What are the three dietary categories of animals?
- Herbivores
- Carnivores
- Omnivores
These categories classify animals based on their dietary habits.
What are the nutritional needs of animals?
- Fuel for all animal requirements
- Biosynthesis – making new molecules
- Essential nutrients (10 amino acids, some fatty acids, vitamins, minerals)
Essential nutrients cannot be synthesized by the body.
List the four stages of food processing.
- Ingestion
- Digestion
- Absorption
- Elimination
These stages describe how food is processed in the body.
What is intracellular digestion?
Digestion that occurs within a cell, e.g., food vacuole + lysosomes
This type of digestion is seen in organisms like amoeba.
What is extracellular digestion?
Digestion that occurs in a specific compartment, e.g., gastrovascular cavity in cnidarians
This allows for more complex digestion processes.
What are two functions of a gastrovascular cavity?
- Digests food
- Distributes nutrients
This structure is found in simple organisms like hydra.
What is the difference between a complete and incomplete digestive system?
- Complete: Two openings (mouth and anus)
- Incomplete: One opening functions as both mouth and anus
Complete systems allow for specialized compartments for digestion.
What is the alimentary canal?
A complete digestive tract
It consists of a series of organs through which food passes.
What is the role of peristalsis in digestion?
Moves food through the digestive tract
It involves waves of muscular contractions.
What are the main components of gastric juice?
- Mucus
- Pepsinogen
- Hydrochloric acid (HCl)
These components aid in the digestion of food in the stomach.
What enzyme begins protein digestion in the stomach?
Pepsin
Pepsin is activated from pepsinogen by hydrochloric acid.
What is the function of bile?
Acts as an emulsifier for fat digestion
Bile is produced by the liver and stored in the gallbladder.
What triggers the release of cholecystokinin (CCK)?
Amino acids or fatty acids in the duodenum
CCK stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder.
What are the accessory glands in the human digestive system?
- Salivary glands
- Pancreas
- Liver
- Gallbladder
These glands secrete substances that aid in digestion.
What is the function of the pancreas?
- Endocrine: Secretes insulin and glucagon
- Exocrine: Secretes digestive enzymes into the duodenum
The pancreas has both endocrine and exocrine functions.
What is chyme?
Gastric juices + partly digested food
Chyme is formed in the stomach and moves into the small intestine.
What is the role of sphincters in the digestive system?
Control the passage of food through the digestive tract
Sphincters are muscular valves that regulate flow.
True or false: Salivary amylase begins carbohydrate digestion in the stomach.
FALSE
Salivary amylase begins carbohydrate digestion in the oral cavity.
What triggers the release of cholecystokinin (CCK) in the duodenum?
Amino acids or fatty acids
CCK stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder.
What does secretin stimulate the pancreas to release?
Sodium bicarbonate
This neutralizes acid chyme from the stomach.
What is the role of gastrin in digestion?
Stimulates the production of gastric juices
Gastrin recirculates via the bloodstream back to the stomach.
What does enterogastrone inhibit?
Peristalsis and acid secretion by the stomach
It slows digestion when acid chyme rich in fats enters the duodenum.
Where does the absorption of nutrients primarily occur?
Small intestine
Specifically, in the villi and microvilli of the intestinal wall.
What are the three functions of the colon?
- Reabsorption of water
- Production of feces
- Hosting rich microflora
The colon is 1.5 m long and includes bacteria that produce vitamins.
