Midterm 1 - Unit 1 Lecture 2 Flashcards
what is membrane potential
difference in distribution of ions(charged atoms) inside and outside the cell
what are elements inside the cell
potassium (K+)
sodium (Na+)
chloride (Cl-)
what are the elements outside the cell
Lots of Na+ & Cl-
Some K+
what is the distribution of ions at resting state
more negative ions inside than outside the neuron
what is the quantitative value for resting membrane potential
-70 mV
what is an action potential
very rapid change in the membrane potential that occurs when a neuron is stimulated.
what triggers and action potential
If membrane voltage reaches threshold
what happens during an action potential
Membrane potential goes from the resting potential to some positive value (approx. +30mV)
why does the membrane potential change during an action potential
Due to sodium channel opening to allow an influx of Na+ ions inside the cell (Depolarization)
what is depolarization
the rapid rise in potential, an all-or-nothing event that is initiated by the opening of sodium ion channels within the plasma membrane
what is hyperpolarization
a change in a cell’s membrane potential that makes it more negative.
what is myelin
fatty substance covering axons allows faster conduction of nerve impulses
what are the nodes of ranvier
axonal segments that lack myelin, allowing the action to jump from node to node
what is a synapse
small gap between two neurons, where nerve impulses are relayed by a neurotransmitter, from a presynaptic terminal of one axon to the postsynaptic receptors of another
what happens during neurotransmitter release
Vesicles release neurotransmitters across synaptic cleft onto other neurons
Released neuro- transmitters bind to postsynaptic receptors, which in turn open ion- channels
