Basics of acid base balance Flashcards
Why is it important to regulate blood pH?
Many chemical reactions are pH sensitive
Excess protons will bind to proteins and change their charge
What will excess protons do to proteins?
Bind to them and change their charge
Body reactions produce enough acid to make a pH of what?
1
What two components make a good buffer?
Weak acid and weak conjugate base
What are the two types of buffer in our bodies?
Intracellular
Extracellular
What are examples of intracellular buffers?
Proteins
Phosphates
Haemoglobin
What is the main buffer of RBCs?
Haemoglobin
What are examples of extracellular buffers?
Bicarbonate ions
Phosphate ions
Proteins
What are the two types of acids you can find in the body?
Volatile
Non-volatile
What are volatile acids?
Acids you can get rid off
What is the main buffer in the blood?
Bicarbonate ions
How is bicarbonate made?
When the unstable intermediate carbonic acid, that is made from the reaction between carbon dioxide and water, breaks down
What are non-volatile acids?
Acids you can’t get rid of (buffer)
What is an example of a non-volatile acid?
Sulphate derived from the metabolism of sulphur-containing amino acids
How are non-volatile acids removed from the body?
Via the kidneys
What gas is central to the control of pH?
Carbon dioxide
Protons determine the pH of blood
TRUE or FALSE
TRUE
How is carbon dioxide controlled in the body?
Negative feedback loop
Chemoreceptors sense the proton concentration of the blood
Increase in ventilation counterracts the increase in pH
What is the result of increasing breathin rate on the pH of the blood?
Increasing breathing rate
Reduces carbon dioxide concentration
Less carbonic acid is produced
Less protons are produced
Reversible reaction is pushed to form more carbon dioxide
Why do we need protein buffers?
Hydrogen ions are transported across membranes
What is the composition of RBC cell membranes?
50% proteins
33% Hb
What parts of the proteins act as buffers?
Carboyl group
Amino groups
What is an important amino acid found in Haemoglobin?
Histidine
Hb = 8% histidine
Why is histidine an important component of Hb?
Histidine’s pKa (buffering capacity) = 6
This means it works best at pH 6
Amino acid with pKa closest to the physiological pH
How does Hb buffer?
Somatic cells release carbon dioxide into the extracellular fluid
Carbon dioxide enters RBC and forms carbonic acid
Carbonic acid dissociates releasing protons
Protons are charged and so cannot leave the cell
Oxyhaemoglobin exchanges oxygen for a proton
Oxygen is released and enters somatic cells
Does chemical buffering work in the long term?
No
Molecules get oversaturated and don’t work anymore
What is a technique used by the body to spread the effects of hydrogen ion changes?
Buffer proteins are found spread throughout the body
What causes disturbances of pH?
Respiratory acidosis
Respiratory alkalosis
Metabolic acidosis
Metabolic alkalosis
What is respiratory acidosis?
Insufficient removal of carbon dioxide
Due to inadequate breathing or high carbon dioxide concentration in the air
Rise in CO2 in plasma = more carbonic acid produced = more protons
What is respiratory alkalosis?
Excess removal of carbon dioxide
Hyperventilation or high altitude
Fall in plasma carbon dioxide = less carbonic acid produced = less protons
What is metabolic acidosis?
Excess production of non-volatile acids
Due to voluntary ingestion of methanol
Or loss of base from the gut during diarrhea
Fall in plasma pH and increase in bicarbonate concentration
What is metabolic alkalosis?
Excess non-volatile bases
Due to vomiting
What causes respiratory acidosis?
Decreased ventilation
Increased carbon dioxide concentration in the air
What causes respiratory alkalosis?
Increased ventilation
High altitude
What causes metabolic acidosis?
Loss of base during diarrhea
Consumption of methanol
What causes metabolic alkalosis?
Vomiting
How does consumption of methanol lead to metabolic acidosis?
Methanoic acid results in increased lactic acid
Since the cytochrome in mitochondria is inhibited
