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PSC 135 > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

what is a neuron

A

-specialized animal cell that purpose is to send, receive, and conduct signals

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2
Q

Name another cell type in the nervous system?

A

glial cells : provide structural support and electrical insulation neurons

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3
Q

define membrane potential

A
  • the electrical charge difference across a cell membrane

- store up source of electrical energy

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4
Q

resting membrane potential

A

-when a neuron is not being excited or inhibited

  • approximately -70mV
  • inside more negatively charged than the outside
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5
Q

what maintains the resting membrane potential

A

-70 mV

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6
Q

voltage-gated channels

A

-an ion channel that opens or closes according to the value of the membrane potential (changes in nearby transmembrane voltage)

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7
Q

ligand-gated channels

A

-an ion channel that opens or closes in response to the binding of a specific chemical (Neurotransmitter) or physical stimuli

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8
Q

non-gated ion channels

A
  • unregulated ion channels that are always open

- always allow the associated ion to pass through

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9
Q

describe the differential ion concentrations in the neuron at rest….is the membrane potential positive or negative at rest

A
  • more negative at rest
  • Na+ outside
  • K+ inside
  • more Cl- outside
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10
Q

describe the driving forces (electrical and chemical) on Na+ and K+ rest (i.e. how would the ions move if a channel opened)

A
  • Na+= chemical and electrical forces IN

- K+= chemical OUT; electrical IN

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11
Q

purpose of Na+ K+ pump

A
  • helps maintain differential concentrations of Na+ and K+ ions
  • balances the ions by pumping Na+ out and K+ in
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12
Q

depolarization

A
  • making a membrane potential less negative

- Na+

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13
Q

hyperpolarization

A
  • making a membrane potential more negative
  • closer to the firing threshold.
  • K+
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14
Q

what happens during an action potential (STEPS)

A
  1. membrane is at rest
  2. depolarizing stimulus make the inside less negative and more likely to fire
  3. depolarization causes Na+ to rush IN making the cell more positive
  4. K+ channels open, K+ rushes OUT
  5. Na+ inside causes sodium influx causing Na+ channels to close (no more Na+ enters cell)
  6. inside more positive so K+ channels open and cause outflow of K+
  7. outflow of K+ causes the membrane to return to rest
  8. Na+ K+ pump resets and re-establishes resting membrane potential: K+ channels close, Na+ channels reset, extra K+ outside diffuses away
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15
Q

all-or-none law

A
  • an action potential either occurs or does not occur

- once triggered, it travels without getting smaller to the end

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16
Q

how is the threshold of excitation of an action potential reached

A
  • with enough excitatory postsynaptic potentials (EPSPs)
  • if enough Na+ ions have entered the cell with the neurotransmitter binding then they add up until it reaches a threshold causing an axon Potential to be generated at the axon hillock
17
Q

how can action potentials represent continuous information when action potentials fire in an all-or-none fashion

A

-variation of firing when on or off

18
Q

absolute refractory period

A
  • time when impossible to initiate another action potential
  • Na+ channels are inactivated

-impossible to fire another action potential, because ions are in the wrong place

19
Q

relative refractory period

A
  • time when it takes a stronger stimulus to initiate an action potential
  • during overshoot hyperpolarization
  • harder to fire AP, takes more stimulation
20
Q

absolute and refractory period similarities

A

-prevent the backwards movement of APs and limit the range of firing

  • keeps it moving in one direction
  • from the axon hillock, to the axon terminals
21
Q

why does an action potential tend to move in one direction in the neuron

A

refractory period : keeps it moving in one direction

22
Q

how does myelin affect the conduction of action potentials

A
  • allows AP to happen only at the Nodes of Ranvier

- causes information to travel faster

23
Q

define saltatory conduction

A

-conduction of action potentials by myelinated axons

  • action potential appears to jump from one node of Ranvier to the next
  • faster conduction
24
Q

synaptic transmission

A

the process by which presynaptic neuron communicates with the postsynaptic neuron

-the sending of neurotransmitter between neurons to keep the message going

25
Q

2 types of synaptic transmission

A
  • chemical synapse: slower, but signal strength maintained

- electrical synapse/gap junctions: faster, but signal can degrade

26
Q

what are dendritic spines, and what is their purpose

A
  • “tree” branches off the soma

- RECEIVE INFORMATION from the terminal buttons of other neurons

27
Q

describe the process of chemical synaptic transmission *

A
  • AP reaches the terminal, causes Ca2+ channels to open
  • Ca2+ flows into cell
  • fusion pore widens and Ca2+ causes vesicles to bind with cell membrane (Ca2+ ions attach to the receptors of the vesicles of the neurotransmitter)
  • release of neurotransmitter by exocytosis into the synaptic cleft
  • transmitter binds with receptor and neurotransmitter to leave terminal button into the synaptic cleft
28
Q

ionotropic receptor *

A

-contains a binding site for a neurotransmitter and is also an ion channel that opens when a molecule of thee neurotransmitter attaches to the bonding site

29
Q

metabotropic receptor *

A

-contains a binding site for a neurotransmitter; activates an enzyme that begins a series of events that opens an ion channel elsewhere

30
Q

EPSP *

A
  • DEPOLARIZATION, EXCITATORY

- often result from Na+ or Ca2+ going into the cell

31
Q

IPSP *

A
  • HYPERPOLARIZATION, INHIBITION

- results from Cl- going into the cell or K+ going out

32
Q

how is neurotransmitter action ceased in the synapse

A

-reuptake or enzymatic deactivation

33
Q

what is the advantage of reuptake over enzymatic degradation in the termination of the neurotransmitter postsynaptic effect?

A
  • terminates the effect in the synapse and takes the neurotransmitter back into the cell and recycles it to use later ,
  • it inhibits a neurotransmitter causing its effects to last longer
  • while the other destroys the neurotransmitter
34
Q

spatial summation

A

g

35
Q

temporal summation

A

g

36
Q

electrical synapse function

A

-Electrical synapses are formed by gap junctions, places where multiple transmembrane proteins in the pre- and postsynaptic neurons connect to create pathways that connect the cytoplasms of the two neurons.

  • rapid (used in escape neurons)
  • less plastic than chemical synapses
37
Q

4 types of glial cells

A
  • astrocytes: support and nutrients
  • oligodendrocytes: myelinate axons in the brain and spinal cord
  • microglia: clean up debris and protect from invading microorganisms
  • schwan: myelinate axons in the periphery body
38
Q

2 differences between Oligodendrocytes and Schwann cells

A
  • oligodendrocytes: in CNS form myelin, can myelinate multiple pieces of axons
  • schwan: in PNS form myelin, can only myelinate one-to one axon

PSC 135 (18 decks)

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