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Chapter 33
Regulation of the Visceral Function by the
Nervous System
I Autonomic Nervous System
1. Basic of the Anatomy
Autonomic Nervous System

Including parasympathetic, sympathetic, and
enteric divisions.

Coordinates cardiovascular, respiratory,
digestive, excretory and reproductive systems.

The enteric system is essentially an independent
nervous system responsible for regulation of
digestive functions.
Somatic and Autonomic Nervous System
Somatic and Autonomic
Nervous System
Somatic





Skeletal muscle
Conscious and
unconscious movement
Skeletal muscle contracts
One synapse
Acetylcholine
Autonomic





Smooth and cardiac
muscle and glands
Unconscious regulation
Target tissues stimulated
or inhibited
Two synapses
Acetycholine by
preganglionic neurons and
ACh or norepinephrine by
postganglionic neurons
侧副神经节
Sympathetic
Division

Preganglionic cell bodies in lateral horns of spinal cord T1-L2
Parasympathetic Division

Preganglionic axons
innervated
Preganglionic cell bodies in
nuclei of brainstem or
lateral parts of spinal cord
（S2-S4）
– Preganglionic axons
from brain pass to
ganglia through cranial
nerves
– Preganglionic axons
from sacral region pass
through pelvic nerves to
ganglia
pass to ganglia within wall of or near organ
Parasympathetic
and sympathetic
nerve
distribution
2. Neurotransmitters and
Neuroreceptors

Acetylcholine and Norepinephrine

All preganglionic neurons are cholinergic

Parasympathetic post ganglionic neurons are cholinergic

Sympathetic post ganglionic neurons are adrenergic
except
– Sympathetics innervating sweat glands, blood vessels in skeletal
muscle, and piloerection muscles are cholinergic
Neurotransmitters
SOMATIC NERVOUS SYSTEM
AUTONOMIC NERVOUS SYSTEM
Sympathetic
ACh
ACh
ACh
Parasympathetic
Ad. M. 
ACh
ACh
Striated
muscle
NE
Heart
Sm. mus.
Glands
ACh
Sweat
glands
ACh
Heart
Sm. mus.
Glands
E,

NE
Acetylcholine

Nicotinic receptors
– Nm (muscular-type or N2): skeletal muscle
– Nn (neuron-type, or N1): autonomic ganglia,
CNS

Muscarinic receptors
– Postganglionic parasympathetic and a few
sympathetic sites, CNS
– Receptor subtypes: M1-5
Catecholamines

Norepinephrine
– Postganglionic sympathetic, CNS, adrenal medulla
– Receptors: a1, a2, b1

Epinephrine
– Adrenal medulla, CNS
– Receptors: a1, a2, b1 , b2

Dopamine
– Autonomic ganglia, CNS
– Receptors: D(1-5), a1, b1
Location of ANS Receptors
3 Function of the Sympathetic and
Parasympathetic Nerve
Properties of the ANS

Tonic discharge
 Double innervation
– Most blood vessels are innervated only by
sympathetic nerves.
– Parasympathetic activity dominates the heart and GI
tract.

Dependent on the states of the target organ
 Different physiological significance
– Sympathetic nerve: fight and flight reaction
– Parasympathetic nerve: Wind down, relaxation,
digestion
SNS

Sympathetic nervous system prototypically “fight” or
“flight”.

Associated with increased
 energy expenditure,
 cardiopulmonary adjustments for intense activity,
 blood flow adjustments for maximum energy expenditure.
SNS - Fight & Flight Reaction
You’re walking alone at night and all the sudden you
hear an unfamiliar noise near by… In a matter of
seconds,
 your heart rate increases dramatically,
 blood vessels in your skeletal muscles dilate,
 blood vessels in the visceral muscles constrict,
 digestion is ceased,
 your liver ramps up glucose release,
 your pupils dilate,
 salivary production decreases,
 sweat increases.
Parasympathetic Nervous
System

If that noise turns out to be the result of
wind,
 the body is returned to “pre-noise” state.
 This is the job of the parasympathetic
nervous system.
Autonomic Nervous System
• Parasympathicus
• Sympathicus
• Wind down, relaxation,
digestion
• Dominated by
Acetylcholine
• Fight & Flight
Reaction
• Dominated by
Noradrenaline
(Adrenaline)
• Fear, exercise, rage
II. Central Regulation of Visceral Function
1. Spinal cord
 bladder and rectum reflex (micturition
and defecation)
 the baroreceptor reflex
 sweating of the skin
2. Medulla oblongata
 Vital (respiratory and cardiovascular) center:
Other autonomic reflexes:
Swallow, cough, sneeze, gag, and vomit.
3. Hypothalamus
Tu :19.17
Hypothalamic Functions








Food Intake
Water Balance
Sleep/wake cycle
Emotions and behavior
Circadian
Endocrine Functions
Body Temperature
Autonomic Nervous System
Food Intake

Ventromedial and Paraventricular Nuclei are satiety
centers
– Lesion causes obesity
– Through disrupting satiety input to the periventricular nucleus

Lateral HT is feeding center
– Stimulation cause food and water intake
– Lesion causes starvation behavior
– Through damage the medial forebrain bundle, leading to
neglect syndrome – no motivation to eat
Water Balance

Thirst center in the hypothalamus (supraotic nucleus)
is stimulated by:
– Cellular dehydration
– Decreased salivary production
– Increased blood osmotic pressure
– Decreased blood volume

Thirst center response
– Release vasopressin
– Cause sensation of thirst
Sleep/Wake Cycle

suprachiasmatic nuc is biological clock

preoptic nuc can initiate sleep

lateral hypothalamus can change cortical
arousal

post hypothalamus lesion can cause coma or
impaired arousal
Emotions and Behavior
 Ventromedial lesions
can cause
viciousness/rage
 Posterior HT stimulates sympathetic
functions
 Anterior HT stimulates parasympathetic
functions
 Mamillary nuclei recent memory
Circadian
Almost all land animals coordinate their behavior
according to circadian rhythms
Suprachiasmatic Nuclei (SCN)
Circadian Rhythms of Physiological Functions
Endocrine Function

Regulation of
Adenohypophysis
 Secretion of
Hormones
(Vasopressin and
Oxytocin)

Functions of the
Hypothalamus
Food intake
 Water balance
 Sleep/wake cycle
 Emotions and behavior
 Circadian
 Endocrine Function
 Body temperature
 Autonomic Nervous System
4 Influence of Brain on
Autonomic Functions
III Function of Sympathetic and
Parasympathetic nerve on the
target organs
Physiology
(Table 5-1)
Eye
Effector
Radial
muscle
Sphinctor
Ciliary
muscle
Cornea
Iris
Lens
Ciliary
muscle
Sympathetic
Parasympathetic
Contraction
—
(mydriasis, a1)
—
Contraction
(miosis)
Slight relaxa- Contraction (near
tion (b2)
vision)
Heart
Atria
SA node
AV node
Ventricles
Effector
SA node
Atria
AV node
Ventricles
Sympathetic
Tachycardia
(b1,b2)
contractility
and conduction
(b1,b2)
conduction
and automaticity (b1,b2)
contractility,
conduction, and
automaticity
(b1,b2,a1)
Parasympathetic
Bradycardia
contractility,
conduction
(usually)
conduction
—
Blood vessels
Effector
Skin and
mucosa
Skeletal
muscle
Salivary
glands
Erectile
tissue
Sympathetic
Constriction
(a1,a2)
Constriction
(a), dilation
(b2)
Constriction
(a1,a2)
Constriction
(a)
Parasympathetic
Dilation (?)
—
Dilation
Dilation
Lungs and salivary glands
Effector
Bronchial
sm. musc.
Bronchial
glands
Salivary
glands
Sympathetic
Parasympathetic
Relaxation (b2) Constriction
(a1),(b2),
secretion
Viscous,
amylase
secretion
(a1,b1,b2)
secretion
Profuse watery
secretion
Gastrointestinal tract and liver
Effector
Smooth
muscle
Sympathetic
Parasympathetic
motility and motility and
tone
tone
(a1,a2,b1,b2)
Sphincters Contraction
Relaxation
(a1)
Secretions secretion (a2) secretion
Liver
Glycogenolysis, Glycogen
gluconeogene- synthesis
sis (a1,b2)