32 terms

Chemical and Physical Processes of Digestion

Digestive tract
Continuous tube that winds through the body from the oral cavity to the anus
Accessory digestive glands
Exocrine gland that secrete enzyme and fluid needed for digestion
Process of breaking down food molecules into smaller molecules with the aid of enzymes in the digestive tract
An enzyme that breaks down H2O to build smaller molecules
Salivary amylase
An enzyme in the oral cavity that breaks down starch and glycogen
Bile salts
Includes bile acid and base used in emulsification of lipids
Enzyme that breaks down protein into amino acids. Secreted by chief cells in the pancreas.
Two factors that play key roles in the efficacy of digestive enzymes
Temperature - hot and cold, enzyme denature when heated, enzyme slow down in cold temp. pH - change in pH can lead to deactivation
Major functions of the digestive system
1. Ingestion 2. Digestion (mechanical and chemical) 3. Absorption 4. Propulsion 5. Defecation 6. Secretion
What does it mean for an enzyme to be substrate specific?
1 enzyme for 1 substrate. Based on the lock-and-key theory
Primary categories into which food molecules fall into
1. Carbohydrates 2. Proteins 3. Lipids
Carbohydrates are broken down into what building blocks?
Proteins are broken into what building blocks?
Amino acids
Lipids are broken into what building blocks?
Fatty acids and monoglycerides
Why do lipids pose special problems for digestion?
Water and oil do not mix. Lipid are fat soluble, are water insoluble, hydrophobic, lipophilic
Breaking down of a water molecule to form smaller molecules
Enzyme that breaks down carbohydrates
Enzyme that breaks down lipids
Optimal pH for salivary amylase? Where is salivary amylase found?
pH of 6 is optimal. Found in oral cavity
Boiling and freezing on enzyme activity
Boiling - denature, destroy, deactivate. Freezing - slows down, inactivate.
Was salivary amylase able to digest cellulose? Why or why not?
No because we do not have the enzyme cellulase
Effect of bacteria on cellulose digestion
Bacteria can digest cellulose if they have cellulase
Where is pepsin secreted?
Found in the stomach so secreted in the stomach
Optimal pH for pepsin
Where is lipase secreted?
From the stomach and pancreas
Optimal pH for lipase
pH of 2 for the stomach. pH of 8 for the pancreas (duodenum has basic environment)
What was the effect of bile salts on lipid digestion?
Emulsification - mechanical digestion because don't change lipid globules
Iodine Potassium Iodide. Test for starch.
Benedicts's Test
Test for reducing sugar
Measure light absorption through liquid medium
pH meter
Measure the level of hydrogen ion
Examples of physical process of digestion
1. Chewing (mastication) 2. Emulsification (breaking fat globules into fat goblets) 3. Segmentation (longitudinal smooth muscle contracts along the esophagus and small intestine, oblique smooth muscle contracts in the stomach)