Digestive System: Fat and Protein Breakdown & Absorption

Dietary Fats

_____ Fats are nutrients that provide energy, help absorb vitamins, and protect organs.

Triglycerides

A triglyceride is made of one glycerol and three fatty acids.

Triglyceride

This is the main form of fat eaten and stored in the body.

Fat Digestion

Fat digestion means turning large fat molecules into smaller, absorbable parts.

Bile

Bile is made by the liver and stored in the gallbladder.

Bile Salts

Bile contains ____ ____, which attach to globs of fat to break them into smaller pieces.

Emulsification

_________ breaks fat into smaller droplets.

Role of Bile

Bile itself does not digest fat but prepares it for digestion.

Lipase

Lipase is the enzyme that breaks fat into fatty acids and glycerol.

Lipase Activity

Lipase works best after bile has broken fat into droplets.

Stomach Digestion

The stomach contains lipase, but no bile.

Duodenum

The duodenum receives bile and pancreatic juice through the Ampulla of Vater.

Pancreas

Main source of lipase in pancreatic juice.

Intestinal Juice

Intestinal juice adds more lipase to complete digestion.

Fat Digestion Site

This is the main site of fat digestion.

Lacteals

Lacteals are lymphatic vessels in the intestine that absorb fatty acids and glycerol.

Fat Absorption

Fat absorption occurs after fats have been emulsified and digested into fatty acids and glycerol.

Bile Function

Bile emulsifies fat; lipase then splits it into fatty acids and glycerol.

Importance of Emulsification

Smaller droplets mean lipase can contact more fat at once.

Fat Digestion Speed

Without emulsification, fat digestion would be very slow.

Lipase Locations

Lipase is active in the stomach, pancreatic juice, and intestinal juice.

Pancreatic lipase

Enzyme from pancreatic juice that acts on emulsified fats to produce fatty acids and glycerol.

Intestinal lipase

Enzyme from intestinal juice that finishes the breakdown of fats if needed.

Jejunum

Part of the small intestine where most fat absorption occurs.

Fatty acids and glycerol

Products of fat breakdown that move through the villi into lacteals.

Lymphatic system

System that fatty acids and glycerol enter after being collected by lacteals, instead of directly into the bloodstream.

Non-water-soluble molecules

Large molecules that are transported through the lymphatic system before entering the bloodstream.

Chemical digestion

The process of breaking down food into smaller molecules by chemical means.

Starch (polysaccharides)

A carbohydrate that is broken down by salivary amylase into maltose (disaccharides).

Salivary amylase

An enzyme that breaks down starch into maltose in the oral cavity.

Maltose (disaccharides)

The product of starch digestion by salivary amylase.

Protein (polypeptides)

A macromolecule that is broken down in the stomach by HCl and pepsin into peptides.

HCl

Hydrochloric acid that activates pepsin and deactivates amylase in the stomach.

Pepsin

An enzyme that breaks down proteins into peptides in the stomach.

Fat (triglycerides)

A type of lipid that is partially digested in the stomach by lipase.

Pancreatic juice

A fluid that contains sodium bicarbonate, pancreatic lipase, trypsin, and amylase, entering through the Ampulla of Vater.

Sodium bicarbonate

A substance that neutralizes acidic chyme in the duodenum.

Peptidase

An enzyme that breaks down peptides into amino acids in the intestinal juice.

Maltase

An enzyme that breaks down maltose into glucose (monosaccharides).

Villi

Small finger-like projections in the intestinal wall that absorb nutrients.

Amino acids

The building blocks of proteins that are absorbed directly into the bloodstream.