Cells and Organs of Immune System Flashcards
(31 cards)
1
Q
Basophils
A
- innate immunity
- granules stain dark blue, are toxic and used to destroy pathogens during phagocytosis
- important for defense against parasites, and possibly allergic and inflammatory reactions
2
Q
Eosinophils
A
- innate immunity
- granules stain bright red, contain toxic substances that destroy pathogens
- important for defense against parasites, and possible allergic reactions
- respond to chemokines released by neutrophils or lymphocytes
3
Q
Neutrophils
A
- innate immunity
- most numerous WBC
- stain neutral pink, have band-shaped nucleus that becomes segmented
- circulates blood stream looking for foreign objects
4
Q
Mast Cells
A
- innate immunity
- generated in the bone marrow
- parasitic infections and allergic reactions
- connective tissue and mucosal mast cells
- similar to basophilic leukocytes
5
Q
Monoctyes/Macrophages
A
- innate immunity
- monocytes circulate the bloodstream an enter tissues to replenish macrophages
- macrophages ingest and degrade bacteria
- macrophages can present antigens to lymphocytes and recycle dead cells
6
Q
Natural Killer Cells
A
- innate and adaptive immunity
- recognize and kill abnormal cells
- contains granules filled with proteins that can form holes in affected cells
7
Q
Dendritic Cells
A
- bone-marrow derived, but undergo maturation in bone marrow, lymphoid, or non-lymphoid tissues
- capture, process, and present antigens to T cells
- upon exposure, travel to secondary lymphoid organs
- Plasmacytoid dendritic cells can secrete type 1 interferons
8
Q
B Lymphocytes
A
- adaptive immunity (humoral)
- mature in bone marrow (bursa of fabricius)
- activated when bind antigens to BCRs
- generate antibodies to specific antigens
9
Q
What is neutralization?
A
the pathogen is covered in antibodies, and cannot further infect host cells
10
Q
What is opsonization?
A
an antibody-bound pathogen serves to alert immune cells (neutrophils and macrophages) to engulf and digest the pathogen
11
Q
T Lymphocytes
A
- adaptive immunity (cellular)
- derived from bone marrow, mature in thymus
- divided in CD8+ and CD4+ T cells
12
Q
CD8+ T Cells
A
- cytotoxic T cells/lymphocytes
- recognize and kill infected or cancerous cells
- contain cytotoxic granules, that have cytotoxins to kill target cells
13
Q
Th 1 Cells
A
- helper T cell, CD4+
- immune responses against intracellular pathogens
- produce and secrete molecules that alert and activate other immune cells
14
Q
Th 2 Cells
A
- helper T cell, CD4+
- immune responses against extracellular pathogens
- alert B cells, granulocytes, and mast cells
15
Q
Th 17 Cells
A
- helper T cells, CD4+
- produce interleukin 17, that activates immune and non-immune cells
- protects surfaces against extracellular bacteria
16
Q
Treg Cells
A
- regulatory T cell
- monitor and inhibit the activity of other T cells
17
Q
Where are lymphoid cells first produced?
Where are they produced in older fetuses and adults?
A
first produced in the yolk sac, fetal omentum, and liver
later produced mainly in bone marrow
18
Q
What are Primary Lymphoid Organs?
A
- organs that regulate the development of lymphocytes
- bone marrow, thymus, Bursa of Fabricius
19
Q
Describe the Thymus
A
- large in newborns, undergoes involution
- consists of lobules covered by CT
- cortex of each lobule contains thymocytes
- medulla contains a few lymphocyte
- no lymphatic vessels leave the thymus
20
Q
What is the function of the thymus?
A
- maturation of T lymphoctyes
- those that bind to self-antigens or cannot bind MHC II molecules are destroyed
- those that are good mature and travel to secondary organs
- maturation regulates by cytokines and thymic hormones
21
Q
Describe the Bursa of Fabricius
A
- found only in birds
- undergoes involution
- epithelium makes folds that extend into sac, called follicles
- cortex of each follicle contains lymphocytes, plasma cells, and macrophages
22
Q
Describe Secondary Lymphoid Organs
A
- develop late in fetal life, persist in adult life
- enlarge in response to antigenic stimulation
- contain dendritic cells that trap and process antigens, then present them to lymphocytes
23
Q
Describe Lymph Nodes
A
- encapsulated secondary lymphoid organ
- B lymphocytes found in cortex, surrounded by capsules
- T cells and DCs found in paracortex
- different types of cells found in medulla
24
Q
What is the function of Lymph Nodes?
A
- act as filters of lymph to trap antigens
- facilitates interaction between dendritic cells and antigen sensitive T and B lymphocytes, to mount immune response
25
What is the flow of lymph through the lymph node?
- afferent lymph flows into the node carrying antigens, lymphocytes, and dendritic cells
- lymph enters the subscapular sinus, then percolates through the node to the medullary sinus
- lymph exits through the efferent vessel
26
Describe the Spleen and its functions
- large encapsulated secondary lymphoid organ
- structured by network of CT trabeculae
- red pulp: filters blood and stores RBCs
- white pulp: rich in lymphocytes, where immune induction occurs
27
Describe Peyer's Patches
- non-encapsulated secondary lymphoid organs
- in the wall of the small intestine (ileum)
- contains densely packed lymphoid follicles containing only B lymphocytes
- covered by epithelial layer containing M cells, which pass antigens to patch
- undergoes involution with age
28
Describe Innate Lymphoid Cells and their function
- immune cells that do not express antigen specific receptors
- secrete high concentrations of cytokines
- localized to mucosal surfaces and respond to secreted molecules from epithelium
29
Group 1 ILCs
- under control of T-bet transcription factor, and include NK cells and ILC 1 cells
- secrete cytokines in response to intracellular pathogens
30
Group 2 ILCs
- produce IL-5, IL-9, and IL-13 in response to extracellular parasite infections
31
Group 3 ILCs
- include lymphoid tissue inducer cells and ILC 3 cells
- includes cells that produce IL-17 and IL-22
- LTi cells are required for the development of lymphoid tissues
