Digestion Quiz Practice Test

The digestive system's primary role is to break down food into smaller molecules so that nutrients can be absorbed into the bloodstream. It does not function in oxygen circulation or temperature regulation.

Digestion begins in the mouth, where food is mechanically broken down by chewing and mixed with saliva containing enzymes. Thus, the mouth is the entry point of the digestive system.

Salivary glands produce saliva, which contains enzymes that initiate carbohydrate digestion in the mouth. This is the first chemical step in the digestive process.

The stomach churns food and mixes it with hydrochloric acid and enzymes to break down proteins and other substances. Nutrient absorption primarily occurs in the small intestine, not the stomach.

The small intestine is lined with villi that increase its surface area, making it the primary site for nutrient absorption. This function is essential for transferring nutrients into the bloodstream.

Peristalsis refers to the involuntary, rhythmic contractions of smooth muscles that propel food through the digestive system. It is a vital mechanism for moving food from the esophagus to the rectum.

Amylase is the enzyme in saliva that begins the breakdown of starches into simpler sugars. The other enzymes listed serve different functions in digestion.

Hydrochloric acid helps to denature proteins and activate enzymes like pepsin, which are critical for protein digestion. It does not digest carbohydrates or emulsify fats.

The liver produces bile, which is later stored in the gallbladder until it is needed for fat digestion in the small intestine. Bile emulsifies fats to improve digestion.

The pancreas produces vital digestive enzymes that break down proteins, fats, and carbohydrates, as well as bicarbonate to neutralize stomach acid. Although it also has hormonal functions, its digestive role is highlighted here.

The large intestine is primarily responsible for absorbing water and electrolytes from indigestible food matter, which helps form solid waste. The small intestine mainly focuses on nutrient absorption.

Villi are small, finger-like projections in the small intestine that significantly increase its surface area for nutrient absorption. They do not secrete enzymes or bile.

The low pH in the stomach creates an environment that can kill many ingested microorganisms, serving as a first line of defense against pathogens. Other organs also support immune function, but the stomach's acidity is key.

The esophagus is a muscular tube that moves food from the mouth to the stomach via peristalsis. It does not play a direct role in chemical digestion or nutrient absorption.

Mechanical digestion involves physically breaking down food into smaller pieces through actions like chewing and churning without changing its chemical structure. Chemical digestion, by contrast, uses enzymes to break down molecules.

The epiglottis is a flap of tissue that covers the trachea during swallowing, ensuring that food is directed towards the esophagus. This helps protect the airway from obstruction.

Brush border enzymes, located on the microvilli of the small intestine, complete the final stages of digestion by breaking down disaccharides and peptides into simpler molecules. They function chemically rather than mechanically.

Bile acts to emulsify fats, breaking them into smaller droplets that can be more easily accessed and broken down by digestive enzymes like lipase. This process is crucial for efficient fat digestion.

Parietal cells in the stomach lining secrete hydrochloric acid, which is essential for creating the acidic environment necessary for protein digestion. Other cells in the stomach have different functions, such as secreting pepsinogen.

Digestive enzymes act as catalysts to accelerate chemical reactions that break complex food molecules into simpler ones, which can then be absorbed by the body. They do not physically alter the size or shape of food particles.