Chapter 6 - Detecting and Responding to Invaders Flashcards
First fine of defence mechanisms
- Keratinised, Intact skin
- Cilia/nasal hairs: filters air and sweeps out pathogens trapped in mucas
- Digestive system: lysosomes in saliva and enzymes and strong enzymes create non-preferable environment.
- Respiratory: Mucas straps pathogens
- Urinary Tract: Flush out pathogens
Second line of defense
Non- Specific defence
- Macrophages, Neutrophils, macrophages, Eosinophils, basophils
- Complement system
- Natural Killer Cells
- Inflammation and fever
- Interferons
Third line of defense
Specific response
B-cells, T-cells
Phagocyte definition &; Examples
- White blood cells that engulf and digest foreign particles.
- EG.) Neutrophils, Macrophages, Monocytes (macrophages in the blood)
Neutrophil
Phagocyte, Not antigen presenting
- It granules contain enzymes and chemical which break down foreign material
Moncytes &; Macrophage
Monocytes in the blood respond to cytokinins, migrate to inflamed site where they squeeze out of blood vessels to become macrophages.
- Macrophages engulf pathogens
- Are antigen presenting
MHC1 & MHC2
MHC proteins act as signposts that display antigen on the hosts cells surface.
MHC1 on all cells
MHC2 Only found on antigen presenting cells
Antigen presenting cells definition and 3 examples
Cells that envelop a pathogen and display antigen fragments on their MHC2 markers.
B plasma cells
Found in Lymph nodes and in blood stream
Exist in millions of different types with unique membrane bound antibodies on surface which detect microbes with antigens which bind to them.
The steps and actions of phagocytes
- ) Detection: Phagocytes detects microbes by chemicals they give off
- ) Ingestion: Microbe is enveloped through endocytosis.
- ) Digestion: Phagosome (vesicle containing thee microbe) fuses with lymosome which contains enzymes which break down the microbe into its chemical constituents. (Enzymes break down microbe)
- ) DIshcharge: Antigens are displayed on MHC2 markers (macrophages) and the rest of the digested contents are discharged
Humoral response
- Plasma cells unique antibodies on its surface bind to complementary non-self antigen.
- Helper T cell (having already met the antigen) activates this B- Cell by producing interlukin, stimulating it to begin “clonal expansion” and divide into B plasma and B memory cells.
- These B plasma cells produce antibodies which help combat the pathogen,
Dendritic cells
Antigen presenting cells that attract antigens and present them to T-Helper cells
epitope
Processed antigen fragment
Granulyte properties and examples
Properties: Granular cytoplasms, multi-lobed nucleus
Eg.) Neutrophil, Eosinophil, Basophils, NKC
Neutrophil Vs Macrophage
Both engulf foreign particles and micro-organisms
Neutrophils arrive at scene faster and have a shorter lifespan than macrophages.
Neutrophils are not antigen presenting, macrophages are
Eosinphil role:
secretes enzymes which break down cell walls of pathogens
Basophil role:
Secrete histamine in case of infection causing inflamation
Mast Cells;
Types of Basophil which produce histamines and is involved in allergic reactions
Macrophges Vs Monocytes
Monocytes turn to macrophages when they leave the blood stream.
They develop in the bone marrow and engulf foreign particles
Dendrite cells:
Antigen presenting cell with long tentacle like arms which grab foreign particles