Chapter 21 Part 2 Flashcards
immune system function
recognizes and attacks specific foreign particles (antigens)
destroys pathogens more and more effectively with each exposure (able to remember pathogens)
lymphocytes
white blood cells that recognize and attack antigens 2 types: B lymphocytes (B cells): multiply and differentiate into plasms cells that secrete antibodies T lymphocytes (T cells): directly attack antigens
types of T cells
cytotoxic T cells: directly lyse foreign cells
helper T cells: stimulate the various cells of the immune system
memory lymphocytes
wait within lymphoid tissue until the body encounters previously encountered antigen
the immune response is much more rapid and amplified
lymphocyte activation
lymphocytes originate in the bone marrow from lymphoid stem cells
ALL START IN BONE MARROW EVEN T CELLS
lymphoid tissue
- specialized type of CT in which vast quantities of lymphocytes gather to pathogens
- contains lymphoid follicles (clusters of densely packed lymphocytes )
location of lymphocyte tissue
- mucous membranes of the digestive, respiratory, urinary, and reproductive tracts, where it is called MUCOSA ASSOCIATED LYMPHOID TISSUE (MALT)
- all lymphoid organs except the thymus
lymphoid organs
primary lymphoid organs: (where it all begins)
- bone marrow
- thymus
secondary lymphoid organs: (where lymphocytes go after they become competent)
- lymph nodes
- spleen
- tonsils
- lymphoid muscles in the intestine and the appendix
functions of lymphoid organs
bone marrow and thymus:
-produce T and B lymphocytes
other lymphoid organs:
-gather and destroy infectious microorganisms within their tissue
thymus
- located in the superior thorax and inferior neck, just posterior to the sternum
- gradually loses its functioning ability as a person grows older
- site of T cell immunocompetence (maturation)
- the only lymphoid organ that does not directly fight antigens
lymph nodes
- the organs which the lymphatic and immune systems interact
- lymphocytes in the nodes challenge antigens where they are destroyed and B and T cells are activated
spleen
-the largest lymphoid organ
- located just posterior to the stomach
-two main blood cleansing functions:
the removal of blood-borne antigens
the removal and destruction of old or defective blood cells
-consists of red pulp and white pulp
-antigens enter the white pulp and activate the immune response
-red pulp is involved with the disposal of worn-out blood cells
tonsils
- swellings of the mucosa lining pharynx (throat)
- four groups of tonsils are arranged so that they surrounds the entrance to the pharynx
- gather and remove many pathogens that enter the pharynx
- gathered pathogens activate an immune system
aggregated lymphoid nodules and the appendix
- sites in the intestine where MALT is especially abundant
- sample many different types of antigens and produce a wide range of memory lymphocytes
- aggregated lymphoid nodules (Peyer’s patches) are clusters of lymphoid follicles in the walls of the distal part of the small intestine
- the appendix (located at the beginning of large intestine )contains heavily concentrated lymphoid tissue
