Figure 2-3 Stomach Muscles
The stomach has three layers of muscles.
Figure 2-4 Emulsification of Fat by Bile
Like bile, detergents are emulsifiers and work the same way, which is why they are effective at removing grease spots from clothes. Molecule by molecule, the grease is dissolved out of the spot and suspended in water, where it can be rinsed away.
In the stomach, the fat and watery GI juices tend to separate. The enzymes are in the water and can’t get at the fat.
When fat enters the small intestine, the gallbladder secretes bile. Bile has an affinity for both fat and water, so it can bring the fat into the water.
Figure 2-4 Emulsification of Fat by Bile (cont’d.)
Bile’s emulsifying action converts large fat globules into small droplets that repel each other.
After emulsification, the enzymes have easy access to the fat droplets.
Figure 2-6 The Liver and Its Circulatory System
Figure 2-7 The Lipoproteins
This solar system of lipoproteins shows their relative sizes. Notice how large the fat-filled chylomicron is compared with the others and how the others get progressively smaller as their proportion of fat declines and protein increases.
Figure 2-7 The Lipoproteins (cont’d.)
A typical lipoprotein contains an interior of triglycerides and cholesterol surrounded by phospholipids. The phospholipids’ fatty acid “tails” point toward the interior, where the lipids are. Proteins near the outer ends of the phospholipids cover the structure. This arrangement of hydrophobic molecules on the inside and hydrophilic molecules on the outside allows lipids to travel through the watery fluids of the blood.
Figure 2-7 The Lipoproteins (cont’d.)
Chylomicrons contain so little protein and so much triglyceride that they are the lowest in density.
Very-low-density lipoproteins (VLDL) are half triglycerides, accounting for their low density.
Low-density lipoproteins (LDL) are half cholesterol, accounting for their implication in heart disease.
High-density lipoproteins (HDL) are half protein, accounting for their high density.
Figure NP2-1 Fight Bac!
Four ways to keep food safe. The Fight Bac! website is at www.fightbac.org.
Figure NP2-4 Recommended Safe Temperatures (Fahrenheit)
Bacteria multiply rapidly at temperatures between 40°F and 140°F. Cook foods to the temperatures shown on this thermometer and hold them at 140°F or higher.
a During the 3 minutes after meat is removed from the heat source, its temperature remains constant or continues to rise, which destroys pathogens.
