What is innate immunity? - Answers 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? - Answers 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? - Answers The cells responsible for this response include
neutrophils, macrophages, dendritic cells (DC), natural killer (NK) cells, and intraepithelial lymphocytes.
Describe each type of leukocyte and explain their function: - Answers 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: - Answers 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? - Answers 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? - Answers The primary cells of the adaptive immune
system are the lymphocytes, APCs (antigen presenting cells), and effector cells.
Describe B & T lymphocytes and discuss their role in immunity: - Answers 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.
What is the function of humoral immunity? - Answers B lymphocytes function in humoral immunity to
produce antibodies.