Personal Nutrition Chapter 6

Peptide bond:

A bond that connects one amino acid with another.

Kwashiorkor

A deficiency disease caused by inadequate protein in the presence of adequate food energy.

Food intolerance

A general term for any adverse reaction to a food or food component that does not involve the body's immune system.

Biological value

A measure of protein quality, assessed by determining how well a given food or food mixture supports nitrogen retention.

Incomplete protein

A protein lacking or low in one or more of the essential amino acids.

Food aversion

A strong desire to avoid a particular food.

Food allergen

A substance in food—usually a protein—that is seen by the body as harmful and causes the immune system to mount an allergic reaction.

Limiting amino acid

A term given to the essential amino acid in shortest supply (relative to the body's need) in a food protein; it therefore limits the body's ability to make its own proteins.

Acid-Base Balance

Acidosis Blood acidity above normal, indicating excess acid. Alkalosis Blood alkalinity above normal. Buffers Compounds that help keep a solution's acidity (amount of acid) or alkalinity (amount of base) constant. Some proteins act as buffers to maintain normal blood pH.

Functions of Body Proteins

Amino acids are constantly needed for the body to build the proteins of new tissue during growth and maintenance. Examples of growth: a developing embryo; a growing child. Examples of maintenance: replacing blood lost to burns, hemorrhage, or surgery; developing scar tissue that heals wounds; replacing hair or nails; replacing cells that are worn out. Amino acids must constantly be resupplied by food for new growth to occur.

Amino Acids

Amino acids pass from the absorptive cells in the small intestine into the bloodstream, where they can be taken up by cells and used to make proteins. Amino acid strands are assembled to make proteins. Nonessential amino acids can be manufactured by the body from fragments of other amino acids. If essential amino acids are missing, protein building will halt.

Essential amino acids:

Amino acids that cannot be synthesized by the body or that cannot be synthesized in amounts sufficient to meet physiological need.

Food allergy

An adverse reaction to an otherwise harmless substance that involves the body's immune system.

Adverse reaction

An unusual response to food, including food allergies and food intolerances.

Amino acids

Building blocks of protein; each is a compound with an amine group at one end, an acid group at the other, and a distinctive side chain.

Hormones

Chemical messengers. Hormones are secreted by a variety of glands in the body in response to altered conditions. Each affects one or more target tissues or organs and elicits specific responses to restore normal conditions.

Bases

Compounds that accept hydrogens from solutions; bases have a high pH.

Acids

Compounds that release hydrogens in a watery solution; acids have a low pH.

Proteins

Compounds—composed of atoms of carbon, hydrogen, oxygen, and nitrogen—arranged as strands of amino acids. Some amino acids also contain atoms of sulfur.

Fluid balance:

Distribution of fluid among body compartments. Shown here are the fluids within and surrounding a cell. Body proteins help hold fluid within cells, tissues, and blood vessels.

Enzyme Action

Each enzyme facilitates a specific chemical reaction.

Reference protein

Egg white protein, the standard with which other proteins are compared to determine protein quality.

Acid-Base Balance

Equilibrium between acid and base concentrations in the body fluids. Acid-base balance of blood is carefully controlled. Normal body processes continually produce acids and bases.

Protein As Energy:

In the absence of adequate energy, the body will sacrifice protein to provide energy. The amine group will be degraded, incorporated by the liver into urea, and sent to the kidneys for excretion in urine.

Antibodies

Large proteins of the blood and body fluids, produced by one type of immune cell in response to invasion of the body by unfamiliar molecules (mostly foreign proteins). Antibodies inactivate the foreign substances and so protect the body. The foreign substances are called antigens.

Food Allergys

Mouth - (swelling of the lips or tongue, itching lips) Airways- (wheezing or breathing problems) Digestive tract(stomach cramps, vomiting,diarrhea) Skin (hives, rashes, or eczema)

Functions of Body Proteins

No living tissue can be built without protein. Protein is part of every living cell. Proteins account for about 20% of our body weight. Proteins come in many forms and perform many vital functions.

Legumes

Plants of the bean and pea family having roots with nodules that contain bacteria that can trap nitrogen from the air in the soil and make it into compounds that become part of the seed. The seeds are rich in high-quality protein compared with those of most other plant foods.

Protein synthesis:

Process by which cells assemble amino acids into proteins.

What Proteins Are Made Of

Proteins are made of many different amino acid units hooked to each other. Strands of proteins are tangled chains, globular in structure. The differing shapes of proteins enable them to perform different tasks in the body. Proteins may repel or attract water. Some proteins contain minerals or vitamins. Several proteins may gather to form a functional group.

Complete proteins

Proteins containing all the essential amino acids in the right proportion relative to need. The quality of a food protein is judged by the proportions of essential amino acids that it contains relative to our needs. Animal proteins are the highest in quality.

Body Structures

Proteins form vital parts of most of our body structures. Examples of body structures include skin, hair, nails, membranes, muscles, teeth, bones, organs, ligaments, and tendons.

Transport Proteins

Specialize in moving nutrients and molecules into and out of cells. The "sodium-potassium pump" is switched on and off by hormones. Special proteins carry vitamins, minerals. Lipoproteins carry lipids.

Immunity

Specific disease resistance derived from the immune system's memory of prior exposure to specific disease agents and its ability to mount a swift response against them. Malnutrition injures the immune system.

Edema

Swelling of body tissue caused by leakage of fluid from the blood vessels, seen in (among other conditions) protein deficiency.

Denaturation:

The change in shape of a protein brought about by heat, alcohol, acids, bases, salts of heavy metals, or other agents. First step in the protein's breakdown. Useful to the body in digestion. Stomach acid opens up the protein's structure, allowing digestive enzymes to cleave peptide bonds. Example: Cooking an egg denatures its proteins

pH

The concentration of hydrogen ions. The lower the pH, the stronger the acid pH 2 is a strong acid, pH 7 is neutral, and pH above 7 is alkaline

Amine group

The nitrogen-containng portion of an amino acid.

Urea

The principal nitrogen excretion product of metabolism, generated mostly by the removal of amine groups from unneeded amino acids or from those amino acids being sacrificed to a need for energy.

Too Much Protein

The problems of protein excess can be found in developed countries. Possible to overload the liver and kidneys. Can promote calcium excretion. Excess protein can be converted to energy and stored as body fat. No apparent benefit to consuming too much protein when caloric intake is adequate.

Complementary proteins

Two or more food proteins whose amino acid assortments complement each other in such a way that the essential amino acids limited in or missing from each are supplied by the others.