The part of the human gut that has an acidic content is the?

1. Analyze the question You are asked which part of the human gut (alimentary canal) has acidic contents. This is about the pH conditions along the digestive tract.

2. Explain the concept

• The stomach has gastric glands. Their parietal (oxyntic) cells secrete hydrochloric acid (HCl), giving gastric juice a pH of about 1.5-2.
• The HCl does three jobs: • It activates the enzyme precursor pepsinogen into pepsin, which digests protein. Pepsin works best in acidic conditions. • It kills most bacteria that enter with food. • It provides the acid medium that pepsin and rennin need.
• When the acidic food (chyme) moves into the duodenum, it is neutralised by bile and by pancreatic juice, which contains sodium hydrogen carbonate. The contents then become alkaline (about pH 7.5-8.5). This suits the enzymes of the small intestine, such as trypsin, lipase and amylase.
• The ileum is also slightly alkaline, where digestion is completed and absorption takes place.
• The colon has roughly neutral to slightly acidic or alkaline contents. It mainly absorbs water and forms faeces, and it is not the part known for acidity.

3. Step-by-step solution

• Option A, stomach: HCl is secreted here, so it is acidic. ✔
• Option B, duodenum: bile and pancreatic juice neutralise the acid, so it is alkaline. ✘
• Option C, ileum: slightly alkaline. ✘
• Option D, colon: not acidic like the stomach. ✘

4. Answer The correct option is A. stomach.

5. Exam tip Remember the order of pH along the gut: Stomach = acid, then everything after it = alkaline. A simple phrase is "Stomach is Sour." If JAMB asks where protein digestion begins or where pepsin works, the answer is again the acidic stomach.