acid-base balance.ppt

Bodyfluid and electrolit

Physiology DepartmentMedical Faculty, Hasanuddin

University

KOMPOSISI Plasma Interstitiel intrasel (meq/l) ( meq/l) ( meq/l)

KATION Na 143,0 140,0 14,0K 4,2 4,0 140,0Ca 1,8 1,2 <1Mg 0,8 0,7 20,0 ANIONCl 108,0 108,0 4,0 HCO3 24,0 28,3 10,0HPO4 2,0 2,0 11,0Protein 1,2 0,2 4,0

Acid base balance

Physiology DepartmentMedical Faculty, Hasanuddin

University

Acid-Base Balance Precise H+ regulation is essential because the

activities of almost all enzyme, cell and body functions in the body are influenced by H+ concentration

Molecules containing hydrogen atoms that can release hydrogen ions in solutions are referred to as acids

A base is an ion or a molecule that can accept an H+, alkali is a molecule formed by the combination of one or more of the alkaline metals—sodium, potassium, lithium, and so forth—with a highly basic ion such as a hydroxyl ion (OH–).

Alkalosis refers to excess removal of H+ from the body fluids, in contrast to the excess addition of H+, which is referred to as acidosis.

Defenses Against Changes inHydrogen Ion Concentration Buffer system

Lung

Kidney

Buffering of Hydrogen Ionsin the Body Fluids

Bicarbonate Buffer System Phosphate Buffer System Proteins: Important Intracellular

Buffers

Bicarbonate Buffer System Consists of a water solution that

contains two ingredients: (1) a weak acid, H2CO3, and (2) a bicarbonate salt, such as NaHCO3

Extracellular fluid

Phosphate Buffer System The main elements of the

phosphate buffer system are H2PO4– and HPO4 =.

plays a major role in buffering renal tubular fluid and intracellular fluids.

Proteins: ImportantIntracellular Buffers Proteins are among the most plentiful

buffers in the body because of their high concentrations, especially within the cells

In the red blood cell, hemoglobin (Hb) is an important buffer, as follows:

60 to 70 per cent of the total chemical buffering of the body fluids is inside the cells, and most of this results from the intracellular proteins

Respiratory Regulationof Acid-Base Balance The second line of defense against

acid-base disturbances is control of extracellular fluid CO2 concentration by the lungs.

An increase in ventilation eliminates CO2 from extracellular fluid, which, by mass action, reduces the H+ concentration

Renal Control ofAcid-Base Balance The kidneys control acid-base balance

by excreting either an acidic or a basic urine

Thus, the kidneys regulate extracellular fluid H+ concentration through three fundamental mechanisms: (1) secretion of H+, (2) reabsorption of filtered HCO3- and (3) production of new HCO3-.