chapter 21- lymphatic and immune systems Flashcards
lymph composition and function
compoasition: proteins, salts, glucose, fats, water, WHITE blood cells
function: fight infections and maintain fluid levels in body
pathway of circulation of lymph
- Collect from terminal lymph capillaries
- Goes through collecting lymphatic vessels with valves
- Goes to superficial lymph nodes *(cervical region, axillary region, inguinal region) or deep lymph nodes (tracheobronchial, aortic, and illiac lymph nodes)
- Lymphatic trunks collect lymph from vessels and nodes
- Then lymph goes to the lymphatic duct (left and right subclavian ducts)
lymphatic vessels that deliver lymph from upper extremities. lower extermities, and abdominopelvic area
lumbar trunks – lower limbs
interstinal trunks - from digestive organs
bronchomediastinal trunks – from thoracic viscera
subclavian trunks – upper limbs and thoracic wall
jugular trunks - from head and neck
unique properties of lymph circulation
lymph vessels contain more valves than veins do
pressure is only 1 mmHg
3 classes of lymphocytes
T-cells (thymus dependent) –> 80%
B-cells (bone marrow-derived) –> ~10-15%
NK cells (Natural killer) –> ~5-10%
types of T cells
CYTOTOXIC (CD+ [MHC I]) T cells –> produce cell-mediated immunity; attack eukaryotic cells infected by viruses, transplanted cells, some cancer cells
HELPER (CD4+ [MHC II) T cells -> stimulate functions of T cells and B cells by secreting cytokine
SUPPRESSOR-INDUCER T cells –> inhibit function of T cells and B cells
REGULATORY T cells (TREGS) –> helper + suppressor T cells that control sensitivity of immune response
MEMORY T cells –? quickly respond to previously encountered antigens
B lymphocytes (and plasma cells)
produce specific antibodies in response to exposure to different antigens
as plasma cells, they produce and secrete immunoglobulkins as part of humoral-mediated immunity –> results in destruction of pathogen
NK cells function
immunological surveillance and atttack foreign cells, virus-infected cells, and cancer cells
part of innate immune response: recognize stressed cells in absence of antibodies and MHC, leading to faster immune reaction; recognize cells that lack “self” cell surface molecules or certain glycoproteins
“Activation” of lymphocytes
ORIGIN – B and T lymphocyte precursors in red bone marrow
MATURATION –> develop immunocompetence and self-tolerance
SEEDING SECONDARY LYMPHOID ORGANS AND CIRCULATION –> naiive lymphocytes leave area and “seed” secondary lymphoid organs + circulate thru blood and lymph
ANTIGEN ENCOUNTER + ACTIVATION –> activated when lymphocyte receptors bind its antigen
PROLIFERATION + DIFFERENTIATION –> activated lymphocytes proliferate + differentiate into effector cells and memory cells, which are continuously in blood and lymph thru secondary lymphoid organs
PRIMARY lymphoid organs
bone marrow
thymus
SECONDARY lyphoid organs
lymph nodes, spleen, tonsils
aggregated lymphoid nodules
appendix
location of SUPERFICIAL lymph nodes
cervial region
axillary region
inguinal region
what is the major function of the lymph nodes?
cleanse lymph of pathogens, act as filters that purify lymph before returning it to venous circulation
thymus location and function
location: mediastinum
two thymic lobes that are divided by septa into smaller lobules
function: is site where immature lymphocytes develop in T lymphocytes (thymosin and thymopoietin)
thymus + aging
thymic involution –> atrophies after puberty (~3% loss weight/year) –> diminishing effectiveness of immune system w/ age
