Chapter 11: Synapses, Neurotransmitters, and Pathways Flashcards
potential difference
the charge difference between the inside and outside of the cell that we want to maintain (homeostasis)
depolarization
when the inside of the cell becomes more positive.
Na+ ions leak in or go through the gated ion channels
repolarization
when the cell becomes more negative.
hyperpolarization
the cell becomes more negative than the resting membrane potential.
Either K+ exits of Cl- enters
graded potentials
a relatively small change in the membrane potential localized to one area of the plasma membrane.
all or none principle
a stimulus is produced, depolarizing the graded potential enough to reach threshold and therefore the permeability changes responsible for the action potential proceed without stopping.
refractory period
the time that it takes once an action potential is produced on the plasma membrane, and the time that the area becomes less sensitive to further stimulation.
action potential frequence
the number of action potentials produced per unit of time in response to a stimulus.
synapse
a junction between two neurons
electrical synapse
connected by gap junctions
connexons
groups of six tubular proteins which are the gap junctions?
chemical synapse
presynaptic terminal, synaptic cleft, and postsynaptic membrane
what are some of the significant neurotransmitters
acetylcholine
biogenic amines such as chatecholamine and indoleamine
amino acids
nitrogen-based compounds such as ATP
neuropeptides
some gases and lipids
convergent pathways
nultople neurons converge upon and synapse with a smaller number of neurons.
divergent pathways
a smaller number of presynaptic neurons synapse with a larger number of postsynaptic neurons to allow information transmitted in one neuronal pathway to diverge into two or more pathways.
