Chapter 4 - Chemical Basis of Synaptic Transmission Flashcards
Drugs Affect Each Stage of ____________ and ___________
Neural Conduction
Synaptic Transmission
Cholinergic Pathways in the Brain
Two types of ACh receptors:
Nicotinic–most are ionotropic and excitatory
Muscarinic–metabotropic and can be excitatory or inhibitory
Drug tolerance
Drug tolerance can develop–successive treatments have decreasing effects
Metabolic tolerance–organ systems become more effective at eliminating the drug
Functional tolerance–target tissue may show altered sensitivity to the drug
A Neural Pathway Implicated in Drug Abuse
Another pathway may involve the insula, a brain region within the frontal cortex.
People with damage to this area have been able to stop smoking effortlessly.
exogenous substances
animal, vegetable, and mineral compounds from external sources
The brain is an ____________ system
electrochemical
most drugs that affect the nervous system do so by…
altering brain chemistry and synaptic transmission
neurochemistry
The branch of neuroscience concerned with the fundamental chemical composition and processes of the nervous system.
neuropharmacology
Also called psycho-pharmacology. The scientific field concerned with the discovery and study of compounds that selectively affect the functioning of the nervous system.
exogenous
Arising from outside the body.
endogenous
Produced inside the body.
most drugs that affect behavior do so by
altering synaptic neurotransmitter chemical communication process at millions, or even billions, of synapses.
endogenous substances
neurotransmitter
To be considered a classic neurotransmitter, a substance should meet the following criteria:
- The substance exists in presynaptic axon terminals.
- The presynaptic cell contains appropriate enzymes for synthesizing the substance.
- The substance is released in significant quantities when action potentials reach the terminals.
- Specific receptors that recognize the released substance exist on the postsynaptic membrane.
- Experimental application of the substance produces changes in postsynaptic cells.
- Blocking release of the substance prevents presynaptic activity from affecting the postsynaptic cell.
amine neurotransmitter
2 sub families
A neurotransmitter based on modifications of a single amino acid nucleus. Examples include acetylcholine, serotonin, or dopamine.
- Quaternary amines
- Monoamines
amino acid neurotransmitter
A neurotransmitter that is itself an amino acid. Examples include GABA, glycine, or glutamate.
peptide neurotransmitter (neuropeptide) 2 sub families
A neurotransmitter consisting of a short chain of amino acids.
- Opioid peptides
- Other neuropeptides
gas neurotransmitter
A soluble gas, such as nitric oxide or carbon monoxide, that is produced and released by a neuron to alter the functioning of another neuron.
Found widely throughout the body, NO has been implicated in processes as diverse as hair growth and penile erection, in addition to its role in the brain.
the major categories of some of the many neurotransmitters presently known
amine neurotransmitter
amino acid neurotransmitter
peptide neurotransmitter (neuropeptide)
gas neurotransmitter
Examples of AMINES
Quaternary amines
- Acetylcholine (ACh)
Monoamines
- Catecholamines: norepinephrine (NE), epinephrine (adrenaline), dopamine (DA)
- Indoleamines: serotonin (5-hydroxytryptamine; 5-HT), melatonin
Examples of AMINO ACIDS
Gamma-aminobutyric acid (GABA), glutamate, glycine, histamine
Examples of NEUROPEPTIDES
Opioid peptides
- Enkephalins: met-enkephalin, leu-enkephalin
- Endorphins: β-endorphin
- Dynorphins: dynorphin A
Other neuropeptides
- Oxytocin, substance P, cholecystokinin (CCK), vasopressin, neuropeptide Y (NPY), hypothalamic releasing hormones
Examples of gas neurotransmitters
Nitric oxide, carbon monoxide
Even if a substance is known to be a transmitter in one location, proving that it
acts as a transmitter at another location may be ___________
difficult.