Question

In the digestive system, the pH of the stomach and the intestine, respectively are,
a. Alkaline, acidic
b. Acidic, alkaline
c. Acidic, neutral
d. Acidic, acidic

Answer 1

Hint: pH is nothing but a measure to tell about the nature of a particular solution, and if the measure of pH is below 7, we can say it as acidic, while if it is above 7, we can say it as basic and exactly the pH of 7 we consider it as neutral.

Complete answer:
- In the digestive system, compared to all parts, the stomach is the area that has less pH, which means that it is the area that is more acidic compared to all parts of the body.
- pH varies in both the upper and lower parts of the stomach where the upper part is less acidic compared to the lower part.
- In the lower part, the mucosa has parietal cells that secrete the gastric juice and it consists of substances such as Hydrochloric acid, potassium chloride, etc, which has the pH of 1.5 to 2.
- These acidic juices are helpful for digestion and they can denature the protein structure and they activate the pepsinogen which is helpful for digestion of proteins to amino acids, and also to protect from microorganisms by digestion.
- But this acidic nature lasts only up to the stomach, where the food enters the intestine, there is a secretion of the pancreatic juices where it contains bicarbonate ions which makes the pH alkaline.
- And the alkaline nature of the intestine is also due to secretions of the bile juice, as it also contains the organic salts which makes the pH alkaline that is 7.4 to 8.
- The main reason for the alkaline nature of the intestine is because pancreatic juices activate only in the base environment.
- So the stomach is acidic and the intestine is alkaline.

Hence, the correct answer is option (B).

Note: Even though the gastric juice is acidic it does not tear or burn the stomach because, mucous cells or goblet cells In the layer of stomach secretes the thick mucous layer which protect the stomach lining from the Hydrochloric acid present in the gastric juice.