Respiratory system bronchoconstriction

Prominent effects within the digestive tract include stimulation of salivation and acid secretion, increased intestinal tone and peristaltic activity, and relaxation of most sphincters. Bronchoconstriction and stimulation of secretions are prominent effects in the respiratory system. Muscarinic agonists can also evoke secretion from nasopharyngeal glands. Urination is promoted by stimulation of the detrusor muscle of the bladder and is facilitated by relaxation of the trigone and external sphincter muscles. 

Asthma A chronic disease of the respiratory system characterized by bronchoconstriction, airway inflammation, and the formation of mucous plugs in the airway. 

Table 9-5 presents data from various animal studies on the acute toxicity of sulfur dioxide. These studies support findings from the human studies, indicating that sulfur dioxide exerts its effect primarily on the respiratory system. Acute effects at relatively low concentrations (<20ppm) induced transient bronchoconstriction and increases in airway resistance. Higher concentrations produced more sustained biochemical, clinical, and histologic changes in the respiratory system. No material effects were noted in organs outside of the respiratory tract after acute exposure to sulfur dioxide. 

Exposure to sulfur dioxide can cause severe irritation of the skin, eyes, mucous membranes, and respiratory system. The effects are coughing, choking, or suffocation bronchoconstriction and skin bum. A 10-minute exposure to 1000 ppm can be fatal to humans. 

The clinical signs of excess acetylcholine at nerve endings mimic hyperactivity of the parasympathetic nervous system. Signs relative to the alimentary tract include excess salivation, lacrimation, abdominal pain, vomiting, intestinal hypermotility, and diarrhea. The muscarinic effects of acetylcholine cause bronchoconstriction and an increase in bronchial secretions. The nicotinic effects of acetylcholine consist of involuntary irregular, violent muscle contractions and weakness of voluntary muscles. Death occurs as a result of respiratory failure. 

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