Water, Minerals, and Body Fluids

1. Water, Minerals, and Body Fluids

2. Major concept of human physiology = Homeostasis:A state of "dynamic (changing) equilibrium (balance)" in which the body's internal environment is maintained within narrow limits even when:1) the external environment changes significantly and 2) things are introduced into or removed from the body Food Urine Drinks Feces Drugs Sweat Air Bleeding Carbon dioxide

3. Two major components of fluid homeostasis: 1. Water balance – Keeping the right amounts of water in the right places 2. Mineral balance – Keeping the right amounts of minerals (also called “ions” and “electrolytes”) in the right places

4. These fluid compartments are in equilibrium with each other as both water and all of the atoms and molecules dissolved in that water (including minerals) move from one compartment to another.

5. That exchange of water and minerals among compartments is possible only because the cells and membranes lining each of those compartments are permeable to them. For example: Fluid from the lumen of the intestine crosses its epithelium to get into the extracellular space, then crosses the epithelium of the blood vessels and lymphatic vessels. o

6. That exchange of water and minerals among compartments is possible only because the cells and membranes lining each of those compartments are permeable to them. For example: Fluid from the lumen of the intestine crosses its epithelium to get into the extracellular space, then crosses the epithelium of the blood vessels and lymphatic vessels. Fluid from the plasma of the blood crosses the epithelium of capillaries to enter the extracellular/interstitial compartment, and those fluids can cross the same epithelium to enter the plasma or lymph compartments. o

7. That exchange of water and minerals among compartments is possible only because the cells and membranes lining each of those compartments are permeable to them. For example: Fluid from the lumen of the intestine crosses its epithelium to get into the extracellular space, then crosses the epithelium of the blood vessels and lymphatic vessels. Fluid from the plasma of the blood crosses the epithelium of capillaries to enter the extracellular/interstitial compartment, and those fluids can cross the same epithelium to enter the plasma or lymph compartments. Fluid from the extracellular/interstitial compartment crosses the plasma membranes of all cells to enter the intracellular compartment, and that fluid crosses the same membrane to enter the extracellular/interstitial compartment.

8. That equilibrium changes every time - water and minerals are added (food, water, etc); or - water and minerals are lost through sweat, urine, feces, respiration, etc.

9. Terms we will be using: 1 Water: A specific molecule composed of one oxygen atom and two hydrogen atoms.

10. Terms we will be using: 1 Water: A specific molecule composed of one oxygen atom and two hydrogen atoms. Mineral: Elements or atoms with certain chemical characteristics (which, fortunately, you do not need to know)

11. Terms we will be using: 1 Water: A specific molecule composed of one oxygen atom and two hydrogen atoms. Mineral: Elements or atoms with certain chemical characteristics (which, fortunately, you do not need to know) Ion: Any atom that has either a positive or negative electrical charge Na+ PO4-3 Ca+2 Cl- Fe+3

12. Terms we will be using: 1 Water: A specific molecule composed of one oxygen atom and two hydrogen atoms. Mineral: Elements or atoms with certain chemical characteristics (which, fortunately, you do not need to know) Ion: Any atom that has either a positive or negative electrical charge Cations have a postiive charge Anions have a negative charge Na+ PO4-3 Ca+2 Cl- Fe+3

13. Terms we will be using: 2 Note: Not all minerals are ions - some are electrically neutral Not all ions are minerals – some have more than one atom In physiology and nutrition, however, the terms Mineral Ion are often used interchangably Electrolyte

14. Water = more than 60% of total body mass Water Balance:

15. Water = more than 60% of total body mass 3 major compartments: Plasma (in blood) ~8% of body water Interstitial (between cells) ~25% of body water Intracellular (inside cells) ~65% of body water Water Balance:

16. Water = more than 60% of total body mass 3 major compartments: Plasma (in blood) ~8% of body water Interstitial (between cells) ~25% of body water Intracellular (inside cells) ~65% of body water Many smaller compartments: ~ 2% Urine, Lymphatic fluid, Cerebrospinal fluid, Saliva, Synovial fluid, Digestive system contents, Semen, Respiratory system fluids, Peritoneal fluid, Tears, Occular fluids, Pericardial fluid, Pleural fluid, etc. Water Balance:

17. Movement of water from one compartment to another is due to the concentration of minerals and other atoms or molecules dissolved in it: Water Balance:

18. Forms urine Forms tears, saliva, CSF, synovial fluid, semen, lymph, etc. Movement among

19. Water intake is primarily through food and drink. Some water is gained from metabolic processes like the synthesis of proteins, lipids, and carbohydrates. Water Balance:

20. Water intake is primarily through food and drink. Some water is gained from metabolic processes like the synthesis of proteins, lipids, and carbohydrates. Water output is primarily through urine, sweat, transcutanous loss, respiration, and feces. These are obviously affected by such things as temperature, exercise, humidity, etc. Water Balance:

21. The FDA has set adequate intakes of 2.7 liters of water per day for women 3.7 liters of water per day for men, but obviously To remain healthy, water intake must be balanced by water ouput. These can vary from ~2 liters per day to over 5 liters per day. Water Balance:

22. Water Balance: To regulate water intake, the body has a complex system of creating a sense of thirst.

23. Water Balance: Loss through the skin, lungs, and feces can not easily be controlled, so the kidneys are the primary organs of water balance by controlling how much water is lost in the urine. To regulate water intake, the body has a complex system of creating a sense of thirst.

24. Water Balance: Some things in our diet can act as diuretics – that is, they interfere with the ability of the kidneys to keep water in the body, thus increasing its loss in the urine. - Alcohol - Caffeine - Theobromines - Theophylline - Drugs used to control blood pressure, heart disease, diabetes insipidus, edema, & other conditions Found in tea, chocolate

25. Water Balance: Some conditions cause rapid water loss & dehydration: - Excessive diuretics - Extreme heat - Exercise without replenishing water - Vomiting - Diarrhea - Burns This is almost always accompanied by loss of minerals Nausea, diorientation, headaches, weakness Muscle spasms, heart failure, kidney failure, death

26. Water Balance: Although not currently common in the US, dehydration from many diseases still kills millions of people each year worldwide, mostly through diarrhea: - Water contaminated with viruses and/or bacteria - Infant malnutrition - Cholera - Shigellosis - Giardiasis - Celiac disease

27. Water Balance: Although less common, the opposite extreme does exist: water intoxication or overhydration is the intake of excess amounts of water, diluting the minerals and other molecules dissolved in body fluids

28. Let’s move on to discuss minerals: • Inorganic micronutrients • Not destroyed by heat, light, acidity, or alkalinity

29. Minerals: • Inorganic micronutrients • Not destroyed by heat, light, acidity, or alkalinity • Involved many ways in body structure and regulation: • For example: • Many = cofactors for enzymes • Sodium and potassium ions carry electrical signals • Sodium and potassium ions regulate blood pressure • Calcium ions regulates muscle contraction • Calcium provides bone rigidity • Iron binds oxygen in hemoglobin • Iodine is part of thyroid hormones • Sulfer is part of some amino acids • Phosphorus is part of DNA, RNA, ATP, phospholipids • etc.

30. Minerals: • Inorganic micronutrients • Not destroyed by heat, light, acidity, or alkalinity • Involved many ways in body structure and regulation: • Found in all plant and animal foods • Not all minerals are easily absorbed in the intestine Major minerals and trace minerals

31. Minerals: Minerals in the diet are often classified as 7 Major minerals and 10+ Trace minerals Each mineral has its own distributrions (where it is found) and functions (what it does) in the body.

32. Minerals: Sodium (Na+) By far: The most common mineral in the American diet is sodium. Adequate Intake for both men and women = 1,500mg/day Tolerable Upper Intake Level = 2,300 mg/day On average: American men consume between 3,000 and 6,000 mg of sodium per day, while women consume between 2,500 and 4,000 mg (due to their lower calorie intake, not because of restricting sodium).

33. Minerals: Sodium (Na+) Sodium is found naturally in many foods, including meat, fish, milk & cheese, eggs, tomatoes, potatoes, nuts, cereals, fruits

34. Minerals: Sodium (Na+) Sodium is found naturally in many foods, including meat, fish, milk & cheese, eggs, tomatoes, potatoes, nuts, cereals, fruits but our major source of sodium is salt.

35. Minerals: Sodium (Na+) Salt is sodium chloride, NaCl. In body fluids the sodium ion (Na+) and the chloride ion (Cl - ) separate, leaving the sodium to function alone.

36. Minerals: Sodium (Na+) Salt is sodium chloride, NaCl. In body fluids the sodium ion (Na+) and the chloride ion (Cl - ) separate, leaving the sodium to function alone. By weight, salt is 40% sodium and 60% chloride One teaspoon of salt (5 grams = 5,000 mg) contains about 2,000 mg of Na+ and It is the most common additive in American food

37. Minerals: Sodium (Na+) Sodium is important in maintaining the composition of all of the fluid compartments – primarily the interstitial compartment and the blood plasma. Like all ions, it attracts water, so cells and organs can move water from one place to another by transporting sodium from place to another.

38. Minerals: Sodium (Na+) Sodium is important in maintaining the composition of all of the fluid compartments – primarily the interstitial compartment and the blood plasma. Like all ions, it attracts water, so cells and organs can move water from one place to another by transporting sodium from place to another. Sodium is also one of the two major ions (potassium is the other) which carries electrical signals on the membranes of nerve cells and muscle cells.

39. Minerals: Sodium (Na+) While excess sodium can be removed by the kidneys and eliminated in the urine, this is not a particularly efficient process since the adrenal glands secrete the hormone aldosterone which causes the kidneys to reabsorb Na+ back into the blood, thus preventing its elimination through the urine. Another hormone, atrial natriuretic hormone produced by the heart, has the opposite effect, stimulating Na+ loss into the urine.

40. Minerals: Sodium (Na+) The resulting high concentrations of sodium can cause a number of problems because - the excess sodium retains water, - which raises blood pressure, - which increases the risks of heart failure, kidney failure, stroke, and vascular damage - Accumulation of sodium in the interstitial fluid also makes it more difficult for nerve and muscle cells to produce electrical signals.

41. Minerals: Sodium (Na+) The resulting high concentrations of sodium can cause a number of problems because - the excess sodium retains water, - which raises blood pressure, - which increases the risks of heart failure, kidney failure, stroke, and vascular damage - Accumulation of sodium in the interstitial fluid also makes it more difficult for nerve and muscle cells to produce electrical signals. Sodium deficiency is essentially unknown in developed countries.

42. Minerals: Chloride (Cl-) The other part of salt, 60% by weight, is chloride, (Cl-). It also attracts water, so cells can move water from one place to another by transporting chloride ions from one place to another Cl- is also necessary for the formation of hydrochloric acid (HCl) in the stomach and for maintaining the acid-base balance of the different fluid compartments. It is necessary for nerve cells and muscle cells to carry electrical signals.

43. Minerals: Chloride (Cl-) Adequate intake = 2,300 mg (2.3 g) per day Tolerable Upper Intake Level = 3,600 mg (3.6 g) per day Like sodium, the modern American diet contains much more chloride than it needs. The average American man consumes 4,500 to 9,000 mg (4.5 to 9 g) of chloride per day, and the average American woman consumes 3,800 to 6,000 mg (3.8 to 6 g) of chloride per day.

44. Minerals: Chloride (Cl-) Fortunately, the kidneys easily remove excess chloride, so it plays little if any role in disease. Except in people with excessive vomiting or sweating, chloride deficiency is almost unheard of in the American population. In populations without excessive salt consumption, it can cause nervous and circulatory problems and can even be fatal.

45. Minerals: Potassium (K+) Potassium is one of the two ions (sodium is the other) which move across the membranes of nerve cells and muscle cells to carry an electrical signal. Because of the much larger mass of of muscles, most of the potassium in the body is in the intracellular fluid. Like all other ions, it attracts water and thus plays a role in maintaining the volume of that fluid compartment

46. Minerals: Potassium (K+) Adequate intake = 4,700 mg (4.7 g) per day No Tolerable Upper Intake Level has been set Dietary sources: dairy products meat, fish, poultry bananas lima beans spinach melons fruits

47. Minerals: Potassium (K+) Most Americans consume only 2,500 to 3,000 mg/day of potassium, below the Adequate Intake of 4,700 mg/day. It can also be lost in the urine, sweat, and feces; and vomiting and diarrhea can cause critical deficiencies. - muscle weakness or cramps - nervous disorders - cardiac arrhythmias - Also linked with bone loss, kidney stones, and acid-base imbalance

48. Minerals: Potassium (K+) The concentration of K+ in the body is primarily regulated by the hormone aldosterone: - it helps retain Na+, but - it stimulates loss of K+ by the kidneys Because the kidneys easily remove excess potassium, the risk of toxicity is low. - cardiac arrhythmias - muscle weakness

49. Minerals: Calcium (Ca2+) Because it is part of bones and teeth, calcium is the most abundant mineral in our body. Forms a large molecule called calcium hydroxyapatite. It also regulates the contraction of muscle (including the heart and smooth muscle in the walls of hollow organs). It is necessary for clotting of the blood, and plays a role in conducting electrical signals in nerves.

50. Minerals: Calcium (Ca2+) Even though calcium is the most abundant mineral in the body, 99% of it is in bones so its turnover is similar to that of other minerals.