Acid-Base Disturbances Flashcards
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Physiological pH range:
7.35-7.45
Disturbances in pH are called:
Acid-base disorders
Types of Acid-Base Disorders:
- Acidosis
- Alkalosis
Properties of Acidosis:
- decrease in pH
- pH < 7.35
- low [HCO3-]/[H2CO3] ratio
- increase in [H+]
Properties of alkalosis
- Increase in pH
- pH>7.45
- High [HCO3-]/[H2CO3] ratio
- decrease in [H+]
What is carbonic acid?
formula and synonym
(H2CO3) is also called dissolved CO2.
Acidosis is essentially…
summary
low bicarbonate to dissolved CO2 ratio
- So there is not enough bicarbonate for the amount of dissolved CO2 there is.
Types of Acidosis or Alkalosis
Respiratory or Metabolic
chemistry
Respiratory Acidosis
high PCO2
PCO2 is H2CO3
chemical pattern of
Metabolic Acidosis
low HCO3-
high H+
What does decrease in dissolved carbon dioxide cause?
Respiratory alkalosis
What does a decrease in protons cause?
Metabolic alkalosis
What does a decrease in bicarbonate cause?
metabolic acidosis
So changes in PCO2 cause…
Respiratory disturbances
While metabolic disturbances are caused by…
H+ or HCO3- changes
How does breathing cause respiratory acidosis?
a decrease in breathing will increase the pCO2 (H2CO3) in blood.
hypoventilation—> hypercapnia—> respiratory acidosis
so the mechanism is:
Decreased breathing (hypoventilation)
Define hypercapnia
increase of pCO2 in blood
Causes for Respiratory Acidosis:
(hypoventilation)
1. Breathing in air that’s high in CO2
2. Depression of Respiratory Centres: General Anesthesia, or Morphine poisoning
3. Chronic diseases: Asthma or Emphysema
4. Obesity
Causes for Respiratory Alkalosis
- Drugs: Salicylate Poisoning
- Hyperventilation: anxiety, fever, hysteria, head injury, high altitudes or hot atmosphere
all decrease concentration of dissolved CO2
Causes of Metabolic Acidosis
9
- overconsumption of acidic foods
- diuretic drugs
- diaherria
- acute kidney failure
- heavy exercise
- diabetes mellitus
- starvation
- bacterial infection
- anoxia
How do diuretic drugs and diahrrea cause metabolic acidosis?
They heavily reduce the concentration of bicarbonate [HCO3-]
Causes of Metabolic Alkalosis:
- Excessive aldosterone secretion
- Vomitting
- Alkaline Drugs like sodium bicarbonate which is used to treat ulcers
Lactic Acid is caused by:
Heavy exercise or shock/ anoxia
What do ketone bodies and lactic acid have in common?
They cause metabolic acidosis.
Physiological Response to Respiratory Acidosis:
increase in dissolved carbon dioxide [pCO2] so it is responded to by the KIDNEYS where they INCREASE bicarbonate [HCO3-] levels.
Physiological response to Respiratory Alkalosis:
decrease in pCO2, kidneys respond by decreasing bicarbonate levels
How do the kidneys reduce the bicarbonate concentration?
It catabolizes bicarbonate into its components CO2 and H2O, and in the process will release ATP.
Physiological Response to Metabolic Acidosis:
Decrease in bicarbonate will be responded to by the LUNGS, where dissolved CO2 is decreased.
Physiological Response to Metabolic Alkalosis:
Increase in bicarbonate will cause for a response in the LUNGS where dissolved carbon dioxide is increased.
Based on the physiological responses to these acid-base disturbances, the relationship between bicarbonate and carbon dioxide is…
DIRECTLY PROPORTIONAL; increase in pCO2 will increase HCO3, and vice versa.
Aldosterone and vomitting cause…
decrease in H+ ions.
Metabolic means
change in H+ or bicarbonate concentrations
Respiratory means
changes in dissolved carbon dioxide (pCO2)
Example of mixed Respiratory Acidosis and Metabolic Alkalosis:
Patients with emphysema that have an obstruction in the duodenum of the small instine, ulcer causing them to vomit a lot.
- The emphysema causes hypoventilation
- prolongued vomitting will increase bicarbonate levels.
An example of mixed Respiratory alkalosis and Metabolic acidosis is:
Salicylate poisoning.
a) Salicylate poisoning stimulates the respiratory centres, causing hyperventilation and a drop in pCO2.
b) then it also affects the metabolism, increasing metabolic acids.
How does shock cause metabolic acidosis?
Shock/anoxia, the decrease in oxygen levels, is a shortage of blood flow to peripheral tissue, making them depend on anaerobic respiration which increases lactic acid concentration.
How does kidney failure cause metabolic acidosis?
DECREASED EXCRETION of H+ ions
Excessive ketone bodies is by…
Diabetes mellitus and starvation.
What causes an excessive quantity of lactic acid?
Shock (anoxia) and heavy exercise.
What are considered metabolic acids?
- Lactic acid
- Ketone bodies
How does aldosterone cause metabolic alkalosis?
It stimulates the excretion of H+.
The drug that treats ulcers is considered to cause…
Metabolic Alkalosis
Is there any “compensation” completed by H+ ion changes?
Yes, in the case of respiratory alkalosis.
Usual/normal
Sources of H+ ion:
Metabolic acids and sometimes cause acidosis when formed in excess quantities.
What are 3 metabolic acids that are sources of H+ ions and their production mechanism?
- Carbonic acid: formed from the oxidation of glucose and fatty acids which produces {CO2 + H2O + ATP}, the reactants for carbonic acid reaction.
- Sulphuric acid: formed from the oxidation of sulfur-containing amino acids
- Phosphoric acid: formed from oxidation of phospholipids and phoso-proteins
Respiratory alkalosis decreases the…
availability of H+
What are unusual sources of H+?
- Heavy exercise [lactic acid]
- Starvation keto-acidosis [ketone bodies]
- DM keto-acidosis [ketone bodies]
- Ingesting of acidifying salts [CaCl and NH4Cl]
What causes for carbonic acid to be released?
and product
Carb + lipids: glucose and fatty acids
- CO2 and water (and energy)
What causes sulfuric acid?
Protein only: sulfur-containing amino acids
What causes phosphoric acid?
lipids and protein: phospholipids and phospho-proteins
Examples of polyprotic acids:
- carbonic acid (H2CO3)
- phosphoric acid (H3PO4)
both are weak acids.
