Human Anatomy and Physiology - Digestive and Respiratory Systems MCQs 2026

The enzyme pepsin, which digests proteins, is active in the highly acidic environment of the

1. AMouth✓
2. BSmall intestine✓
3. CStomach✓
4. DLarge intestine✓

The condition in which stomach acid flows back into the esophagus, causing heartburn, is called

1. APeptic ulcer✓
2. BAppendicitis✓
3. CGastroesophageal reflux disease (GERD)✓
4. DCirrhosis✓

The average adult human takes approximately how many breaths per minute at rest

1. A12 to 20✓
2. B40 to 50✓
3. C2 to 5✓
4. D60 to 80✓

The total surface area of human lungs available for gas exchange is approximately equal to the area of a

1. ASmall classroom✓
2. BTennis court✓
3. CFootball field✓
4. DBasketball court✓

Enzymes that specifically digest nucleic acids in the small intestine are called

1. ALipases✓
2. BProteases✓
3. CAmylases✓
4. DNucleases✓

The main function of the appendix, once thought vestigial, is now associated with

1. AFat digestion✓
2. BVitamin K synthesis✓
3. CHousing beneficial gut bacteria✓
4. DProtein absorption✓

The salivary glands that produce the largest volume of saliva are the

1. ASublingual glands✓
2. BParotid glands✓
3. CSubmandibular glands only✓
4. DBuccal glands✓

The pH of gastric juice in the stomach is typically

1. AStrongly acidic (around pH 1.5-3.5)✓
2. BNeutral (pH 7)✓
3. CStrongly alkaline (pH 9-10)✓
4. DSlightly acidic (pH 6)✓

The process of breathing in (inhalation) is also called

1. AExpiration✓
2. BExhalation✓
3. CInspiration✓
4. DRespiration✓

The small sac-like structures at the end of bronchioles where gas exchange occurs are surrounded by a network of

1. ALymph vessels✓
2. BNerve fibers✓
3. CMuscle fibers✓
4. DCapillaries✓

Smoking is most strongly linked to which respiratory disease

1. ACommon cold✓
2. BTonsillitis✓
3. CLung cancer✓
4. DHiccups✓

The disease in which the alveolar walls are progressively destroyed, reducing surface area for gas exchange, is

1. AAsthma✓
2. BEmphysema✓
3. CLaryngitis✓
4. DBronchitis✓

Pneumonia is a condition characterized by

1. AInflammation and fluid accumulation in the alveoli✓
2. BNarrowing of the trachea only✓
3. CExcess saliva production✓
4. DLoss of taste buds✓

A person suffering from asthma experiences difficulty breathing mainly due to

1. AAlveolar collapse✓
2. BExcess red blood cells✓
3. CDiaphragm paralysis✓
4. DConstriction of bronchial airways✓

The exchange of gases between alveolar air and blood is primarily driven by differences in

1. ABlood pressure✓
2. BTemperature✓
3. CPartial pressure of gases✓
4. DpH levels✓

The thin membrane that lines the lungs and chest cavity, reducing friction during breathing, is the

1. APeritoneum✓
2. BPleura✓
3. CPericardium✓
4. DDiaphragm membrane✓

The maximum amount of air that can be exhaled after a maximum inhalation is called

1. AVital capacity✓
2. BTidal volume✓
3. CResidual volume✓
4. DInspiratory reserve volume✓

The volume of air inhaled or exhaled in a normal, relaxed breath is called

1. AVital capacity✓
2. BResidual volume✓
3. CTotal lung capacity✓
4. DTidal volume✓

The part of the brain that primarily controls the rhythm of breathing is the

1. ACerebellum✓
2. BMedulla oblongata✓
3. CCerebrum✓
4. DHypothalamus✓

Most carbon dioxide in the blood is transported in the form of

1. ADissolved gas in plasma✓
2. BCarboxyhemoglobin✓
3. CBicarbonate ions✓
4. DCarbonic acid crystals✓

Oxygen is mainly transported in the blood bound to

1. AHemoglobin in red blood cells✓
2. BPlasma proteins✓
3. CWhite blood cells✓
4. DPlatelets✓

Gas exchange in the alveoli occurs primarily by the process of

1. AActive transport✓
2. BOsmosis✓
3. CFacilitated diffusion✓
4. DSimple diffusion✓

The windpipe that carries air from the larynx to the bronchi is called the

1. AEsophagus✓
2. BTrachea✓
3. CBronchiole✓
4. DPharynx✓

The flap of tissue that prevents food from entering the trachea during swallowing is the

1. AUvula✓
2. BLarynx✓
3. CEpiglottis✓
4. DGlottis✓

The voice box, containing the vocal cords, is known as the

1. ALarynx✓
2. BPharynx✓
3. CTrachea✓
4. DEpiglottis✓

During inhalation, the diaphragm

1. ARelaxes and moves upward✓
2. BStays stationary✓
3. CExpands laterally only✓
4. DContracts and moves downward✓

The muscle primarily responsible for breathing, separating the thoracic and abdominal cavities, is the

1. AIntercostal muscle✓
2. BDiaphragm✓
3. CTrapezius✓
4. DPectoralis✓

The primary site of gas exchange in the human respiratory system is the

1. AAlveoli✓
2. BBronchi✓
3. CTrachea✓
4. DLarynx✓

The valve that regulates the passage of partially digested food from the stomach to the duodenum is the

1. ACardiac sphincter✓
2. BIleocecal valve✓
3. CPyloric sphincter✓
4. DAnal sphincter✓

The valve that prevents backflow of food from the stomach into the esophagus is the

1. APyloric sphincter✓
2. BIleocecal valve✓
3. CBicuspid valve✓
4. DCardiac (lower esophageal) sphincter✓

Starch is ultimately broken down into which simple sugar for absorption

1. AFructose✓
2. BGlucose✓
3. CGalactose✓
4. DSucrose✓

The end product of protein digestion that is absorbed into the bloodstream is

1. AGlucose✓
2. BFatty acids✓
3. CAmino acids✓
4. DGlycerol✓

The hormone gastrin stimulates the secretion of

1. AGastric acid✓
2. BBile✓
3. CInsulin✓
4. DSaliva✓

The hormone that stimulates the gallbladder to release bile and the pancreas to release digestive enzymes is

1. AGastrin✓
2. BSecretin✓
3. CInsulin✓
4. DCholecystokinin (CCK)✓

Vitamin B12 absorption in the terminal ileum requires a substance called

1. ABile salts✓
2. BIntrinsic factor✓
3. CPepsinogen✓
4. DGastrin✓

The digestion of fats is aided by bile through a process called

1. AHydrolysis✓
2. BAbsorption✓
3. CEmulsification✓
4. DPeristalsis✓

Undigested food waste is stored temporarily before elimination in the

1. ARectum✓
2. BDuodenum✓
3. CIleum✓
4. DEsophagus✓

The primary function of the large intestine (colon) is

1. AProtein digestion✓
2. BAbsorption of water and electrolytes✓
3. CFat emulsification✓
4. DEnzyme secretion for carbohydrate digestion✓

Finger-like projections in the small intestine that increase surface area for absorption are called

1. ARugae✓
2. BCilia✓
3. CPapillae✓
4. DVilli✓

The pancreas secretes which enzyme to digest proteins in the small intestine

1. APepsin✓
2. BPtyalin✓
3. CTrypsin✓
4. DRenin✓

The organ that stores and concentrates bile before releasing it into the small intestine is the

1. AGallbladder✓
2. BPancreas✓
3. CLiver✓
4. DSpleen✓

Bile, which emulsifies fats, is produced by the

1. APancreas✓
2. BStomach✓
3. CGallbladder✓
4. DLiver✓

The three parts of the small intestine, in order from the stomach, are

1. AIleum, jejunum, duodenum✓
2. BDuodenum, jejunum, ileum✓
3. CJejunum, duodenum, ileum✓
4. DDuodenum, ileum, jejunum✓

Most digestion and absorption of nutrients occurs in the

1. AStomach✓
2. BLarge intestine✓
3. CSmall intestine✓
4. DEsophagus✓

Peristalsis refers to

1. ARhythmic muscular contractions that move food along the digestive tract✓
2. BThe mixing of food with saliva✓
3. CThe absorption of nutrients in the intestine✓
4. DThe secretion of bile by the liver✓

The muscular tube that connects the throat to the stomach is the

1. ATrachea✓
2. BPharynx✓
3. CLarynx✓
4. DEsophagus✓

Hydrochloric acid in the stomach is secreted by

1. AChief cells✓
2. BParietal cells✓
3. CGoblet cells✓
4. DMucous cells✓

The enzyme present in saliva that breaks down starch is

1. APepsin✓
2. BSalivary amylase (ptyalin)✓
3. CLipase✓
4. DTrypsin✓

Digestion of carbohydrates begins in the

1. AMouth✓
2. BStomach✓
3. CSmall intestine✓
4. DLarge intestine✓

The process of breaking down food into smaller absorbable molecules is called

1. AEgestion✓
2. BAbsorption✓
3. CAssimilation✓
4. DDigestion✓