Transcript Structure and Physiology of Neurons

Structure and Physiology of
Neurons
Nervous System Lecture 2
Neurons (Nerves)
• Specialized cells to transmit
nerve impulses from one part
of body to another
• 3 main parts
– Dendrite (conducts electrical
current towards cell body)
– Cell body
– Axon (conducts electrical current
away from cell body)
Synapses
• junction between two neurons where
messages are passed on by neurotransmitters
Resting neuron structure
• Contain potassium (K+) ions inside neuron
• Sodium (Na+) ions are outside plasma
membrane and don’t normally pass inward
Polarized neuron
• Inactive (not sending an impulse)
• Inside of neuron negatively charged to
compared to outside
Stimulated neuron- Depolarization
• Na+ gates in membrane open and Na+ rushes
into cell causing inside to be more positive
than outside of cell which activates neuron to
transmit an action potential
Action potential
• nerve impulse which causes the axon to
release a neurotransmitter into synapse that
binds to next neuron stimulating it
Cell Repolarization
• After action potential
• K+ rushes out of cell causing the inside to
become negative again
• Must occur before neuron can send another
nerve impulse
After repolarization
• Na+/K+ pump
– Pumps K+ into cell and Na+ out to restore cell to
make it polarized again