Brainscape's Knowledge GenomeTM

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


See full index

Anatomy & Physiology > Chapter #11: Fundamentals of Nervous System & Nervous Tissue > Flashcards

Chapter #11: Fundamentals of Nervous System & Nervous Tissue Flashcards

1
Q

Sensory Input

A

-allows us to respond to stimuli
-monitors changes that occur inside and outside the body

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

What is responsible for sensory input

A

several different sensory receptors

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

Integration

A

processing & interpretation of input information –> the nervous system “decides” what response to make

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

What is responsible for integration?

A

CNS; usually the brain, but sometimes the spinal cord

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

Motor Output (motor response)

A

response is carried out –> travels to effector organ

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

What is responsible for motor output?

A

muscles/glands are the most common

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

Functions of the nervous system

A

sensory input, integration, and motor output

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

Components of the nervous system

A

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

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

CNS

A

composed of the brain and spinal cord

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

What is the function of the CNS?

A

is responsible for interpreting sensory input and deciding motor output

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

PNS

A

Composed of nerves that extend from the CNS to the rest of the body

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

What is the function of the PNS?

A

allows information to be sent between the CNS and the rest of the body

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

Neurons

A

-nerve cells that can respond to stimuli & transmit electrical signals
-cells of the nervous system specialized to generate or transmit electrical signals (nerve impulses)

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

Why are neurons important?

A

-create and send messages to various parts of the body
-integration and motor output could not occur without neurons

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

Neuroglia (glial cells)

A

provide support and maintenance to neurons

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

Why are neuroglias important?

A

they make sure neurons remain healthy, alive, and functional

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

Types of neuroglia

A

astrocytes, microglial cells, ependymal cells, satellite cells, oligodendrocytes, and schwann cells

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

Astrocytes (CNS)

A

-most abundant, support & protect neurons in CNS
-Star-shaped, with projections connecting to and wrapping around neurons, nerve endings, and surrounding blood capillaries

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

What are the functions of astrocytes?

A
  1. Provide nutrient supply for neuron cells
  2. Allows migration of young neurons
  3. “Clean up” outside neuron cells (leaked K+ ions, neurotransmitters; important for resting membrane potentials)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Microglial Cells (CNS)

A

-contact nearby neuron cells to monitor neuron health
-migrate toward injured neurons & transform into a macrophage and phagocytize the neuron

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

Why are microglial cells important?

A

If a cell is dying off or neuron is damages, they will transform into macrophages because you do not want dead cells taking up space

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

Ependymal Cells (CNS)

A

-most ependymal cells have cilia
-lines central cavities of CNS to circulate cerebrospinal fluid within cavities

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

Satellite cells (PNS)

A

-Support & protect neuron cell in PNS
-similar to astrocytes in the CNS

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

Oligodendrocytes (CNS) & Schwann Cells (PNS)

A

-Wrap around thicker nerve fibers in CNS & PNS
-Function: myelin sheath creates an insulating covering for neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

How is the insulation covering for neurons useful?

A

allows you to speed up the rate at which electrical signals can be sent; makes messages faster

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

General structures of a neuron

A

Cell body, dendrites (found in cell body), and axons (found in cell body)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Characteristics of neurons

A

longevity, amitotic, and metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is longevity?

A

neurons last entire lifetime

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is amitotic?

A

Neurons do not divide and are never replaced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What is metabolism?

A

Neuronal activity is extremely high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Cell body of neuron

A

-portion of cell containing the nucleus
-Function: plasma membrane can receive information from surrounding neurons
-Most cell bodies are found in the CNS & are protected by bone
-Clusters of cell bodies in CNS are called nuclei, those in PNS are called ganglia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Why is it helpful to have cell bodies surrounded by bone?

A

makes it a little less susceptible to damage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Dendrites

A

-main receptive region of neuron
-A single neuron can have dozens of dendrites
-Function: provide increased surface area for incoming signals, convey incoming messages toward the cell body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What would happen if there were no dendrites?

A

the dendrite is the main receptive region of neuron, so the neuron would become less receptive to incoming information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Axon

A

-single, long “nerve fiber” extending from the cell body
-The axon is the conducting region of the neuron
-Function: generates and transmits nerve impulses away from the cell body
-Bundles of axons in the CNS are called tracts, those in PNS are called nerves
-Axon branches at the end to form terminal branches & axon terminals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the function of axon branches?

A

neurotransmitter released at axon terminal to pass the impulse to the next neuron

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Myelin Sheaths

A

-Functions: protects and electrically insulates long and/or large nerve fibers to increase speed at which impulses are transmitted
-Found only on axon portion of the neuron
-Not all axons are myelinated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What happens to transmission speed for unmyelinated axons?

A

message will be sent slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Myelin Sheaths in the PNS (Schwann Cells)

A

-Multiple Schwann cells on the axon form the myelin sheath
-BUT none of the Schwann cells contact each other

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Myelin Sheath gaps

A

region of axon that is “exposed” due to absence of Schwann cell covering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Functional Classification of neurons

A
  1. Sensory (afferent) neuron
  2. Motor (efferent) neuron
  3. Interneuron
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Sensory (afferent) neuron

A

-afferent neurons transmit signals from the body to the CNS
-Receptive endings of this neuron type can function as actual sensory structure, or are associated with larger sensory receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Motor (efferent) neuron

A

-efferent neurons transmit motor response from CNS to the body
-Impulses travel to effector organs (muscle + glands)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Interneuron

A

-lie between sensory and motor neurons
-Function: pass signals through CNS pathways where integration occurs
-Can connect to other interneurons; can communicate with neighbors

45
Q

Why do all cells have to maintain a resting membrane potential of -70mV?

A

the inside of the cell is more negatively charged than the outside

46
Q

Membrane Potentials of neurons

A

-Neurons can change their resting membrane potential faster than other cell types
-Neurons can “communicate” with other neurons when the resting membrane potential changes

47
Q

Why is communication between interneurons necessary or helpful?

A

necessary for more complex actions & decisions needed to be made

48
Q

What does changing the resting membrane potential do?

A

Changing the resting membrane potential allows a neuron to receive, integrate, and send information

49
Q

What is the cause of a change in resting membrane potential of neurons?

A

Changing the permeability of the plasma membrane to one (or more) ions

50
Q

What ion is not allowed to cross the membrane at the resting membrane potential?

A

Na+ (sodium)

51
Q

Types of signals that can be produced by a change in resting membrane potential

A
  1. Graded potential
  2. Action potential
52
Q

Ion channels & membrane potentials

A

Selective proteins in plasma membrane allow passage of ions into/out of cell; they are necessary for a change in membrane potential to take place!!

53
Q

Types of proteins

A
  1. Leakage (non-gated) channels
  2. Gated proteins
54
Q

Leakage (non-gated) channels

A

always open, allow free flow of ions

55
Q

Gated proteins

A

part of protein forms a “gate” that must be opened before ions can move

56
Q

Types of gated proteins

A
  1. Chemically gated
  2. Voltage-gated
  3. mechanically gated
57
Q

Chemically gated

A

only open when a certain chemical (neurotransmitter) binds to protein

58
Q

Voltage-gated

A

open & close in response to changing membrane potentials

59
Q

Mechanically gated

A

open in response to physical deformation of receptor

60
Q

Change in membrane potential voltage due to opening of ion channels can result in:

A
  1. Depolarization
  2. Hyperpolarization
61
Q

Depolarization

A

-decrease in membrane potential
-The inside of the membrane becomes less negative than resting potential; potential becomes more POSITIVE
-Excitation of a neuron

62
Q

Does excitation make the neuron more or less likely to send a message?

A

makes the neuron more likely to generate an electrical impulse to be sent to neighboring neurons

63
Q

Hyperpolarization

A

-increase in membrane potential
-The inside of the membrane becomes more negative than resting potential; potential becomes more NEGATIVE
-Inhibits a neuron

64
Q

Does inhibition of a neuron make it more or less likely to send a message?

A

makes the neuron less likely to generate an electrical impulse

65
Q

Graded potentials

A

-“Graded”: magnitude varies directly with stimulus strength
-Strong stimulus = strong graded potential
-Graded potentials only occur over short distances
-Current dies off quickly
-Can be depolarizing or hyperpolarizing
-Function: graded potentials are necessary to initiate an action potential

66
Q

Where are graded potentials most likely to occur on a neuron?

A

on dendrites

67
Q

Action potentials (nerve impulses)

A

-Action potentials (AP): a very brief reversal of membrane potential (from -70 mV to +30 mV)
-Only produced by neurons and muscle cells
-Action potentials have a consistent strength and are long distance
-APs originate at the beginning of axon arising from cell body (“trigger point”); Change in membrane potential from graded potential causes voltage-gated channels to open at this point

68
Q

Where does an action potential occur on a neuron?

A

Axon

69
Q

Generating Action Potentials

A

Generation of an AP involves opening of voltage-gated ion channels in membrane in response to changing membrane potential

70
Q

How many gates does and Na+ channel have and what are they?

A

2 gates
1. Activation gate: voltage-sensitive, opens at depolarization
2. Inactivation gate: blocks channel to prevent Na+ movement

71
Q

K+ gate

A

only has 1 gate that opens slowly at repolarization

72
Q

Steps to generating action potentials

A
  1. All voltage-gated channels are closed at the resting state (-70 mV)
  2. Depolarization: voltage-gated Na+ channels open at the axon
  3. Repolarization
  4. Hyperpolarization: excess K+ leaves cell
73
Q

Step 1 of generating actions potentials: All voltage-gated channels are closed at the resting state (-70 mV)

A

-Leakage channels are still open here!!!
-Is the permeability of sodium high or low during this stage? low
-Is the permeability of K+ high or low during this stage? high (-70)

74
Q

Step 2 of generating action potentials: Depolarization: voltage-gated Na+ channels open at the axon

A

-voltage-gated, respond to change in potential
-Effect: Na+ freely enters the cell; Inside of the cell becomes less negative b/c of Na+
-Membrane will reach a threshold voltage (-55 mV) as more Na+ enters the cell; At this voltage, depolarization becomes self-generating
-More Na+ channels open to make inside of cell significantly less negative (30 mV at its peak)
-nothing will happen if this threshold is not reached!

75
Q

Step 3 of generating action potentials: Repolarization

A

-This is when the action potential ends to stop ongoing messages from being sent
-Na+ gates close, Na+ permeability drops rapidly, Net influx of Na+ into cell stops completely; this causes AP to stop rising
-Voltage-gated K+ channels open; K+ leaves the cell: restores (-) internal charge of cell
-dips a bit lower to ~ -90mV

76
Q

Step 4 of generating action potentials: Hyperpolarization: excess K+ leaves cell

A

-Result: inside of the cell becomes more negative than resting membrane potential (dips down to ~ -90mV)
-While this happens: Na+ activation gates have closed, inactivation gates reopen
-Na+-K+ pump works to re-establish normal Na+ & K+ concentrations outside and inside the cell
-membrane potential returns to -70mV

77
Q

Action Potentials vs. Stimulus Strength

A

-APs are independent of stimulus strength
-every action potential is always the same, they never change

78
Q

How does the nervous system discriminate between a strong stimulus and weak stimulus?

A

-How frequently nerve impulses are generated!!
-Strong stimuli: impulses are sent more frequently
-weak stimuli: impulses sent less frequently

79
Q

Refractory Period in Action Potentials

A

a period of time in which a second AP cannot be generated at an axon

80
Q

Types of refractory periods

A
  1. Absolute Refractory Period
  2. Relative Refractory Period
81
Q

Absolute Refractory Period

A

-Begins when Na+ gated channels open, continues until Na+ channels reset to their original state
-During this time, another AP cannot be generated in the area, no matter how strong the stimulus is b/c all Na+ channels are open
-Ensures each AP is a separate, all-or-none event
-Enforces one-way transmission of the AP

82
Q

Relative Refractory Period

A

-Occurs after the absolute refractory period (after repolarization)
-Stimuli that are relatively weak cannot stimulate an AP, but an exceptionally strong stimulus can
-Hyperpolarization causes mV to be more negative: need stronger stimulus to reach threshold

83
Q

Action Potentials: Conduction Speed

A

-Impulses can be conducted quickly (ex: postural changes) or more slowly (ex: GI tract, etc.)

84
Q

What 2 factors is conduction speed dependent on?

A
  1. Axon Diameter: larger axon = faster conduction
  2. Degree of myelination: more myelination = faster conduction
85
Q

Types of Conduction

A
  1. Continuous conduction
  2. Saltatory conduction
86
Q

Continuous conduction

A

-propagation in unmyelinated fibers
-Voltage-gated ion channels are adjacent for the entire length of the axon

87
Q

Saltatory conduction

A

-propagation in myelinated fibers
-Voltage-gated ion channels found ONLY in myelin sheath gaps
-AP generated in myelin sheath gap
-AP jumps large distances along length of axon

88
Q

Transmission of Signals

A

Signals are transmitted between neurons at a synapse

89
Q

Synapse

A

Junction between two neurons that sends information from one neuron to the next

90
Q

Presynaptic neurons

A

-conduct impulses toward the synapse
-The neuron that is “sending” the message

91
Q

Postsynaptic Neurons

A

-conduct signal away from the synapse
-The neuron that is “receiving” the message

92
Q

Synaptic Cleft

A

-neurons are separated by synaptic cleft
-fluid filled space

93
Q

Process - Transmission of Action Potentials from One Neuron to Another: Chemical Synapses

A
  1. Action potential arrives at axon terminal of presynaptic neuron
  2. Voltage-gated Ca2+ channels in terminal open in response to AP (Ca2+ enters the axon terminal of presynaptic neuron)
  3. Synaptic vesicles in axon terminal fuse with membrane in response to Ca2+ influx (synaptic vesicles contain neurotransmitters)
    -neurotransmitter enters the synaptic cleft
  4. Neurotransmitter crosses cleft, binds to proteins on postsynaptic neuron
  5. Neurotransmitter binds receptors on the postsynaptic neuron membrane (binds to dendrites)
    -Binding causes ions channels to open
    -Ion flow generates a graded potential
  6. Neurotransmitter in synaptic cleft is disposed of (prevent prolonged response)
94
Q

Neurotransmitter can be disposed of by:

A
  1. Reuptake
  2. Degradation
  3. Diffusion
95
Q

Reuptake

A

Reuptake of neurotransmitter by an astrocyte or by the pre-synaptic neuron

96
Q

Degradation

A

Degradation of neurotransmitter by an enzyme

97
Q

Diffusion

A

Diffusion of neurotransmitter out of the synapse

98
Q

Postsynaptic Potentials

A

-the temporary change in membrane potential (i.e., a graded potential) of the postsynaptic neuron
-postsynaptic potential observed in dendrites
-effect of neurotransmitter can be either excitatory or inhibitory

99
Q

Neurotransmitter binding cause graded potentials that vary in strength according to:

A
  1. Amount of neurotransmitter released
    -larger amount of neurotransmitter = stronger potential
  2. How long neurotransmitter stays in synaptic cleft
    -longer it sits in synaptic cleft = stronger potential
100
Q

Excitatory postsynaptic potential (EPSP)

A

-Binding of neurotransmitter causes the membrane to depolarize
-Increases the chance of generating an action potential
-A single EPSP cannot induce an AP alone (several will summate or be added together to generate AP)

101
Q

Types of summation

A
  1. Temporal summation
  2. Spatial summation
102
Q

Temporal summation

A

-the postsynaptic neuron receives multiple EPSPs in rapid-fire order
-not received by the postsynaptic neuron at the same time; closely packed together

103
Q

Spatial summation

A

-postsynaptic neuron receives multiple EPSPs at the same time
-EPSPs are “added together” simultaneously

104
Q

Inhibitory postsynaptic potential (IPSP)

A

-Binding of neurotransmitter causes the membrane to hyperpolarize
-K+ channels or Cl- channels open, making inside of cell more negative
-decreases the chance of generating an action potential

105
Q

Neurotransmitters

A

-chemical signals produced in the cell body & is transported to the axon terminal
-Most neurons produce at least 2 types
-Neurons can release one or more neurotransmitters simultaneously
-Effects: Can be excitatory, inhibitory, or can be either depending on the receptor type they bind

106
Q

Two types of neurotransmitter receptors

A
  1. Channel-linked receptors
  2. G-Protein Coupled Receptors
107
Q

Channel-linked receptors

A

-mediate fast synaptic transmission
-Receptors are ligand-gated ion channels
-When ligand binds: channel opens
-Na+ influx: depolarization
-Cl- influx: hyperpolarization

108
Q

G-Protein Coupled Receptors

A

Response is indirect & prolonged

109
Q

General process of G-protein Coupled Receptors

A
  1. Neurotransmitter binds to receptor
  2. G-protein is activated inside the neuron
  3. G-protein activates adenylate cyclase
  4. Adenylate cyclase produces cyclic AMP (cAMP)

Anatomy & Physiology (15 decks)

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