ACID_BASE Balance PPT MSC-1.pptx foods and nutrition

foods and nutrition

1. ACID_BASE Balance Jacent K. Asiimwe (PhD)

2. Acids Bases and pH Two types of acids are produced by the body i.e. Votalie acids (H2CO2 from respiration) and non-volatile/fixed acids produced by metabolism of proteins, CHOs and lipids eg . Lactic, keto acids, sulphuric etc

3. Acids and Bases Phisiologically important acids Physiologically important Bases Buffers The ability of an acid-base micture to resist sudden change in pH is called its buffer Buffer is a solution of a weak acid and it its corresponding salt.

4. Homeostasis in the Body Homeostasis in the body is tightly controlled ECF=pH 7.4 Blood= pH 7.35-7.45 (acidosis or alkalosis occurs) <6.8 or > 8.0 death may occur To maintain blood pH, three primary systems that regulate H+ concentration in body fluids come into play

5. The Buffer system First line of defense against pH change Reacts very rapidly within seconds Does not eliminate ions from the body or add them but only keeps them tied up until balance is re-established The 3 major systesm include Bicarbonate buffer Phosphate buffer Protein buffer

6. Bicarbonate Buffer system (NaHCO 3 - /H 2 CO 3 )

7. Importance of the bicarbonate buffer Present in high [ ] (accounts for 40-50%) Have an alkali reserve i.e. ration of (HCO3- to H2CO3 is 20:1). The alkali reserve (HCO3-) has to be high to sufficiently meet the acid load hence the high alkali:acid ratio The base constituent is regulated by the kidneys ( find out how ) The acid part is regulated by the respiratory system (respiratory regulation) Read about the phosphate buffer system

8. The Protein Buffer System Proteins e.g albumin act as buffers in the blood because: They contain large dissociable compounds (COOH and NH 2 i.e acidic and basic groups In acidic solns NH 2 accepts excess H + In Basic solns COOH gives up H +

9. The Hemoglobin Buffer Hemoglobin buffers in the RBC plays an important role in respiratory regulation of pH It transports metabolically produced CO2 from the cell to the lungs for excretion As hemoglobin releases its O2 it gains a great affinity for H+

10. Respiratory Regulation This acts like the second line of defense

11. Chemosensitive Areas

12. Respiratory Control of pH

13. The Renal Mechanism The renal mechanism tries to provide permanent solution to acid base imbalances/ disturbances in contrast to the temporary regulation by the respiratory system The kidneys do this by maintaining the alkali reserve. pH of urine (6 ) is usually acidic indicating acidification when urine is formed from the blood plasma i.e. H+ generated in the body are eliminated as acidified urine. Urine pH varies according to concentration of H +

14. Generation of sodium bicarbonate (NaHCO 3 ), proton H + excretion and ammonia secretion. Proton excretion Bicarbonate Formation Renal regulation of blood pH occurs in three ways Ammonia Secretion

15. Acid-Base imbalances

16. Anion Gap (AG) AG= Measured cations (Na+)-Measured anions (Cl- + HCO3-)= 12mEQ/L

17. Acid-Base Disorder Cause pH PCO2 HCO3 Urine pH Respiratory acidosis Pulmonary CO2 retention    Compensatory mechanism- kidneys increase Metabolic acidosis Accumulation of nonvolatile acid and/or reduction in alkali   Compensatory mechanism – breath fast   Respiratory alkalosis Increased pulmonary loss of CO2    Compensatory mechanism –kidneys eliminate Metabolic alkalosis Excess loss of acid and/or increase in alkali   Compensatory mechanism – breath slow  

18. Sweating Beyond 2% Body Weight Impairs Performance Reduced plasma volume  ability to achieve maximal cardiac output and peripheral circulation. Heart rate increases but can not compensate for stroke volume deficit. Sweating ceases to conserve body water and body temperature rises quickly. A marathon runner can lose 0.5 lb water/mile in hot environment (8 oz water)

19. Adverse effects of dehydration.

20. Are Electrolytes Needed In a marathon, with loss of 5 to 6 L in sweat, rehydration with water alone is adequate, because only about 200 mEq of Na and Cl would be lost. Only in severe conditions of prolonged, high-intensity exercise in heat would electrolyte replacement be indicated. Can be achieved by adding 1/3 tsp of table salt to 1 L of water.