Digestive System Functions and Processes

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Questions and Answers

What is the primary role of pancreatic amylase in digestion?

To assemble chylomicrons

To digest triglycerides into monoglycerides

To resume the digestion of carbohydrates (correct)

To break down proteins into amino acids

Which brush-border enzyme is responsible for digesting sucrose?

Amylase

Sucrase (correct)

Maltase

Lactase

Which monosaccharides result from the digestion of carbohydrates?

Galactose, maltase, glucose

Glucose, fructose, galactose (correct)

Glucose, sucrose, lactose

Fructose, lactose, maltose

How are triglycerides processed within the epithelial cells of the small intestine?

They are digested into monoglycerides and free fatty acids Signup and view all the answers

What are chylomicrons primarily composed of after processing in the small intestine?

Triglycerides, cholesterol, and proteins Signup and view all the answers

What is the fate of absorbed nutrient molecules after they enter the bloodstream?

They depend on the metabolic state of body cells Signup and view all the answers

How do small polypeptides enter the epithelial cells of the small intestine?

They are absorbed by transcytosis Signup and view all the answers

What mechanism transports cholesterol from the lumen of the small intestine?

A transport molecule Signup and view all the answers

What is the primary function of the digestive system?

To mechanically and enzymatically break down food for absorption Signup and view all the answers

Where does the enzymatic digestion of proteins begin?

In the stomach Signup and view all the answers

What happens to carbohydrate digestion when food enters the stomach?

It stops due to enzyme denaturation Signup and view all the answers

Which organ is primarily responsible for secreting digestive enzymes into the small intestine?

Pancreas Signup and view all the answers

What is a proenzyme?

An inactive precursor of an enzyme Signup and view all the answers

What enzyme converts trypsinogen into its active form?

Enteropeptidase Signup and view all the answers

What are brush-border enzymes?

Enzymes expressed on the cell surface of intestinal epithelial cells Signup and view all the answers

Which type of food molecule is NOT one of the main components of the typical American diet?

Minerals Signup and view all the answers

Study Notes

Digestive System Functions

The digestive system breaks down food mechanically and enzymatically, absorbing usable molecules.
Key food types include carbohydrates (poly- and disaccharides), proteins (amino acids), and fats (triglycerides, cholesterol).

Digestion Begins in the Oral Cavity

Digestion starts in the mouth, where food is chewed and enzymes in saliva begin breaking down carbohydrates and fats.
Chewing mechanically breaks down food.
Saliva contains enzymes for carbohydrate and fat digestion.
Swallowing moves food to the esophagus.

Stomach Digestion

Stomach acid continues digestion, primarily proteins, while denaturing carbohydrate-digesting enzymes.
This means that further carbohydrate digestion temporarily stops once food enters the stomach.

Small Intestine Digestion

The small intestine is the main site for digestion and absorption.
Most digestive enzymes come from the pancreas (in an inactive form).
Pancreatic enzymes are activated in the small intestine.
Enzymes (activated from inactive proenzymes) are critical for proper digestion.
Brush-border enzymes, located on the cell membranes of the small intestine, further digest macromolecules.
- Examples: sucrase, maltase, lactase to digest sugars, and others.

Absorption in the Small Intestine

Monosaccharides (glucose, fructose, galactose) are absorbed into the bloodstream after carbohydrate digestion.
Proteins are broken down to amino acids and small peptides, also absorbed into the bloodstream.
Triglycerides and long-chain fatty acids are broken down, enabling absorption across the intestinal cell membrane.
Monoglycerides and free fatty acids then recombine into triglycerides within the epithelial cells.
These fats, combined with cholesterol and proteins, form chylomicrons.
Chylomicrons are released into lymphatic vessels (lacteals).
Chylomicrons eventually enter the bloodstream through the thoracic duct.

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Description

Explore the intricate functions of the digestive system, starting from the oral cavity through to the stomach and small intestine. This quiz covers the breakdown of food into usable molecules and the role of enzymes in digestion. Test your understanding of how different food types are processed in the body.