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Acids and bases - Coggle Diagram
Acids and bases
Buffers
Mixture of weak acid and conjugate base
Buffer + H\(^+\) \(\rightarrow\) H-Buffer + B\(^-\)
HCO\(_3^-\) is the main buffer in plasma
Protein buffers e.g. Hb
Intracellular buffers
Proteins
Hb
Phosphate
Bone buffers (phosphates)
Na\(_2\)HPO\(_4\) + H\(^+\) \(\rightarrow\) NaH\(_2\)PO\(_4\) + Na\(^+\)
Extracellular buffers
Proteins
Phosphate
Bicarbonate - main EC buffer
Bicarbonate buffer system
Intracellular pH
Body's metabolism produces acid
Inside cell pH = ~7.0 = [H\(^+\)] = 100nmol/L
Hydrogen ion sources
CO\(_2\) produced in aerobic metabolism diffuses into circulatory system
Some CO\(_2\) combines with water forming carbonic acid
Carbonic acid freely dissociates to H\(^+\) and HCO\(^{3-}\)
Buffered by Hb
Protein buffer
Buffering only short term, XS H\(^+\) excreted via kidneys
Defence against pH change
Acute
Lungs respond rapidly - respiration problems show more rapid changes in pH and for greater time periods
Ventilation
Buffering (HCO\(_3\))
Long term
Renal excretion
Hepatic metabolism
Lag time for kidney + liver response
Metabolic changes and kidney disease show less rapid change to pH than respiratory problems
GI tract
Produces acid in stomach
Secretes bicarbonate to neutralise acid
Allows digestive enzymes to work
GI problems lead to changes in pH state
Hepatic metabolism of amino acids
Deamination giving rise to ammonia (urea cycle)
Free fatty acids oxidised by liver
Ketones produced
Rapid respiratory compensation
Causes of respiratory acidosis
Airway obstruction
Tumours
Foreign bodies
Depression of respiratory centre
CNS trauma
Infection
Drugs (opiates, benzodiazepines - valium)
Neuromuscular disease
Polio
Muscular dystrophy
Pulmonary disease
Emphysema
Bronchitis
Severe asthma
Causes of respiratory alkalosis
Hypoxia
Increased ventilation
CNS lesions
Trauma
Infection
Anxiety
Pneomonia
Congestive heart failure
Embolism
Slow metabolic compensation
Acute or chronic renal failure
Acidosis
Blood pH
Maintained within narrow limits
100,000 times more tightly controlled than Ca\(^{2+}\)
Bicarbonate reserves control body pH
Bicarbonate levels fall - need to maintain electrical balance between cations + anions in the extracellular fluid
Anion gap
Difference in sums of principle cations and principle anions
Principal anions
Chloride + bicarbonate
Principle cations
Sodium + potassium
pH = 7.36 to 7.44
[H\(^+\)] = 35-45nmol/L
Alkalaemia
Rise in blood pH
Caused by alkalosis
Loss of H\(^+\)
Addition of HCO\(^{3-}\)
In bodily fluids
Acidaemia
Fall in blood pH
Caused by acidosis
Addition of [H\(^+\)] to bodily fluids
Excretion of acid in kidneys
Secretion of H\(^+\) by tubules reclaims bicarbonate from glomerular filtrate
Prevent loss from body
Carbonic anhydrase
in RBCs and kidneys
Important control mechanism
Metabolic acids
Weak
Carbonic acid
Dihydrogen phosphate
Ammonium
Lactic acid
H