The movement of leukocytes through the blood vessel wall is known as __.
A agglutination
B hematocrit
C diapedesis
D leukemia
The correct answer and explanation is:
Correct Answer: C) Diapedesis
Diapedesis is the process by which leukocytes, or white blood cells, move out of the circulatory system and into tissues. This movement takes place through the walls of capillaries and post-capillary venules. It plays a critical role in the immune response, allowing leukocytes to reach sites of infection, inflammation, or injury.
During diapedesis, leukocytes first slow down and roll along the inner lining of the blood vessel. This is facilitated by selectins, a type of adhesion molecule on endothelial cells. Once the leukocytes detect chemical signals like cytokines from inflamed tissues, they become activated and express integrins that enable firm adhesion to the vessel wall. Following this, the leukocytes squeeze between the endothelial cells, passing through the basement membrane to enter the affected tissue. This step is also referred to as transmigration.
Diapedesis is essential in immune surveillance and in responding to infection. Without it, white blood cells would be unable to exit the bloodstream efficiently and target pathogens or damaged tissues. It is tightly regulated to prevent excessive or inappropriate immune cell migration, which can lead to tissue damage, as seen in autoimmune diseases.
The other answer choices refer to different biological concepts. Agglutination (A) is the clumping of particles, typically referring to red blood cells during immune reactions. Hematocrit (B) is the percentage of blood volume that is made up of red blood cells. Leukemia (D) is a type of cancer affecting white blood cells, leading to their abnormal proliferation. These are unrelated to the process of white blood cells moving through vessel walls.
Thus, the correct and specific term for the movement of leukocytes through the blood vessel wall is diapedesis.