Chapter 17 – Part 3

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

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

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