physiology of the nervous system Flashcards
what does the extracellular solution contain more of
more sodium and chloride ions
3 different types of ion channels
- ligand-gated ion channels
- voltage gated ion channels
- mechanically gated ion channels
when do ligand gated channels open
triggered to open when they are bound by specific molecule - LIGAND
what do mechanically-gated ion channels respond to
only open in response to physical forces eg changes in length/ pressure
what is the graded potential
when the resulting change in membrane potential is small and doesnt open voltage-gated ion channels
how does the sodium potassium pump work
quickly replaces equilibrium by removing 3 sodium ions and recieving 2 potassium ions
what is the definition of resting potential
resting potential is the difference in electrical potential across plasma membrane when cell not stimulated/ in a state of relaxation
what does the intracellular solution of resting potential contain more of
potassium ions
- more negative than extracellular
what is the normal difference between intracellular and extracellular compartments
70mV
- intracellular -70mV
- extracellular 0mV
when is electrochemical equilibrium achieved
resting membrane potential reached
why do neurons have few transport channels
- leak channels - always open
- resting potential gradually lost
how much more permeable is potassium
100x more permeable than sodium
4 steps of nerve action potential
- resting potential - Na/K+ pump
- depolarisation - voltage-gated Na+ channel
- repolarisation - voltage gated K+ channel
- resting potential
synaptic junction
- junctions - nerve to nerve, nerve to muscle, nerve to endocrine tissue
- one way transmission
- brief delay
- mediated by specific neurotransmitters
