food processing and digestion

chapter 47

What are the three types of animal nutrition?

Herbivores, carnivores, omnivores.

What is the difference between an incomplete and complete digestive tract?

Incomplete has one opening (mouth = anus); complete has two separate openings for mouth and anus.

What are the four stages of food processing in animals?

ingestion, digestion, absorption, and elimination.

What is mechanical digestion?

The physical breakdown of food (e.g., chewing).

What is chemical digestion?

The breakdown of food using enzymes into smaller molecules.

What is absorption?

The uptake of nutrients into cells, primarily in the small intestine.

What is elimination?

Removal of undigested material as feces.

What are the organs of the human digestive system in order?

Mouth → pharynx → esophagus → stomach → small intestine → large intestine → rectum → anus.

What is the function of the mouth in digestion?

Mechanical digestion by chewing; chemical digestion of starch with salivary amylase.

What is the function of the pharynx and esophagus?

Move food to the stomach using peristalsis.

What is the function of the stomach?

Churns food and digests proteins using pepsin.

What is the function of the small intestine?

Most digestion and absorption of nutrients occur here.

What is the function of the large intestine?

Reabsorbs water and forms feces.

What is the function of the rectum and anus?

Store and eliminate feces.

What are the 4 accessory organs of the digestive system?

Salivary glands, liver, gallbladder, pancreas.

What does the liver produce?

Bile (to emulsify fats).

What does the gallbladder do?

Stores and releases bile into the small intestine.

What does the pancreas do in digestion

Releases digestive enzymes and bicarbonate into the small intestine.

What enzyme starts starch digestion in the mouth?

Salivary amylase.

What enzyme breaks down proteins in the stomach?

Pepsin.

What enzymes does the pancreas release into the small intestine?

Amylase, lipase, trypsin.

What enzymes are produced by the small intestine?

Maltase, lactase, sucrase (for digesting disaccharides).

What macromolecule does lipase digest and what are the products?

Lipids → fatty acids and glycerol.

Where does most nutrient absorption occur?

Small intestine.

What structures increase absorption in the small intestine?

Villi and microvilli.

What do capillaries in villi absorb?

Monosaccharides and amino acids.

What do lacteals in villi absorb?

Fatty acids and glycerol.

What is the function of bile?

Emulsifies fats, increasing surface area for lipase.

What is peristalsis?

Involuntary wave-like muscle contractions that move food through the digestive tract.

Which hormones regulate digestion and how?

Gastrin (stomach acid), Secretin (bicarbonate from pancreas), CCK (bile + enzymes release).

How do carnivores differ from herbivores in digestion?

Carnivores have shorter intestines and sharp teeth; herbivores have longer guts and fermentation chambers.What is a ruminant and give an example?

An herbivore with a 4-chambered stomach, e.g., cow.

What is a hindgut fermenter?

Herbivore with large cecum for fermentation (e.g., rabbit, horse).

What are the three macronutrients?

Carbohydrates, proteins, lipids.

What are micronutrients?

Vitamins and minerals needed in small amounts.

What are essential nutrients?

Nutrients the body can’t make; must be obtained from food (e.g., essential amino acids, some vitamins).

How many kcal per gram are in carbs, proteins, and fats?

Carbs = 4, Protein = 4, Fat = 9 kcal/g.

What causes ulcers in the stomach?

Bacteria Helicobacter pylori.

What is lactose intolerance?

Inability to digest lactose due to missing lactase enzyme.

What causes constipation or diarrhea?

Issues with water absorption in the large intestine.

What is malnutrition?

inadequate intake or absorption of nutrients.