A
  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
Q

Inactivation during an action potential

A

When the membrane potential reaches +35, the sodium gates close and potassium channels open

58
Q

Monosynaptic reflex arc

A

Sensory neuron fires directly onto the motor neuron

59
Q

Polysynaptic reflex arc

A

Sensory neuron fires onto motor neurons as well as interneurons that then fire onto motor neurons

60
Q

Are motor neurons afferent or efferent?

A

Efferent

61
Q

Are sensory neurons afferent or efferent?

A

Afferent

62
Q

Are motor neurons presynaptic or post-synaptic?

A

Post

63
Q

Are sensory neurons presynaptic or post-synaptic?

A

Pre

MCAT (31 decks)

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