ProteinsChapter 17 – Part 3

Protein in the Body

Protein Digestion: Part 1

Figure 6.6

Protein Digestion: Part 2

Figure 6.6

Protein Digestion: Part 3

Figure 6.6

Protein Digestion: Part 4

Figure 6.6

How Does the Body Use Protein? Functions of protein

◦ Provide structural and mechanical support◦ Maintain body tissues◦ Functions as enzymes and hormones◦ Help maintain acid base balance◦ Transport nutrients◦ Assist the immune system◦ Serve as a source of energy when necessary

Essential, Nonessential, and Conditional Essential – must be consumed in the

diet Nonessential – can be synthesized in

the body Conditionally essential – cannot be

synthesized due to illness or lack of necessary precursors

Body creates all of its proteins from 22 different amino acids

13 are manufactured 9 are essential amino acids – body needs

them but cannot make them

AMINO ACID

Protein Quality

Complete proteins ◦ Contain all nine essential amino acids.◦ Usually animal source are complete proteins.◦ Sources: Fish, meat, poultry, eggs, milk,

cheese, yogurt, and many soybean products.

Incomplete proteins ◦ Low in one or more essential amino acid.◦ Plant sources are incomplete.◦ Sources: Beans, peas, nuts, and whole grains.

How Much Protein Do You Need? Healthy, non-pregnant adults

◦ Should consume enough to replace what is used every day

◦ Goal is nitrogen balance Pregnant women, people recovering

from surgery or injury, and growing children◦ Should consume enough to build new

tissue

Muscles, ligaments, tendons, and bones

Without these particular structural proteins, we would look more like this….

Well, maybe not exactly…