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Peripheral Nervous System
+PERIPHRAL NERVOUS SYSTEM
PNS LIES OUTSIDE THE CENTRAL NERVOUS SYSTEM
COMOSED OF NERVES NERVES = BUNDLES OF AXONS WE CALL THEM NERVE FIBERS
SENSORY FIBERS CARRY INFORMATION TO THE CNS
MOTOR FIBRS CARR INFORMATION AWAY FROM THE CNS
Fig. 17.15abundle of
nerve fibers
nerve
single nerve fiber
+Cranial Nerves
Humans have 12 pairs of cranial nerves attached to the brain Some of these nerves bring information from the sense
organs to the brain other cranial nerves control muscles other cranial nerves are connected to glands or internal
organs such as the heart and lungs.
+Cranial Nerves
+Cranial Nerves
+Spinal Nerves
Spinal Nerves 31 pairs Emerge from openings between vertebral column and spinal
cord
Dorsal root (back) Contains sensory fibers that conduct impulses toward the
spinal cord Dorsal Root gangilon
Cell body Ventral root (front)
Contains motor fibers that conduct impulses away from the spinal cord
spinalnerve
dorsalroot
ventralroot
dorsal rootganglion
+PNS
PNS divided into 2 parts Somatic system Autonomic system
+Somatic Nervous System
responsible for carrying motor and sensory information both to and from the CNS
Responsible for all voluntary muscle movements and processing sensory information (hearing, touch, sight)
Made up of nerves that connect to skin, sensory organs and skeletal muscles
+Autonomic Nervous System
regulates the functions of our internal organs like the heart, stomach and intestines.
We are often unaware of the ANS because it functions involuntary and reflexively For example, we do not notice when blood vessels change
size or when our heart beats faster.
2 divisions Sympathetic Parasympathetic
+ANS
The ANS is most important in two situations: In emergencies that cause stress and require us to "fight"
or take "flight" (run away) In non-emergencies that allow us to "rest" and "digest."
+Sympathetic Division
It is a nice, sunny day...you are taking a nice walk in the park.
Suddenly, an angry bear appears in your path.
Do you stay and fight OR do you turn and run away? These are "Fight or Flight" responses.
In these types of situations, your sympathetic nervous system is called into action - it uses energy - your blood pressure increases, your heart beats faster, and digestion slows down.
+Parasympathetic Division
It is a nice, sunny day...you are taking a nice walk in the park.
This time, however, you decide to relax in comfortable chair that you have brought along.
This calls for "Rest and Digest" responses. Now is the time for the parasympathetic nervous to work to save energy
This is when blood pressure can decrease, pulse rate can slow, and digestion can start.
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+ANS
+PNS
https://www.youtube.com/watch?v=QY9NTVh-Awo
