Immunology Flashcards
Immune system:
network of organs and tissues, cells and molecules designed to work together to identify and protect the body from infectious pathogens and other diseases
Primary organs:
(central or regenerative) -Contain developing lymphocytes -bone marrow, thymus
Secondary organs:
(peripheral) -contain more mature cells active in host tissue -spleen, lymph nodes, MALT; includes tonsils, adenoids, appendix, peyer’s patches in GI tract
_______ and ______ of immune system divided into two groups based on role in cellular development and host defense
ORGANS and TISSUES of immune system divided into two groups based on role in cellular development and host defense
Bone marrow is the site of ________ and ___________
Bone marrow is the site of HEMATOPOIESIS and B CELL MATURATION. -as a person ages, most hematopoiesis in flat bones
The ______ is a bi-lobed organ in the upper anterior thorax.
The THYMUS is a bi-lobed organ in the upper anterior thorax. -each lobe is divided into multiple lobules by fibrous septa. -each lobule has outer cortex and inner medulla -cells enter via blood, exit via lymphatic vessels or blood
Where do T Cells mature?
Thymus
Sail sign:
Infants have a much larger thymus - can be seen on x-ray in their top right chest.
What are the two sections of the spleen?
white pulp and red pulp
T cells are near arterioles in the _______ ______. B cells are more _______ in the white pulp.
T cells are near arterioles in the periarteriolar sheath. B cells are more peripheral in the white pulp.
What is red pulp involved in?
Red pulp is involved with red blood cell breakdown
Which organ is the major site of immune responses to pathogens and other foreign substances in the blood?
The spleen
what are lymph nodes?
-small, nodular aggregates of lymphoid tissue located along lymphatic channels/vessels
Describe the structure of lymph nodes:
-outer fibrous capsule -multiple afferent lymphatic vessels and one efferent lymphatic vessel -three concentric regions
What are the three concentric regions of lymph nodes?
cortex, paracortex, and medulla
What is the first organized lymph structure to encounter foreign antigens?
Lymph nodes
Fluid draining from the lymph node is enriched with _______ and ________.
Fluid draining from the lymph node is enriched with antibodies and many more lymphocytes.
What are the lymph node groups?
-Cervical -Supraclavicular -Axillary -Mediastinal -Supratrochlear -Mesenteric -Inguinal -Femoral -Popliteal
Cervical lymph nodes:
-Location: head and neck -Site of drainage: scalp, face, nasal cavity, pharynx
Axillary lymph nodes:
-Location: axilla -Site of drainage: Arm, chest wall, breast
Inguinal lymph nodes:
-Location: Groin -Site of drainage: genitalia, buttocks, anus, abdominal wall, leg
Mediastinal lymph nodes:
-Location: in/near mediastinum, central posterior thorax -Site of drainage: mid-chest, upper abdomen, lungs
Mesenteric lymph nodes:
-Location: lower abdomen, near intestine -Site of drainage: small and large intestine, upper rectum
What does MALT stand for?
Mucosal-associated lymphoid tissue
What is MALT?
aggregates of lymphocytes found throughout mucosal surfaces in body (GI, respiratory, and urogenital tracts)
GALT:
Gut-associated lymphoid tissue (tonsils, adenoid, appendix, Peyer’s patches)
BALT:
Bronchial/tracheal-associated lymphoid tissue
NALT:
nose-associated lymphoid tissue
VALT:
vulvovaginal-associated lymphoid tissue
Number of antibody producing cells in _____ is much larger than in all other tissues combined:
Number of antibody producing cells in MALT is much larger than in all other tissues combined
What tissue provides crucial defense against pathogens encountering mucosal surfaces?
MALT
How is lymph fluid similar/different to blood and blood flow?
-Lymph has white blood cells and plasma, but no red blood cells. -Lymph travels through branching and deep vessels, but is NOT a circular system like vascular system is. Smallest lymphatic vessels extend to tissues and have closed ends.
What are the main functions of the lymphatic system?
-Collect/drain excess fluid from surrounding tissue and return it to the vascular system -Absorb fat from the villi of the small intestine -Be a conduit for immune cells to and through the nodes back into circulation
Lymphatic drainage is initiated by WHAT?
interstitial fluid uptake in lymphatic capillaries
How does lymph flow?
-There is no “pump” -Flow by skeletal muscle contraction, arterial pulsation, unidirectional valves, smooth muscle in walls of larger vessels
Lymph flows through multiple ______ before entering circulation in the _____.
Lymph flows through multiple LYMPH NODES before entering circulation in the BLOOD.
Upper right lymph drainage system:
-Lymph from upper right areas of body (right side of head, heart, and lungs) drains to the right lymphatic duct which empties into the right subclavian vein
Lower/left body lymph drainage system:
Most of the body (besides right side of heat, heart, and lungs) drains into the thoracic duct, which then drains into the left subclavian vein.
How do the contents of lymph fluid change as the fluid progresses closer to circulation?
-phagocytic cells and antigens may be in lymph entering lymph node -Initiation of an immune response, processing of foreign antigens -fluid exiting nodes with higher number of immune cells and antibodies
Virchow’s Node:
left supraclavicular lymph node - palpate by running fingers over left clavicle. This is a super important node - you won’t be able to feel lymph node enlargement with any infection anywhere in the abdomen or left chest, but because of drainage the Virchow’s node will also be enlarged, and will alert you that something is going on in the left chest or abdomen. Abnormal for routine infections, so this patient would need x-rays/imaging. Always a concern for malignancy, especially in older populations.
Common disease processes associated with lymphatic vessels and nodes:
-lack of proper function of lymphatic drainage, can lead to lymphedema -also common problems associated with infection, blockage, malignancy
Lymphedema:
Interstitial collection of lymph due to disruption of lymphatic flow -usually progressive, can lead to tissue hypertrophy and fibrosis -swelling, skin changes, pain, restricted range of motion, and nonpitting edema -complications: skin infections, malignancy, reduced quality of life including aspects of emotional, physical, and social well-being
Primary lymphedema:
Associated with genetic or inherited conditions -associated with lymphatic disruption, can present at any age
Secondary lymphedema:
Due to underlying disease or is a consequence of prior treatment -in US, most due to malignancy or cancer therapy -etiology: obstruction of lymphatic vessels or nodes (compression by a tumor) or infiltration of the vessels by tumor cells; most common breast cancer)
Filariasis:
Most common cause of secondary lymphedema worldwide
Filariasis transmission:
-Due to infection by the nematode Wuchereria bancrofti -Infection is transmitted via mosquitos (adult worms reside predominantly in the lymphatic vessels and nodes, especially legs; scrotum is the top site in post-pubertal males
What is the standard method for diagnosing active infection?
The identification of microfilariae on a thick smear of blood (blood draw at night 10pm-2am, the time period when organisms are in peripheral blood -serologic enzyme immunoassay tests alternative test
The main goal of Filariasis treatment:
To kill the adult worm -DEC is both microfilaricidal and active against the adult worm; this is drug of choice for lymphatic filariasis -Lymphedema and elephantiasis are not indications for DEC treatment - most people with lymphedema are not actively infected with the filarial parasite
Lymphangitis:
Inflammation or infection of the lymph vessels -usually site of infection distal to the affected vessel -most common pathogen is streptococcus pyogenes
Chylothorax:
Term used for accumulation of lymph in the thorax -often consequence of severing the thoracic duct during surgery
Lymphadenopathy:
Enlargement (<1 cm) of one or more lymph nodes -localized - only 1 body area, generalized >2 body areas -lymphadenopathy can be associated with infection, inflammatory disorders, malignancy, etc.
Lymphadenitis:
Lymphadenopathy with pain and/or signs of inflammation (e.g. redness, tenderness) -usually associated with active infection
Lymphoma:
Type of cancer/malignancy of varied cells of the immune system
The first line of defense against microorganisms:
the intact skin and mucous membranes
the second line of defense against microorganisms:
the innate (natural) arm of the immune system
The third line of defense against microorganisms:
The adaptive (acquired) arm of the immune system (takes several days for this to become fully functional_
The two components of the adaptive arm of immunity are:
-Cell-mediated immunity -antibody-mediated (humoral) immunity
Innate responses use:
-Epithelial barriers -Phagocytic cells (neutrophils, macrophages, and dendritic cells) -cells that release inflammatory mediators (basophils, mast cells, and eosinophils) -and NK cells