Does John Have an Acid-Base Disorder? Explain

BTH 2741 Assignment 1

Q1.

(a) Does John have an acid-base disorder? Explain.

Yes. John has an acid-base disorder. From his arterial blood gas results, John had a lower concentration of hydrogen ion (28nm) which is below the normal range (36nm-43nm). In theory, the lower the hydrogen ion concentrations, the higher the pH value (Narins & Emmett, 1980). This shows that John have a high pH which is beyond the normal range hence this is alkalosis results. Alkalosis can be defined as the physiological processes that cause alkali accumulation and acid loss (Berend et al., 2014). Also, the results show high PCO2 which represent acidosis. This is because when CO2 binds with H2O, it will form carbonic acid. Therefore, high PCO2 may result in pH to be more acidic which is not consistent with the pH. High CO3 represent alkalosis which is consistent with the pH, hence it is the initial change. As a result, John can be said to have metabolic alkalosis because the initial change involve HCO3.

(b) If so, how might it have arisen?

Metabolic alkalosis may develop as a result of excessive loss of acids (hydrogen ions) from body fluids, leading to increase bicarbonate concentration, which then contribute to a rise in pH (Narins & Emmett, 1980). In this case, John has been vomiting severely. According to Galla (2000), prolonged vomiting that loses the alkaline contents of stomach contents can result in metabolic alkalosis. This is because gastric juice inside stomach is very acidic as it contains HCl, however when it is loss or leaves the body fluids, this will leave a net increase of basic substances and hence pH shift toward alkaline values. The kidneys compensate for these losses by retaining sodium in the collecting ducts at the expense of hydrogen ions hence leading to metabolic alkalosis (Galla, 2000). Besides, vomiting also causes the depletion of chloride ion (Cl-) due to loss of gastric juice, resulting in loss of hydrogen ion. Hypocalcemia, potassium level is lower than normal range in blood stream also is the cause of metabolic alkalosis (Narins & Emmett, 1980).

Furthermore, metabolic alkalosis could happen due to ingesting too much of antacid preparation, which is the medication to relieve the symptoms of indigestion (Kellum, 2007). An example of it is sodium bicarbonate. This cause John to have a slow and shallow breathing and hence the concentration of carbon dioxide in the blood will increase.

Q2.

(a) Why might these conditions cause a respiratory acidosis?

Fred has respiratory acidosis due to alveolar hypoventilation as lungs cannot function well to remove enough carbon dioxide. Alveolar hypoventilation leads to an increased PaCO2. The increase in PaCO2 consequently decrease the (HCO3–)/PaCO2 ratio and then lower the pH (Cosimo & Maria, 2012). This is because his lungs cannot remove all of the carbon dioxide that body produces as he had injured in a building site accident and was admitted to hospital with a crushed chest. The lung tissue is crushed due to the chest wall bends inward on impact. Normally, the lungs take in oxygen and exhale carbon dioxide. Oxygen then passes from the lungs into the blood while carbon dioxide passes from the blood into the lungs (Kettel, 1971). Hence, in Fred’s case, when the production of carbon dioxide occurs rapidly, the failure of ventilation will increase the partial pressure of arterial carbon dioxide (PaCO2) (Kettel, 1971). As a result, the pH of blood decrease and falls below the normal range. Besides, respiratory acidosis can also develop when muscles of the chest impair breathing hence causing inadequate chest movement (Cosimo & Maria, 2012).

Bill suffers respiratory acidosis because he was a heavy smoker. Tobacco smoking is the major cause that would lead to development of chronic lung disease that can cause respiratory acidosis (Epstein & Singh, 2001). This is because smoking may decreased the lung and alveolar function and causes insufficient exchange of gases in lungs. When this happens, the blood and other fluids may become excessively acidic. Also, smoking may result in obstruction of airways which also is a common cause for respiratory acidosis (Kettel, 1971). From the arterial blood gas results, the PCO2 level is beyond the normal range due to hypoventilation causes Bill to breathe difficultly. Also, the high HCO3- level is result from the metabolic compensation of respiratory acidosis. This disrupts the body acid - base balance (Epstein & Singh, 2001).

(b) Can you explain the differences in their blood chemistry?

Arterial blood gases (ABGs) are an important way to investigate and monitor the acid-base balance of patients. The results of Fred and Bill shows a high level of hydrogen ion (H+), meaning that the pH is low, which is below the normal range. This shows that both of them are develop acidosis condition. However, Fred was acidosis with a normal bicarbonate level while Bill was acidosis with a high bicarbonate level.

Q3.

(a) Changing arginine to lysine usually has little effect

If the chemical properties of the original amino acid and the one replacing it in the mutant are same, it is most likely that the mutant protein will still fold similarly to the original protein and will not cause significant damage to the protein (Pauline & Steven, 2003). For example, arginine is classified as a polar amino acid with positively charged guanidine group while lysine is also a hydrophilic amino acid with positively charged. Also, lysine and arginine have basic amine functions in their side-chains. If the side chain contains an amine functional group, the amino acid produces a basic solution because the extra amine group is not neutralized by the acid group. Since both of them have similar chemical properties and physical properties, arginine thus most favour to substitute for lysine. In summary, changing of an amino acid to a chemically similar one, such as arginine and lysine, often has little effect on a protein and the protein may still working (Pauline & Steven, 2003).

(b) Changing tryptophan to any other amino acid often causes loss of activity.

Tryptophan is unique in its chemical properties and size, hence substitution of it with another amino acid that had different chemical properties may causes significant damage to the activity of the protein. The unique property of Tryptophan is that it was the only amino acid in human plasma that bound to protein which is vital for the control of tryptophan pool in the brain (Yong et al., 2012).

(c) Changing serine to another amino acid often has little effect.