Chapter 12 part 2 Flashcards
(44 cards)
resting neuron
difference in electrical signal across the cell membrane
difference in electrical charge=
-2 things
electrical potential difference = transmembrane potential
difference in electrical charge refers to
difference in charge across the plasma membrane
transmembrane potential
- definition
- how do you measure it
- mV
- what does the sign refer to
- more + or - in the inside
- key concept
- varies from moment to moment depending on the cell
- using a volt meter
- 70mV
- to charges inside the cell
- more -
- all neutral activities begin with a change in the resting membrane potential
what makes the resting membrane potential -70mV
intracellular and extracellular fluids are different from eachother because plasma membrane is selectively permeable
resting cell membrane
- K+ outside the cell
- K+ inside the cell
- Na+ outside the cell
- Na+ inside the cell
- protein -
- low
- high
- high
- low
- negative inside the cell
what is located inside the resting
-3 things
- greater concentration of K+
- negatively charged protein
- other large anionic molecules
what is located outside the cell in the resting cell
-1 things
greater concentration of Na+
what is responsible for establishing these concentration gradients for Na+ and K+?
Largely due to the Na+/K+ exchange pump
how leaky are sodium leak channels
not very leaky because the membrane in a resting neuron is not very permeable to sodium
how leaky are potassium leak channel?
very leaky
action potential
- definition
- where does it begin
- involves
- an abrupt change in the electrical potential difference across the cell membrane which occurs after a stimulus
- at the hillock
- another set of channel proteins in the cell membrane (voltage gated sodium channel and voltage gated potassium channel)
4 steps for development of an action potential
- resting neuron
- application of stimulus
- depolarization
- repolarization
application of a stimulus
- definition
- voltage change
localized change in resting potential causes depolarization to threshold
- -70 mV to -60 mV
depolarization
- what happens to channels
- what happens to plasma membrane
- what happens to Na+
- voltage change
- voltage gated sodium channel opens when threshold is reached
- becomes permeable to Na+
- Na+ quickly flows down its concentration gradient
- -60 mV to +10 mV
Repolarization
- what happens to channels
- what happens to sodium permeability and sodium movement
- what happens to potassium permeability and movement?
- voltage
- voltage gated sodium channel closes around +30 mV and voltage gated potassium channel opens
- stops
- plasma membrane become permeable to K+ and it flows out of cell
- +30 mV to -90 mV to -70mV
absolute refractory period
period when membrane cannot respond to a new stimulus
relative refractory period
Na+ channels are returning to normal resting levels and membrane can respond to a larger than normal stimulus
impulse conduction would be faster in
-why
an axon with a larger diameter
-because a larger diameter offers lower resistance-ions can move more freely within the cytoplasm
All-or-nothing principle for an action potential
if a stimulus is strong enough to initiate an action potential, then the action potential will be conducted at a constant magnitude and rate along the length of the axon
an action potential at the beginning of the axon equals
an action potential at the end of the axon
how does the neuron transmit info about the strength and duration of stimulus that started the action potential?
- definition
- 1 AP/sec produces
- 100 AP/ sec produces
frequency of action potential propagation
- produces a muscle twitch
- produces muscle tenancy
2 types of communication between neurons
- electrical
2. chemical
electrical communication
-2 things
- presynaptic and post synaptic membranes are locked together at gap junction
- action potentials propagate from 1 cell to the other
