Nervous systems
Keywords (reading p. 960-976)
Integration of synaptic signals
Neurotransmitters
Acetyl choline
Norepinephrine
Serotonin
Dopamine
Amino acid neurotransmitters
Endorphins
Nitric oxide (NO)
Guanylate cyclase
Cyclic GMP (cGMP)
Phosphodiesterase
Sample test question:
True or False: The concentrations shown in this diagram are correct
During which part of the action potential does this occur (Na+ entering axon)?
During which part of the action potential does this occur (K+ leaving axon)?
Integration of multiple synaptic inputs
Summation of postsynaptic potentials
Neurotransmitters
Acetylcholine (ACh) - excitatory to vertebrate skeletal muscle; other effects at other sites
Biogenic amine neurotransmitters
Norepinephrine
Dopamine
Serotonin
Usually function within the central nervous system
Dopamine
High levels are linked to schizophrenia
Serotonin
Low levels linked to clinical depression
Prozac: Selective serotonin reuptake inhibitor
Amino acid neurotransmitters
GABA (gamma amino butyric acid
Glycine
Glutamate
Aspartate
Used in the central nervous system
GABA
Inhibitory synapses in brain
Produces hyperpolarization by opening chloride channels
Neuropeptide neurotransmitters
Substance P
endorphins
Substance P
Excitatory signal gives rise to perception of pain
Endorphins
Decrease perception of pain
Receptors for endorphins also recognize opiates (e.g., morphine and heroin)
Endorphins are also hormones produced by the anterior pituitary
Norepinephrine/serotonin and depression
Catecholamine hypothesis - depression represented a decreased availability of norepinephrine and/or serotonin
Treatments are electroshock therapy and drugs to increase norepinephrine and/or serotinin availability
Drug treatments
Selective serotonin reuptake inhibitors (SSRI)
Fluoxetine HCl — Prozac
Trazodone — Desyrel
Sertraline HCl — Zoloft
Paroxetine HCl — Paxil
Drug treatments
- Tricyclic antidepressants
Block high affinity serotonin and norepinephrine reuptake systems
Increase sensitivity of serotonin receptors
Example: Amitriptyline - Elavil
Drug treatments
Monoamine oxidase (MAO) inhibitors
Example: Phenelzine-Nardil
Serotonergic synapse
A newly discovered class of neurotransmitters (gases)
Late 80’s nitric oxide (NO) and carbon monoxide (CO)
NO causes smooth muscle cells to relax resulting in dilation of blood vessels
NO has rapid effects
Produced from the amino acid arginine
NO can readily diffuse through tissues
Half life of NO is only 5-10 seconds
Turned into nitrates and nitrites
Effects of NO occur within seconds, and also end within seconds