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health & disease > L18 - nerve cells & excitability: resting memb potential > Flashcards

L18 - nerve cells & excitability: resting memb potential Flashcards

1
Q

what is a neurone?

A
  • nerve cell
  • most in CNS (brain + spinal cord)
  • post mitotic cells (fully differentiated and unable to divide)
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2
Q

cell body of neurone

A
  • aka soma
  • cytoplasm
  • nucleus
  • mitochondria
  • LACK OF CENTRIOLES (used in cell division)
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3
Q

dendrites

A
  • branches on cell body
  • send electrochemical signals to cell body + axon
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4
Q

axon

A
  • transports A.P across from cell body to terminals
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5
Q

nerve fibre

A
  • some axons are very long
  • myelin sheath covers axons so A.P can jump from node to node to get past quicker
  • saltatory conduction
  • Schwann cells produce this lipid
  • when axon is covered with this it is known as nerve fibre
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6
Q

how do nerve cells communicate with each other?

A
  • through dendrites and axons
  • to terminals
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7
Q

multipolar neurone

A
  • one axon
  • lots of dendrites
  • most common
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8
Q

bipolar neurone

A
  • 2 axons which come out from each side of cell body
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9
Q

unipolar neurone

A

cell body is extended off axon (cell bodies still in the middle)

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10
Q

anaxonic neurone

A
  • no axon
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11
Q

afferent neurone

A

carries sensory information from the body’s periphery to the central nervous system (CNS)

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12
Q

efferent neurone

A

carries signals from the central nervous system (CNS) to muscles, glands, and organs in the body

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13
Q

interneurone

A

neurone which transmits impulses between other neurones, especially as part of a reflex arc

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14
Q

excitable cell

A
  • neurone is an excitable cell
  • cell that can be electrically excited to produce A.P
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15
Q

examples of excitable cells

A
  • neurones
  • muscular cells
  • some endocrine cells
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16
Q

examples of non-excitable cells

A

red blood cells

17
Q

what is resting membrane potential?

A

electrical charge across plasma membrane (inside is more negative than outside)

18
Q

what can resting membrane potential do in excitable cells?

A

change via stimulation

19
Q

resting membrane potential of excitable cells

A

-50mV to -85mV

20
Q

selective permeability of lipid membrane

A
  • lipid soluble molecules easily pass
  • charged ions/ proteins can’t without carrier/ transporter
  • so Na+, K+, Cl- can’t pass
21
Q

electrical gradient

A

gradient based of charge

22
Q

as you increase conc of oppositely charged ions, what happens?

A

increase in forces of attraction

23
Q

facilitated diffusion

A
  • ions diffuse down conc gradient
  • selectively permeable to diff ions
  • the one that doesn’t need to open and close
  • memb spanning protein
24
Q

active transporters (pump)

A
  • moves ions against conc gradient
    -na+/k+ channel
  • uses atp to open and close
25
Q

K+ channels are usually…

A

leaky

26
Q

Na+/K+ pump to maintain excitability

A
  • maintains conc of Na+ and k+
  • 2K+ IN
  • for every 3Na+ OUT
  • always working
27
Q

what is RMP in most neurones?

A

around -70mV (use this one when u see a graph)

28
Q

distribution of charged ions

A
  • conc of ions inside and outside are diff
  • ions move down conc gradient
  • movement restricted by memb
29
Q

why is cell membrane more permeable to K+ than Na+?

A
  • due to K+ leak channels
  • no Na+ leak channels
  • so Na+ cannot return to cell
30
Q

what happens when the Na+/K+ pump works?

A
  • as the Na+/K+ pumps transport K+ into the cell, the conc of K+ increases
  • memb potential becomes more negative
  • so conc gradient of K+ increases
  • K+ begins to diffuse out to area of lower K+ conc
  • RMP established when the diffusion of K+ out of the cell is balanced by the rate of K+ influx from the pump
  • once this inward rate of K+ flow from the pumps balances rate of K+ flow out of the cell through the leak channels a resting membrane potential stabilizes at approximately -70mV.
31
Q

equilibrium potential (Eion), Nernst equation

A

Eion = RT/ zF x logn [ion]outside / [ion]inside

  • R= gas constant, 8.314
  • absolute temp
  • F - faradays constant
  • z = valency of ion
    [ion] outside = ionic conc on outside of cell
32
Q

calculating resting memb potential (Vm), goldman equation

A

look at ppt

health & disease (19 decks)

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