Abdomen 07: Spleen and Immune System Flashcards
Lacteals
Small intestine lymphatics
Chylomicrons
Protein-coated lipid droplets found in lacteals
Where does lymph below the diaphragm drain to?
Posterior abdominal lymph nodes
Where does lymph from the gut drain to?
Preaortic lymph nodes
From what structures does lymph drain into the lateral aortic lymph nodes?
Lateral abdominal body wall, kidneys, suprarenals, testes, ovaries
Cyesterna chyli
The fusion of the preaortic and lateral aortic trunks; the para-aortic trunk also drains into here
Lumbar lymph trunk
Another term for the lateral aortic lymph trunk
Para-aortic lymphatics
Lymphatics that drain from lateral and retroperitoneal structures
What are the three main levels of defense of the immune system?
Barrier, innate immunity, adaptive immunity
What consists the barrier level of the immune system
Physical barriers (skin, epithelia), cemical barriers (mucus, acids), and biological barriers (commensal bacteria)
Innate immunity
Rapid response intensity to a limited number of common antigen patterns acquired at birth
Adaptive immunity
Immunity that is learned from prior infections; slow first response but subsequent responses are quicker and stronger
Approximately how many patterns are encoded in innate immunity?
100
Approximately how many antigens are encoded in adaptive immunity?
10^10
What are the main cellular components of innate immunity?
Neutrophils, macrophages, dendritic cells, natural killer cells
What are the main humoral components of innate immunity?
Complement factors
What are the main cellular components of adaptive immunity?
T and B cells
What are the main humoral components of adaptive immunity?
Antibodies
What are the four tactics to fight off invaders?
Isolation, disruption, ingestion, inflammation
Opsonization
An isolation technique in which an antigen is coated by complement and/or Ig factor to facilitate phagocytosis
How are invaders disrupted?
Apoptosis induced by natural killer cells and cytotocix T cells
A membrane attack complex induced by the complement system
What cells are invovled in invader ingestion?
Macrophages and neutrophils
What activates the immune system?
Antigen recognition
Antigens
Sequences of sugars, fats, or amino acids that are foreign to the body
Epitopes
The smallest part of an antigen that can be detected
MHC 1
Major histocompatability complex 1; binds representative samples of all proteins within the cells and presents them on the surface
How are MHC 1s useful?
They act as a billboard of what’s inside the cell. If killer T cells notice something wrong or missing, it’ll kill the cell
MHC 2
Major histocompatibility complex 2; binds representative samples of antigens encountered
What cells use MHC 2?
Antigen presenting cells and macrophages
Complement system
A system of innate immunity; 20 plasma proteins that can recognize ~100 antigens
What secretes the plasma proteins of the complement system?
Liver and GI tract epithelium
What activates the complement system?
Immunoglobins and antigens
Monocytes
Cells that become macrophages
Neutrophils
Motile phagocytes and granulocytes
Eosinophils
Respond to parasitic worm infections; also modulate inflammatory response in asthma and hay fever
Natural killer cells
Cells that attack cells presenting errors on MHC 1
Basophils
Cells that contribute to anaphylactic reactions and food allergies
Where are macrophages found?
In tissue
Dendritic cells
Cells that watch and run to follicular centers to activate fighters. They are antigen presenting cells
Mast cells
Cells found in the tissue that wait for attacking parasites
How do marophages deal with invaders?
After phagocytosing them, they use MHC2 to present the antigens to activate T cells
Immunoglobins
Produced by B lymphocytes and plasma cells that consist of two heavy chains and two light chains
What are the two regions of immunoglobin light chains?
Variable regions and constant regions
What determines an immunoglobin’s class?
Structure of the constant region
What determines an immunoglobin’s antigen binding specificty?
Structure of the variable region
What do B-lymphocytes differentiate into?
Some memory-B cells and mostly plasma cells
Where are B-lymphocytes activated?
Germinal centers of lymph nodes, MALT, and spleen
How are T-lymphocytes activated?
Antigen-presenting cells throughout the body
What are the four antibody classes?
IgM, IgA, IgG, IgE
IgM
An atibody class Great complement fixer; good opsonizer; first antibody made
IgA
An antibody class Resistant to stomach acid; protects mucosal surfaces; secreted in milk
IgG
An antibody class An ok completement fixer; good opsonizer; helps natural killer cells; can cross the placenta
IgE
An antibody class Protects against parasityes; causes allergies and anaphylactic shoks
What is the primary function of plasma cells
Secrete antibodies
Helper T cells
Differentiated T-lymphocytes that help activate B-lymphocytes
Memory T cells
Differentiated T-lymphocytes that remain in the blood to recognize an infection later on
Cytotoxic T cells
Differentiated T-lymphocytes that travel to tissues to attack infected cells
Primary lymphoid tissues
Bone marrow and thymus
Secondary lymphoid tissues
Spleen, lymph nodes, MALT; where lymphcytes are activated
Bone marrow
Primary site of hematopoiesis for all blood cells
What are the two lineages of blood cells?
Myeloid and Lymphoid
Thymus
Site of maturation of T-lymphocytes. There are no lymphatics here
Which structure exposes lymphocytes to antigens in the lymphatic system?
Lymph nodes
Which structure exposes lymphocytes to antigens in the blood?
Spleen
Which structure exposes lymphocytes to antigens in the outside world?
MALT
MALT
Mucosa Associated Lymphoid Tissue; tonsils, Peyer’s patches, appendices
Primary lymphoid follicles
Islands of follicular dendritic cells in a sea of B cells (mostly inactivE)
Secondary lymphoid follicles
Germinal centers; formed when activated B cells begin to proliferate through clonal division
What cells exist in the lymph node cortex
B lymphocytes in germinal centers
What cells exist in the lymph node paracortex
T lymphocytes
What cells exist in the lymph node medulla
Plasma cells
What cells exist in the lymph node sinuses?
Macrophages
What artery supplies the spleen?
Splenic artery
What nerves innervate the spleen?
Vagus nerve, sympathetics of T7-T9
What is the referred pain region of the spleen?
Left hypochondric region
What is the primary functions of the spleen?
Exposes immune system cells to antigens in the blood; filters blood; site of hematopoiesis in fetuses
Splenic white pulps
Consist of follicles and PALS; where immune functions are performed
Splenic red pulps
Highly vascular splenic tissue; filtration of blood
How does blood flow through the spleen?
Splenic artery -> trabecular artery -> central artery -> penicillary arteries -> sheathed capillaries
PALS
PeriArteriolar Lymphoid Sheath; cylindrical cuff of lymphoid tissue around central arteries containing mainly helper T cells
Marginal zone
A zone between the mantle zone and PALS of the spleen
Transcytosis
The transportation of something through endocytosis on one end of a membrane and exocytosis on the other end
What are the functions of the complement system
Opsonization, membrane attack complex, chemotaxis, clearance of immune complexes
What are the main functions of macrophages?
Phagocytosis, antigen presentation, ctyokine release
What are the three main antigen presenting cells
Dendritic cells, macrophages, B lymphocytes
What are the two subtypes of mast cells
Mucosal and connective tissue variants
What are the steps in dendritic cell activation and presentation of antigens?
1) Antigen capture
2) Activation
3) Maturation during migration
4) Presentation to T-lymphocytes
What cell types are derived from lymphoid progenitor cells?
B lymphocytes, T lymphocytes, natural killer cells
What are the main functions of antibodies?
Neutralization of antigens; opsonization; promoting cytotoxicity; activating the complement system
What are the steps of immune response initiation in the spleen?
1) Antigen diffuses with blood to dendritic cells
2) Dendritic cells capture antigen
3) Dendritic cells activate helper T cells
4) Helper T cells migrate to marginal zone to activate B-lymphocytes
What are the cell types involved in GI tube “sampling”
Dendritic cells and M cells (microfold cells)
