Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

MCAT: Biology > Chapter 4: The Nervous System > Flashcards

Chapter 4: The Nervous System Flashcards

1
Q

Where is the nucleus of a neuron located?

A

In the cell body (soma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Where are the endoplasmic reticulum and the ribosomes of a neuron contained?

A

In the cell body (soma)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is myelin produced by in the central nervous system?

A

Oligodendrocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is myelin produced by in the peripheral nervous system?

A

Schwann cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What carries neural signals away from the soma? What carries them towards the soma?

A
  • Axons carry away

- Dendrites carry towards

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the nodes of Ranvier critical for?

A

Rapid signal transduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the three components of a synapse?

A
  • Nerve terminal
  • Synaptic cleft
  • Postsynaptic membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The cell bodies of neurons of the same type are clustered together into ________.

A

ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The cell bodies of neurons in the same tract are grouped into ________.

A

nuclei

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are tracts?

A
  • In the central nervous system, axons may be bundled together to form tracts
  • Only carry one type of information
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Neurons are supported by other cells, what are they called?

A

Glial cells or neuroglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the function of astrocytes?

A

Nourish neurons and form the blood-brain barrier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is the function of the blood-brain barrier?

A

Controls the transmission of solutes from the bloodstream into nervous tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the function of ependymal cells?

A

Line the ventricles of the brain and produce cerebrospinal fluid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the function of cerebrospinal fluid?

A

Physically supports the brain and serves as a shock absorber

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the function of microglia?

A

Phagocytic cells that ingest and break down waste products and pathogens in the central nervous system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the function of an axon?

A

Transmits an electrical signal (action potential) from the soma to the synaptic knob

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the function of the axon hillock?

A

Integrates excitatory and inhibitory signals from the dendrites and fires an action potential if the excitatory signals are strong enough to reach the threshold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the function of dendrites?

A

Receive incoming signals and carry them to the soma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the function of the myelin sheath?

A

Acts as insulation around the axon and speeds conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the function of the synaptic bouton? Where is it?

A
  • At the end of the axon

- Releases neurotransmitters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does electrical communication occur?

A

Via ion exchange and the generation of membrane potentials down the length of the axon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does chemical communication occur?

A

Via neurotransmitter release from the pre-synaptic cell and the binding of these neurotransmitters to the post-synaptic cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are Nodes of Ranvier?

A

Exposed areas of myelinated axons that permit saltatory conduction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What is the difference between a nerve and a tract?
A nerve may carry multiple types of information, a tract may only carry one
26
What is the resting membrane potential? How does the inside of the neuron compare to the outside?
- -70 mV | - The inside of the neuron is relatively negative compared to the outside
27
How do neurons maintain a negative internal environment? (2)
- Selective permeability | - Na+/K+ ATPase
28
How many ions does the Na+/K+ ATPase move? What does it require?
- Moves 3 Na+ ions out of the cell for every 2 K+ ions moved into the cell - Requires 1 ATP
29
How do the concentrations of Na+ and K+ inside the neuron compare to outside?
- Inside: high K+, low Na+ | - Outside: low K+, high Na+
30
Why is ATP required in the Na+/K+ ATPase? What kind of transport is this?
- Because the ions are moving against their gradients | - Primary active transport
31
What does excitatory input cause?
Depolarization, which raises the membrane potential
32
What does inhibitory input cause?
Hyperpolarization, which lowers the membrane potential
33
What is the threshold value?
Usually in the range of -55 to -40 mV
34
What is temporal summation?
Multiple signals are integrated during a relatively short period of time
35
What is spatial summation?
- The additive effects are based on the number and location of the incoming signals - Signals firing directly on the soma > signals on the dendrites
36
What happens if the neuron is brought to threshold?
- Voltage-gated sodium channels open in the membrane - The Na+ wants to go into the cell because it is more negative inside and has a lower Na+ concentration - Increase of the resting membrane potential (depolarization)
37
What inactivates sodium channels?
When Vm approaches +35 mV
38
How can sodium channels be deinactivated?
By bringing the membrane potential near the resting potential, the inactivation of the sodium channels will be reversed, and will be closed
39
What are the three states of sodium channels?
- Closed (before cell reaches threshold, and after inactivation is reversed) - Open (threshold to approximately +35 mV) - Inactive (+35 mV to resting potential)
40
How does the depolarization of the cell by sodium influence the voltage-gated potassium channels?
- Triggers the potassium channels to open | - Positively charged potassium is driven out of the cell
41
What happens when the potassium channels are open?
Restoration of the negative membrane potential (repolarization)
42
What is the function of hyperpolarization?
Makes the neuron refractory to further action potentials
43
What is the absolute refractory period?
No amount of stimulation can cause another action potential to occur
44
What is the relative refractory period?
There must be greater than normal stimulation to cause an action potential because the membrane is starting from a potential that is more negative than its resting value
45
What happens when the action potential has fired in one segment of axon, allowing it to become momentarily refractory?
Information can only flow in one direction
46
How does an increased length of the axon influence the speed of an action potential?
Results in higher resistance and slower conduction
47
How do greater cross-sectional areas influence the speed of an action potential?
Allow for faster propagation due to decreased resistance
48
Is the effect of length more significant to the effect of cross-sectional areas?
Cross-sectional areas are more significant
49
The membrane is only permeable to ion movement at ___________
the nodes of Ranvier
50
What does increased intensity of a stimulus result in?
- Does NOT result in an increased potential difference of the action potential - Does increase frequency of firing
51
How does the increase of intracellular calcium allow for the exocytosis of neurotransmitters into the synaptic cleft?
Triggers the fusion of the membrane-bound vesicles with the cell membrane at the synapse
52
Neurotransmitter receptors tend to be what? (2)
- Ligand-gated ion channels | - G protein-coupled receptors
53
What are the three mechanisms to remove neurotransmitters from the synaptic cleft?
1) Breaking down by enzymatic reactions 2) Brought back into the presynaptic neuron using reuptake carriers 3) Diffuse out of the synaptic cleft
54
What neural structure initiates the action potential?
The axon hillock
55
Reflexes only require processing at the level of the ___________
spinal cord
56
When reflexes require input from the brain or brainstem, what circuits are used?
Supraspinal circuits
57
What is white matter?
Axons encased in myelin sheats
58
What is grey matter?
Unmyelinated cell bodies and dendrites
59
Does the grey matter lie deeper than the white matter in the brain, or vice-versa?
White matter lies deeper than grey matter
60
What are the four divisions of the spinal cord?
- Cervical - Thoracic - Lumbar - Sacral
61
What is the function of the vertabral column?
Transmits nerves at the space between adjacent vertebrae
62
Where is the grey and white matter situated in the spinal cord?
- White matter lies on the outside of the cord | - Grey matter is deep within the cord
63
Sensory neurons bring information in from the periphery, and enter where?
Enter the dorsal (back) side of the spinal cord
64
Where are the cell bodies of sensory neurons found?
In the dorsal root ganglia
65
Where do motor neurons exit the spinal cord?
Ventrally, or on the side closest to the front of the body
66
The peripheral component of the automatic nervous system contains how many neurons? What are they?
- Two | - Preganglionic neuron and postganglionic neuron
67
Where is the preganglionic neuron located?
- The soma is in the CNS | - Its axon travels to a ganglion in the PNS
68
How are the preganglionic neuron and postganglionic neuron connected?
In the PNS, the axon of the preganglionic neuron synapses on the cell body of the postganglionic neuron, which then affects the target tissue
69
Differentiate the parasympathetic and sympathetic nervous systems.
- Sympathetic: fight-or-flight | - Parasympathetic: rest-or-digest
70
What activates parasympathetic responses? What are its effects?
- Acetylcholine (both preganglionic and postganglionic) - Constricts pupils - Stimulates flow of saliva - Constricts bronchi - Slows heartbeat - Stimulates peristalsis and secretion - Stimulates bile release
71
What activates sympathetic responses? What are its effects?
- Stress - Increases heart rate - Redistributes blood to muscles of locomotion - Increases blood glucose concentration - Relaxes the bronchi - Decreases digestion and peristalsis - Dilates the eyes to maximize light intake
72
What do the sympathetic nervous system neurons release?
- Preganglionic: acetylcholine | - Postganglionic: norepinephrine
73
What does the sympathetic nervous system release into the bloodstream?
Epinephrine
74
Which neural circuits control reflexive behaviour?
Reflex arcs
75
What is a monosynaptic reflex arc?
There is a single synapse between the sensory neuron that receives the stimulus and the motor neuron that responds to it
76
Give an example of a monosynaptic reflex arc.
Knee-jerk reflex
77
What is a polysynaptic reflex arc?
The sensory neuron may fire onto a motor neuron as well as interneurons that fire onto other motor neurons
78
Give an example of a polysynaptic reflex arc.
Stepping on a nail (withdrawal reflex)

MCAT: Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions