portage pathophysiology module 3
define innate immunity - CORRECT ANSWER โโโ Innate immunity, also called
natural immunity, is the first line of defense. This type of defense is in place before
an infection takes place and can function immediately. It is comprised of physical,
chemical, cellular, and molecular defenses.
How does the skin act as a physical barrier? - CORRECT ANSWER โโโ The skin's
design makes it a strong physical barrier. It has closely packed cells in multiple
layers that are continuously being shed. Keratin covers the skin, which creates a
salty, acidic environment inhospitable to microbes. It also contains antimicrobial
proteins and lysozymes that inhibit microorganisms and help to destroy them.
What cells are involved in innate immunity? - CORRECT ANSWER โโโ neutrophils,
macrophages, dendritic cells (DC), natural killer (NK) cells, and intraepithelial
lymphocytes.
Describe each type of leukocyte and explain their function: - CORRECT ANSWER
โโโ Neutrophils are the most abundant in the body and are an early responder in
innate immunity and use phagocytosis to kill microbes.
Eosinophils are active in parasitic infections and allergic responses.
Basophils release histamine and proteolytic enzymes. Monocytes are the largest in
size and are released from the bone marrow and mature into macrophages and
dendritic cells where they engage in the inflammatory response and phagocytize
foreign substances and cellular debris.
Macrophages have a long life span, reside in the tissues, and are the first phagocyte
that organisms encounter. Neutrophils and macrophages work together on behalf of
the host's initial defense system.
Describe adaptive immunity: - CORRECT ANSWER โโโ Adaptive immunity, also
called acquired immunity, is the second line of defense and includes both humoral
and cellular mechanisms that respond to cell-specific substances known as
antigens. Adaptive immunity is acquired through previous exposure to infections
and other foreign agents. It can not only distinguish self from nonself but can
recognize and destroy specific foreign agents based on their different antigenic
properties. This response takes more time but is extremely effective.
What are antigens? - CORRECT ANSWER โโโ Antigens are present on the surface
of pathogens or other foreign substances that elicit the adaptive immune response.
What are the primary cells of adaptive immunity? - CORRECT ANSWER โโโ
lymphocytes, APCs (antigen presenting cells), and effector cells.
Describe B & T lymphocytes and discuss their role in immunity: - CORRECT ANSWER
โโโ B lymphocytes produce the antibodies (humoral immunity) and T lymphocytes
provide the cell-mediated immunity. B and T lymphocytes have the unique function
as the only cells to recognize specific antigens present on the surface of pathogens
and to remember them in the future.
