Chapter 14 Flashcards
The human body has evolved a complex system of defenses to fight
pathogens (organisms that cause disease) and keep us healthy
What is one way the immune system defends the body in a nonspecific way?
by attacking anything foreign
The immune system can also identify
certain invading cells and attack them specifically
The nonspecific immune system consists of
2 lines of defense
the 1st and 2nd line of defense
First Line of Defense
a barrier that helps prevent pathogens from entering the body.
First Line of Defense :
The body has several different types of barriers
skin- blocks pathogens
mucous membranes- release mucus to trap microbes
cilia- in the respiratory system, sweeps out mucus with it’s trapped microbes
stomach acid- kills germs that enter through the nose and mouth
Microbes that get into the body encounter the
second line of nonspecific defense
-it’s not meant to limit the spread of invaders in advance of specific immune responses
How many types of immune responses are there?
inflammatory response
phagocytes
interferons
Inflammatory response
characterized by swelling, redness, soreness, and increased warmth in the area
What is the purpose of the inflammatory response?
to increase the blood supply to the area, thus increasing nutrients - including oxygen and white blood cells to fight disease
How does the inflammatory response work?
histamine and increased body temperature
Histamine
triggers vasodilation (enlargement of blood vessels), which increases blood supply to the area bring more phagocytes to gobble up germs
Histamine is also responsible for the symptoms of the
common cold: sneezing, coughing, redness, and itching and runny nose and eyes- all in attempt to get rid of the body of invaders
Increased body temperature speeds up the
immune system and makes it more difficult for microbes to function
Phagocytes
also consume invading microbes
Macrophages (‘giant’ eaters’)
a type of white blood cell that extend psuedopods and engulf huge numbers of microbes over a long period of time
Interferons
these chemicals are released by the immune system to block against viral infections
The 3rd line of defense is
specific and consists of lymphocytes
2 types of lymphocytes
B lymphocytes and T lymphocytes
- both originate in the bone marrow
- both cell types circulate in the blood, lymph, and lymphatic tissue: spleen, lymph nodes, tonsils, and adenoids
- both recognize different specific antigens (germs)
Antigen
anything that triggers an immune response
B lymphocytes
produce antibodies against a specific antigen in what is called a humoral response
T lymphocytes
fight pathogens by hand-to-hand combat in what is called a cell-mediated response
Antibodies are part of the 3rd line of defense- the specific immune response.
Each antibody has the ability to
bind to only one particular antigen
Antibodies angainst influenza bind to and only
neutralize the influenza virus; they have no effect on the polio virus
Antibodies neutralize antigens by
binding to them and by forming an antigen-antibody complex that can then be consumed by a phagocyte
Clonal selection
a fundamental mechanism in the development of immunity
-antigens that have entered the body bind to specific B or T lymphocytes