Lab 18 - Introduction to the Nervous System

Three Major Functions of the Nervous System (Step 1)

Receptors (photoreceptor) respond to stimuli (light) and transmit information to brain

Three Major Functions of the Nervous System (Step 2)

The central nervous system (CNS) processes & evaluates the information from the receptors

Three Major Functions of the Nervous System (Step 3)

If necessary, the CNS initiates a response as motor output via nerves to effectors (muscles, glands)

Neuron

An excitable cell the imitiates and transmits electrical signals

Myelin

Fatty, electrically insulating covering around an axon that consist of repeating concentric layers of plasma membranes of neurolemmocytes

Myelin sheath

Overlapping inner layers of the plasma membrane of the neurolemmocyte

Myelinated fiber

An axon bearing a myelin sheath

Unmylinated fiber

An axon not bearing a myelin sheath; such axons have associated neurolemmocytes but these do not form the tightly wrapped concentric layers of the sheath

Gray matter

Regions of brain and spinal cord containing mostly cell bodies and unmyelinated fibers

White matter

Regions of brain and spinal cord bearing dense collections of myelinated fibers; primarily fiber tracts

Cell body

Neuron's main biosynthetic center; conduct electrical signals to axon

Neurofibrils

Maintain cell shape & integrity (part of cytoskeleton)

Dendrite

Receive electrical signals from other neurons, conduct them to cell body

Axon hillock

Sum inhibitory & excitatory stimuli; initiate action potential if sum is sufficiently exciatory

Axon

Generate special electrical signals called action potentials and transmit them away from cell body to telodendrion (axon terminal)

Collaterals

Spilt the electrical signal (action potential) to more than one post-synaptic cell

Telodendrion

Upon receipt of an action potential, release neurotransmitter into synaptic cleft

Neurolemmocyte (Schwann cell)

Form the electrically insulating & proctive myelin sheath around an axon

Nurilemma

Protect neurolemmocyte from its surroundings, control movement of substances in and out of the cell, mediate cell adhesion & cell signaling

Neurofibril node

Allow re-initiation of action potential and thereby enable fast saltatory conduction along the axon