Peripheral Nervous System
What do you see?
CNS AND PNS
Characteristics of the P.N.S.
 Nerves that branch out from brain, spinal
column
 Not covered w/ meninges
 No CSF
 Divided into somatic and autonomic
branches
2 Divisions:
 Somatic Nervous System
 CRANIAL & SPINAL nerves
 Afferent Sensory nerves
 Efferent, VOLUNTARY Motor nerves
 Autonomic Nervous System
 Parasympathetic & Sympathetic Systems
 INVOLUNTARY motor nerves
 Maintains homeostasis
Peripheral
Nervous
System
Somatic Nervous
System:
Cranial & Spinal
Nerves
Sensory Nerves
Motor Nerves
(send impulses to
the brain/spinal
cord)
(Send impulses
away from
brain/spinal cord)
Autonomic
Nervous
System
Parasympathetic
Nervous System
(Rest & Digest)
Sympathetic
Nervous System
(Fight or Flight)
PNS: Cranial & Spinal Nerves
You’ve got a lot of nerve! (Cranial
Nerves, that is!)
 Twelve total
 Arise from brain, passing through various
foramina
 Specialized tasks – some sensory, motor, or
both
 Some with multiple branches
 Identified by Roman numeral and anatomical
name
Mnemonic time!
 “Oh, Oh, Oh, To Touch And Feel Very Green
Vegetables… Aah, Heaven”
 …there are more out there… They help you
remember…
 Olfactory, Optic, Oculomotor, Trochlear, Trigeminal,
Abducens, Facial, Vestibulocochlear,
Glossopharangeal, Vagus, Accessory, Hypoglossal
Functions!
Sammy Sosa Made Money, But My
Brother Says Barry Bonds Made More
 S = sensory
 M = motor
 B = both
Spinal nerves have their ups and
downs…
 Sensory and motor
PNS: Autonomic Nervous System
Can you explain each of these?
Autonomic Nervous System
 Regulates internal environment
 Controls glands, cardiac muscle, smooth muscle
 Homeostasis!
 Integrated with endocrine system
 Digestion, sexual functions, stress responses
 No conscious thought…
A nervous system divided…
Parasympathetic
 Cranial nerves, sacral
spinal nerves
 Promotes relaxation,
digestion
 “Post-stress”, P.S.
Sympathetic
 Thoracic, lumbar
spinal nerves
 Prepares body to
react to stress
 “Fight or Flight”
 “S for stress”
It’s all about connections…
 Somatic nerves:
 Full length of nerve connects spinal cord to body
component
 Cell body in gray matter… terminus contacts effector
 Autonomic nerves:
 Two neurons working together
 Preganglionic originates in brain/spinal cord
 Myelinated
 Synapses with postganglionic neuron (non-myelinated)
Form follows function…
 In parasympathetic nervous system…
 Preganglionic neurons long, terminate close to effector (short
postganglionic neuron)
 Allows specific, targeted control
 In sympathetic nervous system…
 Preganglionic neurons short, terminate close to spinal cord
(sympathetic ganglion chain)
 Postganglionic neurons long, travel from ganglion to effector
 Allows widespread activation of body systems
Double agents?
 Effectors receptive to both systems… how?
 Preganglionic nerves of Symp, Parasymp NS
secrete acetylcholine…
 Postganglionic nerves secrete different NT’s
 Parasympathetic NS  acetylcholine
 Sympathetic NS  norepinephrine
 Cause antagonistic effects in effector
Antagonistic effects…
Effector
Sympathetic Action
Parasympathetic Action
Iris
Opens pupil
Closes pupil
Salivary glands
Reduces saliva production
Increases saliva production
Oral/nasal mucosa
Reduces mucus production
Increases mucus
production
Heart
Increases activity
Decreases activity
Lung
Relaxes respiratory muscles Constricts respiratory tree
muscles
Stomach
Reduces digestive action
Increases digestive action
Small intestine
Reduces digestive action
Increases digestive action
Large intestine
Reduces digestive action
Increases digestive action
Kidney
Decreases urine prod.
Increases urine prod.
Bladder
Relaxes bladder
Contracts bladder