view-3.php - Neuronal Physiology Chapter 4 Nerve and muscle...

Info iconThis preview shows pages 1–16. Sign up to view the full content.

View Full Document Right Arrow Icon
Neuronal Physiology Chapter 4
Background image of page 1

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

View Full DocumentRight Arrow Icon
Nerve and muscle tissues are excitable. They can undergo rapid changes in their membrane potentials. They can change their resting potentials into electrical signals.
Background image of page 2
NERVE CELLS USE THESE SIGNALS TO: INITIATE RECEIVE PROCESS TRANSMIT MESSAGES AROUND THE BODY
Background image of page 3

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

View Full DocumentRight Arrow Icon
DEPOLARIZATION REPOLARIZATION The process of changing and then re- establishing resting membrane potential. There are four phases (parts) of this process.
Background image of page 4
THE FOUR STATES OF MEMBRANE POTENTIAL ARE: Polarization Depolarization Repolarization Hyperpolarization
Background image of page 5

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

View Full DocumentRight Arrow Icon
Nerve and muscle cells can develop several electrical states at their membranes . Each state is characterized by a different electrical charge. The charge is a result of ion movement into or out of the cell. This change in charge can be used to send messages around the body.
Background image of page 6
POLARIZATION Polarization - A -70mV charge has been established. (i.e. the membrane is polarized or has potential). Nothing is happening. This is the resting state, waiting for action.
Background image of page 7

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

View Full DocumentRight Arrow Icon
DEPOLARIZATION Depolarization - This change makes the membrane less negative (-70 towards 0mV). This is the change that sends the signal.
Background image of page 8
RE-POLARIZATION Repolarization - A return to resting potential after depolarization. The electrical charge moves back towards negative -70mV. Re-establishing the original potential it had prior to depolarization.
Background image of page 9

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

View Full DocumentRight Arrow Icon
HYPER-POLARIZATION Hyperpolarization - This makes the membrane more polarized, more negative inside. For a brief period of time the electrical potential of the membrane goes beyond -70mV to -90mV. This makes it harder to depolarize the membrane again.
Background image of page 10
Upward deflection = Decrease in potential Downward deflection = Increase in potential Repolarization Hyperpolarization Depolarization Resting potential
Background image of page 11

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

View Full DocumentRight Arrow Icon
Electrical changes occur by changes in ion permeability and ion movement across the plasma membrane of nerve and muscle cells.
Background image of page 12
ION PERMEABILITY MEANS IONS (NA + +) CAN NOW MOVE ACROSS THE CELL MEMBANE A flow of positive ions into the ICF depolarizes the cell. (Na + influx) A flow of positive ions into the ECF can repolarize a cell after depolarization. (K + efflux) From the resting state, a flow of positive ions into the ECF can hyperpolarize the cell. (K + influx)
Background image of page 13

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

View Full DocumentRight Arrow Icon
Electrical changes occur by changes in ion permeability The process starts when ions (namely Na + ) move into the cell. This is what starts the depolarization process. Ion movement occurs across the plasma membrane of nerve and muscle cells.
Background image of page 14
through specific channels or gates. There are two types of gates or channels. Leak channels (open all the time--subject to concentration gradient). Voltage Gated channels (GATES)
Background image of page 15

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

View Full DocumentRight Arrow Icon
Image of page 16
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 05/02/2010 for the course PHYSIO EXERCISE P taught by Professor Gil during the Spring '10 term at UCSB.

Page1 / 81

view-3.php - Neuronal Physiology Chapter 4 Nerve and muscle...

This preview shows document pages 1 - 16. Sign up to view the full document.

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