BIO304 Physiology of Neurons and Muscle
Lecture 1 Notes – Introduction and Visualizing the Nervous System
What is the Nervous System?
1. The nervous system is made up of a network of cells that can sense information
a. About the “outside” world (light, chemicals, temperature, touch)
b. About the “inside” world (internal states, signals from other cells)
2. Cells (neurons) are able to propagate information in the form of electrical impulses
a. Graded potentials
b. Action potentials
3. Cells convey information to each other via chemical and/or electrical synapses s
4. The nervous system generates outputs to coordinate physiology and behaviour
a. Ex. feeding, courtship, locomotion
What are the cells of the nervous system?
 Motor neuron
 Mitral cell
 Pyramidal cell
 Purkinje cell
 Ganglion cell
What are photoreceptor cells?
 Cells in the retina that have special proteins that detect light to trigger a change in voltage
across the cell membrane
o Light is converted into an electrical signal in the receptor cells
 Electrical signals travel to the synapse, where they trigger the release of chemicals
(neurotransmitters) that bind neurotransmitter receptors on post-synaptic bipolar cells
o i.e. chemical synapses convert electrical signals into chemical signals
 the neurotransmitter receptors on bipolar cells produce graded electrical responses
o stronger light  more NT secretion by receptor cells
o more NT  stronger change in membrane voltage (depolarization) of the bipolar
cell
o i.e. we are back to electrical signal
 graded responses reach bipolar cell nerve ter