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Biology 30 > Unit 1: Nervous System/Sensory Reception > Flashcards

Unit 1: Nervous System/Sensory Reception Flashcards

1
Q

What is the function of dendrites in a neuron?

A

Receive impulses from receptors or other neurons

Dendrites are short, branched ends of neurons that connect with other cells.

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2
Q

What is the role of the cell body in a neuron?

A

Contains the nucleus and other cell parts; site of metabolic reactions

It receives input from dendrites and may relay it to an axon.

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3
Q

What is the primary function of an axon?

A

Carry impulses away from the cell body

Axons can be up to 1 meter long.

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4
Q

What are axon terminals?

A

Branched ends of axons that communicate with other neurons or effectors

They release neurotransmitters to receptors or dendrites of other neurons.

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5
Q

What is the myelin sheath?

A

White, fatty insulator made of Schwann cells wrapped around the axon

It speeds nerve impulse transmission and protects neurons.

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6
Q

What are the nodes of Ranvier?

A

Unmyelinated gaps in the myelin sheath between Schwann cells

Impulses ‘jump’ from one node to the next.

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7
Q

What is the neurilemma?

A

Membrane covering neurons that helps regenerate damaged axons in the PNS

It is crucial for repair processes in peripheral nerves.

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8
Q

What distinguishes white matter from grey matter?

A

White matter contains myelinated axons/dendrites; grey matter contains unmyelinated axons, cell bodies, dendrites

This distinction is important for understanding brain and spinal cord structure.

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9
Q

Fill in the blank: The highly branched ends of neurons that receive impulses are called _______.

A

dendrites

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10
Q

True or False: The axon is responsible for receiving impulses.

A

False

Axons carry impulses away from the cell body.

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11
Q
A
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12
Q

What is a reflex?

A

A rapid, predictable, involuntary response to stimuli, often for protection

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13
Q

What is a reflex arc?

A

A simple neural pathway coordinating reflex actions

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14
Q

How many neurons are typically involved in a reflex arc?

A

Often 1 sensory neuron, 1 interneuron in spinal cord, and 1 motor neuron

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15
Q

What is the function of sensory receptors in the reflex arc?

A

Detect stimuli

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16
Q

What is the role of the interneuron in a reflex arc?

A

Acts as the integration center in the spinal cord

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17
Q

What is the role of the motor neuron in a reflex arc?

A

Transmits the response to the effector

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18
Q

What is a nerve impulse?

A

A wave of electrochemical activity which travels along a neuron

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19
Q

What are the four parts of a nerve impulse?

A
  • Resting membrane potential
  • Depolarization
  • Repolarization
  • Hyperpolarization
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20
Q

What is the resting membrane potential of a neuron?

A

-70 mV

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21
Q

What does a resting membrane potential indicate?

A

Inside the neuron is negatively charged, outside is positive

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22
Q

What is the function of the Na+/K+ exchange pump?

A

Actively transports 3 Na+ out for every 2 K+ brought in

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23
Q

Why is there a negative charge inside the neuron?

A

Due to negative ions and proteins inside the cell

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24
Q

Fill in the blank: A nerve impulse can be measured using _______.

A

[microelectrodes and a volt meter]

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25
True or False: The inside of a neuron is positively charged at resting potential.
False
26
What causes the build-up of positive charge outside the cell?
More K+ diffusing out than Na+ diffusing in
27
What occurs during repolarization in myelinated neurons?
Occurs at nodes of Ranvier or all along unmyelinated neurons ## Footnote Repolarization is the process of restoring the membrane potential after depolarization.
28
What triggers the opening of voltage-gated sodium channels?
A rapid change in charge across the membrane ## Footnote This change allows Na+ ions to diffuse into the neuron.
29
What is the threshold potential for sodium channels to open?
-55 mV ## Footnote If this threshold is reached, the membrane will depolarize to +35 mV.
30
What is the all-or-none response in nerve impulses?
Depolarization between -70 mV and -55 mV has no effect ## Footnote This means no nerve impulse is generated unless the threshold is reached.
31
What happens when the threshold potential is reached?
Action potential is produced, and the cell depolarizes to +35 mV ## Footnote The nerve impulse is passed along the neuron.
32
What is saltatory conduction?
Impulse 'jumps' from one node to the next ## Footnote This process occurs in less than 1 ms.
33
What occurs during repolarization after depolarization?
Na+ channels close; voltage-gated K+ channels open at +35 mV ## Footnote K+ ions diffuse out, restoring the negative charge inside the neuron.
34
What is hyperpolarization?
The potential reaches -90 mV ## Footnote This occurs due to the overshooting of K+ efflux.
35
What restores the original resting potential of -70 mV?
Na+/K+ exchange pump uses ATP ## Footnote This pump moves Na+ outside and K+ inside.
36
What is the refractory period?
The time taken to repolarize, a few ms ## Footnote During this time, the neuron cannot receive another impulse.
37
What prevents the nerve impulse from moving backwards along the nerve?
The refractory period ## Footnote This ensures the impulse only moves in one direction.
38
What are the key phases of an action potential?
* Depolarization * Repolarization * Hyperpolarization ## Footnote These phases are illustrated by the changes in transmembrane potential.
39
What happens to the membrane potential during an action potential?
It changes rapidly due to sodium ions flowing in and potassium ions flowing out ## Footnote An action potential lasts only a few milliseconds.
40
Fill in the blank: The neuron cannot receive another impulse until it is fully repolarized to its initial _______.
-70 mV
41
42
What is the process by which Na+ diffuses down a neuron?
Depolarization
43
What is generated in response to a stimulus in a neuron?
Action potential
44
What causes local depolarization in a neuron?
Opening of Na+ channels
45
What is the term for the propagation of the action potential along a neuron?
Nerve impulse
46
After Na+ enters a neuron, ions diffuse throughout the neuron in _______.
Both directions
47
What initiates a new action potential at the next node in a neuron?
Depolarization to threshold
48
Why does a nerve impulse only travel in one direction?
Refractory period
49
What is required for a nerve impulse to occur?
Threshold stimulus
50
What type of response does a nerve impulse exhibit?
All-or-none response
51
What is the maximum membrane potential reached during depolarization?
+35 mV
52
What prevents action potentials from being generated in reverse?
Refractory period
53
What is the space between the axon end of one neuron and the dendrite of the next neuron called?
Synaptic cleft
54
What must happen when an impulse reaches the end of an axon?
Make a connection with another neuron or an effector
55
What is the connection between two neurons or a neuron and an effector called?
Synapse
56
Fill in the blank: The impulse from the axon terminal of one neuron travels across a _______ to the next neuron.
Synapse
57
58
What is the presynaptic membrane?
The membrane the impulse travels to before the synapse (axon end) ## Footnote The presynaptic membrane releases neurotransmitters.
59
What are synaptic vesicles?
Sacs filled with neurotransmitters ## Footnote They are located at the presynaptic membrane.
60
What is the postsynaptic membrane?
The membrane the impulse is traveling to across the synapse (dendrite end) ## Footnote It contains receptor proteins specific to various neurotransmitters.
61
What are neurotransmitters?
Chemical messengers that carry the signal across the synapse ## Footnote They play a critical role in synaptic transmission.
62
What is the first step in synaptic transmission?
Action potential reaches axon terminal, stimulating voltage-gated Ca²⁺ gates to open ## Footnote Ca²⁺ enters the axon terminal.
63
What happens after Ca²⁺ enters the axon terminal?
Synaptic vesicles containing neurotransmitters move towards the presynaptic membrane ## Footnote This is part of the process of neurotransmitter release.
64
How are neurotransmitters released into the synaptic cleft?
Via exocytosis ## Footnote This occurs after synaptic vesicles move to the presynaptic membrane.
65
What occurs after neurotransmitters diffuse across the synaptic cleft?
They bind to specific protein receptors on the postsynaptic membrane, changing its permeability ## Footnote This initiates depolarization on the next dendrite if threshold potential is reached.
66
What happens to neurotransmitters after they have transmitted their signal?
They are destroyed by specific enzymes ## Footnote For example, acetylcholine (Ach) is destroyed by cholinesterase (Achase).
67
What are the two types of neurotransmitter effects?
Excitatory and inhibitory ## Footnote Excitatory causes Na⁺ channels to open and depolarization begins; inhibitory causes K⁺ channels to open and hyperpolarization occurs.
68
What is the role of the cell body in nerve impulses?
It is responsible for integrating many incoming signals received at once ## Footnote This is crucial for the overall response of the neuron.
69
Name two important neurotransmitters discussed.
Acetylcholine and norepinephrine ## Footnote They are key neurotransmitters in the nervous system.
70
How do many drugs affect neurotransmitters?
They act by interfering with normal functioning of neurotransmitters ## Footnote This can alter mood, perception, and behavior.
71
What does the brain do with the impulses it receives?
It counts how many impulses it receives ## Footnote Higher frequency of impulses indicates a stronger stimulus.
72
Fill in the blank: Neurotransmitters can be _______.
excitatory or inhibitory
73

Biology 30 (1 decks)

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