Conduction & amp Speed of Impulses
The type of nerve conduction in myelinated axons where action potentials "leap" from node to node.
What is saltatory conduction
The narrow gap separating the presynaptic terminal bouton from the postsynaptic membrane.
What is the synaptic cleft?
A graded depolarization caused by the influx of Na or Ca that brings membrane potential closer to threshold.
What is an Excitatory Postsynaptic Potential?
Acetylcholine receptors found on skeletal muscle motor end plates that act directly as ligand-gated ion channels.
What are nicotinic ACh receptors?
A stroke patient who understands spoken language perfectly but produces slow, poorly articulated speech has suffered localized cortical damage to this area in the left inferior frontal gyrus
What is Broca's area?[19]
The two primary structural features of a neuron that increase action potential conduction velocity.
What are increased axon diameter and myelination?
Transmembrane protein channels that form gap junctions in electrical synapses.
What are connexin proteins?
A graded hyperpolarization caused by the outflow of K or influx of Cl that moves membrane potential away from threshold.
What is an Inhibitory Postsynaptic Potential?
Acetylcholine receptors found in cardiac and smooth muscle that act indirectly via G-protein pathways.
What are muscarinic ACh receptors?
Located in the diencephalon, this structure serves as the primary relay center for almost all incoming sensory information directed to the cerebral cortex, excluding olfaction.
What is the thalamus?
Unmyelinated gaps along an axon where voltage-gated Na channels are concentrated.
What are the nodes of Ranvier?
The ion that enters the presynaptic axon terminal upon depolarization to trigger neurotransmitter exocytosis.
What is Calcium?
When acetylcholine binds to a nicotinic receptor, both Na and K move a cross the membrane, yet net inward current depolarizes the cell due to this physical gradient factor.
What is a greater electrochemical driving force pushing Na into the cell than K out?
The specific G-protein subunit complex that opens K channels in cardiac tissue to hyperpolarize the cell and slow heart rate.
What is the beta-gamma subunit complex?
Progressive loss of dopaminergic neurons projecting from the substantia nigra to the corpus striatum leads to this classic movement disorder.
What is Parkinson's disease?
The conduction speed of a thick, myelinated axon compared to 1.0 m/s in a thin, unmyelinated axon.
What is 100 meters per second?[3]
The protein sensor that binds Ca and displaces part of the SNARE complex to fuse synaptic vesicles with the membrane.
What is synaptotagmin?
Unlike all-or-none action potentials, these membrane potential changes vary in amplitude based on stimulus strength and can add together.
What are graded potentials?
Plant resin derivative that acts as a nicotinic receptor antagonist, causing muscle paralysis.
What is curare?
Damage to this vital region of the brainstem disrupts autonomic reflex control of heart rate, blood vessel diameter (vasomotor center), and respiratory rhythmicity.
What is the medulla oblongata?
The mechanism by which a sensory neuron communicates a severe, high-intensity pain stimulus compared to a mild touch without altering the amplitude or duration of individual action potentials.
What is increasing action potential frequency (frequency modulation) and recruiting additional nerve fibers?
A presynaptic axon forms a direct junction onto the terminal bouton of a second neuron rather than its dendrites or soma, allowing localized regulation of neurotransmitter release.
What is an axoaxonic synapse?
The specific site adjacent to the axon hillock where the algebraic sum of all converging EPSPs and IPSPs determines whether threshold is reached to initiate an action potential.
What is the axon initial segment?
During surgery, administering curare causes skeletal muscle relaxation and paralysis by blocking acetylcholine binding at this specific receptor type on the motor end plate.
What are nicotinic acetylcholine receptors?
The neuroanatomical explanation for why humans frequently struggle to exercise conscious, voluntary cortical control over their emotional states and visceral drives.
What is the presence of very few direct synaptic connections between the limbic system and the cerebral cortex.