carbonic anhydrase

Examples of carbonic anhydrase in the following topics:

• RBC Physiology

  • Carbon dioxide is associated with blood acidity.
  • RBCs secrete the enzyme carbonic anhydrase, which catalyzes the conversion of carbon dioxide and water to carbonic acid.
  • Carbonic anhydrase also removes water from carbonic acid to turn it back into carbon dioxide and water.
  • This reaction can occur without the presence of RBCs or carbonic anhydrase, but at a much slower rate.
  • With the catalyst activity of carbonic anhydrase, this reaction is one of the fastest in the human body.

• Diuretics

  • Carbonic anhydrase inhibitors inhibit the enzyme carbonic anhydrase which is found in the proximal convoluted tubule.

• Carbon Dioxide Transport

  • Carbon dioxide is carried in the blood through three different ways.
  • This is due to deoxygenated blood's increased capacity to carry carbon dioxide, and from the carbon dioxide loaded from the tissues during tissue gas exchange.
  • This means that carbon dioxide reacts with water to form carbonic acid, which dissociates in solution to form hydrogen ions and bicarbonate ions.
  • Dissolved carbon dioxide is already able to diffuse into the alveolus, while hemoglobin-bound carbon dioxide is unloaded into the plasma.
  • Next, the action of carbonic anhydrase breaks carbonic acid down into carbon dioxide in water, which leaves the cell by diffusion.

• Anion Regulation

  • Bicarbonate ions result from a chemical reaction that starts with carbon dioxide (CO2) and water - two molecules that are produced at the end of aerobic metabolism.
  • Carbon dioxide is produced in large amounts in tissues that have a high metabolic rate and is converted into bicarbonate in the cytoplasm of red blood cells through the action of an enzyme called carbonic anhydrase.

• Carbon Monoxide Poisoning

  • Carbon monoxide poisoning occurs after respiratory inhalation of excessive carbon monoxide (CO).
  • Carbon monoxide is a product of incomplete combustion of organic matter due to insufficient oxygen supply to enable complete oxidation to carbon dioxide (CO2).
  • Carbon monoxide can also have severe effects on the fetus of a pregnant woman.
  • Domestic carbon monoxide poisoning can be prevented by early detection with the use of household carbon monoxide detectors.
  • Carbon monoxide is toxic to the organism at many levels.

• Chemoreceptor Regulation of Breathing

  • Chemoreceptors detect the levels of carbon dioxide in the blood by monitoring the concentrations of hydrogen ions in the blood.
  • Because most carbon dioxide is converted to carbonic acid (and bicarbonate) in the bloodstream, chemoreceptors are able to use blood pH as a way to measure the carbon dioxide levels of the bloodstream.
  • They can be desensitized over time from chronic hypoxia (oxygen deficiency) and increased carbon dioxide.
  • Their increased ventilation rate will remove too much carbon dioxide from their body.
  • Without that carbon dioxide, there will be less carbonic acid in blood, so the concentration of hydrogen ions decreases and the pH of the blood rises, causing alkalosis.

• Blood Flow in the Lungs

  • Pulmonary circulation in the lungs is responsible for removing carbon dioxide from and replacing oxygen in deoxygenated blood.
  • The pulmonary arteries carry deoxygenated blood to the lungs, where they release carbon dioxide and pick up oxygen during respiration.
  • Oxygen passively flows from the air inside the alveoli into the blood in the alveolar capillaries, while carbon dioxide passively flows in the opposite direction.
  • The air, along with the diffused carbon dioxide, is then exhaled.
  • The alveoli are the site of oxygen and carbon dioxide exchange in the lungs.

• The Reason for Breathing

  • Cells require oxygen from the air to extract energy from glucose through respiration, which produces carbon dioxide and water as a waste product.
  • In the alveoli tissue of the lungs, the exchange of oxygen and carbon dioxide molecules between the air and the bloodstream occurs by passive transport, so that oxygen is taken in and carbon dioxide and water are removed.
  • The concentration of hydrogen ions in blood is partially determined by the amount of dissolved carbon dioxide in the blood, so that more carbon dioxide results in more hydrogen, causing the blood to have a lower pH and be more acidic.
  • When the blood pH becomes too high, from too few hydrogen ions because of too little carbon dioxide, the blood will become alkaline, which is also harmful to the body.
  • Alkalosis can happen from hyperventilation (too much breathing) which removes too much carbon dioxide from the bloodstream.

• Henry's Law

  • An everyday example of Henry's law is given by carbonated soft drinks.
  • The drink itself contains dissolved carbon dioxide.
  • Because the pressure above the liquid is now lower, some of the dissolved carbon dioxide comes out of solution as bubbles.
  • If a glass of the drink is left in the open, the concentration of carbon dioxide in solution will come into equilibrium with the carbon dioxide in the air, and the drink will go flat.
  • Carbon dioxide has much higher solubility in the plasma of blood than oxygen (roughly 22 times greater), so more carbon dioxide molecules are able to diffuse across the small pressure gradient of the capillary and alveoli.

• Internal Respiration

  • Gas exchange occurs in the alveoli  so that oxygen is loaded into the bloodstream and carbon dioxide is unloaded from the bloodstream.
  • Oxygen diffuses into the cells of the tissues, while carbon dioxide diffuses out of the cells of the tissues and into the bloodstream.
  • Cellular respiration is the metabolic process by which an organism obtains energy through the reaction of oxygen with glucose to produce water, carbon dioxide and ATP, which is the functional source of energy for the cell.
  • $Glucose + 6 Oxygen -> 6 Carbon Dioxide + 6 Water + 38 ATP$
  • The carbon dioxide waste is the result of the carbon from glucose (C6H12O6) being broken down to produce the pyruvate and NADH intermediates needed to produce ATP at the end of respiration.