Chapter 11- Immunity Flashcards
(45 cards)
Immune system
The body’s internal defense
system
What is a phagocyte? and how are they spread through the body?
Phagocytes are white blood cells that are produced continuously in the bone marrow. They are stored in the bone marrow before being distributed around the body in the blood
What are phagocytes responsible for?
They are responsible for removing dead cells and invasive microorganisms. They carry out what is known as a non-specific immune response
What are the two main types of phagocytes?
Neutrophils
Monocytes (mature to Macrophages)
What is the main action/ process of removing a pathogen by a phagocyte
The process of recognizing and engulfing them.
What are neutrophils?
Neutrophils short-lived phagocyte cells that travel throughout the body and often leave the blood by squeezing through capillary walls to ‘patrol’ the body tissues.
Mode of action of neutrophils
1-neutrophils are attracted to the location of pathogens because of the chemicals the produce.
2-There could also be the attraction made from antibodies as well.
3-Once they move closer, the neutrophils cell surface membrane extends out to the pathogen and engulfs it trapping it within a phagocytic vacuole. (endocytosis)
4- Digestive enzymes are released by lysosomes to destroy the pathogen.
5-After destroying the pathogen, neutrophils die.
What are monocytes?
Monocytes are larger than neutrophils and are long-lived cells. Rather than remaining in the blood, they move into several organs.
How do Monocytes mature to Macrophages?
After being produced in the bone marrow, monocytes travel in the blood and then develop into macrophages once they leave the blood to settle in the various organs.
List down the various organs that macrophages travel to once they leave the blood
-lungs
-spleen
-lymph nodes
-kidney
Mode of action of macrophages
1-Macrophages carry out the same processes as neutrophils however do not break down the pathogen completely
2-They simply cut up the pathogens so that they can display the antigens
3-This makes them to be displayed antigens aka antigen- presenting cell which are then recognised by lymphocytes.
What is an antigen
A foreign substance introduced to the body that stimulates an immune response
What is an antibody
An antibody is a glycoprotein made by plasma cells derived from B-cells and are secreted in response to antigens. Antibodies have complementary shapes to their antigen
What is immune response
A complex series of responses of the body toward foreign antigen with the use of white blood cells
What does Non-self and Self refer to
Non-self: Substances/cells that are recognised as foreign and stimulates an immune response
Self: Substances/ cells that are not recognised as foreign and don’t stimulate an immune response.
Give examples of Non-self substances/cells
-Bacteria
-Viruses
-A different blood type from a blood transfusion
Where are antigens found
-cell Surfaces of pathogens:
-surfaces of viruses
-bacteria cell walls
State the features of a lymphocyte
- smaller than phagocytes
- large nucleus that fills the cell
- produced in the bone marrow before birth
Describe B-lymphocytes
Mention;
- they remain in the bone marrow until they are mature and can travel to the spleen and lymph nodes and other parts
- Each type of B-cell makes one type of antibody however aren’t immediately released.
-Their combinations are specific to the antigen based on the glycoprotein receptor
B-cells that have complementary receptors to the antigen present are stimulated to divide by mitosis. This is known as____________ ________________
CLONAL SELECTION
Describe the mode of action for B-cells
1- One B-cell will contain an antibody receptor that is specific to the antigen that was introduced
2- This B-cell will divide by mitosis to form plasma and memory cells
3- Plasma cells will be able to secrete antibodies that are specific to the antigen in step 1
4- The antigen may re-enter again and due to our memory cells produced in stage 2, they divide once again by mitosis and plasma cells are produced to secrete antibodies.
Describe T-lymphocytes
Mention;
- Immature T-cells leave the bone marrow to mature in the thymus
-They have specific cell surface receptors similar to antibodies that bind to antigens
- there are 2 types of T-cells; killer and helper
What is the function of the T-helper cells
~T-helper cells can secrete a hormone like gland called cytokines. They stimulate B-cells to divide into antibody secreting plasma cells.
~They can also help increase the rate of phagocytosis in macrophages
What is the function of the T-killer cells
-These guys produce toxins that kill body cells and the pathogen by attaching to the antigen .