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physio Exam 2 > Lecture 8 Neurons and AP > Flashcards

Lecture 8 Neurons and AP Flashcards

1
Q

What are Neurons

A

specialized nerve cells that transmit messages

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2
Q

what is the structure of neurons

A
  1. cell body (soma)

2. processes

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3
Q

what does the cell body contain

A

Nucleus

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4
Q

What is the cell body the site of

A

site of metabolism

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5
Q

what are processes

A

fibers taht extend from the soma

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6
Q

what are the types of processes

A

dendrites: receive info
axons: sends info

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7
Q

Functional properties of Neurons

A

Irritability

conductiity

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8
Q

What is irritability

A

ability to respond to a stimulus

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9
Q

what is conductivity

A

ability to transmit an impulse

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10
Q

what is a Resting Neuron

A

Plasma Membrane is polariezd
High concentration of Na+ outside the cell
High concentration of K+ inside the cell
fewer + ions vs. outside –> Resting membrane potential (RMP= _ 70mV)

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11
Q

How is the RMP maintained

A
  1. Na+/K+ pump

2. Leak channels

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12
Q

Na+/ K+ pump does what?

A

generate concentration gradient
3 Na+ out
2 K+ in
cost 1 ATP

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13
Q

What are Leak Channels

A

Small Na+ leak at rest
why:
High force (large gradient) low permwability (Less Channels)
small K+ leak at rest
Why:
Low force (less gradient) high permeability (more channels)

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14
Q

Types of Channels on Neurons

A
  1. Leak Channels
  2. ligand- gated channel
  3. voltage gated channels
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15
Q

what are Leak Channels

A

always open

location throughout th neuron

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16
Q

what are Ligand gated channels

A

open or close when ligand binds to receptors on the membrane
location: usually dendrites and soma

17
Q

what are voltage gated channels

A

opens or closes when membrane potential changes

18
Q

what is Action potential

A

Rapid large depolarization for communication

19
Q

What are the stages of Action Potential

A
  1. Depolarization
  2. Repolarization
  3. hyperpolarization
20
Q

What is depolarization

A

Na+ gates causes Na+ to rush in
RMP: increase from -70mV –> +30 mV
upward movement = depolarization

21
Q

What is Repolarization?

A

K+ gate to open –> K+ to rush out
Na+ gate is clsoed
RMP= drops -30mV–> -70mV

22
Q

What is hyperpolarization?

A

K+ clsoing after RMP

RMP: drops below –> -70mV

23
Q

What is Action potential time?

A

Time: 1-2 ms

24
Q

What is Action Potential properties?

A
  1. All or nothing

2. undirectional propagation

25
Q

What is the all or nothing princple?

A

Threshold: get to or above threshold , minimum depolarization necessary to open Na+ channels–> AP

  • if stimulus is at or above the threshold –> Ap of same magnitude (100mV)
26
Q

All or nothing Terminology

A

subthreshold depolarization–> no AP
Threshold depolarization –> AP
Suprathreshold depolarization –> AP

27
Q

what is unidirectional propagation

A
  • Ap moves down axon toward the terminal

- deoolarization in one patch –> depolarization n adjacent patch

28
Q

what are Voltage gated Na+ channels

A

2 gates

  1. Activation gate
  2. Inactivation gate
29
Q

What is activation gate

A
  • Voltage dependent

- opened threshold and depolarization

30
Q

what is inactivation gate

A
  • voltage and time dependent
  • opened in 1st part of depolarization
  • closed: second part of depolarization
31
Q

3 stages of voltage gated channels (Inactivation/activation gate)

A
  1. Activation: cosed and inactivation gate closed
    • during resting state
    • activation gate capable of opening with stimulus
  2. Activation opened - Inactivation closed
    - during depolarization
    - allows sodium to rush into the cell
  3. Activation opened –> Inactivation closed
    - During 1 ms follwoing depolarization
    - will not open untill returned to resting state
32
Q

what are the 2 types of Refactory period

A
  1. absolute

2. relative

33
Q

what is absolute refractory period ?

A

second AP can not be generated
Na+ gates are inactivated
Time: a;; of depolarization and part of repolarization

34
Q

what is relative refractory period ?

A

second AP can be generated but with a stronger stimulus
Na+ gates closed some inactive
Time: end of polarization and hyperpolarization

35
Q

What are the consequences of Refractory period ?

A
  1. All or nothing
  2. unidirectional propagation
  3. frequency coding
36
Q

what is Frequency Coding

A

Intensity of the stimulus is coded in AP frequency
Higher intensity = Higher frequncy
lower Intensity = lower frequency

physio Exam 2 (5 decks)

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