If both parasympathetic & sympathetic systems were inactivated, what would happen to:


New Member
Blood Pressure
Food-processing activity of the GI tract.

Annoying revision question for Physiology by even more annoying lecturer who is rubbish!


Sympathetic and parasympathetic systems act antagonistically on:

Sympathetic and parasympathetic systems act synergistically on:

Any thoughts?!



New Member
antagonistically : heart rate, pupils, digestive system, respiratory system, bladder, gall bladder

synergistically: fear - heart rate increase (sympathetic), relaxes bladder (parasymp)
exocrine secretion in GI tract - sympath contributes mucus and parasypm increases volume and enzyme content

and Im not sure I understand the 1st question, so if both systems dont work then we have the autonomic failure as the ANS isnt working anymore, so the body isnt able to control its functions anymore. So there is no control over the blood pressure, which probably increases risk of heart attack and stroke. As there is insufficient blood flow to the brain this can leads to loss of consciousness especially when standing up because autonomic reflexes do not occur.
About the digestive system, as ASN regulates almost everything ... starts with secretion of saliva so problems with chewing and swallowing, digestive secretion, smooth muscles contraction in GI tract is affected so intestine peristaltis is much slower, also feeling hunger and fullness.
Im just wondering because its known that even when ANS innervation is removed heart still beats also the peristaltic movement of the gastrointestinal tract continues, but probably even tho it still works there are still some serious alterations. (maybe I should think about it some other time not at 2am :p)
Abt the metabolic function, Sympath system inhibits insulin release from ß-cells in the pancreas and increases glucose release from the liver and increases lipolysis so any disruption in symp system affects availability of blood glucose which directly affects brain functions.

Im not sure if thats what you wanted as its pretty general, but I cant think about any more details at this time :p


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I agree with answer above for the antagonist, and synergy

as for having no symp and parasymp, you get "The Hexamethonium Man" (Hexamethonium is a drug that blocks the post-synaptic NAchRs at the autonomic ganglia, therefore blocking the whole autonomic nervous system):

W. D. M. Paton, Pharm. Rev. 6, 59 (1954)

He is a pink complexioned person, except when he has stood for a long time, when he may get pale and faint. His handshake is warm and dry. He is a placid and relaxed companion; for instance he may laugh, but he can’t cry because the tears cannot come. Your rudest story will not make him blush, and the most unpleasant circumstances will fail to make him pale. His socks and his collars stay very clean and sweet. He wears corsets and may, if you meet him out, be rather fidgety (corsets to compress his splanchnic vascular pool, fidgety to keep the venous return going from his legs). He dislikes speaking much unless helped with something to moisten his dry mouth and throat. He is long-sighted and easily blinded by bright light. The redness of his eyeballs may suggest irregular habits and in fact his head is rather weak. But he always behaves like a gentlemen and never belches or hiccups. He tends to get cold and keeps well wrapped up. But his health is good; he does not have chilblains and those diseases of modern civilization, hypertension and peptic ulcers, pass him by. He is thin because his appetite is modest; he never feels hunger pains and his stomach never rumbles. He gets rather constipated so his intake of liquid paraffin is high. As old age comes on he will suffer from retention of urine and impotence, but frequency, percipitancy, and strangury will not worry him. One is uncertain how he will end, but perhaps if he is not careful, by eating less and less and getting colder and colder, he will sink into a symptomless, hypoglycemic coma and die, as was proposed for the universe, a sort of entropy death.​
To summarize the adverse reactions of ganglion-blocking drugs, the following effects should be kept in mind:

  1. All secretions would be reduced including lacrimation, salivation, sweating and even gastric juices
  2. Marked orthostatic hypotension due to reduction in vascular tone
  3. Cardiac output would be reduced
  4. Patient would be tachycardiac
  5. Sexual dysfunctions will be marked such as impotence
  6. Mydriasis and cyclopegia would be present