Nervous System Flashcards
Neuron
Basic cell of nervous system
Dendrite
branched extensions that bring neural stimuli to the cell body
Axon
long extension that carries neural stimuli away
Cell body (soma)
contains the nucleus and other essential organelles
Schwann cell
supports the neuron by providing a medium for neural impulses
Wrap around an axon, leaving space between each other
Myelin sheath
insulates sections of the axon and facilitates movement of impulses across the axon
Node of Ranvier
portions of the axon that are exposed to extracellular space
Rich with ion channels needed to keep the neural impulse moving
Neural Direction
5 steps
- impulses are picked up by the dendrites
- Dendrites bring impulses to the cell body
- Cell body sends impulses down the axon
- Impulse speed is increased when using myelin as a medium
- Impulse reaches the terminal axon, which are then transferred to other dendrites
Afferent nerves
Conducts neural impulses towards the CNS
Sensory nerves
Efferent nerves
conducts neural impulses away from the CNS
Motor nerves
Somatic nervous system
Voluntary control over the nervous system
Autonomic nervous system
Involuntary control over the nervous system
Sodium channel
A gate that passively allows sodium to travel through the membrane
Potassium channel
A gate that passively allows postassium to travel through the membrane
Sodium-potassium pump
A special gate that actively moves sodium and potassium through the membrane
Resting state
positive sodium cations on the outside of the cell and positive potassium cations inside of the cell
outside of the cell is positive and inside of the cell is negative-makes the cell membrane polarized
Depolarization
impulse stimulates the sodium channels to open and sodium floods into the cell via passive diffusion
Polaritiy shifts
once the threshold is reached the original impulse creates an action potential
Repolarization
Sodium channels close, potassium pumps open causing potassium to evacuate the cell. Restores polarity in the cell
Refractory Period
restores the layout of both cellular spaces
Sodium-potassium pump will actively diffuse both ions back to where they were
the neuron will not respond to any stimulus
Threshold
the limit before delpoarization can occur
the stimulus that triggers the neuron must be strong enough to reach the threshold
The All or nothing concept
if the stimulus is too weak, the threshold is not reached, depolarization will not occur, neural impulse will not complete its path
