PSYCH 275 Chapter 2 -Communication Within the Nervous System (Terms)

Neurons

Cells that convey sensory information into the brain, carry out operations, and transmit commands to the body

Sensory Neurons

Neurons that carry information from the body and outside world into the brain and spinal cord

Motor Neurons

Neurons that carry commands to the muscles and organs to initiate movement

Interneurons

Neurons that connect one neuron to another in the same part of the brain or spinal cord

Unipolar

A neuron with one branch or growth off of its cell body, characteristic of sensory neurons

Bipolar

A neuron with two branches or growths off of its cell body, characteristic of sensory neurons

Multipolar

A neuron with multiple branches or growths off of its cell body, characteristic of motor neurons and interneurons

Polarization

A state in which there is a difference in electrical charge between the inside and outside of the neuron, characteristic of a resting neuron

Ions

Charged atoms that have lost or gained electrons

Ion Channels

Gated protein pores in the membrane formed by proteins that limit the flow of ions into and out of the cell

Sodium Potassium Pump

Large protein molecules found in neuron membranes that move sodium ions through cell membrane to outside and potassium ions back inside

Local Potential

Partial depolarization of an area on the neuron that receives a signal/is disturbed, where polarity in an area shifts towards zero

Action Potential

The abrupt depolarization of the membrane that travels along the axon to allow neurons to communicate

Nondecremental

The property of an action potential with which it travels down the axon without any decrease in size and is propagated at each successive point along the way

All or None Law

The law stating that an action potential will occur at full strength or will not occur at all

Absolute Refractory Period

The period in which sodium ion channels are unresponsive to stimuli, during depolarization and early repolarization

Relative Refractory Period

The period in which sodium ion channels are able to be stimulated, but potassium channels are still open, during polarization

Rate Law

The law in which an axon encodes a stimulus intensity via its firing rate, not the size of the action potential

Glial Cells

Nonneural cells that provide a number of supporting functions to neurons

Myelin

A glial cell comprised of fatty tissue that wraps around the axon to insulate it and keep cell separate from extracellular fluid/other neurons

Nodes of Ranvier

Gaps between the myelin sheath where the axon is exposed

Saltatory Conduction

A form of transmission in which action potentials appear to jump from node of Ranvier to node of Ranvier

Capacitance

Electrical effect of the membrane that slows movement of ions down the axon

Oligodendrocytes

Myelin-producing glial cells which produce myelin in the brain and spinal cord (CNS)

Schwann Cells

Most common type of glial cells which produce myelin in the peripheral nervous system

Radial Glia

Glial cells that form scaffolds during fetal development that guide new neurons to their destinations

Microglia

Glial cells that act as immunity in the brain by responding to injury and disease by removing cellular debris as well as providing energy to neurons

Astrocytes

Glial cells that trigger the formation of seven times as many connections in neurons