Transcript The Nervous System

The Nervous System
The cell membrane
• Selectively semi-permiable membrane
• Bipolar lipid-protein structure
– Gates that allow materials to pass through
• The membrane has a charge
– Membrane potential
– Charge due to ions
• K, Na, Ph, Ca, Cl
Information
• Information is a measure of the state of the system
• Information is a measure of the change in the state
of the system
• If system has changed, then responses can be
made to the changes.
• Nervous system--a system that is designed to
detect and respond to changes in state of the
system.
The cell membrane
• Osmosis--the movement of water through a
selectively permiable membrane.
– Osmotic regulation
• Ionic regulation
Sponges
• Simple structure
• Outer epidermal layer has cell membranes
exposed to the environment
• Simple spreading of the signal with
degradation with respect to distance
Cnidaria
• Ectoderm and endoderm have basal muscle
fibers
• Mesoglea separates the two layers
• Sub-epidermal nerve net
Flatworms
• Sub-epidermal nerve net
• Cephalization--eyes and brain and olfactory cells
in auricula
• Neuron--functional element of the nervous system
– Nerve cell body and fibers going into and out of
– Ganglion is a collection of nerve cell bodies
– Nerve--collection of fibers (dendrons and axons)
• Sensory response and motor response