neuron function part 1 Flashcards
What does the CNS consist of?
Brain and spinal cord
What does the CNS contain?
neurons and glia
Approx amount of nerons and synapses in brain
10^11 neurons
10^14-10^15 synapses
What are the four functional zones?
Signal reception
signal integration
signal conduction
signal transmission occurs at the synapse
What is signal reception?
where and how
dendrites and the cell body (soma)
incoming signal received and converted to change in membrane potential
Signal integration:
where and how
Axon hillock- signal is converted to an action potential
signal conduction
where and how
axon (some with myelin)
AP travels down axon
Signal transmission occurs where?
Occurs at synapse
axon terminals
release of NT
all neurons have what?
A resting membrane potential that is negative
What is depolarization
membrane become more positive
What is repolarization
membrane returns to resting value
what is hyperpolarization?
membrane becomes more negative than resting
What is membrane potential determined by?
by relative permeabilities of its membrane to specific ions
transmembrane concentration gradients of these ions
Resting membrane potential counteracts what?
the chemical gradient of ions so there is no net movement of ions across membrane
leak channels are what?
Always open allowing a specific ion to travel though
non gated and selective
when you have equal concentrations of ions across the cell what with the resting potential be?
0
For every ATP hydorlized how many Na and K exchanged
3Na+ ions are transported out
2K+ ions are imported into the cell
What does electrogenic do?
produces a current
what is the resting potential created by?
leak channels
What maintains the concentration gradients of na K?
Na/K ATPase
Ion gated channels:
How do neurons depolarize of hyperpolarize?
By selectively altering permeability
When do gated ion channels open or close?
in response to a stimulus ex. voltage or NT
Channels only allow what to pass though?
Specific ions to pass though the membrane
ions move down electrochemical gradient
As permeability to a specific ion increase what happens?
membrane potential will approch that ion’s equilibrium potential (Nerst equation)
Conductance approximates what?
permeability and its the reciprical of resistance
equation for conductance?
g=1/R
R= resistance
what is the electrochemical driving force?
how far a membrane potential is from equilibrium
What are examples of votage gated channels?
na, k, ca
Examples of ligand gated ion channels?
Glutamate receptors- NMDA,AMPA,Kainate
GABA
Nicotinic acetylcholine
what is Ohm’s law?
V=IxR
what is capacitance?
Ability to store charge (Q) when a voltage difference in V occurs between two surfaces
what determines if there is current flow
electrochemical driving force (how far membrane is from equilibrium
what are the three features of a capacitor?
material properties
area of two conducting surfaces
- larger area more capacitance
thickness of insulating layer
- greater thickness- decrease capacitance
cells have a capacitance of
1 micro f per cm squared
larger cells have what in terms of capacitance?
larger capacitance
can store more charge
what are the variabilities affecting the time constant?
resistance and capacitance
lower c and r results in what?
lower t
capacitor becomes full faster
faster depolarization
faster conduction
change in membrane potential decreases over distance due to what>
resistance
what is the time constant?
Time over which membrane potential will decay to 37
% of its max
variables effect time constant?
resistance
capacitance
