44.1
What Cells Are Unique to the Nervous
System? 943
Neuronal networks range in complexity
943
Neurons are the functional units of
nervous systems 944
Glial cells are also important components
of nervous systems 946
44.2
How Do Neurons Generate and Conduct
Signals? 946
Simple electrical concepts underlie
neuronal function 947
Membrane potentials can be measured
with electrodes 947
Ion pumps and channels generate membrane
potentials 947
Ion channels and their properties
can now be studied directly 950
Gated ion channels alter membrane
potential 950
Sudden changes in Na+ and K+ channels
generate action potentials 951
Action potentials are conducted along
axons without loss of signal 953
Action potentials can jump along axons
954
44.3
How Do Neurons Communicate with Other
Cells? 955
The neuromuscular junction is a model
chemical synapse 955
The arrival of an action potential
causes the release of neurotransmitter
955
The postsynaptic membrane responds
to neurotransmitter 956
Synapses between neurons can be excitatory
or inhibitory 957
The postsynaptic cell sums excitatory
and inhibitory input 957
Synapses can be fast or slow 958
Electrical synapses are fast but do
not integrate information well 958
The action of a neurotransmitter depends
on the receptor to which it binds
958
Glutamate receptors may be involved
in learning and memory 959
To turn off responses, synapses must
be cleared of neurotransmitter 960
