Ch 41 Digestive System Flashcards
Why is feeding necessary in animals?
To get organic molecules
How do animals receive energy from feeding?
The bonds of organic molecules are broken
Essential nutritents
Molecules necessary for constuction of the body
Can essential nutrients be synthesized by animals?
No
Four classes of essential nutrients
1) Essential amino acids
2) Essential fatty acids
3) Vitamins
4) Minerals
How many amino acids are needed by the human body?
20
How many amino acids needed by the human body can be synthesized by the body?
12
How many essential amino acids (amino acids that cannot be synthesized by the human body) are there?
8
Complete proteins
Foods that contain all 8 essential amino acids
Vitamin
A required organic compound that is not a carbohydrate, fat, protein, or mineral
Digestion
The reduction of food by mechanical and chemical means to simple, soluble molecules that can be absorbed and transported to the cells of the body
Alimentary system
The system involved in the acquisition of nutrients
Five regionalized functions of the alimentary system
1) Ingestion
2) Conduction and storage
3) Grinding and preliminary digestion
4) Final digestion and absorption
5) Water absorption and concentration of waste
What are the two layers that compose the mammal tooth?
1) Enamel
2) Dentin
Enamel
Almost completely mineral
Hardest material in the body
Herbivores typically lack what kind of teeth?
Canines
Herbivores typically have what kind of teeth?
Premolars and molars formed into continuous ridged surfaces
Monotremes and eutherian anteaters lack what?
All teeth
Whales in the suborder Mysticeti lack what?
All teeth
How do whales in the suborder Mysticeti feed?
By filtering seawater through baleen plates composed of keratin
In addition to oral jaws, some fish have what?
Well-developed pharyngeal (throat) jaws used in the processing of food
Gill rakers
Extentions of the gill arches
Gill rakers contribute to what?
The collection of food
Gill rakers reflect what?
Feeding diversity
How do simple multicellular animals digest food?
They combine functions of digestion in single cells
How do sponges, cnidarians, and flatworms digest food?
Intracellular digestion
Intracellular digestion
Food particles brought into cells by phagocytosis
What is the site of extracellular digestion?
A gastrovascular cavity
Crop
An expansion of the esophagus used to store food prior to digestion
Gizzard
Grinds food
What two structures are possessed by birds, insects, and earthworms that facilitate digestion?
1) Crop
2) Gizzard
Gastric cecae
Sites of enzyme secretion, extracellular digestion, and absorption of nutrients in insects
In insects, what serves primarily in water water absorption?
The hindgut portion of the intestine
Salivary glands
Produce mucus secretions
Assist in swallowing and produce amylase
Amylase
Enzyme that breaks carbohydrates into maltose
Epiglottis
A valve in the pharynx that prevents food from entering the trachea
What holds food in the stomach?
Muscular sphincters
What happens to food while it is in the stomach?
It is subjected to mixing
Gastric juices
Secreted by the stomach
Contain hydrochloric acids and pepsin
Pepsin
Enzyme that breaks down proteins into smaller polypeptides
Gastric glands give rise to:
1) Gastric juices
2) Mucus (protects stomach from digestion)
Pepsinogen
Precursor to pepsin
Changes configuration in response to acid
Chyme
Partially digested food
Chyme is released from the stomach into what?
The duodenum of the small intestine
Pancreatic juice
Increases the pH
Pancreatic juice includes what?
Proteases
Proteases
Enzymes that split proteins
Bile
Separate fat into tiny droplets that can be broken down by lipases
Bile is produced where?
Liver
Bile is released by what?
Gallbladder
Primary function of small intestine
Absorption of nutrients
Villi
Finger-like projections of the intestinal epithelium
Microvilli
Finger-like projections of the epithelial cells
How much do villi and microvilli increase the surface area of the small intestine?
1000 times
In the small intestine, what diffuses into the epithelial cells?
1) Amino acids
2) SImple sugars (glucose, fructose)
3) Monoglycerides
What happens after molecules are absorbed into the epithelium of the small intestine?
The molecules are then passed to the blood stream
Large intestine
Consolidates the indigestible remnants of digestion by reabsorption of water for form feces
The large intestine houses what?
Many bacteria
Bacteria in the large intestine can synthesize what vitamins?
1) Vitamin K
2) B vitamins
Cellulase
Enzyme that digest cellulose (sugar of plant cells)
Do any mulicellular animals produce cellulase?
No
Fermentation
Process by which many vertebrate herbivores use microorganisms that produce cellulase to digest cellulose
Foregut fermenters
Cows, sheep, hippos
Chew vegetation repeatedly, as it is passed back and forth between the fermentation chamber and the mouth
Hindgut fermenters
Horses, koalas, pigs
