Autonomic Nervous System (ANS) 1 PDF

Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 1. What are the 1.) Autonomic (involuntary) 2 subsystems 2.) Somatic (voluntary) of the peripheral nervous system? 2. What are the 4 1.) Convey signals between the CNS and tissues ma...

Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 1. What are the 1.) Autonomic (involuntary) 2 subsystems 2.) Somatic (voluntary) of the peripheral nervous system? 2. What are the 4 1.) Convey signals between the CNS and tissues main roles of the 2.) Transmit information to and from the CNS peripheral ner- 3.) Relay sensory and motor impulses between the CNS vous system? and the body surface, skeletal muscles, and internal or- gans 4.) Serve as a channel for communication between the brain, spinal cord, and the rest of the body 3. What is the role Subconscious control of organs and homeostasis and of the autonomic controls all involuntary outputs from the CNS to the body nervous system? except somatic motor innervation (to skeletal muscle) 4. What are the 1.) Sympathetic (fight or flight) 2 main subsys- 2.) Parasympathetic (rest and digest) tems of the au- tonomic nervous system? 5. What is the Noradrenaline (NA) main neurotrans- mitter of the sym- pathetic system? 6. What is the Acetylcholine (ACh) main neuro- transmitter of the parasympa- thetic system? 7. What are the Pre and post-ganglionic 2 neuron sys- Adrenal medulla is an exception: consider as a spe- tems (usually) cialised ganglion & the chromaffin cells as specialised in sympathetic post-synaptic neurons 1/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 and parasympa- thetic systems? 8. Preganglionic -cell body is in the CNS neuron -Small diameter & myelinated -synapses at autonomic ganglia 9. What does Nicotinic receptors ACh act on in post-synaptic neuron? 10. Post-ganglionic -cell body in autonomic ganglion neuron -Small diameter, unmyelinated -synapse close to target organ 11. Autonomic gan- Interface between pre- and post- ganglionic neurons of glion the autonomic nervous system: -In both Sympathetic and Parasympathetic branches Acetylcholine (ACh) is the primary transmitter Most actions via ganglion-type Nicotinic ACh receptors (nAChR) Pentameric ionotropic receptor conducts Na+ in, K+ out (depolarisation and hyperpolarisation) Generate a fast Excitatory Post Synaptic Potential (fast epsp) 12. What are Smooth muscle of gut & bladder, Heart examples of organs where sympathetic and parasympathetic stimulation have opposing actions? 13. Which organs Sweat glands, Blood vessels are regulated by sympathetic stimulation only? 2/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 14. Which organs Ciliary muscle of eye are regulated by parasympa- thetic stimulation only? 15. What aspect Control of heart rate of cardiovascular function does the autonomic ner- vous system reg- ulate? 16. How does the au- Contraction & relaxation tonomic nervous system influence smooth muscle in blood vessels and organs? 17. What is the Most blood vessels have NO parasympathetic innervation typical innerva- tion of most blood vessels by the parasympa- thetic nervous system? 18. What does the Exocrine and some endocrine autonomic ner- vous system reg- ulate in terms of glandular secre- tion? 19. Besides cardio- Metabolism vascular func- tion, what oth- er aspect of 3/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 the body's func- tion does the autonomic ner- vous system in- fluence? 20. Physiological Sympathetic and parasympathetic post-synaptic nerve consequences activation of ganglionic Secretion of adrenaline from the adrenal medulla nicotinic Sympathetic responses dominate receptor stimulation 21. Effects of gan- - Complex due to stimulation of all peripheral ganglia: glionic nicotinic Tachycardia receptor stimula- increase in BP tion increased secretions (sweat, saliva etc.) 22. Give 2 exam- 1.) Hexamethonium ples of ganglion 2.) Local anaesthetics blocking drugs 23. Hexamethonium -Non depolarising nicotinic antagonist as a ganglion -no clinical uses blocking drug -historically used as an antihypertensive 24. Local anaesthet- -Sympathetic ganglion block ics as ganglion -blocks sympathetically-mediated pain pathways blocking drugs -e.g. Lidocaine -co-administered with adrenergic agonist 25. All Pre-ganglion- Releases ACh ic fibres re- lease which neu- rotransmitter? 26. Most postsynap- Noradrenaline (NA) tic sympathet- ic fibres re- 4/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 lease which neu- rotransmitter? 27. Most postsynap- Acetylcholine (ACh) tic parasympa- thetic fibres re- lease which neu- rotransmitter? 28. Sympathetic ner- Most postsynaptic sympathetic fibres release noradrena- vous system: line (NA) Transmitters at Cell bodies are in sympathetic ganglion and send axons target organ ending in varicosities Noradrenaline is synthesised, stored and released at these varicosities Exceptions = sweat glands (ACh) and renal vessels (dopamine) Adrenal medulla can be considered as analogous to a postsynaptic nerve - releases adrenaline 29. Synthesis of NA Multi-enzyme synthetic pathway: -Initial stages of synthesis in cytoplasm. -Final stage of synthesis on membrane of synaptic vesicle. Precursor molecule is the amino acid L-tyrosine (also precursor molecule for dopamine). Final product, NA, regulates synthesis via a negative feedback process on initial step of synthesis. 30. Enzymes in- 1.) Tyrosine hydroxylase: L-tyrosine --> DOPA, found in volved in synthe- cytosol of catecholamine- sis of NA containing cells 2.) DOPA decarboxylase: DOPA --> Dopamine, cytosolic & found in many cell types 3.) Dopamine beta-hydroxylase: Dopamine --> Noradren- aline, located on membrane of synaptic vesicles 4.) Phenylethanolamine N-methyltransferase: Noradren- aline --> Adrenaline, only in chromaffin cells (adrenal medulla) 31. 5/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 Synthesis of Postganglionic fibres send axons to target organ transmitters Enzymes involved in transmitter synthesis made in cell body Synthetic enzymes transported to nerve terminus Transmitter made at terminal varicosities 32. Phaeochromocy- - A rare tumour that forms in the centre of one or both of toma the adrenal glands. - It is made of chromaffin cells that produce and release hormones responsible for the "fight or flight" response. - Symptoms include hypertension, tachycardia, sweating, and headaches 33. Drugs affecting - The initial enzyme in formation of NA (L-tyrosine to synthesis of no- DOPA) is tyrosine hydroxylase radrenaline (first stage) - Inhibited by alpha-methyl-p-tyrosine (Metirosine). - Possible clinical use in pheochromocytoma (cate- cholamine-secreting tumour). 34. Drugs affecting Second stage of synthesis (DOPA to dopamine) by DOPA synthesis of no- decarboxylase radrenaline (sec- Inhibited by carbidopa: ond stage) -Used in Parkinson's disease to prevent peripheral effects of levodopa (= L-DOPA) - reduces levodopa metabolism in the periphery so re- duced sympathetic effects of levodopa (high blood pres- sure and racing heart) -Carbidopa does not cross BBB; increases levodopa avail- ability in CNS 35. Regulation of no- Depolarization of nerve ending opens calcium channels radrenergic re- Leads to vesicle exocytosis lease NA released Released NA activates presynaptic receptors that inhibit adenylyl cyclase This prevents calcium channel opening and limits further release of NA 6/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 36. Termination of NA rapidly removed from synaptic cleft by Neuronal Epi- noradrenergic nephrine Transporter, NET (Uptake 1): transmission (1) -Located on presynaptic nerve terminals -actively transports NA back into nerve varicosities; recy- cles ~70% of NA Uptake into vesicles by Vesicular Monoamine Transporter (VMAT): -Stored in vesicles along with ATP -ATP has opposite charge to NA and helps prevent leak from vesicles -ATP co-released with NA and is a co-transmitter Free concentration of NA low in neuron cytoplasm due to monoamine oxidase (MAO) activity 37. Termination of Extra neuronal Monoamine Transporter, EMT (Uptake 2): noradrenergic -Actively transports catecholamines into the postsynap- transmission (2) tic cell; metabolised in post-synaptic cell by Catechol o-Methyl Transferase (COMT) 38. What are the 2 1.) Monoamine oxidase (MAO): things NA can found mainly in neurones, also liver & GI tract be metabolised NA ’ DOMA by during termi- 2.) Catechol-o-methyl transferase: nation of nora- neuronal and non-neuronal tissue drenergic trans- also metabolises DOMA produced from MAO mission? Liver COMT metabolises circulating catecholamines 39. What are the 3 1.) Methyldopa (Aldomet) drugs that inhibit 2.) Guanethidine (G) NA release? 3.) Reserpine 40. Methyldopa (Al- -Metabolised to methyl-NA: domet) MOA false precursor molecule ±2agonist - Has peripheral and central effects on blood pressure -Sometimes used to treat pregnancy-induced hyperten- sion (fewer effects on foetus) -Also inhibits DOPA decaboxylase (like carbidopa) 7/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 -Methyldopa, is a medication used for high blood pressure. It is one of the preferred treatments for high blood pressure in pregnancy - it relaxes blood vessels 41. Guanethidine -Substrate for NET MOA -Substrate for VMAT: Accumulates in vesicles Stabilises vesicles Displaces NA (slowly) Free NA metabolised by MAO High doses - destroys neuron -Overall effect: block of adrenergic neurons -Historically used as antihypertensive: Obsolete clinically Useful experimental tool 42. Reserpine MOA -inhibits VMAT: prevents transport of NA into vesicles Cytoplasmic NA metabolised by MAO Vesicular levels fall -antihypertensive (sold as an herbal remedy): clinically obsolete side effects similar to methyldopa -also causes depression and Parkinsonism (due to CNS effects) -Useful experimental tool 43. Unwanted ef- -In general all agents will cause anti-sympathetic effects: fects of inhibiting Hypotension NA synthesis/re- Bradycardia lease Digestive disorders Nasal congestion Sexual dysfunction -Central effects common (i.e. not directly via autonomic system) Sedation Mood disturbances Less with carbidopa - does not enter CNS 8/9  Autonomic Nervous System (ANS) 1 Study online at https://quizlet.com/_fuvui4 44. Drugs to remem- carbidopa ber a-methyl-p-tyrosine methyldopa reserpine guanethidine 9/9