Three-year old Ben’s parents are ecstatic because he is now using the potty each time he needs to defecate. What muscle has Ben learned to control?

Question

A.  the cardiac sphincter made of striated muscle
B.  the pyloric sphincter made of smooth muscle
C.  the Sphincter of oddi made of smooth muscle
D.  the internal anal sphincter made of smooth muscle
E.  the external anal sphincter made of striated muscle

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?

Gather Content
· What do you know about the voluntary control of defecation? What other information is related to the question?

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

E.  the external anal sphincter made of striated muscle

Clarify Question
· What is the key concept addressed by the question?
        o The question asks about the voluntary control of defecation.
· What type of thinking is required?
        o You are being asked to apply your knowledge about the voluntary control of defecation.

Gather Content
· What do you know about the voluntary control of defecation? What other information is related to the question?
        o Compacted feces, driven by peristaltic contractions of the large intestine, pass from the large intestine into a short tube called the rectum. From the rectum, the feces exit the body through the anus. Two sphincters control passage through the anus. The first is composed of smooth muscle and opens involuntarily in response to pressure inside the rectum. The second, composed of striated muscle, can be controlled voluntarily by the brain, thus permitting a conscious decision to delay defecation.

Choose Answer
· Given what you now know, what information is most likely to produce the correct answer?
        o Feces pass through two anal sphincters is it passes out of the body. The inner sphincter is not under voluntary control and contains smooth muscles. The outer sphincter is under voluntary control and contains striated muscles. The pyloric sphincter controls movement of food out of the stomach. There is not a cardiac sphincter, reverse flow of blood is regulated by valves.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked you to apply your knowledge about the voluntary control of defecation. If you got the correct answer, great job! If you got an incorrect answer, where did the process break down? Did you think that the inner anal sphincter was under voluntary control? Did you think that the pyloric sphincter was in the rectum?