Question

The chemical reaction that converts carbon dioxide to a bicarbonate ion takes place in a. the blood plasma. b. red blood cells. c. the alveolus. d. the hemoglobin molecule.

Short answer

The chemical reaction that converts carbon dioxide to a bicarbonate ion takes place in red blood cells (option b), with the help of the carbonic anhydrase enzyme. This enzyme speeds up the reaction between carbon dioxide and water, forming carbonic acid, which further dissociates into bicarbonate ions and hydrogen ions. Most of the carbon dioxide in the blood is transported as bicarbonate ions in the plasma.

Step-by-step solution

Identify the correct option

From our understanding of the process of carbon dioxide transportation in the blood, we can determine which among the given options is the correct location for the mentioned chemical reaction. a. the blood plasma b. red blood cells c. the alveolus d. the hemoglobin molecule

Explanation of the correct answer

The chemical reaction that converts carbon dioxide to a bicarbonate ion takes place in red blood cells. The process involves carbonic anhydrase enzyme present in red blood cells, which speeds up the reaction between carbon dioxide and water to form carbonic acid. Carbonic acid then dissociates to form bicarbonate ions and hydrogen ions. Most of the carbon dioxide in the blood is transported as bicarbonate ions in the plasma. Therefore, the correct answer is: b. red blood cells

Key concepts

Red Blood Cells

Red blood cells (RBCs) play a vital role in transporting gases such as oxygen and carbon dioxide throughout the body. These biconcave cells have a unique shape and flexible structure, allowing them to pass through tiny capillaries with ease.
RBCs contain hemoglobin, a protein responsible for oxygen binding. However, when it comes to carbon dioxide, RBCs serve another essential function. They are the primary site where carbon dioxide is converted into bicarbonate ions. This conversion is crucial for maintaining the acid-base balance in the body, as well as transporting a significant portion of carbon dioxide from the tissues to the lungs, where it is eventually exhaled.
The conversion process not only involves chemical reactions but is also aided significantly by an enzyme called carbonic anhydrase.

Bicarbonate Ion Formation

Bicarbonate ion formation is a key process in the transportation of carbon dioxide in the blood. When carbon dioxide enters the red blood cells, it reacts with water to form carbonic acid (H_2CO_3).
Carbonic acid is unstable and quickly dissociates into bicarbonate ions (HCO_3^-) and hydrogen ions (H^+). This reaction is reversible and can be represented as: \[ CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons HCO_3^- + H^+ \]
The formation of bicarbonate ions is a crucial step as it allows for the efficient transport of carbon dioxide in the blood. Once formed, bicarbonate ions are transported out of the RBCs into the blood plasma, where they are carried to the lungs for expulsion.

Carbonic Anhydrase

Carbonic anhydrase is an enzyme that significantly speeds up the reaction between carbon dioxide and water in red blood cells. This enzyme is abundantly present in RBCs and catalyzes the conversion of CO2 and water into carbonic acid, which then dissociates into bicarbonate ions and hydrogen ions.
Without carbonic anhydrase, this conversion would occur far too slowly to meet the body’s demands for gas exchange, particularly during activities that require increased oxygen intake and carbon dioxide expulsion, such as exercise.
The presence of this enzyme allows the conversion process to occur almost instantaneously, facilitating rapid and efficient gas transport throughout the body.

Blood Plasma

Blood plasma is the liquid component of blood in which cells are suspended. It plays a critical role in transporting nutrients, hormones, and waste products throughout the body. When it comes to carbon dioxide transport, blood plasma serves as a carrier for bicarbonate ions.
Once bicarbonate ions are formed within the red blood cells, they are exchanged with chloride ions through a process known as the chloride shift. This exchange allows bicarbonate ions to move into the blood plasma, where they circulate until they reach the lungs.

• The blood plasma enables the safe transit of waste gases away from tissues.
• It acts as a buffer, helping to maintain pH balance in the blood.

This system is essential for maintaining homeostasis and ensuring that metabolic waste products are efficiently removed from the body.

Carbon Dioxide Conversion

The conversion of carbon dioxide in the blood is a complex process central to respiratory function and blood pH regulation. It involves the transformation of carbon dioxide into different forms, including bicarbonate ions, for easier transport.
The process begins when CO2 diffuses into red blood cells. Inside these cells, carbonic anhydrase gets to work, rapidly converting CO2 and water into carbonic acid. The acid then dissociates into bicarbonate and hydrogen ions—this is the core of the carbon dioxide conversion process.
More than 70% of CO2 in the blood is transported as bicarbonate ions, showcasing how efficient and vital this conversion is. It ensures that the bulk of CO2, a potential acidifying agent in the blood, is neutralized, allowing for a steady physiological pH and effective removal of CO2 at the lungs, ready for exhalation.