Digestive System: Key Concepts from Chapter 3 (Digestion, Absorption, and Transport)

A comprehensive set of Q&A flashcards covering digestion, absorption, and transport concepts from the chapter notes.

What is digestion?

The body's way of breaking down foods into nutrients in preparation for absorption.

What is absorption?

The uptake of nutrients by cells of the small intestine for transport into either the blood or the lymph.

What components make up the digestive system as defined in these notes?

The organs and glands associated with the ingestion and digestion of food.

What happens in the mouth during digestion?

Chewing breaks up food; fluids from salivary glands blend with food to ease swallowing; five basic taste sensations (sweet, sour, bitter, salty, umami); aroma, texture, and temperature affect flavor.

What are the two sphincter muscles of the esophagus?

Upper esophageal sphincter and lower esophageal sphincter.

What is chyme?

A semiliquid mass of partly digested food that moves from the stomach into the small intestine.

What is the pyloric sphincter?

The valve that opens the stomach contents into the small intestine (the duodenum).

What are the main components and functions of the small and large intestines?

Small intestine digests and absorbs; large intestine withdraws water; includes ileocecal valve, rectum, and anus.

What is the ileocecal valve and its function?

Valve between the ileum and the cecum that controls flow and prevents backflow.

What is peristalsis?

Circular and longitudinal muscles work together to push intestinal contents along; contractions vary in rate and intensity.

What is segmentation in the small intestine?

Contraction of circular muscles that mixes chyme and promotes contact with digestive juices and absorption cells.

What are the five organs that secrete digestive fluids?

Salivary glands, stomach, pancreas, liver, and small intestine.

What are the main components of digestive secretions?

Water, enzymes, and substances that facilitate hydrolysis.

What enzymes act on all three energy nutrients and where are they released?

Pancreatic juice and intestinal enzymes released via ducts into the duodenum; they act on carbohydrates, proteins, and fats.

What neutralizes acidic chyme?

Sodium bicarbonate.

What emulsifies fats and helps keep them suspended in water?

Bile.

Where is bile produced and where is it stored?

Produced by the liver and stored in the gallbladder.

Where does the pH scale come into play in digestion?

The pH scale helps describe the acidity or basicity of digestive fluids along the GI tract.

What is the length and surface-area characteristic of the small intestine?

About 10 feet long with a large surface area for absorption.

What are the absorptive structures of the small intestine and their roles?

Villi regulate nutrient absorption; microvilli contain enzymes and pumps; goblet cells secrete mucus; crypts secrete intestinal juices.

What is the role of villi cells in absorption?

Villi cells regulate nutrient absorption based on the body's needs.

What is the role of microvilli in digestion?

Microvilli have enzymes and pumps that recognize and act on different nutrients.

What is the function of goblet cells?

Secrete mucus to protect and lubricate the intestinal lining.

What are the three main pathways for nutrient absorption in terms of transport mechanisms?

Simple diffusion, facilitated diffusion, and active transport.

Where do water-soluble nutrients and small fat digestion products go after absorption?

They enter the bloodstream and travel to the liver via the hepatic portal vein.

Where do larger fats and fat-soluble vitamins go after absorption?

They enter the lymphatic system via chylomicrons and initially bypass the liver.

What is the lymphatic system's role in nutrient transport?

A one-way route with no pump; nutrients in lymph eventually enter the bloodstream after bypassing the liver at first.

What are the hormones listed in this chapter's GI hormone section?

Gastrin, Secretin, and Cholecystokinin (CCK).

What does Table 3-2 cover according to the notes?

The primary actions of selected GI hormones.

What does The System at Its Best suggest about maintaining GI health?

A sensitive and responsive system supported by immunity, defense against invaders, healthy blood supply, and lifestyle factors—balance, moderation, adequacy, and variety in foods.

What does the Final Stage Reflection Activity say about bacteria, fiber, undigested residues, and the colon?

Bacteria ferment some fibers; fiber retains water; undigested residues exercise intestinal muscles; the colon absorbs water and recycles dissolved salts.