*When dendrites’ connect to the axon this is a synapse
Signalling within one brain cell: Electrical in nature (Action Potentials)
Signalling between most brain cells: Chemical in nature. (neurotransmitters)
Nerve cells are signalling units for behavioural responses.
Simple stretch reflex: knee jerk reflex
Example of a spinal Reflex (150-151 of text)
Knee jerk reflex: Monosynaptic circuit (1 synapse)
Most spinal reflexes are polysynaptic (More than one synapse)
Plantar reflex: stroke foot- normal response is downward response (curling toes inwards)
Babinski response: upward with fanning of toes. Seen in infants (up to 2 years)
Infant reflex- hidden as we age but can reappear from brain trauma or excessive alcohol use.
In Summary: Four General features of the nervous system:
1. Stereotyped electronically signals (action potentials)
2. Connections (chemical synapse)
3. Specific connection patterns
4. Connections can be modified by experience. Ion Channels in the nerve cell membrane and neurotoxins act on them.
The nerve cell membrane has ion channels (Pores that