Chapter 7 - Nerve Cells and Electrical Signaling Flashcards
What are the two branches of the efferent nervous system?
somatic nervous system and autonomic nervous system
Which part of the nervous system contains motor neurons that regulate skeletal muscle contractions?
somatic nervous system
Which part of the nervous system is not under voluntary control?
autonomic nervous system
What makes up the central nervous system?
brain and spinal cord
90% of cells in the nervous system
glial cells
functional units of the nervous system
neurons
cells that produce action potentials
neurons
branches of an axon
collateral
site where the axon originates from the cell body
axon hillock
What are the three parts of a neuron?
- Cell body
- Axon
- Dendrite
changes in membrane potential
action potential
98% of neurons in the body
interneurons
Which cells provide structural integrity to the nervous system?
glial cells
_____ means “glue” in Latin.
Glia
_____ enables neurons to transmit action potentials more efficiently and rapidly.
myelin
Which two types of glial cells form Myelin?
Schwann cells & oligodendrocytes
groups of cell bodies in the CNS
nuclei
groups of cell bodies in the PNS
ganglia
groups of axons in the CNS
pathways/tracts/commissures
groups of axons in the PNS
nerves
PNS
peripheral nervous system
movement from axon terminal to cell body
retrograde transport
movement from cell body to axon terminal
anterograde transport
ion channel that is always open
leak channel or leaky channel
ion channel that opens or closes in response to the binding of a chemical to a specific receptor in the plasma membrane
ligand-gated channel
ion channel that opens or closes in response to changes in the membrane potential
voltage-gated channel
In a resting membrane, _____ permeability is higher than _____.
potassium; sodium
_____ channels open and close in response to mechanical force on the membrane.
Mechanically-gated
_____ are excitatory and bring the membrane potential closer to threshold.
Depolarizations
_____ are inhibitory and take the membrane potential further away from threshold.
Hyperpolarizations
Threshold occurs when the flux of _____ ions exceeds the flux of _____ ions.
sodium; potassium
During the _____ period, a second action potential cannot be stimulated.
absolute refractory
During the _____ period, stronger stimuli can cause a second action potential.
relative refractory
Action potentials cannot be produced where _____ is present.
myelin
_____ refractory period prevents overlap of action potentials.
Absolute
the jumping of action potentials from node to node
saltatory conduction
In a myelinated neuron, action potentials are produced at the _____.
nodes of Ranvier
When the membrane potential of a cell is at rest, which gates are open and/or closed?
The inactivation gate is open, and the activation gate is closed.
What happens during depolarization?
The activation gate opens and sodium ions move into the cell.
What happens 1 msec after a stimulus?
The inactivation gate closes, and remains closed until membrane potential returns to resting.
The relative refractory period is primarily due to the increased _____.
permeability to potassium
The rising phase of an action potential lasts approximately _____.
0.5 ms
The repolarization phase of an action potential lasts approximately _____.
0.5 ms
During an action potential, hyperpolarization lasts approximately _____.
2 ms
The _____ creates the concentration gradient.
sodium/potassium pump
Action potentials occur in response to graded potentials that _____.
reach threshold
