CHEM  30 B    Dr. R. Rinehart

I.  Types of body fluids:    42 L total 
           A.  Intracellular:  28 L 
                        1.  High K+, HPO4-2; moderate SO4-2 , protein- ; low Na+, Cl-   
                        2.  Partitioned among trillions of cells, but can be considered as a unit           

B.  Extracellular: 14 L   
                        1.  High Na+, Cl-; moderate HCO3-; low K+, Ca+2, HPO4-2    
                     2.  Several types
            a.  Interstitial fluid: 10.5 L
            b.  Blood plasma:  3.5 L
            c.  Cerebrospinal, ocular, joint fluids
            d.  Digestive secretions
            e. URINE


            A. INTAKE                           2400 mL/day     average
        1. Ingested liquids         1500 mL/day
        2. “solid” foods               700 mL/day
3. Electron transport    
  200 mL/day

B.  OUTPUT                          2400 mL/day
1.  Lungs                         350 mL/day    obligatory
2.  Skin: diffusion         
  350 mL/day     (“intangible” perspiration)  obligatory
3.  Skin: perspiration   
  100+ mL/day    (“tangible” perspiration)
4.  Feces                   
      200 mL/day    minimum average; 
5. URINE                     1400 mL/day   average;  500 mL/day obligatory minimum

              C.  G.I. TURNOVER  ~8200 mL/day secreted, ~ 8000 mL/day reabsorbed
Saliva                                      1500  mL/day
Gastric Secretions                2500  mL/day
Bile                                         500  mL/day
Pancreatic juice                     700   mL/day
Intestinal secretions             3000  mL/day  

                    CIRCULATORY TURNOVER
                        Transcapillary fluid exchange ~ 25,000 L/day
                              balance between hydrostatic pressure [varies with distance from heart]
                                and colloid osmotic pressure due to plasma proteins

                                           *********KIDNEY FACTS*****************

                        Total renal plasma flow        650 mL/min   [~20% of cardiac output] 
                        filtration fraction       =          0.19
Glomerular filtration rate     125 mL/min    plasma “reworked” ~ 50X/day
Rate of urine formation        ~ 1 mL/min

D.  “Tonicity”  of  body fluids: isotonic, hypertonic, and hypotonic
                     1.  Isotonic ≡ 
                     2.  Abnormalities of fluid balance
E.  Regulation  

1. Thirst mechanism  
2.  Antidiuretic hormone (vasopressin)

III.  Transport of material by body fluids 
            A.  Oxygen and carbon dioxide 
         B.  Other substances 

            A.  BUFFER CONTROL of blood pH

1. The Henderson-Hasselbalch equation
            pH = pKa + log{[A-] / [HA]} 
2. In blood plasma, the bicarbonate-carbonic acid system is the most important buffer
            H2CO3    H+ + HCO3-
   pKa = 6.1
            7.4 = 6.1 + log {[HCO3-] / [H2CO3]}
            normally, then            [HCO3-] = 20 x [H2CO3]   
3. The LUNGS, under instruction from respiratory control centers in the brain,
      control [H2CO3] by adjusting the rate of respiration 
                        4.  The KIDNEYS control [HCO3-]   

            B.  ACIDOSIS and ALKALOSIS     
1.  Respiratory acidosis: caused by hypoventilation;        [H2CO3] increases 
2.  Respiratory alkalosis: caused by hyperventilation;     [H2CO3] drops 
3. “Metabolic” acidosis:         [HCO3-] drops
            a.  Acid-producing diet (high-protein, S à H2SO4)
            b.  Metabolic disorders like diabetes mellitus: ketoacidosis
            c.  Kidney failure: acid wastes accumulate
            d.  Loss of alkaline fluids: diarrhea 

                        4. “Metabolic” alkalosis:        [HCO3-] increases
            a.  Alkali-producing diet (all-fruit); consumes body H
            b.  Certain kidney disorders
            c. Loss of acidic body fluids: vomiting 

            C. Treatment
1.  Immediate: correct pH imbalance by administering NaHCO3 or ACD and/or
                 respiratory measures like rebreathing CO2 or promoting hyperventilation 
2.  Long-term: correct underlying condition; dialysis

Acid-Base Disorders by Nasr Anaizi 
Physiology of the Kidney by Dr. P. Stewart 
Role of the Kidneys in Acid-Base Balance by Michael W. King at Indiana State U College of Medicine
pH of the Blood: Acid-Base Balance by Michael J. Bookallil at U Sydney 
Blood Gases by Mad Scientist Network

Respiratory Aspects of Acid-Base Balance from the University of Virginia 

Acid-Base Tutorial by Alan W. Grogono of Tulane University School of Medicine
Treatment of Acid-Base Imbalance by Alan W. Grogono of Tulane U

Body Fluids PowerPoint presentation [~ to what was given in class] by James Hardy at U Akron


© Ronald W. Rinehart, 2002, 2006