Transcript PNS

PNS: Autonomic Nervous System
 Motor subdivision of the PNS
 Consists only of motor nerves
 Also known as the involuntary nervous system
 Regulates activities of cardiac and smooth
muscles and glands
 Two subdivisions
 Sympathetic division
 Parasympathetic division
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PNS: Comparison of Somatic
and Autonomic Nervous Systems (P. 266)
Figure 7.27
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PNS: Differences Between Somatic
and Autonomic Nervous Systems
 Nerves
 Somatic: one motor neuron
 Autonomic: preganglionic and postganglionic
neurons
 Effector organs
 Somatic: skeletal muscle
 Autonomic: smooth muscle, cardiac muscle,
and glands
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PNS: Differences Between Somatic
and Autonomic Nervous Systems
 Neurotransmitters
 Somatic: always use acetylcholine
 Autonomic: use acetylcholine, epinephrine, or
norepinephrine
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Somatic
Autonomic
Nerves
One motor neuron
Preganglionic & post
ganglionic neurons
Effector Organs
Skeletal Muscle
Smooth Muscle, cardiac
muscle, and glands
Neurotransmitters (NTX) Always use Ach
(acetylcholine)
Use Ach, Epinephrine,
or norepinephrine
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PNS: Anatomy of the
Autonomic Nervous System (P. 267)
Figure 7.28
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PNS: Anatomy of the Parasympathetic Division
 Preganglionic neurons located in the brain stem
and S2 through S4 levels of the spinal cord
 AKA ”Craniosacral” division
 Always uses acetylcholine as a neurotransmitter
**This can go below the previous diagram.
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PNS: Anatomy of the Sympathetic Division
 Preganglionic neurons located in T1 through L2 of
spinal cord
 AKA “Thoracolumbar” division
 Norepinephrine and epinephrine are
neurotransmitters to the effector organs
**This can go below the previous diagram.
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PNS: Autonomic Functioning
 Parasympathetic
 Most active when body is at rest
 “Housekeeping” activities
 Maintains daily necessary body functions
 Promotes normal digestion & elimination
 Conserves energy
 Remember as the “D” division
 digestion, defecation, and diuresis (urination)
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PNS: Autonomic Functioning
 Sympathetic
 Response to unusual stimulus
 “Fight or flight” division
 Takes over to increase activities
 Heart rate, blood pressure, blood glucose
levels, dilates bronchioles of lungs, dilates
pupils, perspiration, goose bumps
 Remember as the “E” division
 Exercise, excitement, emergency, and
embarrassment
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Effects of the Sympathetic and
Parasympathetic Divisions of the ANS
Table 7.3 (1 of 2)
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Effects of the Sympathetic and
Parasympathetic Divisions of the ANS
Table 7.3 (2 of 2)
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Tracking Down CNS Problems
 EEG
 Used to diagnose & localize brain lesions,
tumors, & abscesses; brain waves are unique
 CT & MRI Scans
 Allow most tumors, intracranial lesions,
plaques, & areas of dead brain tissue to be
ID’ed
 CT scans are the 1st used to determine if
stroke was caused by a clot or a bleed
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Tracking Down CNS Problems
 PET Scans
 Can localize lesions that generate epileptic
seizures & being used to diagnose Alzheimer’s
disease
 Cerebral Angiography
 Injection of dye to make arteries stand out on Xray; used for patients with TIA (warning stroke)
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Development Aspects of the Nervous System
 The nervous system is formed during the first month
of embryonic development
 Any maternal infection can have extremely
harmful effects
 The brain has the highest metabolic rate in the body
 The hypothalamus is one of the last areas of the
brain to develop
 Controls body temp
 Premature babies have trouble maintaining body
temp because hypothalamus isn’t developed
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Development Aspects of the Nervous System
 No more neurons are formed after birth, but
growth and maturation continues for several
years
 The brain reaches maximum weight as a young
adult
 As you age . . .
 Sympathetic NS becomes less efficient
 Constricts blood vessels & lack of oxygen
leads to senility
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