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BIOM3200 > Neuro 2 > Flashcards

Neuro 2 Flashcards

1
Q

Simple diffusion is a type of ____ transport

A

passive transport

- do not consume energy

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2
Q

Small uncharged molecules pass the lipid bilayer via _____

A 
simple diffusion (passive)
i.e. steroid hormones
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3
Q

Active transport requires

A

ATP (energy) because it is moving substances against their electrochemical gradient

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4
Q

All cells in the body have potential difference/voltage across membrane. What is this called?

A

resting membrane potential

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5
Q

What is the resting membrane potential in neurons?

A

-70 mV

all cells -ve inside

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6
Q

What is necessary in terms of electrical activity in axons to conduct an electrical signal in neurons?

A
  • voltage gated ion channels

- channels open and realse change in membrane potential of the cell

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7
Q

What are action potentials?

A

signals that go along nerve from one place to another

  • momentary discharges (depolarizations) of resting membrane potential
  • caused by rapid influx of Na+ from opening of sodium ion channels
  • once initiated, move along axon membrane towards synapse
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8
Q

What is the primary function of a nerve cell?

A
  • receive, conduct and transmit signals
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9
Q

Signals travel long distances, what doe they do to keep the signal going?

A
  • use voltage gated ion channels to continuously reamplify along the way
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10
Q

Explain the opening and closing of the ion channels with respect to action potentials.

A
  • channel closed (resting membrane potential)
  • gated channel opens in response to depolarization (action potential)
  • gated channel closes
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11
Q

What does depolarization mean?

A
  • cell becomes more positive than the resting potential (depolarize/hypopolarize)
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12
Q

With respect to ions, what is happening when the cell depolarizes? What happens to membrane potential?

A
  • rapid influx of Na+
  • explosive increase in Na+ permeability
  • membrane potential from -70 to +30 mV
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13
Q

Where is there a rapid decrease in Na+ permeability?

A
  • Na+ channels close
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14
Q

Due to the closing of Na+ channels closing, how does the cell compensate for all the positive charge inside?

A
  • repolarize
  • K+ (also positive) exits the cell
  • inside less positive
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15
Q

The amplitude of action potentials are always the same. Why?

A
  • amplitude peak = depolarization reaches the threshold
  • action potentials are all or none
  • must reach the maximum potential for the action potential to occur
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16
Q

Why doesn’t the membrane potential become more than 30mV?

A
  • the Na+ channels close quickly and the K+ channels open (to compensate)
17
Q

In non-myelinated axons, the action potential passes _______

A
  • smoothly,

all parts of membrane are depolarized

18
Q

What are myelinated conductions called?

A

saltatory conduction

19
Q

How do action potentials move in saltatory conduction?

A
  • nodes of ranvier (non-insulated parts)
  • action potentials jump between
  • rapid movement of action potentials,
  • need less energy to restore membrane after action potential transmitted
20
Q

What does the refraction period do?

A
  • helps ensure the action potential only goes in one direction down the axon (occurs in the nodes of ranvier after it has jumped)
  • i.e. repolarize
21
Q

The end of a neuron is called the _____

A

synapse

22
Q

In the CNS, the 2nd cell is a ____

A

neuron

23
Q

In the PNS, the second cell is ____

A

a neuron effector cell (in muscle/gland)

24
Q

A terminal bouton is found in the ____ neuron

A

presynaptic neuron
part of the synapse
- releases the NT

25
Q

EPSP =

A

excitatory post synaptic potential

i.e. depolarization of the post-synaptic neuron

26
Q

How does Ca2+ play a role in releasing neurotransmitters in the presynaptic neuron (synapse)

A
  • action potentail reaches axon terminal
  • voltage gated Ca2+ channels open
  • Ca2+ binds sensor protein in cytoplasm
  • Ca2+-protein complex stimulates fusion and exocytosis of neurotransmitter
27
Q

What happens once the NT is released from the presynaptic neuron?

A
  • it opens the chemically gated (ligand gated ) channels in the dendrites and cell bodies
  • inward diffusion of Na+ causes EPSP (the small depolarization that causes the big one cuz of the Na+ rush in)
28
Q

How are membrane potentials recorded?

A
  • electrical currents in spinal neuron grown in cell culture

- microelectrode: patch clamp

29
Q

What is myotonia?

A
  • neuromuscular disorder
  • delayed relaxation of skeletal muscle after voluntary contraction or electrical stimulation
  • caused by mutations in muscle Cl- channels
  • channel gates do not open properly
  • repolarization delayed (several AP firing instead of just one)

BIOM3200 (13 decks)

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