PNB 2265 practice questions and Answers | 2026
UPDATED | 100% CORRECT
What is the primary purpose of mechanical digestion in the mouth?
To chew food into smaller pieces, increasing surface area for digestive enzymes to work.
What are the components of saliva and their functions?
Water, fluoride, bicarbonate (neutralizes acid), lysozyme (breaks down bacteria), and salivary
amylase (begins carbohydrate digestion).
What is a bolus?
Chewed food mixed with saliva.
What is the function of the lower esophageal sphincter (LES)?
It remains closed to prevent acid reflux and relaxes to allow food to enter the stomach.
What is achalasia?
A disorder where the lower esophageal sphincter fails to relax, preventing the bolus from
entering the stomach.
What is the function of the stomach's oblique muscle layer?
It provides extra force for mechanical digestion.
What do chief cells secrete?
Pepsinogen and gastric lipase.
How is pepsinogen activated?
,It is converted into active pepsin when mixed with hydrochloric acid.
What is the role of intrinsic factor?
It helps the body absorb vitamin B12.
What is the function of the proton pump (H+/K+ ATPase) in parietal cells?
It uses ATP hydrolysis to secrete H+ ions into the stomach lumen to form hydrochloric acid.
What is the role of somatostatin in gastric acid regulation?
It acts as a negative feedback signal to inhibit acid production by parietal cells.
What is receptive relaxation in the stomach?
The process where the fundus and body of the stomach stretch to store food.
Why is the stomach not a primary site for nutrient absorption?
It lacks villi and a brush border, though it does absorb alcohol and aspirin.
What is the function of the alkaline mucus barrier in the stomach?
It protects the stomach mucosa from damage by hydrochloric acid.
What is the role of CCK (Cholecystokinin) in digestion?
It is released in response to fats to slow gastric emptying and stimulate pancreatic lipase.
What is the function of secretin?
It is released in response to low pH and stimulates the pancreas to secrete bicarbonate to
neutralize stomach acid.
What is dumping syndrome?
, A condition where stomach contents are emptied into the duodenum prematurely, often
associated with gastric bypass surgery.
What are the three sections of the small intestine?
Duodenum, jejunum, and ileum.
What is the migrating motor complex?
A strong wave of peristalsis that occurs during fasting to clear the small intestine of remaining
substances.
Why are pancreatic enzymes secreted as zymogens?
To prevent autodigestion of the pancreatic tissue.
What is the function of bile?
It is produced by the liver and stored in the gallbladder to emulsify fats.
What is the role of the common bile duct?
It carries bile from the liver and gallbladder to the duodenum.
What are haustra?
Small pouches in the large intestine caused by the contraction of the taeniae coli muscle bands.
What is the primary function of the large intestine?
Absorption of water and electrolytes, and the formation of feces.
What triggers the defecation reflex?
The stretching of the sigmoid colon and rectum.
UPDATED | 100% CORRECT
What is the primary purpose of mechanical digestion in the mouth?
To chew food into smaller pieces, increasing surface area for digestive enzymes to work.
What are the components of saliva and their functions?
Water, fluoride, bicarbonate (neutralizes acid), lysozyme (breaks down bacteria), and salivary
amylase (begins carbohydrate digestion).
What is a bolus?
Chewed food mixed with saliva.
What is the function of the lower esophageal sphincter (LES)?
It remains closed to prevent acid reflux and relaxes to allow food to enter the stomach.
What is achalasia?
A disorder where the lower esophageal sphincter fails to relax, preventing the bolus from
entering the stomach.
What is the function of the stomach's oblique muscle layer?
It provides extra force for mechanical digestion.
What do chief cells secrete?
Pepsinogen and gastric lipase.
How is pepsinogen activated?
,It is converted into active pepsin when mixed with hydrochloric acid.
What is the role of intrinsic factor?
It helps the body absorb vitamin B12.
What is the function of the proton pump (H+/K+ ATPase) in parietal cells?
It uses ATP hydrolysis to secrete H+ ions into the stomach lumen to form hydrochloric acid.
What is the role of somatostatin in gastric acid regulation?
It acts as a negative feedback signal to inhibit acid production by parietal cells.
What is receptive relaxation in the stomach?
The process where the fundus and body of the stomach stretch to store food.
Why is the stomach not a primary site for nutrient absorption?
It lacks villi and a brush border, though it does absorb alcohol and aspirin.
What is the function of the alkaline mucus barrier in the stomach?
It protects the stomach mucosa from damage by hydrochloric acid.
What is the role of CCK (Cholecystokinin) in digestion?
It is released in response to fats to slow gastric emptying and stimulate pancreatic lipase.
What is the function of secretin?
It is released in response to low pH and stimulates the pancreas to secrete bicarbonate to
neutralize stomach acid.
What is dumping syndrome?
, A condition where stomach contents are emptied into the duodenum prematurely, often
associated with gastric bypass surgery.
What are the three sections of the small intestine?
Duodenum, jejunum, and ileum.
What is the migrating motor complex?
A strong wave of peristalsis that occurs during fasting to clear the small intestine of remaining
substances.
Why are pancreatic enzymes secreted as zymogens?
To prevent autodigestion of the pancreatic tissue.
What is the function of bile?
It is produced by the liver and stored in the gallbladder to emulsify fats.
What is the role of the common bile duct?
It carries bile from the liver and gallbladder to the duodenum.
What are haustra?
Small pouches in the large intestine caused by the contraction of the taeniae coli muscle bands.
What is the primary function of the large intestine?
Absorption of water and electrolytes, and the formation of feces.
What triggers the defecation reflex?
The stretching of the sigmoid colon and rectum.
