chapter 48 Flashcards
What’s the purpose of skin as a nonspecific defence?
Acts as a physical barrier to pathogens (keratin). Releases sweat which contains chemicals that are harmful to bacteria and fungi. Sweat contains lysozyme which can destroy the cell walls
of bacteria.
How do Mucous membranes act as nonspecific defence?
they are Epithelial cells that protect the interior surface of the body. They secrete mucous, a sticky fluid that traps pathogens.
How does the inflammatory response act as a nonspecific defence?
- injured cells release chemical alarm signals as pathogens enter through a cut.
- In response, nearby capillaries swell and become porous. The area around the wound swells and becomes
warm. Phagocytes arrive to attack the pathogens. - Phagocytes destroy the pathogens and the wound begins to heal.
How does histamine act as a nonspecific defence?
chemical messenger that triggers increased blood flow to an injury and increases the
permeability of the surrounding capillaries. This response allows white blood cells to pass through the capillary
walls to reach an injury. Redness, swelling, warmth and pain are all symptoms of inflammation.
How does neutrophil act as nonspecific defence?
common type of phagocyte, making up between 50-70% of the white blood cells in the
body. They engulf and destroy any type pathogen they encounter.
How does macrophage act as a nonspecific defence?
type of phagocyte that is found in body tissues. In addition to consuming and destroying
pathogens, macrophages also rid the body of worn-out cells and cellular debris.
How do natural killer cells act as a nonspecific defence?
large white blood cells that differ from phagocytes in that they attack the cells that
have already been infected by pathogens. Natural killer cells are effective at killing cancer cells and viruses
and do so by puncturing the cell membranes of its target cells. This allows water to permeate the cell causing it
to burst.
How do interferons act as a nonspecific defence?
is a protein that inhibits the reproduction of viruses. It is produced in small amounts by cells that
are infected by a virus. Interferon stimulates neighbouring cells to produce and enzyme that inhibits the
synthesis of viral proteins.
How does fevers act as a nonspecific defence?
the elevation of body temperature above the normal 37°C. Some pathogens trigger fever, as do
chemical signals released by macrophages. Fever suppresses the growth of some bacteria and may promote
the action of white blood cells.
Define the immune system.
part of the body’s specific defenses, the immune system has the job of fighting off
invading pathogens and preventing the growth and spread of cancer. The immune system consists of
several organs and the white blood cells found in these organs (including blood and lymph tissue). Immune
system organs include the following: bone marrow, thymus, lymph nodes, tonsils, adenoids, and the
spleen
How does bone marrow act as a specific defence?
manufactures billions of white blood cells needed by the body every day. Some white blood
cells remain in the marrow, while others travel to the thymus, a gland located in the upper chest above the
heart, to mature.
How do lymph nodes act as a specific defence?
are located throughout the body and contain large numbers of white blood. Lymph nodes
filter pathogens from the lymph and expose them to white blood cells.
How does the spleen act as a specific defence?
is a fist-sized organ located behind the stomach that is also stocked with white blood cells and filters
pathogens from the blood.
How do lymphocytes act as a specific defence?
white blood cells of the immune system comprising two types: B cells produced in the bone
marrow and that develop and mature there; T cells also produced in the bone marrow but develop in the
thymus. Lymphocytes contain receptor proteins that recognize and bind to antigens that match their
particular three-dimensional shape. The immune system produces millions of different types of lymphocytes to
defend against the millions of antigens that could potentially harm the body.
How do antigens act as a specific defence?
any substance that the immune system recognizes as a potential pathogen and that provokes an
immune response. Apart from a wide array of pathogens, antigens can include bacterial toxins, insect venom
