Have a single, bean-shaped cell nucleus and lack visible cytoplasmic granules.
In the tissues, monocytes mature into macrophages. Monocytes have a lifespan of 2
weeks; macrophages live for several months.
Macrophages are more effective as phagoc
Phagocytosis is a Nonspecific Defense Mechanism
Metchnikoffs theory of phagocytosis: cells could actively seek out and engulf foreign
particles in the body.
Phagocytosis is the capturing and digesting of foreign particles, including pathogens, by
It is the lymphatic tissues in which lymphocytes mature, differentiate, and divide.
The primary lymphoid tissues consist of the thymus, which lies behind the breast bone,
and the bone marrow. Both are sites are where T and B lymphocytes form or mature.
Inflammation Plays an Important Role in Fighting Infection
Inflammation is a nonspecific defensive response by the body to trauma.
It develops after a mechanical injury, such as an injury or blow to the skin, or from
exposure to a chemical agent. An inf
An Overview to Host Immune Defenses
Immunity: how the human body can generate resistance to a particular disease,
whether by recovering from the disease or as a result of vaccination.
Elie Metchnikoff devised the first experiments to study immunity by inv
Leukocytes (White Blood Cells)
Leukocytes have no pigment in their cytoplasm and therefore appear gray when
These cells are produced in the bone marrow. Number about 4,000-12,000 per microliter
of blood and have different lifespans, depending o
Moderate Fever Benefits Host Defenses
Fever is an abnormally high body temperature that remains elevated above the normal 37
Fever supports the immune system response in trying to gain an advantage over the
pathogens by making the body a less
Complement Marks Pathogens for Destruction
Complement is a group of nearly 30 inactive proteins circulating in the
bloodstream that represents another innate defense to disease.
If a microbe penetrates the body, complement proteins become sequentially
Host chemicals also provide an antimicrobial defense to infection by inhibiting microbial
growth or viral replication.
Resistance in the vaginal tract is enhanced by the low pH (develops when the
lactobacillus species in the microbiota b
The Innate Immune Response
Depends upon the general well-being of individual and proper functioning of the bodys
Innate defenses can contain pathogens, if not eliminate them, while an acquired immune
response is generated or reestablished.