Which of the following is not a function served by plasma proteins? Select one: a. Facilitate retention of fluid in blood vessels b. Contribute to the buffering capacity of the blood c. Transport O2 in the blood d. Serves as antibodies e. Play an important role in blood clotting The correct ranking for modes of CO2 transport in the blood, from least to the most CO2
The Correct Answer and Explanation is:
Plasma Proteins:
The question asks about the functions of plasma proteins. Let’s analyze each option:
- a. Facilitate retention of fluid in blood vessels: This is correct. Plasma proteins, particularly albumin, help maintain osmotic pressure in the blood, preventing excessive fluid from leaking into tissues and ensuring fluid balance.
- b. Contribute to the buffering capacity of the blood: This is correct. Plasma proteins, especially albumin, play a role in buffering by helping maintain the pH of blood.
- c. Transport O2 in the blood: This is incorrect. The transport of oxygen in blood is primarily the function of hemoglobin, not plasma proteins. Hemoglobin is located in red blood cells, not in plasma.
- d. Serve as antibodies: This is correct. Some plasma proteins, like globulins, function as antibodies that help defend the body against pathogens.
- e. Play an important role in blood clotting: This is correct. Plasma proteins like fibrinogen are crucial in the coagulation process, forming a clot to prevent excessive bleeding.
Correct Answer:
- c. Transport O2 in the blood is the function that plasma proteins do not serve. Oxygen transport is a task for hemoglobin, which is found in red blood cells.
CO2 Transport Modes in Blood (from least to most CO2):
The transport of carbon dioxide (CO2) in the blood occurs in three main forms:
- Dissolved in plasma: Only a small percentage of CO2 is dissolved directly in the plasma.
- Bound to hemoglobin (carbaminohemoglobin): A moderate amount of CO2 binds to the amino groups of hemoglobin and other proteins.
- As bicarbonate ions (HCO3-): The majority of CO2 is converted into bicarbonate ions in red blood cells, which are then transported in the plasma.
Correct Ranking (from least to most CO2):
- Dissolved CO2 (least)
- Bound to hemoglobin
- Bicarbonate ions (most)
This ranking reflects the relative amounts of CO2 transported in each form. Most of the CO2 in the blood is carried as bicarbonate (about 70%), with a smaller proportion bound to hemoglobin (around 23%) and a very tiny fraction dissolved directly in plasma (around 7%).
