Neurons, Neurotransmission & Neurotransmitters Flashcards
Therapeutic threshold
As drug absorption progresses following a single dose of a compound, the amount of a compound in the individuals circulation will increase until it reaches the minimal level at which that compound might be effective.
Peak effect dose
As blood level rises over time, the effects will continue to become stronger until the drug reaches its PEAK EFFECT DOSE. Then biotransformation until the compound diminishes until the blood levels fall below the therapeutic threshold.
Site of action
Where the compound(s) carry out their main effects. For most psychoactive phamaceudicals, and the various drugs misused, various neurons in the central nervous system (CNS) will be the site of action.
The receptor site
The location on neuron ‘b’ that receives information ‘a’ through neurotransmission. Key and lock. Molecular ‘key’ (neurotransmitter molecule) slides into the ‘lock’ (receptor site).
Co-transmission
When both primary and secondary neurotransmitters are released.
Reverse tolerance
Also called sensitization is a poorly understood phenomenon in which lower doses of compound produce the same effect as higher does did when the use of the substance was initiated.
Behavioral tolerance
The behavioral outcome of the brain’s efforts to maintain normal function in spite of the presence of foreign molecules.
Up-regulation and down-regulation
If the neuron is constantly being objected to high levels of a neurotransmitter, it might down-regulate (reduce) the number of receptor sites so that the NT molecules have fewer targets.
Drug agonists
Are a compound that activates the receptor site by being able to mimic or enhance the actions of a natural neurotransmitter.
Antagonists
Drugs that are able to fit into the receptor site WITHOUT activating it.
Potency
Potency, of a biologically active compound is the ratio between the size of the dose and the desired response.
Blood-brain barrier (BBB)
Separates the brain from direct contact with the circulatory system. Not really a barrier more like a screen.
No two neurons are alike but most have 3 parts. What are they?
Cell body (soma), dendrites, and axon.
Cell body
Contains the nucleus and carries out metabolic, life sustaining, functions of the neuron.
Dendrites
Branching out from the cell body, they look like leafless branches from a tree, primary receivers of signals from other neurons but cell body can also receive signals directly.
Back propagating
Dendrites can also send messages backwards, this process is called BACK PROPAGATING.
Axon
Appears slender, tail like. Transmitting (signals to dendrites as well as muscles, glands, and other body parts)) end of the neuron, which sprouts into many branches, each ending in an axon terminal.
Glial cells
Specialized cells that hold the neurons together, smaller than neurons, more than half the volume of the brain, remove waste like dead neurons, handle metabolic tasks, and assist in the production of myelin for cell transmission tasks. In spinal cords glial cells are involved in the transmission of pain from various parts of the body to the brain.
Synapse
The junction where axon terminal of a sending neuron communicates with receiving neuron across synaptic cleft. Maybe as many as 100 trillion synapses in the human nervous system.
Resting potential
Inside the axon there are normally more negative than positive ions. When at rest, a neuron carries a negative electrical potential (charge) relative to the fluid outside the cell. The slight negative charge is referred to as the neurons RESTING POTENTIAL
Action potential
When sufficiently stimulated by an oncoming signal, ion channels begin to open in the cell membrane, allowing positive ions to flow through the axon causing membrane potential to change to positive. This brief and sudden reversal is called ACTION POTENTIAL.
Myelin sheath
A white fatty coating wrapped around axons and acts like insulation. Impulses travel up to 100 times faster with myelin sheaths.
Monoamines
4 neurotransmitters dopamine, norepinephrine (noradrenaline), epinephrine (adrenalin), and serotonin. Dopamine (DA) is like acetylcholine, both excitatory and inhibitory. Involved in learning, attention, movement and reinforcement. Also feel pleasure. Norepinephrine (NE) affects eating and alertness and wakefulness. Epinephrine compliments NE by affecting the metabolism of glucose and causes glucose stored in muscles to be released during strenuous exercise. Serotonin is inhibitory. Regulates mood, sleep, impulsivity, aggression and appetite. Also linked to depression and anxiety disorders. Both serotonin and NE are related to positive moods, deficiency linked to depression.
Spinal cord
extension of the brain. Protected by bone and spinal fluid, links body with brain. Responsible for spinal reflexes (taking hand off hot stove) sends message to brain (putting hand in cold water to relieve pain)
Brainstem
Begins at spot where spinal cord enlarges as it enters skull. Includes medulla, pons, and reticular formation.
