PARASYMPATHETIC NERVOUS SYSTEM Department of Physiology It is
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PARASYMPATHETIC NERVOUS SYSTEM Department of Physiology
It is an anabolic system which preserve body energy. Origin : it is cranio-sacral outflow. 1 -CRANIAL OUTFLOW: III - occulomotor nerve VII- Facial nerve XI- Glossopharyngeal nerve X- Vagus nerve 2 - SACRAL OUTFLOW : Arises from the 2, 3&4 sacral segments. The preganglionic fibers unite to form the pelvic nerve. Reference (GUYTON AND HALL) Chapter 60 (Pages 730 -731) Department of Physiology
Parasympathetic supply Department of Physiology
Parasympathetic Nervous System Figure 60 -3; Guyton & Hall Department of Physiology
Parasympathetic supply to head & neck III- Occulomotor nerve : Origin Relay Function VII- Facial nerve : Origin Relay Function Chorda tympani ( branch of facial nerve ) Reference (GUYTON AND HALL) Chapter 60 (Pages 734 -736) Department of Physiology
VD of tongue blood vessels Anterior 2/3 Posterior Of tongue 1/3 of VII tongue IX Department of Physiology
IX- Glossopharyngeal nerve : Origin Relay Function Parasympathetic to thorax & abdomen X Vagus nerve Origin Relay Function Reference (GUYTON AND HALL) Chapter 60 (Pages 734 -736) Department of Physiology
Department of Physiology
1 -In the thorax In the heart In the lungs 2 - In the abdomen Gastro-intestinal tract ( G. I. T. ) Smooth muscles Secretory to the gastric glands Blood vessels vasodilatation The liver The pancreas Reference (GUYTON AND HALL) Chapter 60 (Pages 734 -736) Department of Physiology
Parasympathetic to pelvis Origin Relay Function: Urinary bladder Rectum & anal canal Sex organs Reference (GUYTON AND HALL) Chapter 60 (Pages 734 -736) Department of Physiology
Autonomic Nervous system Department of Physiology
Relation between Sympathetic & parasympathetic Usually there is antagonistic relation: as in heart , lungs & pelvis. Sometimes the relation is synergestic (each system help the other): Salivary secretion Sexual act Reference (GUYTON AND HALL) Chapter 60 (Pages 734 -736) Department of Physiology
Structures supplied by sympathetic alone 1 -The dilator pupillae muscle. 2 -The ventricles of the heart. 3 -Most of the blood vessels. 4 -The spleen 5 -The adrenal medulla 6 - The skin. Structures supplied by the parasympathetic only 1 -The constrictor pupillae muscles 2 -The glands of the stomach & pancreas SYMPATHETIC & PARASYMPATHETIC TONE the tone is the basal rate of activity of both systems. this tone is beneficial Reference (GUYTON AND HALL) Chapter 60 (Pages 734 -737) Department of Physiology
CONTROL OF AUTONOMIC FUNCTION : Most of the autonomic functions are mediated through the autonomic reflexes The autonomic reflexes are controlled by centers present in Spinal cord: for primitive autonomic reflexes Brain stem: Medulla oblongata Pons Mid brain Reference (GUYTON AND HALL) Chapter 60 (Pages 738 -739) Department of Physiology
Department of Physiology
Hypothalamus: It can control the activity of almost all the brain stem autonomic centers. in general the anterior nuclei of hypothalamus control parasympathetic function & the posterior nuclei control sympathetic function. Reference (GUYTON AND HALL) Chapter 60 (Pages 738 -739) Department of Physiology
Cerebral cortex : 1 -Psychogenic control of cardiovascular & gastrointestinal function. 2 -Higher control of micturation & defecation. 3 -Increase blood flow to skeletal muscle near voluntary muscular activity. Reference (GUYTON AND HALL) Chapter 60 (Pages 738 -739) Department of Physiology
CHEMICAL TRANSMISSION The signals are transmitted from neuron to another ( neuro-neuronal ) or from neuron to an effector organ ( neuro-effector ) by the release of chemical substance ( chemical transmitter ) Reference (GUYTON AND HALL) Chapter 60 (Pages 731 -732) Department of Physiology
Department of Physiology
The autonomic fibers are divided according to chemical transmitter released into two types : Cholinergic fibers : those secreting acetyl choline ( A. Ch. ). Adrenergic fibers : those secreting noradrenalin Reference (GUYTON AND HALL) Chapter 60 (Pages 731 -733) Department of Physiology
ACETYL CHOLINE (A Ch) : FORMATION STORAGE & RELEASE REMOVAL Types of choline esterases: 1 - True choline esterase 2 - Pseudo choline esterase SITES OF FORMATION: a-Central b-Peripheral Reference (GUYTON AND HALL) Chapter 60 (Pages 731 -732) Department of Physiology
Receptors of the Autonomic Nervous System adrenergic receptors sympathetic preganglionic neuron postganglionic neuron parasympathetic nicotinic receptors muscarinic receptors Department of Physiology
CHOLINERGIC RECEPTORS : Nicotinic receptors Muscarinic receptors Facing central cholinergic fibers ( all autonomic ganglia, adrenal medulla & at motor end plate ) Facing peripheral cholinergic fibers ( wall of viscera ) Stimulated by small dose of nicotine Stimulated by muscarine Inhibited by large dose of nicotine Inhibited by atropine Reference (GUYTON AND HALL) Chapter 60 (Pages 732 -733) Department of Physiology
Department of Physiology
ADRENERGIC TRANSMISSION CATECHOLAMINE SYNTHESIS RELEASE OF CATECHOLAMINES REMOVAL & INACTIVATION: 1 -NEURONAL REUPTAKE 2 -DIFFUSION 3 -DESTRUCTION BY ENZYMES Reference (GUYTON AND HALL) Chapter 60 (Pages 731 -732) Department of Physiology
Department of Physiology
Department of Physiology
A-POSTSYNAPTIC ADRENERGIC RECEPTORS Reference (GUYTON AND HALL) Chapter 60 (Pages 732 -733) Department of Physiology
Alpha Beta Sub types Alpha 1 & alpha 2 Beta 1 & beta 2 MECHANISM OF ACTION : Alpha 1 : increase intra-cellular calcium Alpha 2 : inhibit adenyle cyclase E. & decrease c. A. M. P. Beta 1 & beta 2 : stimulate adenyle cyclase & thus increase c. A. M. P. RELATIVE SENSETIVITY More sensitive to noradrenaline More sensitive to adrenaline Department of Physiology
FUNCTION Excitatory Causing: -Vasoconstriction -Contraction of dilator pupillae muscle. -Contraction of bladder & intestinal sphincters. -Contraction of piloerector muscle. -Ejaculation. Beta 1 : -specific for the heart -excitatory Stimulate all cardiac properties Beta 2 : inhibitory : -Bronchodilatation. -Vasodilatation. -Intestinal wall relaxation. -Bladder wall relaxation. -Uterine relaxation. Metabolic Effects: -Calorigenesis. -Glycogenolysis. -Lipolysis. Department of Physiology
B- Presynaptic receptors: They are present in the post ganglionic nerve ending membrane. They act as negative feed back control of nor adrenaline release ( decrease release when there is excess nor adrenaline ). They are similar to an α 2 type. They act through inhibition of adenyle cyclase enzyme leading to decrease c AMP. Reference (GUYTON AND HALL) Chapter 60 (Pages 732 -733) Department of Physiology
DIFFERENCES BETWEEN ADRENALINE & NORADRENALINE: ADRENALINE NORADRENALINE SOURCE: Adrenal medulla Postganglionic adrenergic sympathetic neurons & adrenal medulla STRUCTURE : Noradrenalin + methyl group. Adrenalin – methyl group RECEPTOR SPECIFICITY: More beta. Mainly alpha. Department of Physiology
Actions ADRENALINE NORADRENALINE Less Vasoconstriction of blood vessels. More vasoconstriction of blood vessels causing more rise of blood pressure More cardiac stimulation. Less cardiac stimulation. More metabolic effect. Less metabolic effect. Department of Physiology