AUTONOMIC NERVOUS SYSTEM

DR. PETER REONISTO

MOORPARK COLLEGE

• Somatic-outer tube General-widespread• Visceral-inner tube Special-localized

CNS

PNSCranial nerves

and spinal nerves

Sensory (afferent)division

Motor (efferent)division

Somatic sensoryGeneral: Touch, Pain, pressure,

Vibration, temp.,And proprioceptionIn skin, body wall,

And limbsSpecial: Hearing,

Equilibrium, vision,smell

Visceral sensoryGeneral: Stretch,Pain,temperature,

Chemical changes, Irritation in viscera;Nausea and hunger

Special: taste

Somatic MotorGeneral: Motor

Innervation of all skeletal muscles

Visceral MotorGeneral: MotorInnervation of

Smooth muscle,Cardiac muscle, and Glands; equivalents

To ANS

SympatheticDivision

Parasympatheitcdivision

MOTOR NEURONS

• ANS includes a chain of 2 motor neurons:1) Pre-ganglionic neuron – cell body lies within the

spinal cord or brain. a) Preganglionic axon- synapses with the

ganglionic neuron2) Ganglionic neuron- cell body lies in the peripheral

location. a) Postganglionic axon- extends to the visceral

organs

DIVISIONS OF THE ANS1) Sympathetic- “fight, flight, or fright

response”

2) Parasympathetic- body at rest, conserving body energy; directs vital “housekeeping activities” (digestion , urination); “rest and digest”

Both divisions have chains of motor neurons that mostly innervate the same visceral organ, but they cause opposite effects.

Anatomical and biochemical difference:

SYMPATHETIC• originate at the

thoracolumbar region of the spinal cord.

• Long postganglionic fibers.• Sympathetic fibers branch

profusely.• Neurotransmitter released at

postganglionic axons are Norepinephrine mostly.

PARASYMPATHETIC

• originate from the cranial (brain) and sacral (spinal cord) outflow

• Short postganglionic fibers

• Parasympathetic fibers not profusely branched.

• Neurotransmitter released are Acetylcholine

The preganglionic axon terminals of both divisions release acetylcholine

Refer to Table 15.1, page 434

PARASYMPATHETIC NERVOUS SYSTEM

CRANIAL OUTFLOW

- comes from the brain.

- Innervate the head, neck, thorax, and most of the abdomen.

- Preganglionic fibers come from CNIII, VII, IX, X.

SACRAL OUTFLOW

- comes from the sacral sinal cord

- Supplies the rest of abdominal organs and the pelvic organs

Sacral outflow

Cranial outflow

SYMPATHETIC NERVOUS SYSTEM• Paravertebral ganglion

located along both sides of the vertebral column.

• Connected to the ventral rami of nearby spinal nerves

Prevertebral ganglia:

-occur only in the abdomen

1) Celiac

2) Superior mesenteric

3) Inferior mesenteric

4) Inferior hypogastric

Cranial outflow

Sacral outflow

Paravertebral ganglion

SYMPATHETIC NERVOUS SYSTEM AND ADRENAL MEDULLA

The adrenal gland is divided into the:

1) Adrenal cortex

2) Adrenal medulla

SYMPATHETIC NERVOUS SYSTEM AND ADRENAL MEDULLA

Adrenal Medulla

- Cells secretes the hormone norepinehrine and epinephrine

- Innervated only by the sympathetic nervous system

- Considered to be part of the sympathetic nervous system; modified ganglionic cells that lack nerve processes.

- Hormones have a excitatory effect of the “flight, fight, or fright response”

CENTRAL CONTROL OF THE ANS

SUMMARY OF NEURONS CONNECTED TO THE SPINAL CORD

SUMMARY OF ANS FUNCTIONS

EFFECTOR ORGAN

SYMPATHETIC STIMULI PARASYMPATHEITIC STIMULI

HEART Rate

Contractility

SA NODE Conduction velocity

AV NODE Conduction velocity

VENTRICLES Conduction velocity

LUNGS Bronchial smooth muscle

ARTERIOLES Skin, resistance vessels

Skin surface vessels

Mucosa

Increase Decrease

Increase Decrease

Increase Decrease

Increase ------

Relaxation smooth Muscle B2

Contraction smooth Muscle A1

Constriction(direct A1)Dilation(circ Epi at B2)

Both dilation (circAcH at M2) (minor)

Constriction (direct A1) ------

SUMMARY OF ANS FUNCTIONS

EFFECTOR ORGAN

SYMPATHETIC STIMULI PARASYMPATHEITIC STIMULI

ARTERIOLES Abdominal viscera

Skeletal muscles

Coronary

Glands

VEINS

(SYSTEMIC)

GIT Motility and tone

Sphincter contraction

Constriction (direct A1) ------

Dilation (circ Epi at B2) Dilation (circ AcH at M2)

Dilation (circ Epi at B2) Dilation (circ AcH at M2)

Constriction (direct at A1) Dilation (circ AcH at M2)

Constriction (direct at A1) ------

Decrease Increased

Contraction Relaxation

SUMMARY OF ANS FUNCTIONS

EFFECTOR ORGAN

SYMPATHETIC STIMULI PARASYMPATHEITIC STIMULI

SKIN Pilomotor muscle

Sweat glands

SPLEEN CAPSULE

EYE Radial muscle of iris

Sphincter muscle of th iris

Ciliary muscle

GLANDS Gastrointestinal

Piloerection ------

Secretion ------

Contraction ------

Contraction (mydriasis) ------

------ Contraction (miosis)

Relaxation (far vision) Contraction (near vision)

Inhibition of secretion Secretion

SUMMARY OF ANS FUNCTIONS

EFFECTOR ORGAN

SYMPATHETIC STIMULI PARASYMPATHEITIC STIMULI

GLANDS Lacrimal

Nasopharyngeal

Respiratory

Salivary

------ Secretion

------- Secretion

Inhibition of secretion Secretion

Thick secretion Thin secretion

CENTRAL CONTROL OF THE ANSCerebral Cortex(Frontal lobe)

Limbic Lobe(emotional input)

HypothalamusOverall integration of the

ANS

Reticular formation of thebrainstem

Spinal cord

Regulation of pupil size, Respiration, heart, BP,

Swallowing etc.

Urination, defecation,Erection, and ejaculation

reflexes

OVERVIEW OF THE SENSORY ORGANS

Vision Your eyes gather visual

information, which is

sent to your brain to be processed

and understood.

Vision (retina)Vision: Retina 

• Rods sense brightness

• Cones sense color The retina, in the back

of your eye, has cells that are sensitive to light. They connect directly to your brain.

Hearing Sound waves make your eardrum vibrate.

Then, the small bones in your ear vibrate, and

the vibrations go through the snail-

like cochlea, which turns them into

nerve impulses to your brain.

Taste• 10,000 taste buds

in your mouth

• Sweet and salty are least sensitive

• Bitter ones are most sensitive

  

Your tongue picks up four types of

taste: sweet, sour, bitter, and

salty.

Taste Buds• You have 10,000 taste

buds in your mouth.

Tastebuds closeup Molecules of food

stimulate the taste

cells to send

messages to your brain. The

sweet and salty buds are the least sensitive and the bitter

ones are the most sensitive.

SMELLOdor particles

drift into your nose and cause your smell

receptors to send

messages to your brain.

OLFACTORY BULB (SMELL)

The smell part of the brain is in the limbic

region, and is

connected to feeling

and memory.

TOUCH There are at least six types of touch receptors in your skin. One for hot, one for cold, one for pain, one for

pressure, one for touch, and one for fine touch.

END

PLEASE READ THE SENSORY SYSTEM AND THE ENDOCRINE

SYSTEM