ESSENTIAL NUTRIENTS
What are the four classes of organic molecules that provide raw materials and energy for animals?
Carbohydrates, lipids, proteins, and nucleic acids.
What are the four stages of food processing?
Ingestion → Digestion → Absorption → Elimination
What muscular contractions move food through the esophagus?
Peristalsis
Which accessory organ produces bile?
Liver
A carnivore generally has what type of digestive system compared with an herbivore?
A shorter digestive system, with a large, expandable stomach.
How many essential amino acids do humans need to obtain from their diet?
9
Which stage involves taking food into the body?
Ingestion
What organ stores food and secretes gastric juice containing HCl and pepsin?
Stomach
Which organ stores bile?
Gallbladder
What type of feeder filters or traps food particles from the surrounding environment?
Filter feeder
What are the 13 organic molecules required in small amounts that animals obtain from their diets?
Vitamins
Which stage involves breaking food into molecules small enough to be absorbed?
Digestion
Which organ is the major site of digestion and absorption?
Small intestine
What does the pancreas release into the small intestine?
Bicarbonate and digestive enzymes
A caterpillar eating leaves is an example of what feeding strategy?
Substrate feeding
Unlike vitamins, minerals are what type of nutrients?
Inorganic nutrients
What is the difference between mechanical and chemical digestion?
Mechanical digestion physically breaks food into smaller pieces.
Chemical digestion breaks food molecules into smaller molecules, often through enzymatic hydrolysis.
Put these in the correct order: Stomach → Mouth → Small intestine → Esophagus → Large intestine
Mouth → Esophagus → Stomach → Small intestine → Large intestine
What structures dramatically increase the surface area available for absorption in the small intestine?
Villi and microvilli
The duodenum detects amino acids or fatty acids in chyme and releases CCK. What does CCK stimulate?
CCK stimulates the pancreas to release digestive enzymes and the gallbladder to release bile.
A person eats plenty of food but does not get enough of several required vitamins and minerals. Is this necessarily undernourishment?
No. This could be malnutrition, because malnutrition is an imbalance between the nutrients the body needs and receives.
An animal breaks food down into small molecules, but those molecules have not yet entered the body's tissues. Which stage has occurred, but which stage has not?
Digestion has occurred; absorption has not.
Why doesn't the stomach normally digest itself even though it contains strong acid and pepsin?
A mucus barrier containing bicarbonate-rich fluid protects the stomach lining from acid and pepsin.
Lipids are processed into triglycerides inside intestinal epithelial cells and then packaged with phospholipids, cholesterol, and proteins. What are these water-soluble particles called, and where are they transported?
Chylomicrons → lymphatic vessels/lacteals in the villi.
Chyme entering the duodenum is highly acidic. Which hormone responds by causing the pancreas to release bicarbonate, and what is the purpose?
Secretin → stimulates pancreatic bicarbonate release to neutralize the acidic chyme.