Exam 3 Advanced

Explain briefly how calcium and magnesium are absorbed by enterocytes.

calcium enters mucosal cells through TRPV 6 and binds to calbindin or organelles like golgi apparatus, then moves forward to basolateral membrane. calcium is released into extracellular fluid via Ca++ - Mg++ ATPase. calcium can be absorbed by moving between enterocytes, this is called paracellular diffusion. magnesium in the lumen enters enterocytes through TRPV6 and exits on the other side via Ca++ - Mg++ ATPase. magnesium can also be absorbed by moving between enterocytes.

Explain how selenium exerts its physiologic effects in the body.

exerts effects as coenzyme for glutathione peroxidase. GPX functions to reduce organic and hydrogen peroxidase. important for phagocytic cells, peroxidase like leukocytes and macrophages. in these cells, peroxidase are byproducts of oxidative destruction of foreign matter, therefore gpx protects cells from auto destruction.

How does phosphorus circulate in the blood?

70% of phosphorus in the blood circulates as part of phospholipids, in lipoproteins, cells, and platelets. 30% is dissolved inorganic phosphates.

What percent of phosphorus is found in the bone?

85%

Explain briefly the functions of sodium, chloride, and potassium in the body?

sodium potassium and chloride primarily serve as electrolytes in the body. They contribute to most of the establishment of the electric potential across plasma membranes. They are also involved in the maintenance of water balance across cellular membranes.

For which population groups is iron deficiency most likely? Why?

women are most likely to be deficient in iron because they lose iron in the blood every month during their cycle. A lot of pregnant women are also deficient because the adequate intake increases during pregnancy and breastfeeding.

Why are adequate intakes of iodine essential to good health? What are characteristics of iodine deficiencies?

•150 mcg/day to determine deficiency the first method to use is a urine iodine concentration. The second is method is the size of the thyroid gland which may require ultrasound, and the third method is TSH level. if the level is above 5 micro-units per liter it indicates low iodine status.

Which of the following is not a major mineral?

Zinc

Explain three functions of zinc in the body.

Zinc is found in cells throughout the body. It is needed for the body's defensive (immune) system to properly work. It plays a role in cell division, cell growth, wound healing, and the breakdown of carbohydrates. Zinc is also needed for the senses of smell and taste.

In muscle contraction, calcium will bind to this protein to initiate the process.

Troponin

Explain how aging decreases the efficiency of calcium absorption.

As we age we are likely to decrease our activity level, which can contribute to decreased calcium absorption efficiency.

Explain the relationship between calcium, phosphorus, and boron in maintaining healthy bones.

Boron directly and indirectly affects the metabolism of calcium in bone and influences the composition and strength of the bone. 99% calcium is found in bone and teeth.85% of phosphorus is found in bone. calcium phosphate and hydroxyapatite are two complexes containing calcium and phosphate that provide strength and rigidity to bones and teeth. hydroxyapatite provides the hardening effect of bones. They also serve as storage for calcium and phosphate. this portion of bone is depleted during bone demineralization diseases like osteoporosis and osteomalacia. calcium binds with protein like bone Gla protein and matrix Gla protein to promote mobilizationof bone calcium. .

What are common body functions of chromium and manganese?

Chromium aids in glucose transport, interacts with insulin, enhances the action of insulin, which enhances glycolysis, glycogen synthesis, and fatty acid and protein synthesis. Manganese is concentrated in mitochondria and nucleus. It is involved in cartilage tissue formation or remodeling using cofactor for prolinase, which produces proline. It also is involved in carbohydrate metabolism.

Explain and list the various factors that decrease calcium absorption.

Decreased vitamin D and PTH, consuming phytate, fiber and oaxalates during the same meal, decreased need, increased diet Zinc or magnesium, high fat diets or decreased fat digestion and excess diet phosphorus, magnesium, and vitamin A.

Postmenopausal bone loss is primarily associated with decreased levels of the hormone

Estrogen

How does a diet high in iron affect zinc status in the body?How does a high-zinc diet affect copper status? Explain.

Excess iron decreases the absorption of zinc. Excess iron or zinc intake decreases copper absorption. Zinc and iron may compete for absorption, because an iron-to-zinc intake ratio of 2:1 or higher substantially reduces zinc absorption in humans. Also, DMT1, the same protein that is involved in nonheme iron absorption binds zinc and transfer it across the brush border membrane. As dietary zinc increases, metallothionein synthesis in enterocytes increases. Metallothionein has a greater affinity for copper and it will cause copper to be sequestered within enterocytes and excreted in feces.

Which of the following is NOT a major function of phosphorus in the body?

Helps to regulate blood pressure levels

What are some dangers of excessive calcium intake?

Increase calcium deposition in tissue such as muscle, blood vessels, and lungs. Affecting their activity by making them rigid. Individuals can be more prone to calcium containing renal stones.

Identify the dietary sources of three major minerals and three minor minerals.

Major: Calcium: dairy (milk, yogurt, cheese), vegetables, legumes; collard greens, tofu Phosphorus: dairy, meat, nuts and seeds, grains, vegetables and also soda; yogurt, pork, whole wheat bread, potatoes, sunflower seeds Magnesium: legumes, nuts, grains, vegetables, dairy, meats; lentils, peanuts, wheat germ, peas, cheese, chicken Sodium: meat, dairy, grains, other; corned beef, ham , cottage cheese, bagel, dill pickles, canned raviolis, bacon Potassium: vegetables, fruit, dairy, meats, grains; potato, squash, avocado, raisins, yogurt, trout, pork, raisin bran minor: iron: meat, vegetables, grains, fruits; liver, soybeans, cooked spinach, fortified breakfast cereal, prune juice zinc: meat, grains, legumes, nuts and seeds, dairy; lamb, liver, oatmeal cooked, baked beans, cashews, sunflower seeds, cheese and milk iodide: iodized salt, cottage cheese, haddock, shrimp, egg, cheese and ground beef copper: liver, cashews, peas, molasses, sunflower seeds, v-8 juice, tofu, refried beans, cocoa powder, dried prunes, salmon, pizza, whole wheat bread, milk chocolate, milk 2% selenium: baked snapper, halibut baked, baked salmon, steamed scallops, seamed clams, raw oysters, molasses, sunflower seeds, ground beef, baked chicken, whole wheat bread, egg, milk chromium: meat, grains, fruits and vegetables; turkey ham, waffle, english muffin, broccoli, grape juice, apple

The level of calcium in the blood is maintained within a narrow limit by two hormones. __________ raises blood calcium and ___________ lowers blood calcium levels.

Parathyroid hormone; Calcitonin

How do parathyroid hormone and calcitonin maintain blood calcium levels?

Parathyroid hormone stimulates calcium release from bones, alpha hydroxylase to produce 1,25 (OH)2D, and the reabsorption of calcium by the kidney tubules. 1,25 (OH)2 enhances calcium absorption by stimulating the small intestinal cells to produce calcium uptake of protein, calbindin, TRPV6 calcium channel and a vitamin D regulated calcium and magnesium ions ATPase

How do phytates, tannins and oxalates affect the absorption of minerals? Give three examples.

Phytates and oxalates can bind to calcium and magnesium leading to a decrease in their absorption. Calcium must be liberated from food to be absorbed but with phytates attached, it cannot be absorbed. Magnesium has a similar absorption process. It has also been shown that an increase in dietary oxalate and phytate can lead to zinc deficiency. Tannins found in tea, spinach, chard, berries, chocolate, decrease nonheme iron absorption

Explain the role of minerals (major or trace minerals) in disease prevention. Give at least three examples.

calcium, phosphorus, and boron - healthy bones calcium has been found to prevent cancer and hypertension parathyroid hormone and calcitonin maintain blood calcium levels sodium, chloride, and potassium - electrolytes and water balance in cell membranes electrolytes — such as potassium, sodium, chloride — help trigger and conduct the electrical impulses in your heart. Electrolyte levels that are too high or too low can affect your heart's electrical impulses and contribute to arrhythmia development low selenium has been associated with causing some types of cancer. antioxidants properties of selenium. marginal chromium deficiency has been linked to type 2 diabetes, because it enhances the effect of insulin.

Discuss briefly the conditions under which iron toxicity occurs. What diseases are associated with iron toxicity?

congenital atransferrinemia is rare characterized by lack of transferrin. autosomal recessive anomaly accompanied by hypo chromic anemia and iron overload involving the liver, heart, pancreas and almost complete lack of iron in bone marrow. iron overload may be induced clinically by blood transfusions in patients with aplastic anemia, pure red blood cell anemia, black fan diamond syndrome, myelodysplasia, sickle cell disease. neonatal iron overload associated with perinatal metabolic disorders like hypermethioninemia and fatal liver disease.

What are factors that enhance iron absorption? What are factors that interfere with iron absorption? Discuss.

many factors are involved with iron absorption. level of iron in food, form of iron, and proteins bound to iron. vitamin C increases iron absorption by promoting the formation and stabilization of ferrous iron, which is better absorbed than ferric iron. high altitudes create bigger need for iron, and greater iron abrosption is needed to synthesize more red blood cells under control of erythropoietin. high phytic acid intake decreases absorption. polyphenolic substances like tannins, phytates in whole grains and preservative EDTA decrease iron absorption by chelation. as well as supplement calcium doses. calcium in milk zinc competes with ferrous iron for absorption via common transporter and decrease abrosption.