30 Questions
What is the primary cause of defecation in patients with infectious diarrhea or other inflammatory conditions?
Loss of discriminating ability of receptors
What is the purpose of the intrinsic defecation reflex?
To cause peristaltic waves in the descending colon, sigmoid and rectum
What is the role of the parasympathetic defecation reflex?
All of the above
Which nerve is responsible for voluntary control of the external anal sphincter?
Pudendal nerve
What is the purpose of the external anal sphincter?
To counteract the defecation reflex
What is the relationship between the intrinsic and parasympathetic defecation reflexes?
The parasympathetic reflex greatly intensifies the intrinsic reflex
What is the primary function of segmentation contractions and tonic contractions in the small intestine?
To facilitate absorption of nutrients
What is the characteristic pattern of peristaltic movements in the small intestine?
They are faster in the proximal small intestine than in the distal small intestine
What is the purpose of the muscularis mucosae contractions in the small intestine?
To increase absorption of nutrients
What is the role of the muscle fibers in the villi of the small intestine?
To increase lymph flow from the villi
What is the characteristic pattern of the basic electrical rhythm (BER) in the colon?
The frequency increases along the colon
What are the two primary functions of the motor activities in the colon?
To mix colonic contents and facilitate absorption, and to propel the contents
What is the primary reason for mass peristalsis not always resulting in the desire to defecate?
The colonic contents stop moving before reaching the rectum.
Which of the following is NOT mentioned as a potential trigger for mass movements?
Consuming a high-fiber diet.
What is the primary mechanism behind the gastro-colic and duodeno-colic reflexes?
Both nervous and hormonal mechanisms.
Where are the fecal masses typically stored before entering the rectum?
The sigmoid colon.
What is the approximate increase in intra-luminal pressure of the rectum that will usually cause the desire to defecate?
$18$ mmHg
What are the receptors in the rectal wall capable of differentiating?
Whether the increase in pressure is due to solid feces, liquid, or gas.
What is the function of mixing or segmentation contractions in the small intestine?
Mix chyme with digestive enzymes and mucus
Where are the basic electrical rhythms (BER) initiated in the small intestine?
Outer circular muscle layer near the myenteric plexus
What determines the local response to the slow wave in the small intestine?
Myenteric plexus and enteric hormones
How do tonic contractions affect segments of the small intestine?
Prolonged contractions isolating segments
What is the approximate frequency of basic electrical rhythms (BER) in the duodenum?
12/min
Which layer of the small intestine houses pacemaker cells for basic electrical rhythms (BER)?
Outer circular muscle layer
What is the primary role of the conscious mind in controlling defecation?
Relaxing the external anal sphincter when the time is suitable
Which of the following actions facilitate defecation when the time is suitable?
Taking a deep breath, closing the glottis, and contracting the abdominal muscles
What happens if the time is not suitable for defecation?
The external anal sphincter remains contracted, and the reflex dies out
Which disease is characterized by the release of enterotoxins, leading to severe diarrhea and dehydration?
Cholera
What is the primary cause of diarrhea in celiac sprue?
Damage to the intestinal mucosa caused by gluten intake
Which of the following statements about the defecation reflex is true?
It will not return until an additional amount of feces enters the rectum
Test your knowledge on the movements in the small intestine, colon, and defecation reflex. Learn about the basic electrical rhythm (BER) in the small intestine and its characteristics.
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