Bio 231 - Electrical Signalling, Resting Membrane Potential, and Action Potentials

What defines excitable tissues? How do they differ in structure? What organ system best represents excitable tissues?

Animal cells’ interior usuallu shows net negative charge - membrane potential (Vm) is stable is most cells

Neurons + Muscle cells: group of tissues made up of excitable cells - meaning their Vm changes wildly within milliseconds. These changes are all propagated over very long distances at very high speeds

The central nervous system includes the brain + spinal cord

The peripheral nervous system includes motor neurons, sensory neurons, and interneurons

Name the two main types of cells in the nervous system

Neurons: (sensory, motor, interneurons) carry out electrical tasks

Glial cells: carry out critical support and protective roles

Label / name the main segments of a neuron + their function

Soma: Cell body - includes the nucleus, endomembrane system

Dendrites: Incoming information

Axons: Outgoing information

Myelin sheath: Segmented insulation that covers most of the axon (makes room for nodes of ranvier)

Nodes of ranvier: Locations where axon plasma membrane uninsulated by myelin

Synapse: Junction where synapse knob contacts with next xell in the pathway

• Proximal synaptic knob → distal neuron dendrite

• Knob → soma

• Dendrite → dendrite

Axon hillock + Initial segment

(Neuron = single excitable cell; Nerve = a bundle of neuronal axons)

Explain the basis of a resting membrane potential.