Autonomic nervous system - Sympathetic and Parasympathetic NS
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Overview of Autonomic nervous system - structure, function. Cranial nerve pathways. Horners syndrome. Urinary Bladder control.
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Autonomic nervous system - Sympathetic and Parasympathetic NS
- 1. AUTONOMIC NERVOUS SYSTEM - 1 Dr. Dhananjay Gupta DM Neurology Ramaiah Meddical college, Bangalore
- 2. INTRODUCTION o = Involuntary nervous system o = Visceral nervous system o Controls the sub-conscious functions o Maintains the internal milieu – homeostasis o oSympathetic + parasympathetic + enteric NS
- 3. AUTONOMIC NERVOUS SYSTEM SOMATIC NERVOUS SYSTEM 1. Sympathetic and parasympathetic 2. Pre-ganglionic and post ganglionic fibres connected in series b. α- and γ- motor neurons connected in parallel 3. Pre-ganglionic : B or unmyelinated C- 1-5 μm 0.2- 15 m/s c. Heavily myelinated Aα : 12-22 μm 7-120 m/s 4. Post-ganglionic : unmyelinated C- fibres 0.1- 2 μm 0.2- 2 m/s d. Heavily myelinated Aγ : 5– 13 μm 15- 40 m/s 5. Exit from CNS : Brain and whole SC e. Cranio-sacral and thoraco-lumbar 6. Pre and post ganglionic fibres make 2 synapses f. Make 1 synapse – directly on intra/extra fusal fibres 7. Cell bodies in SC – ventral horn g. IML (lamina VII), CAN – lamina X
- 6. AUTONOMIC NERVOUS SYSTEM SOMATIC NERVOUS SYSTEM 8. NT : Ach, NE, E h. Ach mainly 9. Receptors : Ganglia : N Effector : N, M, α, β i. Nicotinic cholinergic mainly 10. Supply : Glands, visceral, cardiac j. Skeletal muscles mainly 11. Effector junction : varicosities, ramifications k. N-M junction
- 7. NN NM M α β
- 9. AUTONOMIC NERVOUS SYSTEM SOMATIC NERVOUS SYSTEM 12.Innervation : dual (S + P) some exceptions l. Each sk. Fibre receives one α 13.Spontaneous activity may persist Develop hypersensitivity to NT m. Denervation : Atrophy and paralysis 15. Higher control : Limbic, hypothalamus, BS o. Cerebral cortex, BG, cerebellum, BS 14.Sensory input : visceroreceptors – chemo/ baro/ nociceptors n. Exteroceptors/ proprioceptors
- 10. SYMPATHETIC PARA-SYMPATHETIC 1. Origin : Thoraco-lumbar a. Cranio-sacral 2. Ganglia near SC b. Ganglia near end organ 4. Long post-ganglionic – adrenergic Travel within the 31 pairs of spinal nerves d. Short post-ganglionic – cholinergic 3. Short pre-ganglionic - cholinergic c. Long preganglionic - cholinergic 5. Pre : post ganglionic 1: 20 e. Pre : post 1: 3 6. Divergence co-ordinates activity of neurons at multiple levels of SC f. Limited divergence 7. Activity involves mass discharge of entire system g. Limited discharge to end-organs FIGHT and FLIGHT REST AND DIGEST
- 12. AUTONOMIC GANGLIA o Site of physiological contact between pre and post ganglionic o 3 types 1. Lateral (paravertebral) : sympathetic chain : 23 (3+12+4+4) 2. Collateral (pre-vertebral) : may be mixed 3. Terminal : parasympathetic
- 14. SYMPATHETIC NERVOUS SYSTEM - ANATOMY
- 27. ↑ Glucose release by liver ↓ Digestive activity
- 28. Contracts the rectum ↓ Digestive activity
- 29. Relaxes bladder Secretes E/ NE from adrenal/ kidney
- 30. PARA - SYMPATHETIC NERVOUS SYSTEM
- 40. RECEPTORS AND NEURO- TRANSMITTERS ACETYL CHOLINE
- 42. Rate – Limiting Step
- 46. FUNCTIONS OF ANS o Maintains homeostasis o Body temperature o Blood flow, BP o Pupillary diameter o Airway resistance o Bowel/ bladder functions o Sexual functions o Fluid volume o Glucose homeostasis o Immune functions o Inflammatory reactions o glandular secretions The ultimate responsibility of the ANS is to ensure that the physiological integrity of cells, tissues, and organs throughout the entire body is maintained (homeostasis) despite perturbations exerted by both the external and internal environments.
- 47. FUNCTIONS OF ANS ONLY SYMPATHETIC CONTROL o Sweat glands o Pineal gland o Blood vessels o Brown adipose tissue PARA-SYMPATHETIC CONTROL o Ciliary muscles o Naso-pharyngeal glands
- 49. FUNCTIONS OF ANS ANTAGONISTS : o Bronchi o Heart o Stomach o UB SYNERGISTS : o Iris muscles in eye o Sexual organs
- 53. BLADDER CONTROL
- 60. 1. 2. 3. 4.
- 61. BLADDER PROBLEMS
- 62. STORAGE PROBLEMS Frequency >7/ >1 * Urgency * Nocturia Urge Incontinence
- 63. VOIDING PROBLEMS *Hesitancy *Slow stream *Straining *Terminal dribbling *Feeling of incomplete evacuation *Residual
- 64. 1. SENSORY NEUROPATHY Sensory arc damage MS DM, Tabes Small fibre neuropathy No sensation – so cannot initiate micturition Overflow dribbling Constant dribbling Absent sensation High infection risk Bulbo-cavernous and
- 66. 2. MOTOR NEUROPATHY L-S meningomyelocele Tethered cord syndrome Lumbar spinal stenosis Extensive pelvic surgery Pelvic trauma/ tumours Sensation + Cannot initiate micturition PAINFUL retention Residual volume high Infection risk high Bulbo-cavernous and Anal reflex absent!!
- 68. 3. SACRAL LESION – LMN - AREFLEXIC Conus, Cauda, Sp. shock No detrusor, No EUS AUTONOMOUS ~ Motor paralytic Fills w/o emptying No urgency Overflow dribbling Constant dribbling Flaccid UB Absent sensation High infection risk
- 70. 4. THORACIC LESION – UMN - HYPREFLEXIC Spastic UB AUTOMATIC bladder Uninhibited UB Hyper-reflexic UB Brain or SC lesion MS, tumours, CVA Incontinence, freq Urgency Voiding is unpredictable Incomplete
- 72. 5. SUPRA-PONTINE –CORTICAL UB Brain MS, tumours, CVA NPH Frontal tumours ACA aneurysm PD Incontinence, frequency Urgency, inconti Voiding is Complete Minimal/ Nil residual Normal sensation
- 73. 4. THORACIC LESION – UMN - HYPREFLEXIC Spastic UB AUTOMATIC bladder SC trauma Compressive myelop Syringomyelia, myelitis Incontinence, frequency Urgency, inconti Voiding is INComplete Small residual
- 74. ? CVA ? NPH ? Dementia ? MS ? PD ? MSA ? DM cystopathy ? Herpetic bladder ? Myelopathy levels TO BE CONTINUED !!!
Editor's Notes
- Central autonomic nucleus – dorsal to the central canal – lamina X
- Nuclei of pre-ganglionic symp neurons located in 4 areas – 1. IML- lateral horn, 2.dorsal to CC, 3. just medial to IML – in a region of GM called the intercalated nucleus, 4. scattered in WM of lateral funiculus
- ALL NEURONS WHICH EXIT THE CNS HAVE ACH AS THE NT. One neural unit v/s one motor unit. 1 MU ranges from 5(lat. Rectus) to 2000 (medial gastrocnemius).
- All ACH receptors then act through ligand gated channels, however the only difference is – ganglia have Nn type and NMJ have Nm type. Differences we will leave for the pharma people.
- ACH are clear vsicles, NE containing are dense core vesicles. No nerve terminal, no motor end plate, no synaptic cleft (all 3 = NMJ)
- preganglionic neuron may also travel more rostrally or caudally (upward or downward) in the ganglion chain to synapse with postganglionic neurons in ganglia at other levels. The long postganglionic neurons originating in the ganglion chain then travel outward and terminate on the effector tissues. This divergence of the preganglionic neuron results in coordinated sympathetic stimulation to tissues throughout the body. The concurrent stimulation of many organs and tissues in the body is referred to as a mass sympathetic discharge
- 4 possible origins of pre-ganglionic fibres- RED. Travel along with motor- alpha and gamma in ventral root of spinal nerve. Shortly after exiting CNS – they exit via the WHITE ramus (ramus= branch). White coz thinly myelinated. Noe further they have 4 pathways. 1st – they enter the adjacent PARA-vert symp chain, synapse – start post gang. 2nd – they can travel up/ down the SC – end on a paravert ganglion far away/ of a different segment.
- These pre-ganglionic fibres- along with the paravert ganglia form the paravertebral sympathetic chain – which is present on both sides of the SC – B/L symm
- 1st and 2nd pathwyas of White rami – we discussed. Now the 3rd pathway is they end on the pre-vert or the collateral ganglia – these are the ganglia located near the abdo and pelvic viscera – C/ SE/ IE/ P/ Aorticorenal. The difference is that while the sympth chain is B/L – these ganglia are usually singular
- Posterior abdominal wall
- A 4th pathway is that these pre-ganglionic fibres directly end at the visceral organ – the adrenal medulla – CCH PRODUCING ENTEROCHROMAFFIN CELLS. Thus calling medulla as analogous to symp ganglia would not be wrong. This is further proven by the fact that embryologically their origin resembles the ganglia. – both from NCC. So basically this is a sympth ganglion which lost its post-ganglionic axon, got covered by a gland and releases its NT directly into blood – which then goes far and wide. What is the NT released here ?
- ACH are clear vsicles, NE containing are dense core vesicles. The post ganglionic fibres branch multiple times to end on a number of muscle fibres and the ends are beaded – so called the vesicles, which contain the NT. An individual post-ganglionic neuron can have upto 20,000 vesicles. – Mass reflex. Synapse en passant. A neuron synapses with another neuron at places other than axon. (in passing)
- Fibres from cervical ganglia supply the sweat gland and erector pili muscles of face.
- Fibres from thoracic ganglia supply the sweat gland and erector pili muscles of thorax.
- Symp activity in bladder maintains it in a relaxed state – so that bladder can fill the whole time without any urge to urinate – till a certain level/ volume. In addition, sympathetic system maintains a basal level of tone in the BV – the arterioles – responsible for the TPR, maintaining BP – this is the reson that we commonly use powerful drugs like alpha blockers for controlling BP.
- In contrast to the sympathetic, PNS – system has well defined anatomical and functional supply – thus predicting the end organ effects is easier. There are mainly 4 cranial nerves which constitute PNS. 3, 7, 9 are limited to the face while vagus supplies far and wide. In fact vagus alone constituts 75% of whole of the PNS. “Rest and Digest” system.
- Fibres from the EWN and the nuclei dorsal to oculomotor nuclei end on the ciliary ganglion from where post=gang fibres supply sphinter puppillae (miosis) and the ciliary body msl (helping in accommodation). The ciliary body msl is probably the only part of ANS where a “somewhat voluntary” action can be performed.
- Fibres from the EWN and the nuclei dorsal to oculomotor nuclei end on the ciliary ganglion from where post=gang fibres supply sphinter puppillae (miosis) and the ciliary body msl (helping in accommodation). The ciliary body msl is probably the only part of ANS where a “somewhat voluntary” action can be performed.
- preganglionic neurons are scattered in the pontine tegmentum in a region called the superior salivatory or lacrimal nucleus travel in the intermediate nerve, a branch of the facial nerve to reach the geniculate ganglion. GSPN which contains the parasympathetic fibers that project to the sphenopalatine (or pterygopalatine) ganglion. postganglionic innervate the lacrimal glands and nasal, palatine, and pharyngeal mucosal glands.
- The other branch of the intermediate nerve is called the chorda tympani or lingual nerve which includes the parasympathetic preganglionic fibers that project to the submandibular ganglion
- preganglionic neurons from the medullary inferior salivatory nucleus travel In the glossopharyngeal nerve TO reach the inferior ganglion, a small branch of the IXth (Jacobsen’s nerve) containing the parasympathetic fibers separates to join the tympanic nerve to reach the tympanic plexus. fibers form the lesser petrosal nerve which synapses in the otic ganglion. postganglionic neurons join a branch of the trigeminal nerve and form the auriculotemporal nerve to innervate the parotid.
- preganglionic neurons from the medullary inferior salivatory nucleus travel In the glossopharyngeal nerve TO reach the inferior ganglion, a small branch of the IXth (Jacobsen’s nerve) containing the parasympathetic fibers separates to join the tympanic nerve to reach the tympanic plexus. fibers form the lesser petrosal nerve which synapses in the otic ganglion
- 2 nuclei – 1. NA – lightly myelinated – supply updo diaphragm, 2. Dorsal MN vagus – unmyelinated – supply subdiaphragmatic updo transverse colon, though some efferents also go to thoracic organs. . Again remember “rest and digest”
- The sacral parasympathetic bundle is called nervi erigentes (responsible for erection)
- We discussd earlier that all neurons originating from CNS secrete Ach at terminal axon. This Ach is synthesized and stored in vesicles inside the terminal ony and when an impulse comes – it is secreted.
- Acts on the post terminal N and M receptors and bind to ion channels or GPCR. To terminate the action, it is needed to remove the Ach from endings, an action done by the hydrolysin enz.. Choline-esterase. The choline is readily available in plasma and reuptaken via Na dependant pump. This uptake is the rate limiting step. A number of drugs act on this.
- The basic precursor of all Cch is Tyrosine. Hydroxylase converts it to DOPA. Decarboxylase to Dopamine. Dopamine is then transported into vesicle by VMAT. Beta-hydroxylase then changes it to NE. NE comes out of vesicle, is converted to E. then E again goes into vesicle. Conversion of NE-E requires enzyme phenyletanolamine-N-me-tr, present in medulla and brain.
- While most of these have dual innervation, that is both sympathetic and para, few have either only sympa or parasymp
- Whereever there is dual, it is because both the arms act opposite to control a function, in a couple of places like, they act together to result in an action
- First order neurons sstart from hypothalamus and descend down through the brainstem and cervical SC to the ciliospinal centre of budge. From here the 2nd order beurons start and exit through the ventral root, passing through the grey rami communicans, arch over the apexof lung, beneath the subclavian artery to enter the cervical sympathy chain. Here they ascend till the sup cx ganglion to end on the 3rd order neurons. Post ganglionic 3rd order neurons from the per-carotid plexus follow two paths – those for the facial structures go along ECA and those for eye go along ICA. These fibres migrate to the VI for a short distance before they join the naso-ciliary branch of V. This then passes the SOF to continue as long ciliary nr supplying pupilodilator muscles. Along with this, they supply the smooth muscles in both U and L lids – the retractors – mullers in U and one in L.
- Ptosis + miosis = occulosympathetic paresis + anhidrosis = horners (or Bernard horner). Hydroxyamphetamine differentiates a 3rd order from others – dialate in 1st or 2nd order. Apraclonidine demonstrates denervation hypersenti – pupils dialate – alpha agonist
- The parasympathetic pelvic nerve fibers join the postganglionic sympathetic fibers within the hypogastric nerve to form the inferior hypogastric plexus which projects to the target organs. The pelvic nerve terminates on ganglia in the pelvic plexus (including the hypogastric ganglia and paracervical ganglia in females) that are scattered near the bladder, rectum, and genitalia.
- Lateral or storage centre tonically activates the ONUF;s nucleus in the ventral horn – pudendal nerve – EUS -- contracts
- The main supra spinal control is the pontine MC – or Barrington nu. Responsible for initiating micturition reflex. After 300-400 ml urine is filled, micturition urge starts. PMC – medial – projects onto IML – parasympth fibres – contracts detrusor. Pontine centre takes 2-3 years to dev. The pudendal nerve is inhibited, as is sympathy. Parasympth discharges increase
- Barrington nucleus in pontine tegmentum has 2 area- M and L. Afferent go through PAG. Now till now, whatever is happening is unconscious – PMC has decided that it will start micturition, but now for that u need to find a bathroom. If u cannot – then here is where cortex and the conscious control comes in. cortex will then inhibit the PMC
- Cat experiments – 1.. Pontine transection – permanent disturbance of UB emptying 2. Intercollicular level – lowered micturition threshold – so means this area inhibits PMC – suggested to be MB lateral to PAG 3. Hypothalamus – cause increased micturition threshold – means hypothalamus is facilitatory to PMC
- When UB is not able to hold in – leads to leakage – IRRITABLE UB – even small volumes of urine will keep leaking out
- Cannot get it out. If voiding, cannot void completely – so post void residue. Cause : failure of neurological control, failure of UB muscle – detrusor, failure of EUS relaxation or dyssynergy
- Similar will happen in BOO – but conscious effort and sensation +
- Now lets suppose both these motor nerves damaged – sacral cord is intact, but the efferents gone. Causes – problems with this pelvic region – either trauma/ surgical manipulation or tumour. Other causes are
- Similar will happen in BOO – but conscious effort and sensation +
- The parasympathetic pelvic nerve fibers join the postganglionic sympathetic fibers within the hypogastric nerve to form the inferior hypogastric plexus which projects to the target organs. The pelvic nerve terminates on ganglia in the pelvic plexus (including the hypogastric ganglia and paracervical ganglia in females) that are scattered near the bladder, rectum, and genitalia.
- Lesions of the peripheral nerves/ sacral seg – conus medullaris. Basically now spinal cord is gone – bladders friend is gone, it is left to fend on its own – so called autonomous.
- The parasympathetic pelvic nerve fibers join the postganglionic sympathetic fibers within the hypogastric nerve to form the inferior hypogastric plexus which projects to the target organs. The pelvic nerve terminates on ganglia in the pelvic plexus (including the hypogastric ganglia and paracervical ganglia in females) that are scattered near the bladder, rectum, and genitalia.
- Pyramidal lesions – above sacral – supra-sacral controls lost – so now micturition occurs as a local sacral spinal reflex. Now through S234 both the Detrusor and EUS are activated, the problem is there is no coordination
- Urinations is sudden, precipitous, complete
- DSD is a rule