CHEM  30 B    Dr. R. Rinehart
BODY  FLUIDS

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

 II. FLUID BALANCE    

            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 
 

IV.  ACID-BASE BALANCE   
            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 
http://home.eznet.net/~webtent/acidbase.html 
Physiology of the Kidney by Dr. P. Stewart 
http://www.nda.ox.ac.uk/wfsa/html/u09/u09_016.htm 
Role of the Kidneys in Acid-Base Balance by Michael W. King at Indiana State U College of Medicine
 http://web.indstate.edu/thcme/mwking/ionic-equilibrium.html
pH of the Blood: Acid-Base Balance by Michael J. Bookallil at U Sydney
 http://www.usyd.edu.au/su/anaes/lectures/acidbase_mjb/acidbase.html 
Blood Gases by Mad Scientist Network 
http://www.madsci.com/manu/indexgas.htm
 

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

http://www.med.virginia.edu/med-ed/handouts/physiology/respiratory/sect9/sect9.html 

Acid-Base Tutorial by Alan W. Grogono of Tulane University School of Medicine
http://www.acid-base.com/
Treatment of Acid-Base Imbalance by Alan W. Grogono of Tulane U
 http://www.tmc.tulane.edu/departments/anesthesiology/acidbase/treatment.html

Body Fluids PowerPoint presentation [~ to what was given in class] by James Hardy at U Akron
 http://ull.chemistry.uakron.edu/genobc/Chapter_25/

 

© Ronald W. Rinehart, 2002, 2006