Human Digestive System

Описание: 1.Which enzyme initiates starch digestion in the mouth?**
A) Pepsin
B) Amylase
C) Lipase
D) Trypsin
**Answer: B) Amylase
2. *Low pH in the stomach primarily activates:*
A) Bile production
B) Pepsinogen → Pepsin
C) Insulin secretion
D) Amylase function
*Answer: B) Pepsinogen → Pepsin*
Explanation: HCl creates acidic conditions converting pepsinogen to active pepsin.

3. *Nutrient absorption occurs MAINLY in the:*
A) Stomach
B) Duodenum
C) Jejunum and ileum
D) Colon
*Answer: C) Jejunum and ileum*
Explanation: Small intestine's villi maximize absorption; jejunum/ileum handle most nutrients.

4. *Bile is critical for digesting:*
A) Proteins
B) Carbohydrates
C) Fats
D) Nucleic acids
*Answer: C) Fats*
Explanation: Bile emulsifies fats into smaller droplets for lipase action.

5. *The primary function of the large intestine is:*
A) Protein digestion
B) Water and electrolyte absorption
C) Bile storage
D) Enzyme secretion
*Answer: B) Water and electrolyte absorption*
Explanation: Colon reabsorbs water/electrolytes, forming solid feces.

6. *Which structure prevents food from entering the trachea?*
A) Uvula
B) Epiglottis
C) Pyloric sphincter
D) Esophageal sphincter
*Answer: B) Epiglottis*
Explanation: Epiglottis covers the larynx during swallowing.

7. *Villi and microvilli enhance function by:*
A) Producing bile
B) Increasing surface area
C) Secreting gastric juice
D) Storing glycogen
*Answer: B) Increasing surface area*
Explanation: These structures maximize nutrient absorption in the small intestine.

8. *Pepsin is inactive in the duodenum because:*
A) Low pH denatures it
B) Bile neutralizes it
C) Pancreatic bicarbonate raises pH
D) Amylase inhibits it
*Answer: C) Pancreatic bicarbonate raises pH*
Explanation: Bicarbonate neutralizes acid, inactivating pepsin.

9. *The hepatic portal vein carries blood from the ____ to the liver.*
A) Heart
B) Lungs
C) Digestive organs
D) Kidneys
*Answer: C) Digestive organs*
Explanation: Nutrient-rich blood from GI tract goes to the liver for processing.

10. *Gastrin, secretin, and CCK are:*
A) Digestive enzymes
B) Hormones regulating digestion
C) Bile components
D) Absorbed nutrients
*Answer: B) Hormones regulating digestion*
Explanation: These hormones control gastric motility, enzyme/bile release, and pH.

11. *Which macronutrient is digested FIRST by stomach enzymes?*
A) Carbohydrates
B) Proteins
C) Fats
D) Fiber
*Answer: B) Proteins*
Explanation: Pepsin begins protein digestion in the stomach.

12. *Gallstones blocking the bile duct would impair digestion of:*
A) Starch
B) Vitamins
C) Fats
D) Proteins
*Answer: C) Fats*
Explanation: Bile duct obstruction reduces fat emulsification.

13. *Chief cells in the stomach secrete:*
A) HCl
B) Mucus
C) Pepsinogen
D) Gastrin
*Answer: C) Pepsinogen*
Explanation: Chief cells produce inactive pepsinogen; parietal cells secrete HCl.

14. *After resection of the ileum, absorption of ____ is MOST affected:*
A) Glucose
B) Amino acids
C) Vitamin B₁₂
D) Water
*Answer: C) Vitamin B₁₂*
Explanation: Ileum absorbs vitamin B₁₂ via intrinsic factor.

15. *Peristalsis refers to:*
A) Enzyme secretion
B) Wave-like muscle contractions
C) Nutrient diffusion
D) Bile production
*Answer: B) Wave-like muscle contractions*
Explanation: Peristalsis propels food through the GI tract.

16. *Trypsinogen is activated to trypsin in the duodenum by:*
A) Enterokinase
B) HCl
C) Bile salts
D) Pepsin
*Answer: A) Enterokinase*
Explanation: Enterokinase (from duodenal mucosa) converts trypsinogen → trypsin.

17. *A patient with chronic pancreatitis would likely have difficulty digesting:*
A) Only proteins
B) Only fats
C) Proteins and fats
D) Carbohydrates