BS Flashcards
Neurotransmitter
- Electrical signal to chemical
- Released at end of nerve fiber, diffuses across synapse and causes impulse transmitter
Synaptic vesicle
- Axon near presynaptic membrane
- Releases neurotransmitters into synaptic cleft
Node of ranvier
Gap in myelin sheath of nerve fiber
- Where diffusion occurs
Saltutory conduction
Propagation of action potential along myelin between nodes of ranvier
Neuromodulator
- Potentiator or inhibitor of nerve transmission
- Modify effect of transmitters
- Not means of transmission
Autoreceptor
- Neurotransmitter receptor at presynaptic terminal of same neuron
- Self regulation
Heteroreceptor
- Binding site of neuromodulator created by a different neuron
Inotropic receptor (ligand gated channels)
- Binding of neurotransmitter causes conformational change allowing ions to pass through
Metabotropic receptors
- Signal transduction
- Indirectly linked receptors that begin signal cascade, G proteins
G coupled protein receptors
- Metabotropic receptors
- Activate signal transduction pathways
- React to light sensitive compounds, odors, pheromones
Homologus desensitization
- Decreased response with high concentrations of agonist
Heterologus desensitization
- Repeated stimulation causes broad desensitization of many agonists
Reuptake
- Reabsorption of neurotransmitter at presynaptic terminal
- Neurotransmitter recycling
Amino acids
- Glutamate
- GABA
- gylcine
Monoamines
- Norepi
- Epi
- Dopamine
- Serotonin
Neuropeptides
- Large molecules transmitters
- Substance P
- Encephalin
- Vasopressin
Glutamate
- Excitatory
- Inotropic and metabotropic receptors
- Permits influx of Na and K- fast excitatory post-synapse response
- Synth in Krebs or nerve terminals
- Release: Ca+ dependent exocytosis
GABA
- Inhibitory, mediates presynaptic and postsynaptic inhibition
- Synth from glutamate
- Decreases Ca+ influx
Glycine
- Inhibitory
- CA++ dépendant
- Increase Cl- conductance
Acetylcholine
- Both
- Synth in nerve terminal cytoplasm
- Released when impulse triggers Ca++ into terminal
- Must be rapidly removed for depolarization to occur
- hydrolysis in cleft
Norepi
- Excitatory
- Synth from tyrosine
- Sympathetic postganglionic endings
- alpha, beta adrenergic receptors
Epi
- Excitatory
- Released via exocytosis
- Act on beta and alpha receptors
Dopamine
- Both
- Secreted at synaptic cleft
- acts on the nigrostriatal system within basal ganglia
- Motor control, reward
Serotonin
- Inhibitory
- Synth from tryptophan
- Released from vesicles in serotonergic neurons
- Highest concentration platelets, GI tract, raphe nuclei
- Mood stabilization
- Balances excessive excitatory firing
Substance P
- Both
- 11 amino acid residues
- Regulated pain signal transmission from spinal cord to brain
- Potent arterial vasodialtor, venous contractor mediates NO
- Stimulates salivary glands, diuresis
Mu opioid receptors
- Endorphins
- Brain, spinal and GI tract
- Resp depression, constipation, spinal analgesia
- Increased secretion of growth hormone, prolactin
- Miosis
- Euphoria
Kappa receptor
- Enkephalins
- Brain and spinal cord
- Spinal analgesia
- Diuresis
- Sedation, dysphoria
- Miosis
Gamma opioid receptor
- Dynorphins
- Brain
- Physical dependence
- Antidepressant
- Convulsions
- Spinal analgesia
Nitric oxide
- Vasodilation
- Smooth muscle relaxation
- Endothelial tissue
Cannabinoids
- THC
- Short term euphoria, altered sensory perception
- Receptors in brain and periphery, pain tx?
Somatostatin
- Hypothalamus and pancreas
- Inhibitor- insulin, glucagon, gastrin, GH and TSH
- Decreased gut motility,
