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PSYCH 101 > Week 6 > Flashcards

Week 6 Flashcards

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1
Q

What is the nervous system composed of (cells)?

A
  • two basic cell types: glial cells (aka glia) and neurons
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2
Q

What is the typical role of glial cells?

A
  • play a supportive role to neurons, both physically and metabolically
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3
Q

What is the ratio of glial cells to neurons?

A
  • 10:1
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4
Q

What do glial cells do? (5)

A
  • provide scaffolding on which the nervous system is built
  • help neurons line up closely with each other to allow neuronal communication
  • provides insulation to neurons
  • transports nutrients and waste products
  • mediate immune responses
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5
Q

What do neurons do?

A
  • serve as interconnected information processors that are essential for all of tasks of the nervous system
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6
Q

How many neurons do we have at birth and what is their role? (2)

A
  • 100 billion strong at birth

- central building blocks of the nervous system

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7
Q

what is the semipermeable membrane and what does it do? (2)

A
  • make up the outer surface of a neuron
  • allows smaller molecules and molecules without an electrical charge to pass through, while stopping larger or highly charged molecules
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8
Q

what is the soma and what does it contain? (2)

A
  • cell body

- contains the nucleus of the neuron

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9
Q

dendrites (2)

A
  • branching extensions from the soma

- serve as input sites where signals are received from other neurons

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10
Q

nucleus

A
  • small information processor
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11
Q

axon

A
  • major extension of the soma
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12
Q

terminal button

A
  • axon terminal containing synaptic vesicles
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13
Q

synaptic vesicles

A
  • storage site for neurotransmitters
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14
Q

neurotransmitters

A
  • chemical messenger of the nervous system
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15
Q

where do the signals go after they enter through the dendrites?

A
  • transmitted electronically across soma and down the axon, which ends at multiple terminal buttons
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16
Q

what is the myelin sheath and what is it made up of? (2)

A
  • fatty substance that
    coat and insulate axons
  • made up of glial cells
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17
Q

what is the purpose of the myelin sheath? (2)

A
  • increases speed at which signals travel

- crucial for normal operation of neurons within the nervous system

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18
Q

multiple sclerosis (MS, 4)

  • what is it
  • what does this cause
  • symptoms
  • cure?
A
  • autoimmune disorder that involves large-scale loss of myelin sheath on axons throughout nervous system
  • interference in electrical signal prevents quick transmittal of information by neurons
  • symptoms include dizziness, fatigue, loss of motor control and sexual dysfunction
  • currently no cure
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19
Q

synapse

A
  • small gap between two neurons where communication occurs
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20
Q

receptors (2)

A
  • protein on the cell surface where neurotransmitters attach

- vary in shape, with different shapes matching different neurotransmitters

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21
Q

in healthy individuals, how are neuronal signals transmitted? (2)

A
  • neuronal signals move rapidly down axon to the terminal buttons, where synaptic vesicles release neurotransmitters into synapse
  • neurotransmitters travel across synapse and bind with corresponding receptors on dendrite of an adjacent neuron
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22
Q

how do neurotransmitters know which receptor to bind to?

A
  • lock and key relationship: specific neurotransmitters fit specific receptors
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23
Q

how does a neuron exist in a fluid environment? (2)

A
  • surrounded by extracellular fluid

- contains intracellular fluid

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24
Q

membrane potential

A
  • difference in charge across the membrane which provides energy for signals
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25
Q

what is the role of the neuronal membrane?

A
  • keeps extra and intracellular fluid separate which keeps the fluids electronically different
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26
Q

what causes the electrical charges in cellular fluids? (2)

A
  • charged molecules (ions) dissolved in the fluids
  • neuronal membrane restricts movement of charged molecules and some charged particles tend to become more concentrated on inside or outside of cell
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27
Q

resting potential (3)

  • what is it
  • what do ions do
  • where do ions move after
A
  • state of readiness of a neuron membrane’s potential between signals
  • ions line up on either side, ready to rush across membrane when neuron goes active and gates open
  • ions in high-concentration are ready to move to low concentration and positive ions are ready to move to areas of negative charge
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28
Q

What are the concentrations of sodium and potassium inside and outside the cell and how does this affect movement? (2)

A
  • sodium has higher [ ] outside the cell, so it will tend to move into the cell
  • potassium is more [ ] inside the cell, so it will tend to move out of the cell
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29
Q

How does the charge inside the cell affect sodium movement? (2)

A
  • inside of cell is slightly negatively charged compared to outside
  • provides additional force on sodium, causing it to move into the cell
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30
Q

threshold of excitation

A
  • level of charge in the membrane that causes neuron to become active
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31
Q

repolarization (2)

A
  • membrane potential returns to negative charge
  • at first, it hyperpolarizes, becoming slightly more negative than the resting potential, and then levels off restoring resting potential
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32
Q

action potential (2)

A
  • electrical signal that moves down the neuron’s axon

- constituted by the positive spike

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33
Q

how does the electric signal move through the axon?

A
  • like a wave; at each point, some of the sodium ions that enter the cell diffuse to the next section of the axon, raising the charge past the threshold of excitation and triggering a new influx of sodium ions
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34
Q

all-or-none phenomenon(2)

A
  • phenomenon that incoming signal from another neuron is either sufficient or insufficient to reach threshold of excitation
  • there is no in-between and no turning off the action potential once it starts
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35
Q

Explain traits of the action potential as a result of the all-or-none phenomenon. (2)

A
  • action potential is recreated/propagated at its full strength at every point along the axon
  • does not fade away as it travels down the axon
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36
Q

reuptake

A
  • neurotransmitter is pumped back into the neuron that released it to clear up synapse
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37
Q

After signals are delivered, what happens to excess neurotransmitters in synapse?

A
  • drift away and are broken down into inactive fragments or are reabsorbed in reuptake
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38
Q

What does clearing the synapse do? (2)

A
  • provides clear “on” and “off” state between signals
  • regulates the production of neurotransmitter (full synaptic vesicles indicate no additional transmitters need to be produced)
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39
Q

biological perspective

A
  • view that psychological disorders like depression and schizophrenia are associated with imbalances in one or more neurotransmitter systems
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40
Q

In the biological perspective, what helps improve disorders?

A
  • psychotropic medications can help improve symptoms associated with disorders
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41
Q

psychotropic medications (2)

A
  • drugs that treat psychiatric symptoms by restoring neurotransmitter balance
  • act as agonists or antagonists for a given neurotransmitter system
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42
Q

agonists

A
  • chemicals that mimic neurotransmitters at the receptor site, strengthening its effects
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43
Q

antagonists

A
  • block or impedes normal activity of neurotransmitter at the receptor
44
Q

What are agonists and antagonists drugs used for?

A
  • prescribed to correct specific neurotransmitter imbalances underlying a person’s condition
45
Q

Parkinson’s disease and treatment (2)

A
  • progressive nervous system disorder associated with low levels of dopamine
  • dopamine agonists are used to mimic effects of dopamine by binding to dopamine receptors
46
Q

Schizophrenia and treatment (2)

A
  • certain symptom are associated with overactive dopamine neurotransmission
  • antagonists for dopamine used as they block dopamine’s effects by binding to receptors without activating them
47
Q

reuptake inhibitors

A
  • prevent unused neurotransmitters from being transported back to neuron
  • leaves more neurotransmitters in synapse for longer time, increasing its effects
48
Q

depression and treatment (2)

A
  • consistently linked with reduced serotonin levels

- treated with selective serotonin reuptake inhibitors (SSRIs) that prevent uptake and strengthen serotonin effects

49
Q

What drug is similar to serotonin

A
  • LSD as it affects same neurons and receptors as serotonin
50
Q

What are the downsides of psychotropic medications? (3)

A
  • not an instant solution and must be taken for several weeks to see improvement
  • many have significant negative side effects
  • individuals vary dramatically in how they respond to the drugs
51
Q

What is done to improve chances of success when taking psychotropic drugs?

A
  • combine drug therapy and other forms of therapy (psychological and/or behavioural)
52
Q

Sharps microelectrode technique (2)

A
  • type of intracellular recording using a fine tip intracellular electrode that is made of glass and filled with salt solution and an extracellular electrode
  • can compare electrical potential inside and outside of cell
53
Q

What us the membrane potential/voltage of a healthy neuron and what does it mean? (2)

A
  • 60 to -80 mV

- voltage inside the neuron is -60 to -80 mV less than the voltage in the outside of the cell

54
Q

Why is there polarization of about -70 mV? (2)

A
  • unequal distribution of ions
  • heavy negative charge inside the cell because of negatively charged proteins (making inside more negative than outside)
55
Q

Why is there an unequal distribution of ions? (4)`

A
  1. Differential Permeability
  2. Movement down concentration gradient
  3. Electrostatic pressure
  4. Sodium-potassium pump
56
Q

differential permeability

A
  • due to presence of ion channels that allow only certain ions to pass through the neuronal membrane (Na+ ion channel is very resistant at resting potential and K+ ion channel is not very resistent)
57
Q

What movements occur because ions tend to move down their concentration gradients? (2)

A
  • Na+ will tend to enter

- K+ will tend to exit

58
Q

negative internal charge/ electrostatic pressure (2)

A
  • creates pressure for both Na+ and K+ to enter the cell

- created by negative protein ions present in cell

59
Q

Sodium-potassium pump

A
  • transports 3 Na+ out for every 2 K+ it transports in
60
Q

membrane potential

A
  • difference in charge between the interior and exterior of the cell
61
Q

polarized membrane

A
  • when the membrane is at its resting potential (about -70 mV)
62
Q

What are the two localized effects that occur when a transmitter molecule binds to a postsynaptic receptor and examples? (2)

A
  1. depolarize the membrane
    - decrease membrane potential from -70 to -67
  2. hyperpolarize the membrane
    - increase membrane potential from -70 to -72
63
Q

excitatory postsynaptic potential (EPSP) and effects (2)

A
  • excited when a neurotransmitter molecule binds to a postsynaptic receptor and depolarizes the membrane
  • increases likelihood that postsynaptic neuron will fire an action potential (AP
64
Q

inhibitory postsynaptic potential (IPSP) and effects (2)

A
  • induced when a neurotransmitter molecule binds to a postsynaptic receptor and hyperpolarizes the membrane
  • decreases likelihood that postsynaptic neuron will fire an AP
65
Q

What are the characteristics of the transmission of postsynaptic potentials (PSPs) (3)

A
  • graded, rapid and decremental
  • PSPs travel like am electrical signal along uninsulated wire
  • travel quickly and get smaller along length of neuron
66
Q

how long does an action potential typically last?

A
  • 1-2 milliseconds
67
Q

How do EPSPs and IPSPs sum?

A
  • spatially and temporally
68
Q

Spatial Summation (3)

A
  • 2 simultaneous EPSPs sum to produce a greater EPSP
  • 2 simultaneous IPSPs sum to produce a greater IPSP
  • a simultaneous EPSP and IPSP cancel each other out
69
Q

Temporal summation

A
  • sum over time of EPSP and IPSP
  • 2 EPSPs in rapid secession summate to produce a larger EPSP
  • 2 IPSPS in rapid succession summate to produce a larger IPSP
70
Q

when is an action potential generated?

A
  • sump of EPSPs and IPSPs that reaches axon initial segment is sufficient to depolarize the membrane above its threshold of excitation
71
Q

action potential (video definition)

A
  • massive momentary reversal of membrane potential (from -70 to +55)
72
Q

What are the characteristics of the action potential?

A
  • not graded or decremental and less rapid
73
Q

What does the term “graded” mean?

A
  • tendency to be of varying sizes
74
Q

What does the term “decremental” mean?

A
  • tendency to get smaller in size when travelling across a neuron
75
Q

voltage-activated ion channels

  • what does it cause
  • how does it work
A
  • cause generation and conduction of action potentials

- opens when the membrane potential reaches a certain potential

76
Q

What happens right after the threshold of excitation is reached? (4)

  • what happens
  • effects on Na+
  • effects on K+
  • phase name
A
  • voltage-activated Na+ channels open and Na+ enters the cell
  • influx of Na+ ions rapidly reverses cell membrane potential to about +55 mV
  • soon the voltage-activated K+ channels open and K+ slowly leaves the cell
  • characterizes the rising phase of the action potential
77
Q

What happens at the peak of the action potential? (2)

A
  • Na+ channels close

- K+ channels still open and K+ is still leaving the cell

78
Q

What happens after the peak of the action potential? (2)

A
  • K+ channels do not close until membrane potential is near resting potential helping the membrane potential to repolarize
  • called the repolarization phase
79
Q

hyperpolarization phase

A
  • when K+ channels are closing and excess K+ ions exiting the cell cause the membrane potential to hyperpolarize
80
Q

refractory period

A
  • impossible or very difficult to illicit another action potential
81
Q

Where is the action potential initially ggenerated?

A
  • axon initial segment which lies at the very beginning of the axon
82
Q

subthreshold stimuation

A
  • stimulation below the threshold of excitation
83
Q

What happens as a consequence of a subthreshold stimulation? (2)

A
  • excitatory potential is produced, but is not sufficient to elicit an action potential
  • degrades along the length of the axon
84
Q

suprathreshold stimulation

A
  • stimulation above the threshold of excitation
85
Q

What happens as a consequence of a suprathreshold stimulation? (2)

A
  • excitatory potential produced that exceeds threshold of excitation and produces an action potential
  • does not degrade along the length of the axon
86
Q

Conduction in an unmyelinated axon (2)

A
  • chain reaction that causes subsequent sodium channels to open
  • as action potential travels between sodium channels it is degretory
87
Q

conduction in a myelinated axon

A
  • action potential travels through myelin sheath
88
Q

nodes of ranvier (2)

A
  • areas rich in sodium and potassium channels

- regeneration of action potential occurs here

89
Q

neuromuscular junction and characteristics (3)

A
  • synapse where classic model of neurotransmission was based
  • axon splits in many non-myelinated branches, each cell has a single input and are typically large synapses compared to those in the central nervous system
  • single neurotransmitter, acetylcholine (ACH), is released at his synapse
90
Q

What does it mean if each cell has a single input?

A
  • each motor neuron can supply many muscle fibers but muscle fibers can only receive input from one motor neuron
91
Q

What generalizations were made that are true for neuromuscular junctions that are not true for all nervous system synapses? (7)

A
  1. each cell has a single output
  2. neurotransmission occurs at directed synapses
  3. neurotransmitters are deactivated by enzymes (eg. acetylcholinesterase)
  4. neurotransmitters are packaged in vesicles
  5. neurotransmitters produce EPSPs or IPSPs
  6. each neurotransmitter has a single receptor
  7. each cell releases a single neurotransmitter
92
Q

Each cell has a single input (2)

A
  • true at neuromuscular junction where each muscle fiber receives input from only one motor neuron
  • neuromuscular junction is an exception, most cells in nervous system receive input from many cells
93
Q

Neurotransmission occurs at directed synapses (2)

A
  • true at neuromuscular junction: boutons from motor neuron lie directly adjacent to muscle fibers
  • not necessarily true elsewhere” non-directed synapses are also possible, no clear relationship between pre and postsynaptic element where neurotransmitters can be released in extracellular fluid and interact with cells they come into contact with
94
Q

varicosities

A
  • bulbous shapes in axons that contain vesicles with neurotransmitters
95
Q

Neurotransmitters are deactivated by enzymes (2)

A
  • true at neuromuscular junction where enzyme acetylcholinesterase deactivates acetylcholine (ACh)
  • rare at non-cholinergic synapses where reuptake is major mechanism for deactivation of neurotransmitters
96
Q

Neurotransmitters are packaged in vesicles (2)

A
  • true at neuromuscular junction: ACh is packaged in vesicles prior to release into the synapse
  • true for many neurotransmitters but not for all: unconventional transmitters are not packaged in vesicles
97
Q

unconventional transmitters (2)

A
  • soluble gases (nitric oxide and carbon monoxide)

- anandamide, THC mimics this

98
Q

Neurotransmitters produce EPSPs or IPSPs (2)

A
  • true at neuromuscular junction for skeletal muscles where ACh produces EPSPs
  • whether or not a neurotransmitter produces EPSP or IPSP was later shown to be a function of receptor type/subtype
99
Q

Each neurotransmitter has a single receptor (2)

A
  • discovered that some ACh receptors bind nicotine better than muscarine, whereas for others the reverse is true
100
Q

How are nicotinic receptors and muscarinic receptors distributed in the PNS?

A
  • many nicotinic receptors exist at synapses between motor neurons and skeletal muscle fibers, whereas many muscarine receptors are in the autonomic NS
101
Q

What kind of receptors are nicotinic receptors?

A
  • ionotropic

- when neurotransmitters binds it opens an ions channel that allows an ion to flow in or out of cell

102
Q

What kind of receptors are muscarinic receptors?

A
  • metabotropic
  • when neurotransmitters binds it causes G protein to activate that produces second messenger molecules that open nearby ion channels or act on nucleus of cell to effect the production of proteins
103
Q

Each cell releases a single neurotransmitter (2)

A
  • “coexistence” of different transmitters has been found in many cells in the nervous system
  • some neurons are capable of changing type of neurotransmitter they release during their lifetime
104
Q

In general, what are the characteristics of neurotransmission?

A
  • complicated and heterogenous activity
105
Q

tripartite synapse (3)

A
  • in addition to the presynaptic and postsynaptic elements, a third element exists as a process from an astroglia cell
  • serves to wrap synapse to insulate and trap neurotransmitters within the synapse
  • also binds neurotransmitters and may even release its own transmitters itself
106
Q

glial network (2)

A
  • glial cells are capable of transmission between themselves
  • glial cells for networks between themselves and send signals to each other and to neurons

PSYCH 101 (5 decks)

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