Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MCAT Biology > Ch 4 - The Nervous System > Flashcards

Ch 4 - The Nervous System Flashcards

You may prefer our related Brainscape-certified flashcards:
MCAT flashcards AP® Biology flashcards Biology 101 flashcards
1
Q

What are neurons?

A

highly specialized cells responsible for the conduction of impulses

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

How do neurons communicate?

A

using both electrical and chemical forms of communication

  • electrical occurs via ion exchange and the generation of membrane potentials down the length of the axon
  • chemical occurs via neurotransmitter release from the presynaptic cell and the binding of these neurotransmitters to the postsynaptic cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are dendrites?

A

appendages that receive signals from other cells

- carry signal toward soma

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

What are soma?

A

the cell body; the location of the nucleus and organelles like the ER and ribosomes

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

What is the axon hillock?

A

where the cell body transitions to the axon, and where action potentials are initiated
- integrates excitatory and inhibitory signals from the dendrites and fires and AP if the excitatory signals are strong enough to reach threshold

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

What is an axon?

A

a long appendage down which an action potential travels

- carry signal away from soma

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

What is the nerve terminal?

A

(or synaptic bouton) is the end of the axon from which neurotransmitters are released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is 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
9
Q

What is a synapse and the synaptic cleft?

A
  • the synapse consists of the nerve terminal of the presynaptic neuron, the membrane of the postsynaptic cell, and the space between the 2 (synaptic cleft)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are many axons coated in?

A

myelin, an insulating substance that prevents signal loss

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is myelin created?

A

by oligodendrocytes in the CNS and Schwann cells in the PNS

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

What does myelin prevent?

A

dissipation of the neural impulse and crossing of neural impulse from adjacent neurons

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

What are individual axons bundled into?

A

nerves or tracts

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

What type of information do single nerves carry v tracts?

A
  • single: many types like sensory, motor, or both

- tracts: only one type of information

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

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

A

CNS: nucleus
PNS: ganglion

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

What are neuroglia?

A

(or glial cells) other cells within the nervous system in addition to neurons

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

What do astrocytes do?

A

nourish neurons and form the blood-brain barrier, which 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
18
Q

What do ependymal cells do?

A

line the ventricles of the brain and produce CSF, which 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
19
Q

What are microglia and what do they do?

A

phagocytic cells that ingest and break down waste products and pathogens in the CNS

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

What resting membrane potential do all neurons exhibit?

A

approximately 70 mV
- potassium is high inside the cell and low outside the cell while sodium is high outside the cell and low inside the cell

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

How is resting potential maintained?

A

using selective permeability of ions as well as the Na+/K+ ATPase

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

How does the Na+/K+ work?

A

pumps three sodium ions out of the cell for every 2 potassium ions pumped in
- Na wants to go into the cell because the cell is more negative inside and has a lower concentration of Na inside

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

What type of signals can incoming signals be?

A
  • excitatory: cause depolarization of the neuron

- inhibitory: cause hyperpolarization of the neuron

24
Q

What is the difference between temporal and spatial summation?

A
  • temporal: the integration of multiple signals near each other in space
  • spatial: the addition of multiple signals near each other in space
25
Q

What is an action potential used for?

A

to propagate signals down the axon

26
Q

What happens to the channels when enough excitatory stimulation occurs?

A

the cell is depolarized to the threshold voltage and voltage-gated sodium channels open

27
Q

What happens once the voltage-gated sodium channels are opened?

A
  • sodium flows into the neuron due to its strong electrochemical gradient depolarizing the neuron
  • at the peak of the action potential (~ +35 mV), sodium channels are inactivated and potassium channels open
28
Q

What happens once potassium channels are opened?

A
  • potassium flows out of the neuron due to its strong electrochemical gradient, repolarizing the cell
  • potassium channels stay open long enough to overshoot the action potential, resulting in a hyperpolarized neuron; then the potassium channels close
29
Q

What restores the sodium and potassium gradients?

A
  • once the potassium channel is closed, the Na+/K+ ATPase brings the neuron back to the resting potential
30
Q

What is the refractory period and the the difference between absolute and relative?

A
  • axon in refractory period while it is hyperpolarized
  • absolute: cell is unable to fire another action potential
  • relative: the cell requires a larger than normal stimulus to fire an action potential
31
Q

Why does the impulse propagate down the length of the axon? Why can the action potential only travel in one direction?

A
  • because the influx of sodium in one segment of the axon brings the subsequent segment of the axon to threshold
  • the fact that the preceding segment of the axon is in its refractory period means that the the action potential can only travel in one direction
32
Q

Where are the neurotransmitters released?

A

at the nerve terminal into the synapse

33
Q

When to the voltage-gated calcium channels open?

A

when the action potential arrives at the nerve terminal

34
Q

What does the influx of calcium cause? Where do the neurotransmitters bind?

A
  • fusion of vesicles filled with neurotransmitter with the presynaptic membrane, resulting in exocytosis of neurotransmitter into the synaptic cleft
  • neurotransmitters bind to the receptors on the postsynaptic cell, which may be ligand-gated ion channels or G protein-coupled receptors
35
Q

Why must neurotransmitters be cleared from the postsynaptic receptors and how are they cleared?

A

to stop the propagation of the signal

  • enzymatic degradation
  • reuptake
  • diffusion
36
Q

What are the 3 types of neurons in the nervous system?

A
  • motor (efferent)
  • sensory (afferent) - enter the spinal cord on the dorsal side
  • internerouns
37
Q

How is the nervous system divided?

A
  • CNS (brain and spinal cord)

- PNS (cranial and spinal nerves)

38
Q

What does white matter and grey matter consist of in the CNS, brain, and the spinal cord?

A
  • CNS: white with myelinated axons, grey with unmyelinated cell bodies and dendrites
  • brain: white is deeper than grey
  • spinal cord: grey is deeper than white
39
Q

How is the PNS divided?

A

somatic (voluntary)

autonomic (automatic)

40
Q

How is the autonomic nervous system divided?

A

parasympathetic (rest and digest)

sympathetic (fight or flight)

41
Q

How do reflex arcs work?

A

use the ability of interneurons in the spinal cord to relay information to the source of a stimulus while simultaneously routing it to the brain

42
Q

What is the difference between a monosynaptic and polysynaptic reflex arc?

A
  • mono: the sensory (afferent, presynaptic) neuron fires directly onto the motor (efferent, postsynaptic) neuron
  • poly: sensory neuron may fire onto a motor neuron as well as interneurons that fire onto other motor neurons
43
Q

Which 2 types of glial cells, if not properly functioning, will make an individual most susceptible to a CNS infection?

A
  • astrocytes nourish neurons and form the blood-brain barrier, which helps protect the brain from foreign pathogens gaining entrance
  • microglia ingest and break down waste products and pathogens
  • disruption of wither would increase susceptibility to a CNS infection
44
Q

What type of glial cells are being targeted in an autoimmune disease that cases demyelination of the PNS?

A
  • oligodendrocytes produce myelin in the CNS while Schwann cells produce myelin in the PNS
  • Schwann cells are being targeted
45
Q

What is saltatory conduction?

A

signal hops from node to node

46
Q

What is the difference between electrical and chemical transmission in neurons?

A
  • within a neuron, electricity is used to pass signals down the length of the axon
  • between neurons, chemicals (neurotransmitters) are used to pass signals to the subsequent neuron
47
Q

What neural structure initiates the action potential?

A

axon hillock

48
Q

What ion is primarily responsible for the fusion of neurotransmitter-containing vesicles with the nerve terminal membrane?

A

calcium

49
Q

What are the first and second neurons in the autonomic nervous system called?

A
  • 1: preganglionic

- 2: postganglionic

50
Q

What does the myelin sheath do?

A
  • increases the conduction of velocity by insulating segments of the axon so that the membrane is permeable to ions only at the nodes of Ranvier
  • arranged on the axon discontinuously; the gaps between the segments of myelin are called nodes of Ranvier
  • action potential jumps from node to node (saltatory conduction)
51
Q

How is the magnitude and speed determined for impulses?

A

once action potential is triggered, an impulse of a given magnitude and speed is produced

52
Q

When the potential across the axon membrane is more negative than the normal resting potential, what is the state of the neuron?

A

hyperpolarized, occurs right after an action potential and is caused by excess potassium exiting the neuron

53
Q

Which neurotransmitter is used in the ganglia of both the sympathetic and parasympathetic nervous systems?

A

Acetylcholine

54
Q

What would happen if a disease blocked the voltage-gated calcium channel?

A
  • no influx of calcium = no release of neurotransmitters

- so the neuron cannot send excitatory signals, neurons cannot communicate

55
Q

What are the consequences of clipping the dorsal root ganglion?

A
  • loss of sensation at that level

- dorsal root contains cell bodies of sensory neurons only

MCAT Biology (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions