Transcript Neurons & Transmission of Information

Neurons & Transmission of Information
•Neuron = specialized cell that conducts
impulses (sends messages) through the
nervous system
•contains 3 major parts--cell body,
dendrites, & an axon
–Cell body = contains the nucleus & carries out the
metabolic (life-sustaining) functions of the neuron
–dendrites = receivers of signals from other neurons
(look like tree branches)
–axon = tail-like extension of the neuron that transmits
signals to the dendrites or cell body of other neurons or
to the other muscles or glands
–myelin sheath = fatty coating wrapped around some
axons that acts as insulation & enables impulses to
travel much faster
•Note: neurons are not connected to each other--separated
by tiny, fluid-filled gaps called synaptic clefts
•Synapse = junction where the axon terminal of the
sending neuron communicates with a receiving neuron
across the synaptic cleft
•Neurotransmitters = chemical that is released into the
synaptic cleft from the axon terminal of the sending
neuron, crosses the synapse, & binds to appropriate
receptor sites on the dendrites or cell body of the receiving
neuron & influences the other cell
•receptor site = site on the dendrite or cell body of a neuron that will
receive only specific neurotransmitters
•variety of neurotransmitters = regulate actions of glands, muscles,
learning, memory, sleep, emotions, relief from pain, etc.
•Two types of neurons:
–A sensory neuron is a nerve cell that relays impulses from a
receptor such as those in the eye or ear to a more central location
in the nervous system.
•Also known as _________________________
–A motor neuron is a nerve cell that sends impulses from a central
area of the nervous system to an _________________ such as a
muscle
•Also known as ______________________