![notes
• β1 are Excitatory and present only in the heart [↑ HR].
•β2 are Inhibitory and causes vasodilatation & Relaxation of [Uterus,
GIT &Urinary Bladder wall, Bronchial smooth muscles].
•α1 are Excitatory and causes vasoconstriction and contraction of
[Dilator Pupillae ms, Piloerector ms. of hair, and GIT & Urinary
Bladder sphincters].
• α2 are Inhibitory and present only in GIT wall causing its dilatation.](https://image.slidesharecdn.com/ans-240106223921-52b34e84/85/ANS-ppt-18-320.jpg)
![Mass discharge of the
sympathetic N.S
The sympathetic nervous system is usually activated by the
hypothalamus all as one unit. This occurs in cases of stress, either
mental [e.g. Fear, Exam, embarrassment, etc] or physical [e.g.
Exercise, Escape, Fight].](https://image.slidesharecdn.com/ans-240106223921-52b34e84/85/ANS-ppt-24-320.jpg)
![Horner’s syndrome
It is a group of manifestations that results from interruption of the sympathetic
supply to the head & neck (the lesion usually at sympathetic chain).
These manifestations include:
[Ptosis – Miosis – Enophthalmos – Anhydrosis – Warm red skin].](https://image.slidesharecdn.com/ans-240106223921-52b34e84/85/ANS-ppt-25-320.jpg)
![ The cholinergic receptor could be affected by administration of drugs. These drugs
may:
1- Stimulate the cholinergic receptors. They include:
a- Dugs has similar action to Ach [e.g. Methacholine, Pilocarpin, Nicotine
(small dose)].
b- Anticholineesterases [e.g. Neostigmine, Prostigmine].
2- Inhibit the cholinergic receptors. They include:
a- Anticholinergics [e.g. Atropine, Homatropine].
b- Ganglion blockers [Hexamethonium, Nicotine (large dose)].
c- Neuromuscular blockers [e.g. Curare, Succinyl choline].](https://image.slidesharecdn.com/ans-240106223921-52b34e84/85/ANS-ppt-32-320.jpg)
![ The N.A is released from the following sites:
1- All the postganglionic sympathetic fibers [Except the 2
cholinergic fibers].
2- The adrenal medulla secretes noradrenaline (20%) and
adrenaline (80%).
3- N.A acts as NT inside the CNS.](https://image.slidesharecdn.com/ans-240106223921-52b34e84/85/ANS-ppt-36-320.jpg)
ANS.ppt
- 1. Autonomic nervous System DR /Ibrahim AL-Gubani DEPARTMENT OF PHYSIOLOGY FACULTY OF MEDICINE THAMAR UNIVERSITY
- 2. Definition ANS is a part of the nervous system concerned with regulation and control of all involuntary processes in the body (BP ,GI motility and secretion ,UB emptying ,sweating ,body temperature ,and many other activities . Some are controlled completely and others only partially .
- 3. Anatomically : nervous sys. is divided to central (brain and spinal cord ) and peripheral (cranial and spinal nerves ). Physiologically : nervous system is divided to somatic (voluntary ) and autonomic (involuntary or visceral ). Centers of ANS located in spinal cord ,brain stem ,hypothalamus and limbic system
- 4. In ANS : -2 efferent neurons pre& post ganglionic (in somatic only one efferent neuron) -preganglionic fiber synapse with postganglionic in a ganglia located outside the CNS -Autonomic flow is diffuse (preganglionic neuron synapses with several postganglionic neurons -------------- spreading the effect over a large area.
- 5. Autonomic motor reflex Somatic motor reflex
- 6. Autonomic nervous system It is involuntary 2 types (sympathetic ¶sympathetic ) 2 efferent neurons (pre & post ganglionic ) It supplies smooth muscles, cardiac muscles, and all exocrine glands . Somatic nervous system It is voluntary one type . one efferent neuron . It supplies skeletal muscles.
- 7. Autonomic nervous system It is regulator system (responsible for regulation of all processes in the body ) so it is excitatory or inhibitory . Its neurotransmitters acetylcholine or norepinephrine Somatic nervous system It is operator system (always excitatory ) Its neurotransmitter is only acetylcholine
- 8. Autonomic nervous system The presence of autonomic ganglia where preganglionic fibers end and postganglionic fibers originate Arise from lateral horn cells Somatic nervous system No autonomic ganglia . Arise from anterior horn cells
- 9. Divisions of the ANS Divided to 2 systems according to origins of preganglionic neurons : 1)Sympathetic nervous system Arise from lateral horn cells of T1-L3 (thoracolumbar ) segments of spinal cord Most sympathetic pre-ganglionic fibers are very short ,synapse with cell bodies of post-ganglionic neurons within ganglia that lie in sympathetic chain located on either side of the spinal cord and long post-ganglionic fibers originating from this ganglion chain and terminate in the effector organ .
- 10. Some pre-ganglionic fibers pass through sympathetic chain without relay and terminate in collateral ganglia located between the spinal cord and innervated organ.
- 11. Autonomic ganglia It is a collection of nerve cells outside the CNS,and contains nerve cells of the postsynaptic neurons . Types : lateral ,collateral ,terminal and adrenal medulla 1)Lateral ganglia (paravertebral sympathetic chain) 3 cervical ,12 thoracic ,4 lumber and 4 sacral (relay of preganglionic sympathetic fibers only) 2)Collateral ganglia present in abdomen near big branches of the aorta (celiac ,superior and inferior mesenteric) (relay of preganglionic sympathetic and parasympathetic fibers mainly sympathetic)
- 12. 3)Terminal ganglia : present near or on the effector organ (relay of preganglionic parasympathetic fibers only) 4)Adrenal medulla : it is a modified sympathetic ganglion ,the nerve cells inside adrenal lose there axons and become changed to secretory cells (secrete catecholamines in response to sympathetic stimulation)
- 13. Functions of autonomic ganglia: Relay station for preganglionic nerves and origin for postganglionic nerves Distribution centers to allow the autonomic discharge to be distributed to almost all visceral and involuntary organs Site of action of drugs that modify autonomic functions
- 14. Parasympathetic division of ANS is called the (craniosacral outflow )because, the fibers of this division arise from brain (CN III ,VII ,IX, X)and sacral segments (S2-S4)of spinal cord. The preganglionic fibers end on short postganglionic neuron located on or near the visceral structure Sympathetic and parasympathetic preganglionic neurons release the same neurotransmitter (acetylcholine) Parasympathetic postganglionic neuron also release acetylcholine While most of the sympathetic postganglionic neurons release epinephrine (except sympathetic postganglionic neurons to sweat glands and blood vessels of skeletal muscles ) So all autonomic preganglionic fibers are called cholinergic and most postganglionic fibers are called adrenergic
- 15. Comparison between sympathetic and parasympathetic Parasympathetic division Sympathetic division Features Nuclei of III, VII, IX and X cranial nerves and sacral (S2 to S4) segments of spinal cord Thoracolumbar segments of spinal cord Location of preganglionic neuron Near or in the target organ Away from target organ Location of postganglionic neuron Relatively long Relatively short Length of preganglionic fibers Relatively short Relatively long Length of postganglionic fibers Acetylcholine Acetylcholine Preganglionic neurotransmitter Acetylcholine Noradrenaline Postganglionic neurotransmitter
- 16. Parasympathetic division Sympathetic division Features Nicotinic and muscarinic (cholinergic )receptors Alpha and beta (adrenergic) receptors Type of receptors An anabolic system dominates in quit relaxed situation A catabolic system dominate in emergency situation Dominance Localized Generalized Distribution
- 18. notes • β1 are Excitatory and present only in the heart [↑ HR]. •β2 are Inhibitory and causes vasodilatation & Relaxation of [Uterus, GIT &Urinary Bladder wall, Bronchial smooth muscles]. •α1 are Excitatory and causes vasoconstriction and contraction of [Dilator Pupillae ms, Piloerector ms. of hair, and GIT & Urinary Bladder sphincters]. • α2 are Inhibitory and present only in GIT wall causing its dilatation.
- 19. Functions of ANS Autonomic nervous system is concerned with the regulation of functions, which are beyond voluntary control. By controlling the various vegetative functions, ANS plays an important role in maintaining constant internal environment (homeostasis).
- 20. General functions: a)General Sympathetic actions(sympathetic tone): Continuous sympathetic impulses ,even during rest to : -Adrenal medulla: leading to basal secretion of catecholamines -Smooth muscles of arterioles :leading to partial continuous degree of vasoconstriction These actions are called sympathetic tone ,they help in maintenance of blood pressure and blood glucose
- 21. b)General parasympathetic actions (parasympathetic tone): Continuous parasympathetic impulses ,even during rest to : -GI tract :leading to continuous partial degree of contraction &secretion of small amount of digestive juices to prevent distension and maintain intra-gastric pressure -S-A node of the heart (vagal tone on the heart):leading to decrease in the intrinsic high rhythm of the heart from 120 to 70-80 during rest to preserve
- 22. Systemic functions of ANS parasympathetic division Sympathetic division Effector organ Contraction Constriction Relaxation dilatation Ciliary muscle pupil Eye Increase in secretion Decrease in secretion Lacrimal glands Increase in secretion and vasodilatation Decrease in secretion and vasoconstriction Salivary glands Acceleration Increase Relaxation Contraction Inhibition Decrease Constriction relaxation Motility Secretion Sphincters Smooth muscles GI tract contraction Relaxation Gall bladder Contraction Relaxation Relaxation Contraction Detrusor muscle Internal sphincter Urinary bladder
- 23. Systemic functions of ANS Contraction Relaxation Relaxation Contraction Detrusor muscle Internal sphincter Urinary bladder -- Increase in secretion Sweat glands Decrease Increase Heart rate and force Dilatation Constriction of all blood vessels except heart and skeletal muscles Blood vessels Constriction Dilatation bronchioles
- 24. Mass discharge of the sympathetic N.S The sympathetic nervous system is usually activated by the hypothalamus all as one unit. This occurs in cases of stress, either mental [e.g. Fear, Exam, embarrassment, etc] or physical [e.g. Exercise, Escape, Fight].
- 25. Horner’s syndrome It is a group of manifestations that results from interruption of the sympathetic supply to the head & neck (the lesion usually at sympathetic chain). These manifestations include: [Ptosis – Miosis – Enophthalmos – Anhydrosis – Warm red skin].
- 26. Chemical transmission in autonomic junction Transmission at the synaptic junction between pre and post synaptic neurons and between post synaptic neuron and effector organ The principle transmitter agents are acetylecholine and norepinephrine Usually neurotransmitter exert their actions by combination with specific receptors in post synaptic membrane
- 27. Note the adrenaline (epinephrine) and noradrenaline (norepinephrine) have similar effect, except that adrenaline is more potent on the heart and metabolism, while noradrenaline is more potent on blood vessels (vasoconstriction).
- 28. Chemical divisions of ANS On the basis of chemical mediator released ,ANS can be divided into: -cholinergic system(release acetylcholine) -Noradrenergic system(release noradrenaline)
- 29. At the cholinergic neurons A)synthesis of acetylcholine (ACh) Choline + acetyl CoA -----choline acetyl transferase -------------------- ACh + CoA B) Storage of ACh in synaptic vesicles until needed C)Release of ACh when the impulse arrives at nerve ending ----open Ca channels -- ----
- 30. cholinergic system All preganglionic neurons (autonomic ganglia ) All parasympathetic postganglionic neurons Sympathetic post-ganglionic neurons which innervate sweat glands and blood vessels of skeletal muscles Preganglionic neurons supplying adrenal medulla
- 32. The cholinergic receptor could be affected by administration of drugs. These drugs may: 1- Stimulate the cholinergic receptors. They include: a- Dugs has similar action to Ach [e.g. Methacholine, Pilocarpin, Nicotine (small dose)]. b- Anticholineesterases [e.g. Neostigmine, Prostigmine]. 2- Inhibit the cholinergic receptors. They include: a- Anticholinergics [e.g. Atropine, Homatropine]. b- Ganglion blockers [Hexamethonium, Nicotine (large dose)]. c- Neuromuscular blockers [e.g. Curare, Succinyl choline].
- 33. II – Noradrenaline (norepinephrine) (N.A):
- 34. ♦ In the adrenal medulla, 80% of the noradrenaline converts into adrenaline by the action of N-methyl transferase enzyme which is not present at nerve terminals, thus adrenaline is formed only in adrenal medulla.
- 35. ♦ The N.A is removed mainly (50-80 %) by active reuptake to the nerve terminals. The remaining small amount of N.A is removed by: 1- Enzymatic destruction: it is either by: a- Oxidation: by monoamine oxidase enzyme (MAO). b- Methylation: by catechol-O-methyl transferase enzyme (COMT). 2- Diffusion to surrounding tissues..
- 36. The N.A is released from the following sites: 1- All the postganglionic sympathetic fibers [Except the 2 cholinergic fibers]. 2- The adrenal medulla secretes noradrenaline (20%) and adrenaline (80%). 3- N.A acts as NT inside the CNS.
- 37. Note: Alpha receptors are more sensitive to NA > ADR, while Beta are equally sensitive to NA & ADR.