Transcript The PNS - Mr. Lesiuk

Organization of the Nervous System
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The Peripheral Nervous System
The peripheral nervous system (PNS) contains nerves (bundles of axons)
and ganglia (cell bodies).
Sensory nerves carry information to the CNS, Motor nerves carry
information away, and Mixed nerves have both types of fibers.
Humans have 12 pairs of Cranial nerves and 31 pairs of Spinal nerves.
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The dorsal root of a spinal nerve contains sensory fibers that conduct
sensory impulses from sensory receptors toward the spinal cord.
Dorsal root ganglia near the spinal cord contain the cell bodies of
sensory neurons.
The ventral root of a spinal nerve contains motor fibers that conduct
impulses away from the spinal cord to effectors.
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Somatic System
The Somatic System serves the skin, skeletal muscles, and tendons.
The brain is always involved in voluntary muscle actions but somatic
system reflexes are automatic and may not require involvement of the
brain.
Somatic Motor Nerves only require one Motor Neuron length to17-4
reach
the effector.
Autonomic System – Think Automatic
The autonomic system of the PNS regulates the activity of cardiac and
smooth muscle and glands.
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Their motor nerves require TWO Neurons to bridge the gap to reach effector.
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The system is divided into
Sympathetic and
Parasympathetic divisions that:
1)
Function automatically and
involuntarily;
2)
Innervate all internal organs; and
3)
Use two neurons and one
ganglion.
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Sympathetic Division
The Sympathetic division is associated with responses that occur during
times of stress, including “fight or flight” reactions.
The postganglionic axon releases mainly NOREPINEPHRINE which acts
similar to adrenaline, the hormone from the adrenal medulla.
Everything is
stimulated to prepare
the body to flee
danger or fight for
survival. However,
the digestive system
processes are
inhibited.
Note that the
motor nerves
branch off of spine
in the Thoracic and
Lumbar regions of
spine
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SYMPATHETIC DESIGN IN MOTOR PATHWAY – SHORT
presynaptic neuron, with LONG post-ganglionic neuron.
Therefore Ganglion is found FAR from the effector.
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Parasympathetic Division
The Parasympathetic system is associated with responses that occur
during times of relaxation and promotes “housekeeper” activities.
The postganglionic neurotransmitter used by the parasympathetic
division is acetylcholine.
Everything is now stimulated to
work at a slower more relaxed
pace. However, digestive
processes are now fully stimulated
Note that the motor nerves
Branch off of spine from the
Sacral (Bottom of spine) and
Cranial (Brain) regions of
Central Nervous System.
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PARASYMPATHETIC DESIGN IN MOTOR PATHWAY – LONG
presynaptic neuron, with SHORT post-ganglionic neuron.
Therefore Ganglion is found NEAR the effector
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Autonomic Nervous System
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I COULD USE A LITTLE HELP HERE!
S – Nerves off of SACRAL region of spinal cord
C- Nerves off of CRANIAL region of CNS (brain)
A – Use ACETYLCHOLINE for normal stimulation
N – Runs vital organs at NORMAL relaxed level
N – Ganglion is found NEAR the effector
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I COULD USE A LITTLE HELP HERE!
F – Ganglion is found FAR from effector
E- Runs vital organs during EMERGENCY/EXCITATORY
situations
E – Use norEPINEPHRINE for extra stimulation
L – Nerves off of LUMBAR region of spinal cord
T – Nerves off of THORACIC region of spinal cord
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OK – Just How Smart Are You ?
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What neurotransmitter is released from this
nerve and what affect will it have on the liver?
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What will the neurotransmitter leaving this
nerve pathway do to your pupils?
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