7.4 Immune Flashcards
What are the lymphoid tissues?
Bone Marrow: site of white blood cell production
Lymphatic Vessels: carry lymph from tissues to lymph nodes and lymph organs before returning to blood
Lymph Nodes, Tonsils, MALT, appendix: collections of lymphocytes for immune response and macrophages to remove debris
Spleen: replaces worn out blood cells, collections of lymphocytes for immune response and macrophages to remove debris
Thymus: site of T-lymphocyte (T-cell) maturation
What are the 3 functions of the lymphatic system?
Immune Support**
Fat Transport (lacteal)
Blood Volume
How does lymph return to the heart?
Valves Milking action of skeletal muscle Contraction of smooth muscle in vessel walls Pressure changes in the thorax Through lymphatic vessels
What are lymphocytes?
Naïve lymphocytes circulate through the blood and lymphatic vessels
Lymphocytes that
encounter pathogens
in lymph nodes stop
circulating
What are lymph nodes? Where are they located? Fxn?
tiny organs clustered along lymphatic vessels
less than 1inch in length, shaped like a lima bean
Concentrated in the cervical, axillary, and inguinal regions
2 functions:
Filtration: macrophages to clean up debris
Immune activation: lymphocytes to search for pathogens, infection
Describe a lymph node
Follicles “slow down traffic”
optimize pathogen lymphocyte interaction
concentrated regions of B-cells and T-cells, also macrophages
become swollen with infection when lymphocytes proliferate
What is the function of the tonsil?
Contain lymphocytes that destroy and remove pathogens that enter through air and food
Where are tonsils located?
Pharyngeal Tonsils (2) – posterior wall of the nasopharynx Palatine tonsils (2) – boundary between the soft palate and pharynx Lingual tonsil – base of tongue
How is the appendix important?
contains a high concentration of lymphoid follicles
protect against harmful bacteria in intestines
lymphocyte source for intestines
What is the fxn of the spleen?
Contains lymphocytes that initiate immune responses to antigens in the blood (blood borne pathogens)
removes debris and old blood cells and platelets from blood
stores RBC breakdown products
stores platelets and WBC’s
Where is the thymus? When is it active? What does it do?
bi-lobed developmentally regulated organ in the mediastinum
Function:
maturation of T-lymphocytes
Most active during childhood, it stops growing during adolescence and then gradually atrophies
What is an antigen
are any molecule or partial molecule that can trigger an immune response
= small part of something “other” that our cells recognize
What is an immunogen?
an antigen that invokes an immune response
What is immunogenicity?
ability to stimulate specific lymphocytes
What is a hapten?
foreign protein (carrier) + other molecule =basis for allergies a small molecule antigen that only elicits an immune response when combined with another protein
What are the 5 stages of infection?
incubation period: active replication of pathogen, no symptoms (1 day, upto months)
prodromal stage: first symptoms appear, vague sense of illness (malaise, myalgia, headache, fatigue), contagious
acute stage: full infection, rapid proliferation, inflammation, contagious
convalescent stage: resolution and containment begins (days to months)
resolution phase: total elimination of pathogen, signs and symptoms absent
What are neutrophils?
50-70% of WBC’s in circulation
first responders to injury, stress, acute inflammation
phagocytic activity
contain lysosomal enzymes to destroy bacteria
release free radicals, can cause injury to surrounding tissue
What are monocytes/macrophages? What’s the difference between the two?
monocytes within circulation, become macrophages in tissue
3-7% of WBC’s in circulation
inflammation response, later and more likely in chronic response than neutrophils
phagocytes
engulf, ingest, digest debris and antigens
synthesize and secrete cytokines
What are lymphocytes?
B-lymphocytes (B-Cells), T-lymphocytes (T-Cells)
25% of WBC’s in circulation
long term, adaptive immune response
recognize, target, form memory cells for antigens
B-cells: produce antibodies against pathogens
T-cells: target infected and cancerous cells
What are basophils?
<1% of WBC’s in circulation
increase in response to infection, primarily parasites
release histamine, heparin, prostaglandins, leukotrienes
assist with recruiting neutrophils
What are eosinophils?
2-4% of WBC’s in circulation
release histamine, peroxidase, ribonuclease, deoxyribonuclease, lipase, plasminogens
increase during allergic reactions and parasitic infection
What are the innate immune responses?
External Defenses: mechanical, chemical, microbial Phagocytes Natural Killer Cells Interferon Complement Fever Inflammation
What are the adaptive immune responses?
Antibody Mediated (Humoral) Immunity Cell-Mediated (Cellular) Immunity
How do mechanical external defenses function?
prevent entry of pathogens into the body
Skin
Fluid: flow of fluid flushes surfaces and body regions to remove pathogens
examples: mucus, urine, sweat, tears
cough & sneeze reflexes propel irritants out
