Saliva helps protect the teeth against decay-causing bacteria.
Correct Answer
True
True. Saliva rinses the teeth, buffers acids and contains antibodies and other protective substances, so a dry mouth raises the risk of dental decay.
Category: Oral Cavity and Swallowing
Question 2
Swallowing is entirely involuntary from the moment food enters the mouth.
Correct Answer
False
False. The first stage of swallowing, in which the tongue pushes the bolus back into the pharynx, is voluntary; once the bolus reaches the pharynx, the rest of swallowing is an involuntary reflex.
Category: Oral Cavity and Swallowing
Question 3
During swallowing, the soft palate and uvula rise to keep food from entering the nasal cavity.
Correct Answer
True
True. Raising the soft palate seals off the nasopharynx while the bolus passes through the pharynx toward the esophagus.
Category: Oral Cavity and Swallowing
Question 4
The stomach wall has an extra oblique layer of smooth muscle that helps churn food.
Correct Answer
True
True. Besides the circular and longitudinal layers found along the digestive tract, the stomach has an inner oblique layer that allows vigorous churning and mixing.
Category: Stomach Structure and Secretion
Question 5
Villi line the small intestine but are not found in the large intestine.
Correct Answer
True
True. Villi are unique to the small intestine, where most nutrient absorption occurs; the large intestine mainly absorbs water and electrolytes.
Category: Small Intestine and Absorption
Question 6
Hydrochloric acid in the stomach does little to kill microorganisms swallowed with food.
Correct Answer
False
False. Stomach acid destroys many swallowed microorganisms, which is one of its protective functions along with helping to digest protein and absorb minerals.
Category: Stomach Structure and Secretion
Question 7
Histamine, gastrin and acetylcholine each stimulate the acid-secreting cells of the stomach.
Correct Answer
True
True. Each of these signals binds receptors on parietal cells and increases acid secretion, so blocking only one of these signals, such as histamine, reduces but does not abolish acid output.
Category: Stomach Structure and Secretion
Question 8
Most nutrient absorption takes place in the stomach.
Correct Answer
False
False. The stomach absorbs very little; the small intestine, with its villi and large surface area, absorbs most nutrients.
Category: Small Intestine and Absorption
Question 9
Bile contains enzymes that chemically digest fat.
Correct Answer
False
False. Bile has no digestive enzymes; its bile salts emulsify fat into small droplets so that pancreatic lipase can digest it.
Category: Pancreas, Liver and Bile
Question 10
Bacteria in the colon ferment fiber and other material that the small intestine cannot digest.
Correct Answer
True
True. Colon bacteria break down undigested carbohydrates such as fiber, producing gas and short-chain fatty acids, and they also make some vitamins.
Category: Large Intestine
Question 11
The enteric nervous system in the gut wall can produce peristalsis only when it receives signals from the brain.
Correct Answer
False
False. The enteric nervous system, a network of neurons in the wall of the digestive tract, can coordinate peristalsis and secretion on its own; input from the brain and spinal cord through autonomic nerves adjusts its activity.
Category: GI Function and Disorders
Question 12
Irritable bowel syndrome is subtyped by its main stool pattern, such as constipation, diarrhea or a mix of both.
Correct Answer
True
True. The subtypes include IBS with constipation, IBS with diarrhea and mixed IBS, and drug choice depends on the subtype.
Category: GI Function and Disorders
Question 13
Pancreatic juice is strongly acidic, which helps continue protein digestion in the small intestine.
Correct Answer
False
False. Pancreatic juice is alkaline because it is rich in bicarbonate, which neutralizes acidic chyme and protects the small intestine.
Category: Pancreas, Liver and Bile
Question 14
Bile contains bilirubin, a pigment produced from the breakdown of old red blood cells.
Correct Answer
True
True. The liver secretes bilirubin into bile, and bacteria in the intestine convert it to the pigments that give stool its brown color.
Category: Pancreas, Liver and Bile
Question 15
The large intestine secretes enzymes that complete the digestion of protein.
Correct Answer
False
False. Protein digestion is completed in the small intestine by pancreatic proteases and peptidases of the intestinal lining; the large intestine secretes mucus but not digestive enzymes.
Category: Large Intestine
Question 16
A layer of mucus and bicarbonate helps protect the stomach lining from acid and pepsin.
Correct Answer
True
True. Mucus secreted by the surface mucous cells of the stomach lining traps bicarbonate against the lining, and loss of this barrier allows acid and pepsin to cause gastritis or ulcers.
Category: Stomach Structure and Secretion
Question 17
Food reaches the stomach by gravity alone, so the esophagus does not use peristalsis.
Correct Answer
False
False. Waves of peristalsis push the bolus down the esophagus, which is why a person can swallow even while lying down.
Category: Oral Cavity and Swallowing
Question 18
Hydrochloric acid in the stomach converts inactive pepsinogen into active pepsin.
Correct Answer
True
True. Chief cells secrete pepsinogen, and the acidic environment converts it to pepsin, which begins protein digestion.
Category: Stomach Structure and Secretion
Question 19
Most chemical digestion is finished by the time chyme leaves the stomach.
Correct Answer
False
False. Most chemical digestion takes place in the small intestine, where pancreatic enzymes, bile and enzymes of the intestinal lining act on chyme.
Category: Small Intestine and Absorption
Question 20
Saliva production decreases when food is present in the mouth.
Correct Answer
False
False. Food in the mouth increases saliva secretion through a parasympathetic reflex, which moistens the food and starts starch digestion.
Category: Oral Cavity and Swallowing