Neural Unit 1 Definitions

Sherrington

synapse (connection between 2 clles), reflexes, active inhibition, basis of locomotion

Graham Brown

central pattern generators

Wachholder and Altenburger

electromyography

Bernstein

father of motor control, evolution-based approach multilevel scheme for the construction of movements, physiology of activity

reductionism

reducing the elements of a system to a basic level of functioning elements (finer details)

complex system approach

knowledge of the elements is essential to understanding the system but greater emphasis is placed on investigating and understanding the system as a whole

convection

movement of the solvent and solutes under a pressure gradient

diffusion

Movement of solutes from high to low concentration under the concentration gradient

membrane channels

involved with the movement of substances through the cell membrane

resting membrane potential

difference in electrical potential across the membrane (-70)

sodium potassium pump

an active mechanism maintaining resting potential

threshold

potential when the membrane generates an action potential (-55mV)

action potential

a standard time series of changes in the membrane potential after reach the threshold that allows for rapid communication

All or None law

when the stimulus leads to depolarization of the membrane potential to the point of generating an action potential an action potential will be generated

depolarization

cell becomes more positive; Sodium comes into the cell

hyperpolarization

cell becomes more negative; potassium leaves the cell

Relative refractory period

following the generation of an action potential which is possible to generate another action potential. The second action potential may not be generated with the same intensity of stimulus. Due to hyperpolarization

Absolute refractory period

following the generation of an action potential in which it is not possible to generate a new action potential due to sodium channel inactivation

orthodromic conduction

from soma to terminal branches (down the axon)

antidromic conduction

from the end of axon to the soma (up the axon)

soma

body of the cell; sire of input signals

dendrites

short branches originating from the soma; site of inputs

axon

long branch; transmits output signals

axon hillock

site where the axon exits the soma; typically, the site of generation of action potentials

terminal branches

a "brush" at the end of the axon

myelin

a fat like substance covering the axon; it increases the speed of conduction of action potentials

nerve (peripheral) or neural tract (central)

many axons running together

Persistent Inward Currents

currents occurring through ion channels leading to effective drop in the threshold for action potential generation by other inputs (increases number of action potentials generated)

synapse

site of information exchange between excitable cells

obligatory synapse

AP on the presynaptic membrane always gives rise to an AP on the postsynaptic membrane (1:1 ratio)

Nonobligatory Synapse

a single AP on the presynaptic membrane is typically unable to induce an AP on the postsynaptic membrane (more than 1 pre to get 1 post)

temporal summation

type of summation uses many action potentials from the same presynaptic membrane arriving within a short time period to cause a postsynaptic action potential?

Spatial summation

type of summation uses multiple action potentials from different presynaptic membranes arriving very close to each other (adjacent locations) to cause a postsynaptic action potential?

Saltatory conduction

action potentials jumping from node to node along a myelinated axon.