TOPIC 1: Gastrointestinal Anatomy & Physiology
Question 1
Which segment of the large intestine is responsible for water and electrolyte absorption?
A) Rectum
B) Sigmoid colon
C) Ascending colon
D) Entire large intestine
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Correct Answer: D
Rationale: The entire large intestine absorbs water and electrolytes. While the ascending colon absorbs
the majority of water, all segments of the large intestine contribute to this function. The rectum
primarily serves as a storage reservoir for feces before elimination.
Key Point: Water absorption occurs throughout the colon, which is why stool becomes progressively
more formed as it moves distally through the large intestine.
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Question 2
Normal stool color is primarily due to:
A) Bile pigments (stercobilin)
B) Blood
C) Diet alone
D) Bacteria
<details> <summary><strong>Answer & Rationale</strong></summary>
,Correct Answer: A
Rationale: Bile pigments, specifically stercobilin (a breakdown product of bilirubin), give stool its
characteristic brown color.
Red stool → Lower GI bleeding
Black, tarry stool (melena) → Upper GI bleeding (digested blood)
Clay-colored (pale) stool → Bile duct obstruction
Green stool → Rapid transit time (bile not fully broken down)
Key Point: Color changes are clinically significant and often indicate underlying pathology.
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Question 3
Which of the following represents a normal bowel movement frequency range?
A) Once per week
B) Once per month
C) Three times per day to three times per week
D) Daily only
<details> <summary><strong>Answer & Rationale</strong></summary>
Correct Answer: C
Rationale: Normal bowel frequency ranges from three times per day to three times per week. This
wide range reflects individual variation in diet, activity level, fluid intake, and metabolism.
Key Point: "Normal" is patient-specific. What matters most is whether the pattern is consistent for that
individual and whether stool is passed without excessive straining or discomfort.
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Question 4
The nurse is assessing a patient's stool. Which finding requires immediate notification of the provider?
A) Brown formed stool
B) Black, tarry stool (melena)
, C) Yellow stool
D) Green stool
<details> <summary><strong>Answer & Rationale</strong></summary>
Correct Answer: B
Rationale: Black, tarry stool (melena) indicates upper GI bleeding (esophagus, stomach, or duodenum).
The black color results from digestion of blood by gastric acid. This is a medical emergency requiring
immediate evaluation.
Yellow stool may indicate fat malabsorption or rapid transit
Green stool is often benign (rapid transit, leafy greens, iron supplements)
Key Point: Melena suggests significant bleeding (typically >100 mL) and requires urgent intervention.
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Question 5
What characteristic of stool should a nurse expect for a client with lower gastrointestinal tract bleeding?
A) Black, tarry stool
B) Bright, red-tinged stool
C) Clay-colored stool
D) Green stool
<details> <summary><strong>Answer & Rationale</strong></summary>
Correct Answer: B
Rationale: Lower GI bleeding (distal colon, rectum, anus) presents as bright red or red-tinged stool
because the blood has not been digested by stomach acid.
Upper GI bleeding → Black, tarry (melena)
Lower GI bleeding → Bright red (hematochezia)
Biliary obstruction → Clay-colored
Key Point: The color of blood in stool helps localize the source of bleeding.
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