Flashcards in Lecture 3 Deck (50)
enclosed in a sheath made of nonneural cells (glial cells)
The ____________ has breaks (Ranvier nodes) where action potentials are generated
Slow nerve conduction speed
Fast nerve conduction speed
Sound in air speed
Light or electromagnetic field
Conduction of an Action Potential
1. Membrane depolarization to the threshold
2. Generation of an action potential
3. Local currents spread passively
4. They depolarize adjacent areas of the membrane
5. A new action potential is generated
Myelin increase what in local currents?
Myelin increases the effective distance of local currents
What is the velocity of conduction in myelinated fibers?
velocity in m/s
from soma to terminal branches
from the end of the axon to the soma
body of the cell; the site of input signals
shot branches originating from the soma; sites of inputs
a long branch; transmits output signals
the site where the axon exits the soma; typically, the site of generation of action potentials
a "brush" at the end of the axon
a fatlike substance covering the axon; it increases the speed of conduction of action potentials
breaks in the myelin sheath; places where action potentials are generated
Nerve (peripheral) or neural tract (central)
many axons running together
How many ion channels are there under the myelin sheath in a neuron?
there are virtually no ion channels under the myelin sheath.
How many ion channels are there in the Ranvier nodes in neurons?
There are many ion channels in the Ranvier nodes.
the importance of ______ for the generation of APs has gained prominence lately (steady depolarization) in neurons.
What is a PIC?
a depolarizing inward current that activates as long as the membrane potential is depolarized
PIC's allow for an increase _________________.
in the number of action potentials that are generated.
Recent studies have reported that PIC's are strong in ____________ during everyday tasks.
human alpha motorneurons
PIC's are likely strong enough to play a major role in defininf the patterns of ________________________.
recruitment and derecruitment of motor units
PIC's are very sensitive to ___________ inhibition, meaning they can be controlled?