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| CONDUCTION VELOCITY depends on |
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Definition
1. Axon diameter- the larger the axon’s diameter, the faster is conducts impulse
2. Degree of myelination- action potentials propagate because they are regenerated by voltage-gated channels in the membrane |
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| AP jumps from each voltage gated ion channel: SLOW |
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| AP’s are triggered only at the nodes of ranvier |
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CLASSIFICATION
Group A fibers- are mostly somatic sensory and motor fibers serving the skin, skeletal muscles, and joints. They have the largest diameter and thick myelin sheathes; conduct impulses at speeds ranging up to 150 m/s |
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Definition
| are autonomic nervous system motor fibers serving the visceral organs; visceral sensory fibers and the smaller somatic sensory fibers transmitting afferent impulses from the skin (such as pain);lightly myelinated fiber of intermediate diameter, transmit impulses at a rate of 15 m/s |
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Definition
| are autonomic nervous system motor fibers serving the visceral organs; visceral sensory fibers and the smaller somatic sensory fibers transmitting afferent impulses from the skin (such as pain); have the smallest diameter and are unmyelinated; incapable of salutatory conduction; conduct impulses at 1 m/s |
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Definition
| a junction that mediates information transfer from one neuron to the next or from a neuron to and effector cell; it’s where the action is |
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Definition
| synapses between the axon endings of one neuron and those of other neurons |
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Definition
| synapses between axon endings of one neuron and cell bodies of other neurons |
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Definition
| the neuron conducting impulses toward the synapse |
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Definition
| the neuron transmitting the electrical signal away from the synapse |
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Definition
less common variety; Consist of gap junctions
Contain protein channels (connexons)
;Connexons- allow ions and small molecules to flow directly from one neuron to the next (electrically coupled)
;Provide a simple means of synchronizing the activity of all interconnected neurons |
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Definition
| are specialized for release and reception of chemical neurotransmitters; made of two parts |
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Term
| two parts of a chemical synapse |
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Definition
1. A knoblike axon terminal of the presynaptic neuron, contains synaptic vesicles that contains thousand of neurotransmitter molecules
2. A neurotransmitter receptor region on the membrane of a dendrite or the cell body of the postsynaptic neuron |
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Definition
| seperates presynaptic and post synaptic membranes |
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Definition
| the integration of input from thousands of synapses in CNS |
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Definition
| Postsynaptic neuron is stimulated by a large number of terminals at the same time |
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| One or more presynaptic neurons transmit impulses in rapid-fire order |
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Definition
| Released at neuromuscular junctions and some ANS neurons; Synthesized by enzyme choline acetyltransferase; Degraded by the enzyme acetylcholinesterase (AChE) |
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Definition
Catecholamines
Dopamine, norepinephrine (NE), and epinephrine ; Indolamines; Serotonin and histamine; Broadly distributed in the brain; Play roles in emotional behaviors and help regulate the biological clock Imbalances are associated with mental disease |
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Definition
GABA—Gamma (γ)-aminobutyric acid; Glycine; Aspartate
Glutamate |
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Term
| Peptides (neuropeptides) include |
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Definition
Substance P; Mediator of pain signals; Endorphins; Act as natural opiates; reduce pain perception; “runner’s high”; Gut-brain peptides produced by non-neural tissues
;Somatostatin and cholecystokinin |
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Definition
| Act in both the CNS and PNS; Produce fast or slow (2nd messenger) responses; Induce Ca2+ influx in astrocytes; Provoke pain sensations; e.g. caffeine blocks adenosine receptors |
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Definition
| Nitric oxide (NO); Synthesized “on demand” ; Activates the intracellular receptor guanylyl cyclase to make cyclic GMP; Involved in learning and memory; Causes intestinal smooth muscle to relax; Carbon monoxide (CO) is also a regulator of cGMP in the brain |
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Definition
| Endocannabinoids:Lipid soluble; synthesized on demand from membrane lipids; Bind with G protein–coupled receptors in the brain; Cannabinoid receptors are the most common G protein-coupled receptors in the brain; Involved in learning and memory |
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Term
| Functional Classification of Neurotransmitters |
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Definition
| Neurotransmitter effects may be excitatory (depolarizing) and/or inhibitory (hyperpolarizing |
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Definition
Neurotransmitter binds to channel-linked receptor and opens ion channels; Promotes rapid responses
Examples: ACh and amino acids |
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Definition
| Neurotransmitter binds to a G protein-linked receptor and acts through an intracellular second messenger; Promotes long-lasting effects; Examples: biogenic amines, neuropeptides, and dissolved gases |
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Term
| Channel-Linked (Ionotropic) Receptors |
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Definition
Ligand-gated ion channels
Action is immediate and brief
Excitatory receptors are channels for small cations
Na+ influx contributes most to depolarization
Inhibitory receptors allow Cl– influx or K+ efflux that causes hyperpolarization |
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Definition
| Functional groups of neurons that:Integrate incoming information; Forward the processed information to other destinations |
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| Single presynaptic fiber branches and synapses with several neurons in the pool |
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| neurons most closely associated with the incoming fiber |
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Definition
| neurons farther away from incoming fiber |
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Definition
| o One incoming fiber stimulates an ever-increasing number of fibers, often amplifying circuits; May affect a single pathway or several; Common in both sensory and motor systems |
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Definition
| Opposite of diverging circuits, resulting in either strong stimulation or inhibition; Also common in sensory and motor systems |
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| Reverberating (oscillating) circuit |
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Definition
| Chain of neurons containing collateral synapses with previous neurons in the chain |
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| Parallel after-discharge circuit |
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Definition
| Incoming fiber stimulates several neurons in parallel arrays to stimulate a common output cell |
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Definition
| Input travels along one pathway to a specific destination; Works in an all-or-none manner to produce a specific response; Example: reflexes—rapid, automatic responses to stimuli that always cause the same response |
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| Input travels along several pathways; One stimulus promotes numerous responses Important for higher-level mental functioning; Example: a smell may remind one of the odor and associated |
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Definition
| brain and spinal cord; integration and control centers |
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Term
| peripheral nervous system |
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Definition
| cranial nerves and spinal nerves; communication lines between the CNS and rest of body |
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Term
| Sensory afferent division |
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Definition
| PNS subdivision: somatic and visceral sensory nerve fibers; conducts impulses from the receptors to CNS |
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Definition
| PNS subdivision: nerve fibers; conducts impulses from the CNS to effectors (muscles and glands) |
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| PNS subdivision of the motor division; somatic motor (voluntary) conducts impulses from the CNS to the skeletal muscles |
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Definition
| subdivison of the motor part of the PNS; visceral motor (involuntary) conducts impulses from the CNS to cardiac muscles, smooth muscles and glands |
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| PNS: subdivision of ANS: mobilizes body system during activity; arouses |
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| PNS subdivision of ANS; conserves energy; promotes house keeping functions during rest; calms |
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Definition
| glial cells; provide a supportive scaffolding for neurons |
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