Question

Give reason: Monocytes are called scavengers.

Answer 1

Hint: The blood contains many types of cells including RBCs, Platelets along with WBCs. It is the job of white blood cells, WBCs to protect the body from foreign infections. Within WBCs there are many subtypes such as Monocytes, Lymphocytes and Granulocytes each of which has different functions.

Complete answer:
a) Monocytes are a subtype of leukocytes (White blood cells) that are also the largest of the blood cells and make 7-8 percent of the total leukocytes.
b) Monocytes have pronounced nucleus with a large number of granules in their cytoplasm.
c) Unlike lymphocytes which are involved in immunity-related reactions, the main function of monocytes is phagocytic.
d) While normally fewer in number and inactive, monocytes are migrating and can actively travel in the bloodstream.
e) In case of injury, these cells migrate and transform into highly phagocytic macrophages that are capable of engulfing large debris, infectious microbes as well as other blood cells. Their activity also alerts the immune system which triggers the activity of neutrophils that actively destroy the pathogen around the site of injury.
f) Thus in case of injury, monocytes help in preventing entry of pathogens into the body and further infections.
g) In normal conditions, Monocytes are responsible for removing injured and old cells from the tissues, as well as pathogens and infected cells, to prevent further infection in the body.
h) Monocytes/Macrophages are also responsible for removing cellular debris and any other foreign substance that may find its way into the bloodstream thus acting as a scavenger.

Note: Monocytes are an essential part of the immune system, their numbers tend to increase when you are suffering from any kind of infection. Monocyte count is also typically higher in children (~3000/ microliter of blood) than adults (800/ microliter).