the visceral nervous system
DESCRIPTION
The Visceral Nervous System. SHANDONG UNIVERSITY Liu Zhiyu. The Visceral Nervous System. Composition Visceral motor nerves (autonomic nervous system) Sympathetic part Parasympathetic part Visceral sensory nerves. Somatic and Autonomic Nervous System. - PowerPoint PPT PresentationTRANSCRIPT
The Visceral Nervous System
SHANDONG UNIVERSITY
Liu Zhiyu
The Visceral Nervous System
Composition Visceral motor nerves (autonomic nervous system)
Sympathetic part Parasympathetic part
Visceral sensory nerves
Somatic and Autonomic Nervous System
Main Differences Between Somatic Motor and Visceral Motor n.
Somatic Visceral Effectors Skeletal muscles Cardiac, smooth muscles and glands
Control Voluntary (consciousness)
Involuntary (unconsciousness )
From lower center to effect require
Single neuron Two neurons: preganglionic neuron and postganglionic neuron
Kind of fibers One Two: sympathetic & parasympathetic
Fibers Thick myelinated Preganglionic: thin myelinated postganglionic: unmyelinated
Distributive form Nerve trunk Nerve plexuses
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 Acetylcholine by preganglio
nic neurons and ACh or norepinephrine by postganglionic neurons
Neurotransmitters
ACh AChSweatglands
Striatedmuscle
AChSOMATIC NERVOUS SYSTEM
HeartSm. mus.Glands
ACh AChParasympathetic
ACh E, NE
Ad. M.
HeartSm. mus.Glands
ACh NE
AUTONOMIC NERVOUS SYSTEMSympathetic
Sympathetic Part
Lower center: located in intermediolateral nucleus (lateral gray horn) of spinal cord segments T1~L3
Sympathetic ganglia Paravertebral ganglia Prevertebral ganglia
Paravertebral Ganglia
Arranged on either side of vertebral column
Consist of 19~22 of oval-shaped ganglia 3 cervical 10~12 thoracic 4 lumbar 2~3 sacral Ganglion impar : unpaired on
the anterior face of coccyx
Paravertebral Ganglia
Superior cervical ganglion: largest, situated in front of transverse processes of C1~C3 vertebra
Middle cervical ganglion: smallest, is at level of transverse processes of C6 vertebra
Inferior cervical ganglion: situated at level of C7 vertebra, and may be fused with first thoracic ganglion to form cervicothoracic ganglion
Paravertebral Ganglia
Sympathetic Trunk
Formed by paravertebral ganglia and interganglionic branches
Lie on either side of vertebral column from base of skull to coccyx
The trunks of two side unite in front of the coccyx at a small swelling, the ganglion impar
Prevertebral Ganglia
Lie anterior to vertebral column and near the arteries for which they are named
Celiac ganglion Aorticorenal ganglion Superior mesenteric ganglion Inferior mesenteric ganglion
Preganglionic Fibers
Preganglionic fibers 15 pairs white communicating branches
Sympathetic trunk (only spinal levels T1~L3 have
white communicating branch)
Three Fates of Preganglionic Fibers
1. Relay in corresponding ganglion
2. Ascend or descend in sympathetic trunk and relay in higher or lower ganglia
3. Pass without synapse to a prevertebral ganglion for relay
Preganglionic Fibers Greater splanchnic nerve
formed by preganglionic fibers from T5~T9 ganglia, and relay in celiac ganglion.
Lesser splanchnic nerve formed by preganglionic fibers from T10~T12 ganglia, and relay in aorticorenal ganglion.
The postganglionic fibers supply the liver, spleen, kidney and alimentary tract as far as the left colic flexure.
Preganglionic Fibers
Lumbar splanchnic nerve Formed by preganglionic fibers from
L1~L4 ganglia, and relay in preverte
bral ganglia.
The postganglionic fibers supply desc
ending and sigmoid colon, rectum, pe
lvic viscera and lower limbs.
Three Fates of Postganglionic Fibers
Back to a spinal nerve along gray communicating branches to terminate in blood vessels, arrector pili muscles and sweat glands of head, neck, trunk and limbs
The fibers form their networks around blood vessels passing to visceral end organs
Terminate directly in certain organs
Postganglionic Fibers
Distribution of Sympathetic Nerve
Preganglionic fibers Postganglionic fibers
T1~T5 Head, neck, upper limb and thoracic viscera
T5~T12 Abdominal viscera
L1~L3 Pelvic viscera and lower limb
Parasympathetic Part Lower center: located in four pairs parasympathetic nuclei in b
rain stem and in sacral parasympathetic nucleus of spinal cord segments S2~S4
Parasympathetic ganglia: terminal ganglia are near or within the wall of a visceral organ Para-organ ganglia
Ciliary ganglion Pterygopalatine ganglion Submandibular ganglion Otic ganglion
Intra-organ ganglia
Cranial Portion of Parasympathetic Nerve
Ⅲ
ciliary ganglion
sphincter pupillae and ciliary muscles
pterygopalatine ganglionⅦlacrimal gland
submandibular ganglion
sublingual glandsubmandibular glandⅨ
otic ganglionparotid glandⅩ
terminal ganglia
heart, lungs, liver, spleenkidneys,alimentary tractas far as left colic flexure
Cranial Portion of Parasympathetic Nerve
Ⅲaccessory oculomotor nucleus 〈○ sphincter pupillae and ciliary muscles
ciliary ganglion
pterygopalatine ganglion Ⅶ 〈○ lacrimal glandsuperior salivatory nucleus 〈○ sublingual gland submandibular ganglion submandibular gland
Ⅸinferior salivator nucleus 〈○ parotid gland otic ganglion
Ⅹ heart, lungs, liver, spleen, dorsal nucleus of vagus n. 〈○ kidneys,alimentary tract terminal ganglia as far as left colic flexure
Sacral Portion of Parasympathetic Nerve
Preganglionic fibers from sacral parasympathetic nucleus leave spinal cord with anterior roots of the spinal nerves S2~S4,
Then leave sacral nerves and form pelvic splanchnic nerve and travel by way of pelvic plexus to terminal ganglia in pelvic cavity
Postganglionic fibers terminate in descending and sigmoid colon, rectum and pelvic viscera
Main Differences Between Sympathetic and Parasympathetic
Sympathetic Parasympathetic
Lower center Intermediolateral nucleus (lateral gray horn) of spinal cord segments T1~L3
Four pairs parasympathetic nuclei and sacral parasympathetic nucleus
Ganglia Paravertebral, prevertebral Terminal
Preganglionic f. Shorter Longer
Postganglionic f. Longer Shorter
Pre: Postganglionic 1: many more 1: a few
Distributions Throughout the body Limited primarily to head and viscera of thorax, abdomen, and pelvis
Different action Prepares for emergency situation (expends energy)
Conserve and restore body energy (conserves energy)
Main Differences Between Sympathetic and Parasympathetic
Sympathetic Parasympathetic
Different action Prepares for emergency situation (fight or flight)
Conserve and restore body energy (rest and relaxation)
Pupil Dilates Constricts
Heart Increases force of contraction
Decreases force of contraction
Rhythm of the heart To become more rapid To make slow
Blood pressure Heighten Depress
Bronchi Dilates bronchi Constricts bronchi
Main Differences Between Sympathetic and Parasympathetic
Sympathetic neurone
Dilator pupillae
Sphincter pupillaePupil
GanglionParasympathetic neurone
Normal light
Low light:-iris dilates
Bright light:-iris constricts
FUNCTION OF THE IRIS
Visceral Plexuses Cardiac plexuses
Superficial , below aortic arch
Deep, anterior to bifurcation of trachea
Pulmonary plexus
Visceral Plexuses Celiac plexus Abdominal aortic plexus Hypogastric plexus
Superior hypogastric plexus Inferior hypogastric plexus
(pelvic plexus)
Visceral Sensory Nerves
Enteroceptors
Ⅶ ,Ⅸ , Ⅹ
Nucleus of solitary tract
Sympathetic nerve Pelvic splanchnic nerve
Posterior horn
Thalamus
Hypothalamus
Cerebral cortex
Somatic motor neurons visceral motor neuclei
Effectors
Referred Pain
Pain originating from organs perceived as coming from skin
Site of pain may be distant from organ
Referred Pain
Convergence theory: This type of referred pain occurs b
ecause both visceral and somatic afferents often converge on the same interneurons in the pain pathways.
Excitation of the somatic afferent fibers is the more usual source of afferent discharge, so we “refer” the location of visceral receptor activation to the somatic source even though in the case of visceral pain.
The perception is incorrect.The convergence of nociceptor input from the viscera and the skin.
Referred Pain