CHAPTER 2 - Chemical Events at the Synapse (Module 2.2) Flashcards
who is otto loewi?
he is the guy who discovered the chemical transmission of nerve impulses with a frog’s heart
What was Loewi’s evidence that neurotransmission depends on the release of chemicals?
When Loewi stimulated a nerve that increased or
decreased a frog’s heart rate, he could withdraw fluid from the area around the heart, transfer it to another frog’s heart, and thereby increase or decrease its
rate also.
Blood flow increases to the most active brain areas. How does the blood “know” which areas are most active?
In a highly active brain area, many stimulated neurons release nitric oxide, which dilates the blood vessels in the
area and thereby makes it easier for blood to flow to the area
what are neurotransmitters?
chemicals released by a neuron that affects another neuron
what is nitric oxide?
it is a gas released by many local neurons that is poisonous in large quantities yet neurons contain an enzyme that allows them to make it efficiently
what do neurons synthesize almost all neurotransmitters from?
amino acids
what is epinephrine, norepinephrine and dopamine known as?
they are known as catecholamines because they contain a catechol group and an amine group
Name the three catecholamine neurotransmitters.
Epinephrine, norepinephrine, and dopamine.
Do not confuse the term catecholamine with acetylcholine
what is exocytosis?
bursts of release of neurotransmitter
from the presynaptic neuron
When the action potential reaches the presynaptic terminal, which ion must enter the presynaptic terminal to evoke release of the neurotransmitter?
Calcium
what are the channels controlled by a neurotransmitter called?
transmitter-gated or ligand-gated channels
what is a ligand?
it is a chemical that binds to something
what is the most abundant neurotransmitter in the nervous system?
glutamate
Why does the nervous system use so many chemicals, if they all produce the same type of message?
they do not produce the same type of message since it is more complicated and more varied, when a neurtransmitter attaches to its receptor, it may exert a IONOTROPIC EFFECT or a METABOTROPIC EFFECT
what is a G protein?
a protein coupled to guanosine triphosphate (GTP), an energy-storing molecule
what are neuropeptides also referred to as?
neuromodulators, because they have properties that set them apart from other transmitters
How do ionotropic and metabotropic synapses differ in speed and duration of effects?
Ionotropic synapses act more quickly and more briefly
What are second messengers, and which type of synapse
relies on them?
Second messengers are chemicals that alter
metabolism or gene expression within a postsynaptic neuron.
At metabotropic synapses, the neurotransmitter attaches to a receptor and thereby releases a second messenger
How do neuropeptides compare to other transmitters?
Neuropeptides are released only after
prolonged stimulation, but when they are released, they are released in large amounts by all parts of the neuron,
not just the axon terminal.
Neuropeptides diffuse widely, producing long-lasting effects on many neurons.
How do LSD, nicotine, and opiate drugs influence behavior?
SD binds to one type of serotonin receptor.
Nicotine
binds to one type of acetylcholine receptor.
Opiates bind
to endorphin receptors.
what is reuptake
is a biological process in psychology that involves the reabsorption of neurotransmitters after they have transmitted a neural impulse
what does reuptake occur through?
special membrane proteins called TRANSPORTERS
what inhibits the transporters for dopamine, serotonin, and norepinephrine
stimulant drugs, including amphetamine and cocaine
What happens to acetylcholine molecules after they stimulate a postsynaptic receptor?
The enzyme acetylcholinesterase breaks acetylcholine molecules into two smaller molecules, acetate and choline, which are then reabsorbed by the presynaptic terminal
What happens to serotonin and catecholamine molecules
after they stimulate a postsynaptic receptor?
Most serotonin and catecholamine molecules are reabsorbed by the presynaptic terminal. Some of their molecules are broken down into inactive chemicals, which then diffuse away
How do amphetamine and cocaine influence synapses?
They block reuptake of released dopamine, serotonin, and norepinephrine.
Why is methylphenidate generally less disruptive to behavior than cocaine is despite the drugs’ similar mechanisms?
The effects of a methylphenidate pill develop and decline in the brain much more slowly than do those of cocaine.
what will happen to transmitter molecules that the transporters do not take?
they will break down by an enzyme called COMT
what are autoreceptors?
receptors that respond to
the released transmitter by inhibiting further synthesis and
release.
what are the active chemicals in marijuana called?
cannabinoids
How do cannabinoids affect neurons?
Cannabinoids released by the postsynaptic neuron
attach to receptors on presynaptic neurons, where they inhibit further release of both glutamate and GABA.
is a chemical secreted by cells in one part of the body and conveyed by the blood to influence other cells.
a hormone
Which part of the pituitary—anterior or posterior—is neural tissue, similar to the hypothalamus?
The posterior pituitary is neural tissue, like the hypothalamus
Which part of the pituary is glandular tissue and produces hormones that control the secretions by
other endocrine organs?
The anterior pituitary is glandular tissue and produces hormones that control several other endocrine organs
In what way is a neuropeptide intermediate between neurotransmitters and hormones?
Ordinary neurotransmitters are released in small amounts close to their receptors.
Neuropeptides are released into a brain area in larger amounts or not at all. When released, they diffuse more widely. Hormones
are released into the blood for diffuse delivery throughout
the body.
