Transcript The Nervous System

REVIEW:

CNS
◦ Brain and spinal cord
◦ Protected by
 Meninges
 skull and vertebrae

PNS
◦ All the other neurons
◦ Serves limbs and organs
◦ Sensory and motor
branches
◦ Exposed to toxins and
more susceptible to
injuries
Involuntary (e.g.
Heartbeat,
peristalsis)
Quick Responses
(fight or flight)
Slower
Responses
(rest & digest)
Dendrites (receives electrical stimulation from other neurons)
Cell Body
Axon terminals (transmits
electrical stimulation to other
neurons)

Sensory Neurons
◦ E.g. Those in skin
◦ Receive sensory information & transmit the information (as
a nerve impulse) to the CNS (brain & spinal cord)

Motor Neurons
◦ Take information from CNS to effectors (e.g. Muscles,
glands, other organs)

Interneurons
◦ Link sensory & motor neurons
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Sensory neurons are stimulated by
the pricking of the rose thorns
signal travels to the spinal cord
along sensory neurons
synapse with interneurons within
the CNS
Interneurons stimulate motor
neurons
travels along their axons to the
muscle
Muscle contracts to withdraw the
hand

Oligodendrocytes
◦ form the myelin sheaths of axons in CNS

Schwann cells
◦ form a myelin sheath around each axon in PNS


80% lipid + 20% protein
Protects the axon and helps speed up the
conduction of nerve impulses

Make yourself a glossary for the following
terms:
◦ Glial Cell, Myelin Sheath, node of Ranvier
◦ Central Nervous System, Peripheral Nervous System
◦ Somatic Nervous System, Autonomic Nervous
System, Sympathetic Nervous System,
Parasympathetic Nervous System