Topic 3 - NERVOUS SYSTEM I (Neuronal Physiology - Electrically Excitable Cells | GP to AP) Flashcards

1
Q

electrically excitable cells

A
  • ONLY muscle and nerve cells
  • capable of producing departures from RMP in response to stimuli (=changes in the external or internal environment)
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2
Q

electrically excitable cells:

when a neuron is stimulated

name 3 things that happen

A
  1. gated channels open
  2. membrane potential changes, producing a graded potential. If the threshold potential is reached
  3. triggers an action potential
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3
Q

Graded potential

  • stimulus causes what? located where? how?
A
  • stimulus causes a small change in membrane potential, usually on dendrite or cell body (no longer at rest) by opening gated channels (changes membrane permeability)
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4
Q

what are the 2 possible results of graded potentials?

A
  1. more positive than RMP = depolarization
    • ​​e.g. -70mV to -65mV (closer to 0)
  2. more negative than RMP = hyperpolarization
    • ​​e.g. from -70mV to -75mV
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5
Q

name 1/4 characteristics of graded potentials

1

    1. graded potentials are short distance signals - die away quickly (short-lived)
  1. magnitude and distance traveled by potential varies directly with the strength of the stimulus
  2. graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
A

ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane

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6
Q

name 1/4 characteristics of graded potentials

2

  1. ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
    1. magnitude and distance traveled by potential varies directly with the strength of the stimulus
  2. graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
A

graded potentials are short distance signals - die away quickly (short-lived)

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7
Q

name 1/4 characteristics of graded potentials

3

  1. ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
  2. graded potentials are short distance signals - die away quickly (short-lived)
    1. graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential
A

magnitude and distance traveled by potential varies directly with the strength of the stimulus

example:

larger stimulus ⇒ larger graded potential that travels further across the membrane

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8
Q

name 1/4 characteristics of graded potentials

4

  1. ions move passively (unlike charges attract (+ & -) = current flow, causing depolarization or hyperpolarization on adjacent membrane
  2. graded potentials are short distance signals - die away quickly (short-lived)
  3. magnitude and distance traveled by potential varies directly with the strength of the stimulus
    4.
A

graded potentials can summate - 1st graded potential present when 2nd stim occurs ⇒ these add (sum) to create the resulting larger graded potential

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9
Q

what happens after a graded potential occurs?

A

repolarization = return to RMP after depolarization or hyperpolarization

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10
Q

Graded potential to Action Potential

  • Graded potentials are essential in what?
  • IF
A
  • essential in initiating a nerve impulse (action potential)
  • IF it is depolarized and IF it is large enough or multiple GPs sum to be large enough (if there is a critical stimulus) ⇒ leads to an action potential
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11
Q

what are the 3 steps from GP to AP

A
  1. critical stimulus
  2. Graded potential reaching threshold
  3. action potential
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12
Q

GP to AP

the story so far (draw diagram)

A
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