Ch. -2 Kjemiske prosesser i synapser Flashcards
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.
Name the three catecholamine neurotransmitters.
Epinephrine, norepinephrine, and dopamine. Do not confuse the term catecholamine with acetylcholine.
When the action potential reaches the presynaptic termi- nal, which ion must enter the presynaptic terminal to evoke release of the neurotransmitter?
Calcium
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 neurotransmit- ter 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 manu neurons
Hvilke reseptorer binder disse nevrotransmitterne seg til?
- LSD
- Nicotine
- Opiater
LSD - til en type serotonin reseptor
Nicotine - til en type acetylcholine reseptor
Opiates - til en type endorfin reseptor
What happens to acetylcholine molecules after they stimu- late a postsynaptic receptor?
The enzyme acetylcholinesterase breaks acetylcho- line molecules into two smaller molecules, acetate and choline, which are then reabsorbed by the presynaptic ter- minal.
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
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.
Which part of the pituitary—anterior or posterior—is neural tissue, similar to the hypothalamus? Which part is glandular tissue and produces hormones that control the secretions by other endocrine organs?
The posterior pituitary is neural tissue, like the hypo- thalamus. The anterior pituitary is glandular tissue and produces hormones that control several other endocrine organs.
In what way is a neuropeptide intermediate between neu- rotransmitters 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.
