Download Nervous_System_Neurons

Central Nervous System
Most highly organized and complex
system of the body
-Communication and coordination
system of the body
-Seat of intellect and reasoning
-Consists of the brain, spinal cord,
and nerves







NEURON = Nerve cell
Transmits a message from one neuron to
the next
NEUROGLIA = nerve “glue”, holds nerve
together






DENDRITES
Nerve cell processes that carry impulse to
the neuron
axon
May be one or many
AXON
Carries impulse away from neuron
Only one on a neuron
dendrites




NEURILEMMA (MYELIN SHEATH)
Myelin is a fatty substance that protects the
axon
Speeds up the nerve impulse as it travels
along the axon
SYNAPSE – space between neurons,
messages go from one cell to the next
The ends of the dendrites and axons never touch at
the synapse
 So how is the nerve message continued along
the axon/dendrite route???


The synapse contains
Neurotransmitters
Chemicals which help the message “jump” across
the synapse
 i.e. Dopamine, Epinephrine
Acetylcholine
Endorphins are neurotransmitters produced
in the brain that reduce pain
 They have also been known to induce
euphoria. Drugs such as morphine, heroine
and cocaine are classic endorphin-releasing
entities
 Laughter, chocolate, acupuncture, exercise
trigger an endorphin release
“runner’s high”


All neurons have 2 characteristics:

1. irritability: neurons can react when
stimulated

2. conductivity: neurons can transmit an
impulse to another neuron



3 Types of Neurons
SENSORY NEURONS (AFFERENT) – emerge from
the skin or sense organs, carry impulses to spinal
cord and brain
MOTOR NEURONS (EFFERENT) – carry
messages from brain and spinal cord to muscles
and glands
INTERNEURONS (ASSOCIATIVE NEURONS)–
carry impulses “in between” sensory neurons and
motor neurons found in the spinal cord