Ch. 18: Nutrition and Metabolism

Vitamin E

A group of compounds; resistant to heat and visible light; unstable in presence of oxygen and ultraviolet light; stored in muscles and adipose muscles. Function: an antioxidant; prevents oxidation of Vitamin A and polyunsaturated fatty acids; may help maintain stability of cell membranes. Excess: Nausea, headache, fatigue, easy bruising and bleeding. Deficiencies: rare, uncertain effects

Vitamin D

A group of steroids; resistant to heat, oxidation, acids, and bases, stored in liver, skin, brain, spleen, and bones. Function: promotes absorption of calcium and phosphorus;promotes development of teeth and bones. Excess: diarrhea, calcification of soft tissues, renal damage Deficiencies: rickets, bone decalcification and weakening

Identify the part of the brain where hormones act, controlling appetite.

Appetite is the drive that compels us to seek food. Several types of interacting hormones control appetite by affecting part of the hypothalamus called the arcuate nucleus.

List some factors that affect an individual's needs for carbohydrates.

Carbs provide the primary source of fuel for cellular processes. The need for carbs varies with individual energy requirements. Physically active individuals require more carbs than those who are sedentary. The minimal requirement for carbs in the human diet is unknown, but getting at least 125-175 grams daily is probably necessary to avoid protein breakdown and to avoid metabolic disorders resulting from excess fat use. An average diet includes 200-300 grams of carbs daily.

****Summarize the importance of cellulose in the diet.

Cellulose is a complex carbohydrate abundant in out food. We cannot digest cellulose, and most of it passes through the alimentary canal largely unchanged. However, cellulose provides bulk (aka fiber/ roughage) against which the muscular wall of the digestive system can push, facilitating the movement of intestinal contents.

Vitamin C (ascorbic acid)

Chemically similar to monosaccharides; stable in acids but destroyed by oxidation, heat, light, and bases. FUNCTION: required for collagen production, conversion of folacin to folinic acid, and metabolism of certain amino acids; promotes absorption of iron and synthesis of hormones from cholesterol. EXCESS: exacerbates grout and kidney stone formation DEFICIENCY: scurvy, lowered resistance to infection, wounds heal slowly.

Review the major functions of cholesterol.

Cholesterol is used to produce bile salts. It also provides structural material for cell and organelle membranes. It furnishes starting materials for adrenal cortex hormone production and synthesis of certain sex hormones

Distinguish between complete and incomplete proteins.

Complete proteins contain adequate amounts of the essential amino acids to maintain human body tissues and promote normal growth and development. Incomplete proteins are unable, by themselves, to maintain human tissues or to support normal growth and development.

Define deamination and explain its importance.

Deamination is a process that occurs in the liver that removes the nitrogen-containing portions (-NH2 groups) from the amino acids. These -NH2 groups subsequently react to form a waste called urea. The liver therefore produces urea from amino groups formed by deamination of amino acids. The blood carries urea to the kidneys, where it is excreted in urine.

Vitamin B1 (thiamine)

Destroyed by heat and oxygen, especially in an alkaline environment. Function: part of co-enzyme required for oxidation of carbs; co-enzyme required for ribsose synthesis. Excess: uncommon vasodialation, cardiac dysrhythmias Defenciecy: Beriberi, muscular weakness, enlarged heart.

Vitamin B5 (pantothenic acid)

Destroyed by heat, acids, and bases. FUNCTION: part of co-enzyme A required for oxidation of carbs and fats. EXCESS: none known DEFICIENCY: rare, loss of appetite, mental depression, muscle spasms.

Distinguish between essential and nonessential amino acids.

Essential amino acids are those that must be obtained in the diet as the body either cannot manufacture them in sufficient quantities or are unable to produce them at all. A nonessential amino acid is one that the body can produce in sufficient quantities.

Vitamin K

Exists in several forms; resistant to heal but destroyed by acids, bases, and light; stored in liver. Functions: Required for synthesis prothrombin, which functions in blood clotting. Excess: jaundice in formula-fed newborn's Deficiencies: prolonged clotting time

Explain what happens to excess glucose in the body.

Glucose is stored as glycogen in the liver and muscles. It is also stored as adipose tissue.

Vitamin B6 (pyridoxine)

Group of 3 compounds; stable to heat & acids; destroyed by oxidation, bases, and UV light. FUNCTION: Co-enzyme required for synthesis of proteins and various amino acids, for conversion of tryptophan to niacin, for production of antibodies, and for nucleic acid synthesis. EXCESS: numbness, clumsiness, and paralysis DEFICIENCY: rare, convulsions, vomiting, seborrhea lesions

Vitamin A

It exists in several forms, synthesized from carotene; it is stored in the liver, stable in heat, acids, and bases. It is unstable in light. It is an antioxidant necessary for synthesis of visual pigment, mucoproteins, and mucopolysaccharides; for normal development of bones and teeth. & for maintenance of epithelial cells. -excess: nausea, headaches, dizziness, hair loss, birth defects. -Deficiencies: night blindness, degeneration of epithelial tissues

Vitamin B9 (folacin)

Occurs in several forms, destroyed by oxidation in an acid environment or by heat in an alkaline environment. Stored in liver where it is converted into folinic acid. FUNCTION: co-enzyme reuired for metabolism of certain amino acids and for DNA synthesis; promotes production of normal red blood cells. EXCESS; none known DEFICIENCY: megablastic anemia

Explain why a protein deficiency may accompany edema.

Protein deficiency causes tissue wasting and also deceases the level of plasma proteins, which decreases the colloid osmotic pressure of the plasma. As a result, fluids collect in the tissues,producing nutritional edema.

Vitamin B3 (Niacin)

Stable to heat, acids, and bases; converted to niacinamide by cells, synthesized from tryptophan. FUNCTION: part of co-enzymes NAD and NADP required for oxidation of glucose and synthesis of proteins, fats, and nucleic acids. EXCESS: Flushing, vasodialation, wheezing, liver problems. DEFICIENCY: Pellagra, dermattitis, diarrhea, metal disorders

Vitamin B7 (Biotin)

Stable to heat, acids, and light; Destroyed by oxidation and bases. FUNCTION: co-enzyme required for metabolism of amino acids and fatty acids and for nucleic acid synthesis. EXCESS: none known DEFICIENCY: Rare, elevated blood cholesterol, nausea, fatigue, anorexia

Vitamin B2 (Riboflavin)

Stable to heat, acids, and oxidation; destroyed by bases and UV light Function: part of enzymes and co-enzymes such as FAD, required for oxidation of glucose and fatty acid and for cellular growth. Excess: none known Deficiency: dermatitis, blurred vision

Describe the livers' role in fat metabolism.

The liver can convert fatty acids form one from to another. The Liver regulates circulating lipids- synthesizing triglycerides, phospholipids, and lipoproteins. Liver controls total amount of cholesterol in body by synthesizing cholesterol and releasing it into the blood or removing it from blood and excreting it into the bile. Cholesterol is used to make bile salts. Cholesterol provides structural materials for cell and organelle membranes, it furnishes starting materials for synthesis of certain sex hormones and adrenal cortex hormones.

*****Explain why a temporary drop in blood glucose concentration may impair the nervous system functioning.

The neurons depend upon a continuous supply of glucose for survival. Any decrease in the normal amount required will have an effect on the person's neurological state.

Define beta oxidation

The splitting of fatty acids into two-carbon acetyl-coenzyme A. Fatty acid catabolism producing acetyl groups.

****Identify dietary sources of lipids.

Triglycerides are found both in plant and animal based foods. a. Saturated fats mainly found in foods of animal origin, such as meat, eggs, milk, and lard, as well as in palm and coconut oil. b. Unsaturated fats contained in seeds, nuts, and plant oil. Foods of plant origin do not contain cholesterol.

Vitamin B12 (cyanocobalamin)

complex, cobalt-containing compound, stable in heat, inactivated by light, strong acids, and strong bases. absorption regulated by intrinsic factor from gastric glands; stored in liver. FUNCTION: part of co-enzyme required for synthesis of nucleic acids and metabolism of carbs; plays a role in myelin synthesis, required for normal blood production. EXCESS: none know DEFICIENCY: Pernicious anemia