Ch. 3 Digestion, Absorption, & Transport Flashcards
Define digestion. What is the goal of digestion? What are the “absorbable units?”
Def: Process by which food is broken down into absorbable units.
Goal: break down food into absorbable units.
Absorbable Units:
- -CHO: fructose, glucose, galactose
- -PRO: dipeptides, AA
- -FAT: monoglycerides, fatty acids, glycerol
Familiarize yourself with the anatomy of the digestive tract.
So, you should go study your anatomy notes on the digestive system right now. :)
Digestive system: Mouth Stomach Small Intestine Large Intestine Liver Gallbladder Pancreas
Describe the role of the mouth in digestion.
Chews and mixes food with saliva.
Describe the role of the stomach in digestion.
Churns, mixes, and grinds food into a liquid mass: adds acid, enzymes, and fluid.
Describe the role of the small intestine in digestion.
Secretes enzymes that digest all energy-yielding nutrients to small nutrient particles; cells of wall absorb nutrients into blood and lymph.
Describe the role of the large intestine in digestion.
Absorbs water and minerals; passes waste (fiber, bacteria, and unabsorbed nutrients) along with water to the rectum.
Describe the role of the liver in digestion.
Manufactures bile salts, detergent-like substances, to help digest fats.
Describe the role of the gallbladder in digestion.
Stores bile until needed.
Describe the role of the pancreas in digestion.
Manufacture enzymes to digest all energy-yielding nutrients and releases bicarbonate to neutralize acid chyme that enters the small intestine.
How are CHO, PRO, and FAT digested in the mouth?
CHO: salivary amylase beings CHO digestion.
PRO: no digestion
FAT: lingual lipase. Little fat digestion.
How are CHO, PRO, and FAT digested in the stomach?
CHO: stomach acid inactivates salivary amylase, stops CHO digestion.
PRO: Parietal cells (secrete HCl):
–uncoils PRO (increasing surface area), activates pepsinogen to pepsin
Goblet cells (secretes mucus which helps protect stomach from HCl)
Chief Cells: secrete pepsinogen
FAT: little fat digestion
How are CHO, PRO, and Fat digested in the small intestine?
CHO: digestion resumes.
- Pancreatic amylases (from pancreatic duct to duodenum)
- brush border amylases (on surface of intestinal cells)
- ->intestinal maltase: maltose breaks down into glucose + glucose
- ->intestinal sucrase: sucrose breaks down into glucose + fructose
- ->intestinal lactase: lactose breaks down into glucose + galactose
PRO: pancreatic proteases, intestinal proteases
FAT: Bile (emulsifier), pancreatic lipases, intestinal lipases
What is the role of saliva in the digestive process?
Contains water, salts, and enzymes. Helps moisten food, begins CHO digestion.
What is the role of enzymes in the digestive process?
Catalysts, proteins.
Identified by organ they come from and compound they work on.
What is the role of bile in the digestive process?
Emulsifier:
–brings fat into suspension in water so that enzymes can break down the fat.