13.2 Nervous System Flashcards

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0
Q

Neurobiological reserach on nervous system made on…

A

Giant squid (axon up to 1mm in diameter)

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1
Q

The function of the nervous system is to?

A

Produce behaviour

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2
Q

3 tasks performed by nervous system?

A
  1. Detection and analysis of sensory signals
  2. Decision making
  3. Generation of coordinated motor output
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3
Q

Nervous system in…
A) Sea anemone?
B) Earthworm + squid?
C) Human?

A

A) Nerve net
B) Ganglia + nerves
C) CNS + PNS

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4
Q

Nervous systems consist of nerve cells and….

A

Glia (electrical isolation or nerve cells + blood-brain barrier + uptake of transmitter)

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5
Q

Role of neurons?

A

Generate and transmit electrical signals

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6
Q

Role of glial cells?

A

Provide nutrients, oxygen, maintain extracellular environment, make the bloodbrain barrier, fight infections, insulate neurons

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7
Q

Which is more present - neurons or glial cells?

A

Glial cells (5-10x)

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8
Q

How do neurons work?

A

Electrochemically

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9
Q

What prevents the free movement of ions?

A

Lipid biulayer

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10
Q

What control the ion flux across the membrane?

A

Ion channels and ion transporter proteins

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11
Q

Typical ion concentration - intracellular?

A

A lot of K+, a medium amount of Na+, a bit of Cl-, a lot of A-

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12
Q

Typical ion concentration - extracellular?

A

Little K+, lots of Na+, lots of Cl-, no A-

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13
Q

What is the membrane potential?

A

The electrical potential difference across membrane

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14
Q

What is the resting potential?

A

-65 mV

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15
Q

The interaction of …. determines membrane potential

A

Two forces

  1. Diffusion: favours net movement of ions down their concentration gradient (intra–>extracellular)
  2. Electromagnetic force: favours net movement of ions according to potential difference (extra–>intracellular)
16
Q

What is equilibrium potential?

A

When the diffusion force and the electromagnetic force are balanced for a given ion

17
Q

What ion shows sizable leak current at rest?

A

K+

18
Q

Resting membrane potential is dominated by ….. equilibrium potential

A

K+

19
Q

What happens when channels open?

A

Ions follow their electrochemical gradient, which moves the membrane potential towards the equilibrium potential of that ion

20
Q

How are ion channels gated?

A
  • Voltage-gated
  • Mechanically-gated
  • Chemically-gated
21
Q

Use of energy by ion channels?

A

None

22
Q

At resting potential - what happens to voltage-gated Na+ channels?

A

They are closed

23
Q

When membrane is depolarized, what happens to voltage-gated Na+ channels?

A

They open

24
Q

What happens during the depolarization phase?

A

Na+ flows into the cell

25
Q

What happens during the repolarization phase?

A

K+ flows out of the cell

26
Q

What happens when threshold level of depolarization reached at - 50mv?

A

Depolarization becomes regenerative: action potential

27
Q

What happens after repolarization?

A

Membrane is briefly hyperpolarized, but then returns to resting potential with only K+ leak channels open

28
Q

The ion flux during a single spike …….. the concentration gradients.

A

Barely changes. (Neurons can fire many spikes before concentration gradients are lost)

29
Q

How are cocnentration gradients of ions maintained in the long run?

A
By active (energetically expensive) processes
- Na+/K+ pump moves 3 Na+ out for every 2 K+ it moves in - requires ATP
30
Q

Action potentials are …… events

A
  • All-or-none events - they do not decay with distance along the axon (they get “regenerated” along the axon)
31
Q

What are graded potential?

A
  • Strength and temporal pattern of input determines membrane potential
  • Decays with distance along nerve fiber
  • Only works over short distances
32
Q

.

A

.