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2013-03-18 00:27:39


water and food
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  1. three basic water principles
    • a unified whole
    • body water compartments
    • particles in the water solution
  2. summarize a unified whole
    all water inside body surrounding cells protected and held by skin
  3. summarize a body water compartment
    • dynamic areas within the body.
    • total body water
    • total in individual locations in body
    • membranes seperate
    • water is shifted to where its needed
  4. summarize particles in water solution
    • concentration and distribution of part in water
    • determines internal shifts and balance amung compartments
  5. hemeostasis
    bodys state of dynamic balance
  6. wb cannan studied
  7. body water supply has 4 characteristics
    • acts as solvent
    • serves as means of transport
    • regulates temp control
    • provides lubrication for body
  8. solvent
    water is basic liquid solvent for all chem reactions
  9. polarity
    • interaction bs the pos charged end of one molecule and neg end of another.
    • effectively dissolves and ionizes substances
  10. transport
    water circulates thru body to meet the needs of cells
  11. thermoregulation
    temp rises = sweat cools body
  12. lubricant
    lubes moving bd parts eg joints
  13. women bd water requirements
    • 2.7 L
    • 19% from food
    • 74 oz fluid
  14. men bd water requirements
    • 3.7 L
    • 0.7 from food
    • 101 oz fluid
  15. two factors increasing water requirements
    • physical activity
    • environment temp
  16. surrounding environment factor
    • hot- body sweats
    • cold - body shivers
  17. hypoxia
    cold induced diuresis
  18. activity level factor
    • more water is lost in sweat
    • more water needed in metabolic demand
  19. athletes should drink how much
    5-7 ml per kg bd wt 4 hrs before
  20. athletes rehydrate
    16-24 oz per lb lost during exercise
  21. functional losses factor
    disease altered, water loss often thru urine
  22. metabolic needs factor
    1000ml water needed for metabolism of every 1000kcal in diet
  23. age factor
    high infancy
  24. infant bd water content
    • 70-75% total bd wt
    • mostly outside cells, easily lost
  25. other dietary factors
    • additives and meds
    • natural diuretic effect
    • individuals need monitored
    • alcohol and caffeine
  26. dehydration keys
    • excessive loss
    • after 2% of normal wt lost
    • thirst, ha, decreased urine output, drymouth, dizziness
  27. advanced dehydration s/s
    visual impairment, hypotension, loss of appetite, muscle weakness, kidney failure, seizures
  28. chronic dehydration
    increase resting heart rate, kidney infections, fallstones, constipation, adversely influence cognitive functions
  29. hypothalamus is
    regulatory center for thrist, hunger, bd temp, water balance, and bp
  30. elderly dehydration concern
    • hypothalamus changes occur
    • decreased thirst, reduced fluid intake

    • pysiological changes
    • eg kidneys
  31. hyponatremia
    low serum sodium levels of less than 136 meq/l
  32. water intoxication
    • hyponatremia
    • blood volume is diluted
    • water moves into intracellular fluid spaces to reestablish equilibrium w na concentration--EDEMA, LUNG CONGESTION, MUSCLE WEAKNESS
  33. polydipsia
    excessive thirst and drinking
  34. those at risk for hyponatremia are
    infants, psychiatric pts w polydipsia, pt taking psychotrpic drugs, prolonged endurance
  35. normal body water content for adults is
    45-75% total bd wt
  36. men have more water content because
    higher ration of muscle to fat mass
  37. which has more water content
    muscle or addipose tissue
  38. extracellular fluid
    • total amount outside cell
    • ecf
    • 20% total bd wt
    • 34 % total bd water
  39. 1/4 of ecf
    blood plasma
  40. remaining 3/4 total bd wt 15%
    • water that surrounds and bathes tiss
    • water in lymphatic circulation
    • water moving thru bd tiss secretions
  41. what helps w movement of materials in and out of bd cells
  42. interstitual fluid
  43. transcellular fluid is the
    • smallest component of ecf
    • in gi tract, ocular and jnt fluid, urine in bladder
  44. intrecellular fluid
    • total bd water insde cells
    • twice amount of % total bd water
  45. overall water balance
    water enters and leaves bd various routes controlled by basic mechanisms
  46. average adult metabolizes
    2.5 - 3 L of water per day
  47. water enters the body in 3 forms
    • liquids consumed
    • foods
    • product of cell oxidation when nutrients in body are burned for energy
  48. xerostomia
    severe reduction in flow of saliva that negativelty effects food intake
  49. recommended minimum fluid intake
    1500-200 ml per day
  50. water leaves the bd thru
    kidneys, skin, lungs, and feces
  51. obligatory water loss
    water that must be excreted thru urine to eliminate metabolic waste
  52. average fluid output per day
    2400 ml
  53. two main solutes in bd water
    electrolytes and plasma proteins
  54. electrolytes are
    small inorganic substances that can dissaciate or break apart in solution and carry an electrical charge
  55. electical charged particles
  56. cations
    • carry pos charge
    • eg na, k, ca, mg
  57. anions
    • carry neg charge
    • cl, becarbonate cho, phosphate po, sulfate so
  58. constant balance bw electrolytes maintian
    electrochemical and cell membrane potentials
  59. meq represent
    number of ionic charges or electrovalent bonds in a solution
  60. plasma proteins
    • albumin and globulin
    • are organic compounds of large molecular size
    • dont move as freely
    • retained in bld vessels
    • control water movement and blood v
  61. colliods
    influence shift of water in and out of capillaries in balance w the surrounding water

    plasma proteins
  62. colloidal osmotic pressure
    maintian integrity of bld vol
  63. small organic compounds
    • dissolved in bd water
    • too small to influence shifts of water
    • can be found in large concentration to influence movement
  64. example of a small organic compound solvent
    • glocuse
    • can increase water loss leading to polyuria when in high concentrations
  65. seperating membranes
    seperate and contain water thruout bd
  66. 2 types of seperating membranes
    capillary membranes, cell membranes
  67. capillary membranes
    • water molecules and small parts can move across thin capillary walls
    • electrolytes and nutrient materials flow free
  68. cell membranes
    • specially constructed to protect and nourish cells contents
    • molecules and ions use channels within the phospholipid bilayer to pass across membrane
  69. osmosis
    movement of water molecules from an area of low solute to an area w high solute concentraion
  70. osmotic pressure
    when solutions of concentrations exist on either side of selectively permeable membranes this pressure moves water across membrane to help equalize both sides
  71. diffusion
    force by which parts move outward in all directions from an are of greater concentration to an area of lesser
  72. facilitated diffusion
    membrane transporters assist parts w the crossing of the membrane.
  73. filtration
    water is forced or filtered thru small pores of membrane
  74. active transport
    • vital part must move thru bd processes at all tiems
    • carries upstream
    • helper-carrier ferries
  75. pinocytosis
    • larger molecule attach to outside cell and cell engulfs them
    • encased in vacuole
    • main way fat in absorbed in sml intestine
  76. one of bds most important controls in maintaining overall water balance is
    capillary fluid shift mechanism
  77. purpose of cap fluid shift mech
    • water and nutrients must get out of bld vess--
    • metablolites must get back to cap--
    • by means of opposing fluid pressure
  78. opposing fluid pressures
    • 1 hydrostatic pressure- intracapillary bp from contracting heart muscle pushing bld into circ
    • 2 cop - pressure from plasma prot draws tiss fluids back into ongoing circ
  79. process of cap fld shift mech
    • greater bp from heart forces water and small parts into tissues to bathe and nourish cells--then cop draw back water and metabolites--
    • balanced bw bp and osmotic pressure of plasma proteiin parts
  80. 2 major organ systems that help protect homeostasis of bd water
    gi circ and renal circ
  81. gi circ
    all secretions, except bile, are water--latter portions of intestines water is reabsorbed--constant movement maintained isotonicityw surrounding extracellular water-- risk for clinical imbalances
  82. law of isotonicity
    • gi fluids part of ecf capartments, also include blood--
    • isotonic state of equal osmotic pressure--
    • if you consume only water, electrolytes and salts enter intestine to even out--
    • if you consume only food, additional water is drawn into intestine
  83. most common cause of clinical fluid and electrolyte problems
    upper and lower gi losses
  84. renal circulation
    kidneys filter blood, reaborb water and needed nutrients-- laundering of bld by millions of nephrons water balance and proper solution of bld are maintained
  85. 2 hormonal controls to help maintian sonstant bd water balance
    • antidiuretic hormone mechanism
    • renin-angiotensin-aldosterone system
  86. antidiuretic hormone mechanism
    • vasopressin
    • syntehsized by hypothalamus
    • stored in pit gland for release

    • conserves water
    • works on kidneys nephrons to induce reabsorption of water
    • stressful situation-released to conserve water
  87. renin-angiotensin-aldosterone system
    • when bld flow to kidneys drop below normal, enzyme renin is released into bld.
    • renin converts angiotensinogen to "1, "1 travels to lungs where ace converts to "2- vasoconstriction triggers release of aldosterone from adrenal glands- aldo stim kidneys nephrons to reabsorb na

    • activated by stress also
  88. acid base balance
    • optimal degree acid/alkin must be maintained
    • achieved by chem and physical buffer systems
  89. concept of acids and bases
    • hydrogen ion concentration. pH
    • higher hydro ion concentration = lower pH
    • lower than 7 acidic
    • higher alkaline
  90. acids
    compound that has more h+ and has enough to relase extra when it is in solution
  91. bases
    • compound w fewer h+
    • in solution, accepts H+, reducing solutions acidity
  92. acid base buffer system
    bd deals w degrees of acidity by maintaining buffer systems to handle and excess acid or base
  93. chem buffer system
    • mixture of acidic and alkalinine components
    • acid and base partner that protect solution from wide variants of pH
  94. bodys main buffer system is
    carbonic acid/becarbonate
  95. h2co3/nahco3 main reasons
    • availability of materials
    • base-to-acid ratio
  96. physiologic buffer system
    • resp and renal systems respond
    • when chem buffers cannot reestablish equilibrium
  97. resp control of pH
    co2 leaves w breath, changes in resp rate can incr or decr loss of acids
  98. acidosis
    • pH less than 7.35
    • accumulation of co2
    • significant loss of bicarbonate
  99. alkalosis
    • pH more than 7.45
    • resp alk caused by hyperventilation and excess loss of carbon dioxide
    • extensive vomitting w hydrochloric acid lost and bicarbonate secreted
  100. urinary control of pH
    • when chem and resp buffers do not reestablish pH, kidneys can adapt by excreting more or less H+
    • if blood is too acidic, kidneys will accept more H+ in exchange for na+
    • na+ are basic, blood is losing an acid while gaining base- increasing blood ph back to normal