Download Chapter 14 Autonomic Nervous System

Chapter 14
Chapter 15
Autonomic Nervous System
Neural Integration
Lecture # 33, 34
Objectives: 1. Define autonomic nervous system and explain its relationship to the peripheral
nervous system as a whole.
2. Compare the somatic and autonomic nervous systems relative to effectors,
efferent pathways, and neurotransmitters released.
3. Compare and contrast the general functions of the parasympathetic and
sympathetic divisions.
4. For the parasympathetic and sympathetic divisions, describe the site of CNS
origin, locations of ganglia, and general fiber pathways.
5. Define cholinergic and adrenergic fibers, and list the different types of
cholinergic and adrenergic receptors.
6. State the effects of the parasympathetic and sympathetic divisions on the
following organs: heart, blood vessels, gastrointestinal tract, lungs, adrenal
medulla, and external genitalia.
7. Describe the levels of control of autonomic nervous system functioning.
8. Define EEG and distinguish between alpha, beta, theta, and delta brain waves.
9. Compare and contrast the events and importance of slow-wave and REM
sleep.
10. Describe consciousness clinically.
Autonomic Nervous System: motor division of PNS
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Consists of motor neurons that innervate smooth and cardiac muscle and glands.
Motor units of ANS consist of two neuron chains and the muscles they innervate.
Hypothalamus is in control. Divided into sympathetic and parasympathetic divisions.
Preganglionic neuron: found in brain or spinal cord; preganglionic axon is lightly myelinated
and synapses with postganglionic neuron. The postganglionic neuron begins in ganglion outside
of CNS.
Postganglionic neuron: The postganglionic, unmyelinated neuron begins in ganglion outside
of CNS and extends to the effector. Conduction, obviously, is slower, due to lack of myelination.
Neurotransmitters: Norepinephrine (NE) is released by postganglionic neurons of the
sympathetic division. Acetylcholine (ACh) is released by postganglionic neurons of the
parasympathetic division, and all preganglionic neurons of the ANS.
Dual Innervation: The same visceral organs are served by both divisions to counterbalance
each other’s activities and to maintain homeostasis.
Parasympathetic Division: usually in control of our visceral organs; works during nonstressful
situations. Nicknamed the “feed or breed” response. Body energy use is low. Effects are of
short duration and localized. Nerves originate from the craniosacral region of the spinal cord.
Ganglia are close to organs, making preganglionic neurons long and postganglionic neurons
short.
Sympathetic Division: works during stressful situations. Nicknamed the “flight or fight”
response. Body energy use is high. Effects are of long duration and widespread (effuse).
Nerves originate from the thoracolumbar region of the spinal cord. Ganglia are located in a chain
close to spinal cord (white chain ganglia), making preganglionic neurons short and postganglionic
neurons long.
Cholinergic fibers: those fibers which release Ach (the parasympathetic pre/postganglionic
and the sympathetic preganglionic) and the receptors for such. The receptors come in two
types:
1. Nicotinic: ACh binding is stimulatory, found in all ganglionic neurons.
2. Muscarinic: ACh binding is either stimulatory or inhibitory; found on all effector cells
that are parasympathetic target organs and sweat glands.
Adrenergic fibers: those fibers which release NE (sympathetic postganglionic) and the
receptors for such. The receptors come in two types:
1. alpha (): effect of NE/epinephrine is stimulatory.
2. beta (): effect of NE/epinephrine is inhibitory (except the  receptors of cardiac
muscle which are stimulatory).
Effects of Divisions
Target Organ/System
Parasympathetic effects
Sympathetic effects
Eye (iris)
Stimulates constrictor muscles to
constrict pupil
Stimulates secretory activity
Stimulates dilator muscles to
dilate pupil
Inhibits secretory activity
No innervation
Stimulates sweating
Glands (lacrimal, nasal,
pancreas, salivary,
gastric)
Sweat glands
Adrenal medulla
No innervation
Arrector pili muscle
No innervation
Heart muscle
Decreases rate; slows and
steadies heart
Constrict
Stimulates release of
epinephrine
Stimulates to contract
(goosebumps)
Increases rate and force of
heartbeat
Dilate
Contraction of wall of bladder,
relaxes sphincters, promotes
voiding
Constricts bronchioles
Relaxation of bladder wall,
constricts sphincters, inhibits
voiding
Dilates bronchioles
Digestive tract organs
Increases peristalsis and secretion
of digestive juices, relaxes
sphincters
Liver
No innervation
Gall bladder
Kidney
Causes gall bladder to contract to
expel bile
No innervation
Decreases activity of glands
and muscles of digestive
system and constricts
sphincters
Epinephrine stimulates
release of glucose into blood
Relaxes
Penis
Erection
Vagina/clitoris
Vasodilation
Heart: coronary blood
vessels
Bladder/urethra
Lungs
Blood vessels
Causes vasoconstriction,
decreases urine output
Ejaculation
Contraction of vagina,
increases mucus
No effect; vessels return to normal Vasoconstriction, raises
diameter following sympathetic
blood pressure, dilates
stimulation
vessels leading to skeletal
muscles
Autonomic Control: hypothalamus is the boss, but the reticular formation exerts the most
direct influence.
EEG: records some aspects of the continuous electrical activity of neurons.
Brain Waves
I. Alpha: low amplitude, slow, synchronous. Brain is in “idle”. Calm, relaxed state of
wakefulness (hitting the snooze alarm).
II. Beta: rhythmic, more irregular than alpha and higher frequency. Awake and mentally alert,
as when we concentrate (like what you should be doing right now).
III. Theta: more irregular than beta, common in children (until the age of eight when they take
on the beta pattern), and abnormal if present in adults who are awake.
IV. Delta: high amplitude, low frequency, deep sleep, RAS is anesthetized; indicates brain
damage in awake adults.
Sleep
I. Slow-wave: cycles of nonREM sleep. During first 30-45 minutes of sleep. Must occur for
REM sleep to occur. 4 stages of NREM.
II. REM: 90 minutes into sleep, EEG waves become more alpha-like (awake) and REM has
begun. Body temperature, heart rate, respiration, and blood pressure all increase. Oxygen use
by the brain is greatest. Eyes move, but other skeletal muscle is inhibited. Most dreaming
occurs during REM. Nightmares/night terrors occur in stage 3-4 of sleep.
Consciousness: the conscious perception of sensations, voluntary initiation and control of
movement.
Stages/levels: 1) alertness
2) drowsiness/lethargy 3) stupor
4) coma
 involves simultaneous activity of large areas of cerebral cortex.
 Superimposed on other types of neural activity
 Holistic and totally interconnected: a memory recalls several routes
 Fainting or syncope: inadequate cerebral blood flow from low blood pressure,
hemorrhage or stress.
Epilepsy: a torrent of electrical discharges of groups of neurons. Genetic, trauma, stroke, fever,
watching Pokemon, etc.
 Absence seizures (petit mal): expressionless, young children
 Grand mal: convulsive seizures
 Auras may occur prior to seizure
 Treat with anticonvulsives, vagus nerve stimulator, sever corpus callosum,
hemispherectomy