Lec 6- Synaptic Transmission and Neuronal Integration Flashcards
Synapse
The specialized junction between two neurons where an action potential in the presynaptic neuron influences the membrane potential of the postsynaptic neuron, typically by releasing a chemical messenger that diffuses across the small cleft between the neurons.
Synaptic Potential
Synaptic potential refers to the potential difference across the postsynaptic membrane that results from the action of neurotransmitters at a neuronal synapse. In other words, it is the “incoming” signal that a neuron receives.
Graded Potential
Local changes in membrane potential that occur in varying grades or degrees of magnitude or strength.
EPSP (excitatory postsynaptic potential)
A small depolarization of the postsynaptic membrane in response to neurotransmitter binding, bringing the membrane closer to threshold.
IPSP (inhibitory postsynaptic potential)
A small hyperpolarization of the postsynaptic membrane in response to neurotransmitter binding, thereby moving the membrane farther from threshold.
Neurotransmitter (NT)
The chemical messenger released from the axon terminal of a neuron in response to an action potential that influences another neuron or an effector with which the neuron is anatomically linked.
Presynaptic Neuron
The neuron that conducts its action potentials toward a synapse.
Postsynaptic Neuron
The neuron the conducts its action potentials away from a synapse.
Synaptic vesicles
Store a specific chemical messenger.
Synaptic cleft
Space between the presynaptic and postsynaptic neurons.
Too wide for the direct spread of current from one cell to the other and therefore prevents action potentials from electrically passing between the neurons.
Voltage-gated channels
Voltage-gated ion channels are a class of transmembrane proteins that form ion channels that are activated by changes in the electrical membrane potential near the channel. The membrane potential alters the conformation of the channel proteins, regulating their opening and closing.
ACh (acetylcholine)
The neuromuscular junction NT
Nicotinic ACh channel receptors
Found on the postganglionic cell bodies in all autonomic ganglia and the adrenal medulla.
Also found on motor end plates of skeletal muscle fibers.
Respond to Ah released from both sympathetic and parasympathetic preganglionic fibers.
Muscarinic Receptors
Found on effector cell membranes (smooth muscle, cardiac muscle, and most exocrine and some endocrine glands).
AChE (acetylcholinesterase)
Inactivates ACh.
NMJ (neuromuscular junction)
The juncture between a motor neuron and a skeletal muscle fiber.
Curare
Antagonist.
Reversibly binds to the ACh receptor-channels on the motor end plate.
Monoamine NT’s
Includes serotonin, norepinephrine, and dopamine.
Serotonin
Involved in regulation of mood, behavior, appetite, and cerebral circulation.
LSD is structurally similar.
Norepinephrine (NE)
In PNS sympathetic NT.
In CNS affects general level of arousal.
Dopamine
Involved in motor control and emotional reward.
Degeneration of dopamine motor system neurons causes Parkinson’s disease.
Catecholamines
Hydrophilic. Synthesis in cytosol. Receptor site on surface of target cell.
MAO (monoamine oxidase)
Degrades serotonin and NT at presynaptic neuron
MAOI (monoamine oxidase inhibitor)
Stops action of MAO enzyme.
COMT (catachol-o-methyltransferase)
Degrades catecholamines (NE, EPI, and Dopamine)
SSRI (serotonin-specific Reuptake inhibitors)
Selective serotonin reuptake inhibitors are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder and anxiety disorders.
Prozac
Prozac is an antidepressant. It is mainly used to treat major depression, obsessive-compulsive disorder, and panic disorder. Also known by its generic name, fluoxetine, Prozac is a selective serotonin reuptake inhibitor (SSRI).
Zoloft
Antidepressant, blocks the re-uptake of serotonin.
Paxil
Antidepressant, blocks the re-uptake of serotonin.
Luvox
Selective serotonin reuptake inhibitor (SSRI) antidepressant. This medicine affects chemicals in the brain that may be unbalanced in people with obsessive-compulsive symptoms.
Parkinson’s Disease
Gradual destruction of neurons that release the NT dopamine in the basal nuclei.
Amphetamines
a synthetic, addictive, mood-altering drug, used illegally as a stimulant and legally as a prescription drug to treat children with ADD and adults with narcolepsy.
Amino acid NT’s
Glutamic acid, aspartic acid, glycine, GABA
Glutamic acid
Major excitatory NT in CNS
Aspartic acid
Major excitatory NT in CNS
Glycine
Major inhibitory in CNS; opens CL- channels and as CL- -> into cells, hyperpolarizes membrane
GABA (gamma-aminobutyric acid)
Major inhibitory in CNS; opens CL- channels and as CL- -> into cells, hyperpolarizes membrane
Schizophrenia
Too much dopamine
