1. Chapter 12 Water and the Major Minerals

2. I. Water and the Body Fluids A. Water Balance & Recommended Intake 1. Water intake a. regulation 1. Thirst  weakness  exhaustion  delirium  death 2. thirst mechanism a. lags behind actual requirement

3. Regulation of Thirst (cont) b. hypothalamus senses blood concentration of sodium is high 1. Initiates drinking behavior c. water intoxication 1. rare 2. consuming too much water or inability to get rid of water (kidney problems)

4. Water Balance and Recommended Intake (cont) 2. Water sources a. water and other beverages b. foods such as fruits, vegetables, meats, cheeses c. metabolic water 1. energy yielding nutrients are broken down to CO 2 and H 2 O

5. Water Balance and Recommended Intake (cont) 3. Water losses a. in order for the kidney to eliminate waste from metabolic reactions water is required 1. minimum amount needed (obligatory loss) about 500 ml 2. required to dilute waste 3. average excretion 2500 ml/day

6. Water Balance

7. B. Blood Volume and Blood Pressure think of the cardiovascular system as a closed system B. Blood Volume and Blood Pressure think of the cardiovascular system as a closed system 1. Hypothalamus and ADH a. Blood volume gets low (low blood pressure) 1. same amount of solid particles in the blood so they become more concentrated b. Cells in the brain (hypothalamus) sense increase in concentration and release antidiuretic (ADH) hormone c. ADH stimulates kidneys to reabsorb H 2 O d. Blood volume goes up, concentration of particles decreases and ADH secretion stops

8. B. Blood Volume and Blood Pressure (cont) 2. Liver, Lungs, Kidney and Angiotensin a. Blood volume gets low b. Cells in the kidney sense low pressure and secrete renin c. Renin causes the kidneys to retain Na + d. Renin is an enzyme that converts angiotensinogen to angiotensin e. Angiotensin is a vasoconstrictor (narrows blood vessels)

9. B. Blood Volume and Blood Pressure (cont) 3. Hypothalamus, Adrenal Gland and Aldosterone a. Blood volume gets low 1. Angiotensin stimulates release of aldosterone (adrenal gland) b. Aldosterone stimulates the kidney to retain Na +, thus water

10. Regulation of Water Balance

11. Hormone Overview Blood pressure affected by water, salt and blood vessel constriction ADH  causes kidneys to retain water Aldosterone  causes kidneys to retain sodium Renin/Angiotensin  affect tension in blood vessel

12. C. Fluid and Electrolyte Balance 1. Dissociation of salt in water a. Salt = NaCl º Na + + Cl - b. Water is also polar so electrolytes attract water 2. Extracellular and intracellular electrolytes a. K + is major intracellular cation b. Na + is major extracellular cation c. Transporters control electrolyte balance in and out of the cell, thus water balance

13. Water and Electrolytes

14. Electrolytes

15. C. Fluid and Electrolyte Balance (cont) 3. Concentration a. Water moves from an area of low solute concentration to an area of high solute concentration b. So by controlling solute concentration water movement is controlled c. Kidney and intestine control solute concentration, thus water balance

16. D. Fluid and Electrolyte Imbalance (dehydration) 1. Loss of electrolytes a. Na + and Cl - most affected (extracellular) 1. sweating, vomiting, diarrhea, burns 2. Loss of fluid due to disease a. Diabetes (8 blood glucose º polyuria, polydipsia, polyphagia) 3. Replacing losses a. Water and food in most cases b. Severe cases IV fluids and electrolytes

17. E. Acid-Base Balance 1. pH a. Acid = low pH 7.0 (9 H + ) 2. Electrolytes and proteins act as buffers a. Buffers >buffer= changes in pH (bind or release H + maintaining pH in the narrow range 3. Excretion a. Kidneys and lungs get rid of H +

18. Sodium Bicarbonate Buffer System

19. II.The Minerals Inorganic Elements 1. Cannot be destroyed Minerals in the Body (figure 12-5) 1. Can be toxic Variable Bioavailability 1. Bioavailability depends upon food consumed

20. Minerals in a 60 kg Person

21. A. Sodium 1. Roles in the body a. major extracellular cation b. regulates volume of extracellular fluid c. maintains acid-base balance (kidney) d. essential to cell (nerve, muscle) function 2. Sodium recommendations a. minimum requirement = 500 mg/day b. suggested intake < 3000 mg/day c. persons with hypertension < 2000 mg/day 1. salt sensitive individuals (15%) 2. lower intake º lower blood pressure

22. Sodium (cont) 3. Sodium intakes a. salt is 40% sodium b. 5 grams salt = 1 teaspoon c. vary widely º US average male- 3300 mg Na + /day or about 8 g salt/day, average Asian male around 30 g salt/day

23. Sodium (cont) 4. Sodium in foods a. 85% from foods (~90% during processing), 15% from cooking and table b. high in processed foods (table 11-4) c. canned or instant soups d. Cheese e. condiments f. salted of smoked meats or fish g. Read food labels

24. Sodium (cont) 5. Restricting sodium a. avoid highly salted foods b. do not add salt in cooking c. do not add salt from saltshaker d. read food labels e. avoid fast foods f. use sodium-free seasonings 1. Potassium chloride (KCl) g. adapt to using less salt slowly 1. wean yourself from Na +

25. Sodium (cont) 6. Sodium toxicity a. Edema 1. Na + is major extracellular cation b. hypertension (high blood pressure) 1. habitual high sodium diet 2. 15% of people retain sodium a. causes water retention  inc blood pressure

26. Sodium (cont) hypertension (cont) 3. Treatment a. low salt diets b. no discretionary salt (table/cooking) c. sometimes difficult to maintain 1. diuretics (increase fluid loss) 2. beta-blockers 3. ACE inhibitors (inhibit synthesis ofangiotensin)

27. B. Chloride (Cl - ) 1. Roles in the body a. Major extracellular anion b. Maintains fluid and electrolyte balance c. Forms part of HCl (acid in the stomach) 2. Recommendations and intakes a. No RDA b. Associated with NaCl 1. 60% of salt is Cl - 3. Deficiency and toxicity a. Unlikely

28. C. Potassium (K + ) 1. Roles in the body a. maintains blood pressure 1. maintain fluid and electrolyte balance b. nerve transmission c. muscle contraction 1. Deficiencies (hypokalemia)  sore muscles and cramps 2. Excess (hyperkalemia) associated with disease  irregular muscle contraction (heart)

29. Potassium (K + ) (cont) 2. Recommendations and food sources a. 2000 mg/day b. fresh fruits, vegetables and legumes c. Processed foods low in K + as opposed to being high in Na +

30. Potassium (K + ) (cont) 3. Potassium deficiency a. unlikely but possible b. most likely due to excessive losses 1. Sweating 2. Vomiting 3. Diarrhea 4. Drugs a. weight loss pills b. Diuretics 5. Potassium toxicity a. Unlikely

31. Potassium in Foods

32. Na and K in Processed Foods

33. D. Calcium (Ca ++ ) 1. Roles of Calcium in the body a. calcium in bones/teeth 1. 99% of body calcium a. bone structure b. calcium bank b. calcium in fluids and soft tissue 1. blood clotting 2. nerve conduction 3. muscle contraction

34. Bone Tissue

35. Calcium (Ca ++ ) (cont) 2. Calcium regulation a. blood levels drop 1. parathyroid hormone (PTH) is secreted from the parathyroid gland a. PTH increases the amount of active vitamin D 1. increase intestinal absorption of Ca ++ 2. decrease urinary calcium 3. move calcium from bone to blood (activates osteoclast cells that cause bone breakdown)

36. Calcium (Ca ++ ) (cont) b. blood levels rise 1. calcitonin is secreted from the thyroid gland a. Shuts off PTH release 1. So active vitamin D declines as do the effects of vitamin D b. Activates osteoblasts which build bone

38. Calcium Metabolism

40. Calcium (Ca ++ ) (cont) 3. Calcium absorption a. about 30 % in adults b. about 50-60% during growth c. about 50% during pregnancy/lactation d. controlled by Vitamin D 1. increase calcium binding protein in intestinal cell (calbindin) 2. changes to intestinal cell

41. Calcium (Ca ++ ) (cont) e. increased bioavailability 1. stomach acidity 2. vitamin D 3. Lactose 4. Exercise 5. proper calcium/phosphorous ratio f. decreased absorption 1. aging - lower stomach acid 2. high fiber diets a. Oxalates b. phytates

42. Calcium Absorption

43. Calcium (Ca ++ ) (cont) 4. Calcium recommendations a. 800 mg/day adults over age 24 b. 1200 mg/day adults 19-24 years c. (1200 - 1500 mg/day post-menopause women, supplements may be required) 5. Osteoporosis and calcium a.1/3 of all women over age 65 suffer spinal fractures b. over 1 million per year have fractures

44. What’s Your Calcium Intake Calcium intake = 200 mg (General Diet) plus # Dairy Servings (x 250 mg) plus # Dark Green Leafy Vegetables (x 100 mg)

45. Calcium (Ca ++ ) (cont) Osteoporosis (cont) c. 250,000 plus hip fractures/year 1. do women fall and break their hip or dose their hip break and then they fall? d. occurs with loss of trabecular bone 1. spongy bone a. spinal vertebrae b. heads of long bones c. pelvis (hip)

48. Osteoporosis and Trabecular Bone

49. Calcium (Ca ++ ) (cont) Osteoporosis (cont) e. Age 1. bones lose density after age 30 a. See Ca ++ requirements 2. bones are strongest and densest in young adult f. gender 1. faster calcium loss in women with ageing 2. a large increase in urinary calcium is associated with menopause

50. Loss of Bone and Height

52. Calcium (Ca ++ ) (cont) Osteoporosis (cont) g. Genetics 1. bones more dense in blacks 2. less dense in Asians, and Hispanics h. physical Activity 1. weight bearing exercises increases bone density i. smoking and Alcohol 1. smoking increases risk a. 5-10% less bone mass in adult smokers b. increased urinary calcium 2. moderate alcohol suspected risk 3. alcoholism high risk

53. Calcium (Ca ++ ) (cont) 6. Calcium and nutrition a. bone stores important in maintaining Ca ++ balance 1. maximize input (RDA) during bone formative years (<30) 2. calcium intake as adult controversial a. some research shows that bone loss not related to intake b. loss most important 1. Insufficient intake 2. Inactivity b. excess dietary protein intake causes loss of calcium in urine

54. Calcium and Osteoporosis

55. Calcium (Ca ++ ) (cont) 7. Recommendations a. RDA for calcium b. physical activity c. limit alcohol/smoking d. estrogen and calcium supplementation after menopause

56. Bone Density Testing

57. Calcium toxicity Need intakes that exceed 10,000 mg/day Supplements (i.e., excess Tums intake) Toxic effects – Increased bleeding – Weak bond structure – Muscle contraction problems  cramps

58. Calcium in Foods

59. Absorption of Calcium

60. E. Phosphorous (P) 1. Roles in the body a. functions with Ca ++ in bone mineralization b. functions in buffering systems c. part of DNA, RNA d. part of cell membrane 1. Phospholipid (polar and non-polar) e. ATP (adenosine tri-phosphate)

61. E. Phosphorous (P) (cont) 2. Recommendations a. same as that for Ca ++ 3. Intakes a. widely available in diet b. deficiency unknown

62. F. Magnesium (Mg ++ ) 1. Roles in the body a. Functions as a necessary cofactor in hundreds of enzyme systems 1. DNA synthesis 2. ATP synthesis 3. Opposes Ca ++ in muscle contraction and blood clotting 2. Intakes a. RDA for men 350 mg, women 280 mg b. Food supplies about 75%, amount in water varies throughout the country

63. F. Magnesium (Mg ++ ) 3. Deficiency a. Associated with disease 1. Muscle tetany (muscle spasms) 2. Alcoholism, prolonged vomiting or diarrhea 4. Hypertension a. Vasculature undergoes changes and becomes less elastic with Mg ++ deficiency