Study Guide Test IV Water and The Major Minerals

Water

  • 50-70% of body weight
  • Survive only few days without water

Water in the Body

  • Intracellular fluid- fluid contained within a cell
  • Extracellular fluid – fluid present outside the cell
  • Intravascular fliud – fluid within the blood stream
  • Interstitial fluid – fluid in between cells
  • Osmosis – the movement of water through a membrane from an area of HIGHER concentration to lesser concentration
  • Osmolality – a measure of total concentration of a solution (solute particles)

Functions of Water

  • Serves as a solvent and helps to form a solution
  • Regulates temperatures because of its high heat capacity (specific heat)
  • Helps remove wastes (ex: 1-2 liters of urine per day)
  • Helps form lubricants found in knees and other joints
  • Water volume directly involved in the regulation Blood and Blood Pressure!
  • It is basis for saliva, bile, and amniotic fluid

Water Needs

  • Need 1ml of water per kcal expended
  • Consume about 1 liter a day (in various forms of liquids)
  • Therefore water supplies around 2400 milliliters per day for a 2400 kcal diet
  • Of the 2400, 1400 are used to produce urine
  • Insensible losses of water - the lungs (400ml), feces (150 ml), and skin (500 ml)
  • Water Deficiency:
  • Thirst – mechanism occurs but imperfect indicator of how much water is really needed
  • Water loss is common in athletes infants , elderly, sickness
  • Regulation of water
  • Hormones compensate for imperfect thirst mechanism
  • Antidiuretic hormone (ADH) - synthesized in hypothalamus, stored in and released by pituitary; causes reabsorption of water in kidney
  • Renin-Angiotensin mechanism
  • If blood volume decreases, the enzyme renin (produced in kindey)
  • Renin then cleaves angiotensinogen (produced by liver) into angiotensin I
  • Angiotensin I is then converted (via an enzyme called ACE made in lungs) into Angiotensin II
  • Angiotensin II then causes 1) vasoconstriction of blood vessels, 2) release of Aldosterone, and 3) release of ADH
  • Aldosterone - hormone that prevents the loss of sodium in the kidneys, thus decreasing the loss of water
  • Water toxicity
  • Water intake without sufficient electrolyte intake (hyperhydration)

Minerals

  • Major (requiring 100mg or more/day) and trace minerals
  • Minerals are primarily excreted though urine
  • Functions
  • Cofactors
  • Transmission of nerve impulse
  • Water balance
  • Food sources – plant and animal sources

Sodium (Na)

  • Sodium found in sodium chloride (NaCl) – 40% sodium 60% chloride
  • 95% sodium is absorbed in the small intestine
  • Transported in blood stream
  • Excreted via the kidneys when in excess
  • Regulated by rennin-angiotensin
  • 10% of sodium consumed is needed by the body
  • The rest is eliminated via kidneys, skin, and GI tract
  • Functions:
  • Positive cation of extracellular fluid therefore helps maintain fluid balance
  • Involved in nerve transmission
  • Deficiency (or depletion): causes muscle cramps, vomiting, dizziness.
  • Sources: table salt and processed foods
  • RDA: 500 mg
  • Toxicity: causes hypertension

Potassium (K)

  • 90% of potassium absorbed in the small intestine
  • Transported in the blood stream
  • Excreted via kidneys
  • Levels in the body regulated by kidneys and aldosterone
  • Functions:
  • Positive cation of intracellular fluid therefore helps maintain fluid balance
  • Involved in nerve transmission
  • Deficiency:
  • Caused by use of diuretics
  • Irregular heart beat, muscle cramps
  • Sources: fresh fruits and vegetables
  • RDA: 2000 mg
  • Toxicity: hyperkalemia, slowed heart rate

Chloride (Cl)

  • Functions:
  • Anion of extracellular fluid
  • Aids in the production of stomach acid (hydrochloric acid)

Calcium (Ca)

  • Absorption requirements:
  • A ph below 6 and presence of vitamin D
  • Parathyroid hormone
  • Absorption limiting factors:
  • Vitamin D deficiency
  • Increased intestinal flow (diarrhea)
  • Functions:
  • Bone and tooth strength
  • Blood clotting
  • Conversion of prothrombin to thrombin
  • Muscle contractions
  • Deficiency:
  • Osteopenia (bone loss)
  • Osteoporosis(extreme bone loss)
  • Sources: dairy products, leafy vegetables

Phosphorus (P)

  • Vitamin D enhances absorption
  • Excreted by kidneys
  • Functions: used in bone (calcium phosphate), used in many compounds (ex: ATP).
  • Deficiency: bone loss
  • Sources: dairy products and processed cheese

Magnesium (Mg)0-60% of dietary Magnesium absorbed in the small intestine

  • Vitamin D enhances absorption
  • Excreted by kidneys but some stored in bone and muscle
  • Deficiency: rapid heart beat, muscle spasm, disorientation, nausea and vomiting
  • Toxicity: from use of antacids and laxatives; may cause diarrhea.

Sulfur (S)

  • Element used in amino acid synthesis;
  • No deficiencies, no RDA, no toxicities

Minerals and Hypertension

  • How are minerals involved in the regulation of blood pressure and blood volume?

Aldosterone causes sodium retention which causes water retention which will raise blood pressure

Trace Minerals

Trace Minerals Overview

  • “A daily nutritional need of less than 100 mg”
  • Difficulties studying trace minerals
  • Only minute amounts needed by body
  • Clinical signs and symptoms may only appear with severe deficiency
  • Trace minerals in food
  • Minerals in plants directly related to mineral content of soil
  • Minerals in animals higher because of the variety of plants and other foods cons

Iron (Fe)

  • 70% of iron in the body is found in hemoglobin
  • High body demand for red blood cells
  • Transferin
  • Low body stores
  • Ferritin
  • Hemosiderin
  • Decreased absorption:
  • Phytic acid (in dietary fiber)
  • Some antacids
  • Deficiency
  • Reduction in red blood cell production – iron deficiency anemia
  • Produces fatigue
  • Hematocrit levels below 34-37% and blood hemoglobin < 10-11 g/100 ml blood
  • Other causes of iron deficiency anemia: hemorrhaging
  • Sources: cooked spinach, sirloin steak, pot roast, fried beef liver,

Zinc (Zn)

  • Functions:
  • Zinc is a cofactor of nearly 100 enzymes
  • Immune function
  • Development of sexual organs and mineralization of bone-matrix
  • Alcohol dehydrogenase (alcohol metabolism)
  • Sources: Same as Mg.

Copper (Cu)

  • Copper is primarily absorbed in the stomach and duodenum of small intestine
  • Ceruplasmin, albumin, and transcuperin transport copper to liver and kidney then body tissue
  • Most copper in body is found in liver, brain, blood, skeletal muscle, and bone
  • Functions:
  • Aids in iron absorption
  • Part of enzyme
  • involved in myelin (insulates nerves)
  • involved in antioxidant reactions

Selenium (Se)

  • Found in many ionic forms but most selenium is bound to the amino acids methionine and cysteine

Iodide (I)

  • Deficiency linked to goiter in 1920s
  • Commonly found in fortified table salt (iodized)
  • 75% of iodide found in the thyroid and is used in the synthesis of thyroid hormone (T3 ad T4)
  • Functions: used in the synthesis of thyroxine (T4) which is converted to T3, T3 used in controlling the rate of cell metabolism
  • Deficiency: goiter, mental retardation

Fluoride (F)

  • 50% of iodide absorbed is deposited in calcified tissues, bones, and teeth
  • Functions: reduces dental caries(cavities) by
  • Reducing acid of the enamel
  • Increase the deposition of minerals that retard the development of cavities
  • Sources: drinking water