318 INFLUENCE OF BLOOD ON THE INTESTINE. 



health occur (cuperistalsis) provided no other stimulus be applied to the 

 intestine. 



3. All stimuli applied to the plexus myentericus increase the peri- 

 stalsis, which may become so very violent as to cause evacuation of 

 the contents of the large gut, and may even produce spasmodic con- 

 traction of the musculature, of the intestine. This condition may be 

 termed dysperistalsis, corresponding to dyspnoea. The condition of the 

 blood flowing through the intestinal vessels has a most important effect 

 on the peristaltic movements. 



Condition of the Blood. Dysperistalsis may be produced by (a) interrupting 

 the circulation of blood iu the intestines, no matter whether anasmia (as after 

 compressing the aorta Schiff,) or venous hypertemia be produced. The stimu- 

 lating condition is the want of 0, i.e., the increase of COo. Very slight dis- 

 turbance in the intestinal blood-vessels, e.g. , venous congestion after copious 

 transfusion into the veins, whereby the abdominal and portal veins become 

 congested, causes increased peristalsis. The intestines become nodulated at 

 one part and narrow at another, and involuntary evacuation of the foces 

 takes place when there is congestion, owing to the plugging of the intestinal 

 blood-vessels when blood from another species of animal is used for trans- 

 fusion (p. 202 Landoia). The marked peristalsis which occurs on the approach 

 of death is undoubtedly due to the derangements of the circulation, and the con- 

 sequent alteration of the amount of gases in the blood of the intestine. The same 

 is true of the increased movements of the intestines which occur as a result of 

 psychical excitement, e.g., grief. The stimulus, in this case, passes from the 

 cerebrum through the medulla oblongata (vaso-motor centre) to the intestinal 

 nerves and causes anosmia of the intestine, (corresponding to the palor occurring 

 elsewhere). When the normal condition of the circulation is restored, the peri- 

 stalsis diminishes. (b) Direct stimulation of the intestine, conducted to the 

 plexus myentericus, causes dysperistalsis ; direct exposure of the intestines to the 

 air (stronger when C0 2 or Cl is present) the introduction of various irritating 

 substances into the intestine increased filling of the intestine when there is any 

 difficulty in emptying the gut (often in man) direct stimulation of various kinds 

 (also inflammation), all act upon the intestine, either from without or from 

 within. Induction shocks applied to a loop of intestine in a hernial sac cause 

 lively peristalsis in the hernia. The intestinal movements are favoured by heat, 

 and cease below 19C. (Horwath). 



4. The continued application of strong stimuli causes the dysperi- 

 stalsis to give place to rest, owing to over-stimulation, which may be 

 called " intestinal paresis" or exhaustion. 



This condition is absolutely different from the passive condition of the intestine 

 in aperistalsis. Continued congestion of the intestinal blood-vessels ultimately 

 causes intestinal paralysis, e.g. , when transfusion of foreign blood causes coagula- 

 tion within these vessels (Landois). Filling the blood-vessels with " indifferent " 

 fluids, after the peristalsis has been previously caused by compressing the aorta, 

 also causes cessation of the movements (0. Nasse). The movements cease when 

 the intestines are cooled to 19C. (Horwath), while severe inflammation of the 

 intestine has a similar effect. Under favourable circumstances, the intestine may 

 recover from this condition. Arterial blood admitted into the vessels of the 

 exhausted intestine causes peristalsis, which at first is more vigorous than normal. 



