The Immune System Flashcards
The Immune system
The immune system is a collaboration between cells and proteins that work together to defend the body against infection.
Label and name the parts of the immune system
Tonsils, lymph nodes, thymus, bone marrow, spleen, peyer’s patch and appendix.
What are the roles of WBC?
1) White blood cells move through the bloodstream and in tissues, looking for signs of infection or tissue damage.
2_ They seek out and destroy pathogens (harmful organisms or substances foreign to the body that can cause disease).
3) They can identify antigens (substances on the surface of pathogens) and cause an
immune response.
Two main groups of WBC
The two main groups of white blood cells (leukocytes) are phagocytes and
lymphocytes.
Phagocytes
Phagocytes: absorb invading bacteria.
Neutrophils are a common phagocyte that help to fight bacteria.
In order to fight foreign invaders,
white blood cells must:
1) Exit the bloodstream to get to
where the invaders are
(DIAPEDESIS)
2) Engulf the invaders
(PHAGOCYTOSIS)
Lymphocytes
Lymphocytes: help the body remember the invaders and destroy them.
Describe diapedesis
WBCs must first go to the location of the invasion.
Once they arrive near the infected location, WBCs are able to change their shape to fit hrough very small spaces between capillary cell walls. This is known as diapedesis.
Diapedesis ensures that WBCs can get to interstitial spaces (not in blood vessels) where foreign invaders might be.
Describe phagocytosis
Phagocytosis is a form of cellular eating.
The phagocyte releases pseudopods, which are arm-like projections, that surround the foreign body and absorb it.
Once the foreign body is inside the phagocyte, enzymes break down (eat) the foreign body.
Lymphocytes maturation and differentiation process
Lymphocytes start out in the bone marrow and either stay there and mature into B cells or go to the
thymus gland to mature into T cells.
Innate immunity:
Everyone is born with innate (or natural) immunity, a type of general protection.
For example, the skin acts as a barrier to block germs from entering the body and the immune
system recognizes when some invaders could be dangerous.
Adaptive (active/acquired/specific) immunity
Develops throughout our lives. We develop adaptive immunity when we’re exposed to diseases or when we’re immunized against them with vaccines.
Lymphocytes allow the body to remember threats and help to destroy them.
In other words, the adaptive immune system prepares the body for future threats
Passive immunity
“borrowed” from another source, and it lasts for a short time. For example,
antibodies in a mother’s breast milk give a baby temporary immunity to diseases the mother has been exposed to.
B cells
B cells secrete (produce) antibodies that tell the T cells what invaders to destroy.
T cells
T cells are produced by the thymus gland. They help to destroy invaders.
