Immunology Flashcards
Granulocytes and Agranulocytes
Granulocytes: neutrophils, basophils, eosinophils
Agraonulocytes: lymphocytes, monocytes
GALT (gut-associated lymphoid tissue) organs
Tonsils, Adenoids, Peyer’s patches, Appendix
Neutrophils
- Phagocytic
- Short-lived (≤5 days)
- Target bacteria, even those that have been opsonized, by chemotaxis
- Dead neutrophils = pus
Eosinophils
- Bright red-orange granules
- Allergic reaction & invasive parasitic infections
- Activation releases histamine, causing inflammation
- Vasodilation and blood vessels more leaky, lead to more immune cells move to affected tissue
Basophils
- Allergic reactions
- Release histamine
- Least populated
- Related to mast cells
Mast cells
- Smaller granules but closely related to basophils
- In tissues, mucosa, epithelium
- Release histamine
Different names for macrophages in different locations
- CNS: Microglia
- Skin: Langerhans cells
- Bone: Osteoclasts
Defensins
Antibacterial enzymes on the skin
Complement system
Proteins in the blood that act as a nonspecific defense against bacteria. Punches hole in cell wall of bacteria. Has two pathways of action
Complement system pathways
- Classical pathway: requires binding of an antibody to a pathogen
- Alternative pathway: does not require antibodies
Interferons
Proteins that prevent viral replication & dispersion. Upregulates MHC Class I and II molecules (to present more antigens).
Causes nearby cells to:
- Decrease production of both viral and cellular proteins
- Decrease permeability
Actions of Macrophages
- Phagocyte the invader via endocytosis
- Digest the invader
- Present a tiny bit to other cells vis MHC
- Release cytokinesis
NK Cells
Detect downregulation of MHC (that are often caused by viruses)
Suppressor T-cells
- Express Foxp3 and CD4
- Help tone down immune response once infection is controlled
- Self-tolerance: turn off self-reactive lymphocytes
Helper T cells: types, actions
- Th1: release IFN-𝛾, promote macrophages (common in bacterial infection)
- Th2: activate more B-cells (more in parasitic)
Functions of the lymphatic system
- Equalize fluid distribution
- Transport fats and fat-soluble compounds in chylomicrons
- Provide sites for mounting immune responses
Lacteals
small lymphatic vessels in center of each villus in small intestine. Fats in chylomicrons travel here for transport
Chyle
milky white lymphatic fluid carrying many chylomicrons
Germinal centers
collection where B-cells proliferate and mature
