Lecture 3- Neurophysiology Flashcards
what is the nervous system bathed in
electrolyte fluid that has a high concentration of ions
what are neurons filled with
electrolyte fluid with different ion concentrations than that of in extra cellular space
what is current
electric current is the flow rate of electric charge past a specific point.
The net flow of electric charge
carried by ions in the electrolyte
- ——-In neurons a current is produced when ions flow thru specialized pores in the cell membrane
what is voltage
Electrical potential difference between the inside and outside of the cell
by controlling the difference of the concentraiton of the ions on either side of the membranes creates a difference and drives action potentials and pumps K+ in and Na+ out
how do neurons create a voltage
By moving ions across the cell membrane thru specialized pores
Ion channels
active transporters
neurons excitable membranes
phospholipid bilayers impermeable to ions.
trans membrane channels are the only way in or out
Active transporters move against gradient and ion channels flow with gradient
molecular diffusion force
Moving from high to low concentration with the gradient
to become equally distributed
what molecules go in and out of neurons and what is their concentration like
K+ Na+ Cl- Ca2+
K+ only molecule with high concentration inside the cell
K+ channels
Open and close slow
allows K+ in and out and more gets in because cant slam shut
Na+ channels
Sodium channels open and close very fast
can be closed, open, or inactive
cutaneous receptors cause gates to open allow Na+ in and reach voltage threshold and inside gets positive and action potential occurs and after shuts closed by becoming inavtiaated
Ligand gated channels
Lock and Key
Ligand the neuro transmitter binds to gate and causes it to open
allows for flow of molecules
thermally and mechanically gated ion channels
Heat sensitive allow Na+ inside and opens when exposed to heat, almost like denaturing
or mechanically like lifting a gate
PRIMARILY FOUND IN SENSORY NEURONS
AFFERENT NEURONS
COMPLEX PROTEIN STRUCTURES
Electrochemical equilibrium in neurons and how equilibrium is reached
the pumps move K+ across the channels, with the concentration gradient.
but then the inside gets more negative pulling positive molecules back over
Ionis current will flow until electro chemical equilibrium is reached, when ELECTRO-STATIC forces are equal and opposite to Chemical diffusion(so the number of K+ on that side is the same to the other side)
Glutamate and Gaba
glutamate is an excitatory transmitter that speeds up firing neurons opens it and causes Na+ to rush in
Gaba inhibits and opens chloride channels so the voltage decreases and it is harder to reach action potential
