CH 2.2 Summary Flashcards
The great majority of synapses operate by transmitting a chemical neurotransmitter from the
Presynaptic cell to the postsynaptic cell.
Otto Loewi demonstrated chemical transmission by stimulating a
Frog’s heart electrically and then transferring fluids from that heart to another frog’s heart.
Many chemicals are used as neurotransmitters.
Most are amino acids or chemicals derived from amino acids.
An action potential opens calcium channels in the
Axon terminal, and the calcium enables release of neurotransmitters.
At ionotropic synapses, a neurotransmitter attaches to a receptor that opens
The gates to allow a particular ion, such as sodium, to cross the membrane. Ionotropic effects are fast and brief.
Most excitatory ionotropic synapses use glutamate, and
Most inhibitory ionotropic synapses use GABA.
At metabotropic synapses, a neurotransmitter activates a second messenger inside the postsynaptic cell
Leading to slower but longer-lasting changes.
Neuropeptides diffuse widely, affecting many neurons for a period of minutes.
Neuropeptides are important for hunger, thirst, and other slow, long-term processes.
Several drugs including LSD, antipsychotic drugs, nicotine, and opiate drugs
Exert their behavioral effects by binding to receptors on the postsynaptic neuron.
After a neurotransmitter (other than a neuropeptide) has activated its receptor
Many of the transmitter molecules reenter the presynaptic cell through transporter molecules in the membrane. This process, known as reuptake
It enables the presynaptic cell to recycle its neurotransmitter. Stimulant drugs and many antidepressant drugs inhibit reuptake of certain transmitters.
Postsynaptic neurons send chemicals to receptors on the presynaptic neuron to inhibit further release of neurotransmitter.
Cannabinoids, found in marijuana, mimic these chemicals.
Hormones travel through the blood, affecting receptors in many organs.
Their mechanism of effect resembles that of a metabotropic synapse.
