2 Excitability and Action Potential

2 Excitability and Action Potential - EXCITABILITY & ACTION...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
EXCITABILITY & ACTION POTENTIALS AC Brown page 1 A7a INTRODUCTION A. Excitable Tissue: able to generate Action Potentials (APs) (e.g. neurons, muscle cells) B. Neurons (nerve cells) a. components 1) soma (cell body): metabolic center (vital, always present, contains cell nucleus): information integration 2) dendrites (branches from the soma): receive information, generally but not always present 3) axons (one or two generally long branches from the soma): transmit information b. organization 1) Central Nervous System (CNS): neurons of the brain and spinal cord 2) Peripheral Nervous System (PNS): neurons outside the brain and spinal cord Note: Sometimes the neurons within the alimentary tract are considered a separate division, the enteric nervous system 3) axon groups: axons running together in the PNS are termed nerves ; axon groups running together and of similar function are in the CNS generally called tracts , although other terms are frequently used (column, lemniscus, etc.) 4) a group of somas of similar function in the PNS is called a ganglion ; in the CNS, it is generally called nucleus
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
EXCITABILITY & ACTION POTENTIALS AC Brown page 2 A7a PHENOMENON OF EXCITABILITY A. Response to brief Electrical Stimulus (Pulse) 1. Effect of brief depolarization (inside less negative) Weak stimulus: Brief depolarization followed return to resting potential; due to ion movement, particularly K + and Cl - Stronger stimulus: Action potential; due to regenerative Na + influx B. Properties of the Action Potential (AP)
Background image of page 2
EXCITABILITY & ACTION POTENTIALS AC Brown page 3 A7a PHENOMENON OF EXCITABILITY B. Properties of the Action Potential (AP) – continued 1. shape ("spike") a. brief membrane depolarization b. overshoots zero (membrane positive), usually c. duration about 1 msec ( millisecond, 0.001 second) d. may or may not undershoot resting potential (after potential) when AP is complete, but eventually returns to resting level
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/03/2012 for the course BIO 308 taught by Professor Acbrown during the Spring '10 term at Portland.

Page1 / 7

2 Excitability and Action Potential - EXCITABILITY & ACTION...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online