Kidney 4
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What pH do enzymes usually work in?
7.35-7.45
Where are 2 acid intakes into the body?
Metabolic acid production and H+ intake.
What are the two organs that acid is excreted from?
Lungs (volatile) and kidney (non-volatile)
What are the 4 ways which hydrogen ions is gained into the body?
• Generation of hydrogen ions from C02. • Production of non-volatile from the metabolism of protein and other organic molecules. • Gain of hydrogen ions due to loss of bicarbonate in diarrhea or other non gastic GI fluids. • Gain of hydrogen due to loss of bicarbonate in the urine.
What are 4 ways in which hydrogen ions are lost in the body?
• Utilisation of hydrogen ions in the metabolism of various organic anions • Loss of hydrogen ions in vomitus • Loss of hydrogen ions in the urine • Hyperventilisation
Every day, how many milli moles of carbon dioxide is added to plasma?
20,000
What reaction happens between carbon dioxide and water?
CO2 + H20 -> carbonic acid -> bicarbonate ions and H+
Loss/gain of H+? Hyperventilating Hypoventilating
Hyperventilating - net loss of hydrogen ions Hypoventilating - net gain of hydrogen ions
What acids are the in the body that are non-volatile?
Lactic, phosphoric and sulphuric acid.
How many mmol of protein can be added in a high protein diet?
40-80mmol/day
What expulsion mechanism removes H+? HC03-? Explain what occurs in each?
H+ in sick HCO3- in diarrhea If you lose bicarbonate, the reaction is not reversible so the H+ cannot be breathed out so it increases. Vice versa with H+.
What is the equation for pH? What is the normal nM of H+?
pH = -log(H+) 35-45nM
Respiratory acids? Non-respiratory acids?
• CO2 production (oxidative metabolism) - Other acids (e.g. phosphoric acid) excreted by kidneys.
What numerical range is plasma acid in? Acid production?
nM mM
Bicarbonate system What does an increase/decrease in H+ do to the system?
Increase pushes it right Decrease pushes it left
Give all the buffers in the body under these titles: Blood: Interstitial Fluid: Intracellular Fluid: Urine:
Blood: Bicarbonate Haemoglobin Plasma proteins Interstital fluid: Bicarbonates Very little protein Intracellular fluid: Intercellular proteins Phosphates A little bicarbonate Urine: Phosphate Ammonia
What happens to the intracellular pH? All the organelles are in acidic conditions except which one?
Below 7.35 Except mitochondria (pH 8)
Which mathematical equation is important in buffer solutions? What does buffer effectiveness depend on?
Henderson Hasselbach Depends on its concentration and pK.
When does pH = pK?
When the acid is half dissociated
What can be used in the Henderson Hasselbach equation to replace the value for bicarbonate acid solution? Why?
Partial pressure for carbon dioxide Easier to measure
State the normal plasma values for each of these
Arterial CO2 = 5.3kPa Arterial [HCO3-] = 25nM Venous [HC03-] = 25nM Arterial pH = 7.4
What are the 2 processes which are controlled by acid-base balance?
• Matching output (i.e. excretion) to input 2. Regulating the ratio of base to weak acid in buffers
What part of the buffer do the lung and the kidney regulate?
Kidney deals with HCO3- concentration and lung with pC02.
What is a big advantage of the bicarbonate buffer?
The addition of acid causes pCO2 to rise. This drives respiration which increases elimination of CO2 from the body.