Membrane potentials

Question 1

membrane potential

Answer 1

• the difference in electric potential between the outside and inside of the cell
  
  • usually -50 to -70

Question 2

Nerst potential

Answer 2

• the cell membrane potential when the ion of reference no longer wants to move
  
  • chemical gradient equals electrical gradient

Question 3

Nerst equation

Answer 3

E = 61 * log [K_o]/[K_I]

answer in mV

Question 4

Answer 4

measuring the electrical flow of sodium through a channel. rises in the graph are when the channel is open

Question 5

voltage gated channel

Answer 5

opens when the cell potential reaches a certain voltage

Question 6

ligand-gated channel

Answer 6

opens when a ligand adheres to channel

ex. G protein coupled receptor

**can be intracellular or extracellular

Question 7

mechanically gated channel

Answer 7

opens when physically opened

Ex: by touch or vibrations for hearing

Question 8

Goldman-Hodgkin-Katz equations

Answer 8

E = -61 * log (C_Nai*P_Na+C_ki*P_K+C_Clo*P_cl) / C_Nao*P_Na+C_Ko*P_K+C_Cli*P_Cl

Question 9

conductance

Answer 9

permeability

Question 10

Answer 10

• Na
  
  • Activation gate is voltage sensitive
  • Inactivation “gate” is time sensitive
• K
  
  • Activation gate is voltage sensitive
  • same gate closes based on voltage change
• Na gate being inactive is what forces the potential to go in one direction

Question 11

Absolute refractory period

Answer 11

• no action potential can be generated
  
  • Na gate is inactivated

Question 12

Relative refractory period

Answer 12

• action potential can be stimulated, but will require stronger stimulus

Question 13

dendrites

Answer 13

Extension of the nerve cell that receives messages from other cells

• signals received result in changes in local membrane potential
• All the dendrites receive signals that hyperpolarize or depolarize, eventually the entire neuron will get enough depolarization to initiate an action potential at the axon hillock and is send down the axon to synapses with other neurons and muscle cells.

Question 14

axon hillock

Answer 14

• last spot where the membrane potentials are summed up before being translated to the axon

Question 15

acetylcoline

Answer 15

neurotransmitter

Question 16

hyperpolarizers

Answer 16

Cl^-

K+ (leak channel)

Question 17

depolarizers

Answer 17

Na⁺

Ca⁺⁺

Question 18

SSRIs

Answer 18

slow the re-uptake of seratonin (neurotransmitter) so it has a longer affect

Question 19

Excitatory vs inhibatory fibers

Answer 19

• There are more excitatory neurotransmitters
• the inhibitory get used more

Question 20

Answer 20

• inhibatory fibers can either attach directly to the excitatory fiber
• or attach to the neuron nearer to the Axon Hillock

Question 21

schwann cells

Answer 21

cell that provides the myelin sheath around the neuronal axon

Question 22

oligodendrocytes

Answer 22

provide myelin sheath for axons in central nervous system

Question 23

node of ranvier

Answer 23

gap in myelin sheath between schwann cells that allows for saltatory conduction and allows signal to move faster

Question 24

size and myelination vs velocity of signal

Answer 24

• bigger and mylenated axons move signals faster
• smaller unmyelinated fibers move slower