Movement in Small & Large Intestine Quiz

What is the primary cause of defecation in patients with infectious diarrhea or other inflammatory conditions?

Loss of discriminating ability of receptors (correct)
Weakening of the intrinsic defecation reflex
Relaxation of the external anal sphincter
Overactive parasympathetic defecation reflex

What is the purpose of the intrinsic defecation reflex?

To cause peristaltic waves in the descending colon, sigmoid and rectum (correct)
To relax the external anal sphincter
To stimulate the parasympathetic defecation reflex
To relax the internal anal sphincter

What is the role of the parasympathetic defecation reflex?

To cause contraction of the descending colon, sigmoid and rectum
To relax the internal anal sphincter
To relax the external anal sphincter
All of the above (correct)

Which nerve is responsible for voluntary control of the external anal sphincter?

Pudendal nerve (B) Signup and view all the answers

What is the purpose of the external anal sphincter?

To counteract the defecation reflex (B) Signup and view all the answers

What is the relationship between the intrinsic and parasympathetic defecation reflexes?

The parasympathetic reflex greatly intensifies the intrinsic reflex (A) Signup and view all the answers

What is the primary function of segmentation contractions and tonic contractions in the small intestine?

To facilitate absorption of nutrients (B) Signup and view all the answers

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 (C) Signup and view all the answers

What is the purpose of the muscularis mucosae contractions in the small intestine?

To increase absorption of nutrients (D) Signup and view all the answers

What is the role of the muscle fibers in the villi of the small intestine?

To increase lymph flow from the villi (C) Signup and view all the answers

What is the characteristic pattern of the basic electrical rhythm (BER) in the colon?

The frequency increases along the colon (D) Signup and view all the answers

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 (D) Signup and view all the answers

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. (A) Signup and view all the answers

Which of the following is NOT mentioned as a potential trigger for mass movements?

Consuming a high-fiber diet. (A) Signup and view all the answers

What is the primary mechanism behind the gastro-colic and duodeno-colic reflexes?

Both nervous and hormonal mechanisms. (D) Signup and view all the answers

Where are the fecal masses typically stored before entering the rectum?

The sigmoid colon. (B) Signup and view all the answers

What is the approximate increase in intra-luminal pressure of the rectum that will usually cause the desire to defecate?

$18$ mmHg (A) Signup and view all the answers

What are the receptors in the rectal wall capable of differentiating?

Whether the increase in pressure is due to solid feces, liquid, or gas. (A) Signup and view all the answers

What is the function of mixing or segmentation contractions in the small intestine?

Mix chyme with digestive enzymes and mucus (B) Signup and view all the answers

Where are the basic electrical rhythms (BER) initiated in the small intestine?

Outer circular muscle layer near the myenteric plexus (B) Signup and view all the answers

What determines the local response to the slow wave in the small intestine?

Myenteric plexus and enteric hormones (D) Signup and view all the answers

How do tonic contractions affect segments of the small intestine?

Prolonged contractions isolating segments (D) Signup and view all the answers

What is the approximate frequency of basic electrical rhythms (BER) in the duodenum?

12/min (D) Signup and view all the answers

Which layer of the small intestine houses pacemaker cells for basic electrical rhythms (BER)?

Outer circular muscle layer (D) Signup and view all the answers

What is the primary role of the conscious mind in controlling defecation?

Relaxing the external anal sphincter when the time is suitable (B) Signup and view all the answers

Which of the following actions facilitate defecation when the time is suitable?

Taking a deep breath, closing the glottis, and contracting the abdominal muscles (C) Signup and view all the answers

What happens if the time is not suitable for defecation?

The external anal sphincter remains contracted, and the reflex dies out (A) Signup and view all the answers

Which disease is characterized by the release of enterotoxins, leading to severe diarrhea and dehydration?

Cholera (C) Signup and view all the answers

What is the primary cause of diarrhea in celiac sprue?

Damage to the intestinal mucosa caused by gluten intake (B) Signup and view all the answers

Which of the following statements about the defecation reflex is true?

It will not return until an additional amount of feces enters the rectum (C) Signup and view all the answers