Neuron Flashcards
(22 cards)
Neuron
The basic cell of the nervous system
Conducts electrical impulses and communicates with other neurons, organs, and muscles
Neuron parts: dendrites
Extension off of cell body, reviews chemicals (neurotransmitters) from other neurons
Cell body
Contains nucleus and other organelles & transmits electrical impulses from dendrites to axons
Axon
Long extension from cell body
Contains cytoplasm that conducts electrical impulses
Myelin sheath
Insulation around axon
Speeds up electrical impulses
Formed by Schwann cells
Schwann cells are on outside,
Myelin sheath on inside
Nodes of ranvier
Gap between myelin sheath
Impulse jumps from node to node,
Increasing speed of impulse
Axon terminal
End of axons
Axon terminal releases neurotransmitters (chemicals) that are
Picked up by dendrites of next neuron
Action potential potential:
Difference in charge (volts) across the membrane through gated channels
Three steps
- Resting potential
- Depolarization (action potential)
- Repolarization
Resting potential: neuron is
not conducting an impulse
Inside the neuron is
-70 mV (millivolts)
Inside the neuron are
Large negative proteins
Sodium (Na+) channels
Closed
Potassium (K+) channels
Open
Depolarization (action potential) a stimulus causes a
Positive change in membrane potential near the axon
K+ channels
Close
Na+ channels
open and Na+ ions
flood into the axon swinging the charge inside to +40 mV
Repolarization
Na+ gates close and stops the flood of Na+
ions into cell
K+ gates open allowing K+ out of the cell
● The sodium/potassium pump re-establishes -70 mV by pumping out 3 Na+ out and 2 K+ in
