Lecture Two Flashcards
What is the immune system?
- a collection of organs, vessels, cells and molecules
- a system in constant motion and change (not static)
- a system with access to virtually every part of the body
What does the immune system do?
- monitors molecular shapes within body
- distinguishes between self and nonself antigens
- protects us from infection
- speeds up recovery from infection
- helps us maintain adequate relationship with environment we live in
What does the immune system respond to?
Molecular shapes. Either
- Because they are strange shapes
- Because they are familiar shapes in strange contexts
What are antigens?
Molecular shoes the immune system recognises
List some sources of antigens
Viruses, Bacteria, Parasites Dust particles, Cells From other people
What can function as an antigen?
Anything big enough and greater than a certain complexity
What is innate immunity?
- Non specific immunity
- first line barrier
- not improved by repeated antigen exposure
- consists of physical barriers and biochemical barriers
- if breeched, stimulates adaptive immunity
What are some biophysical barriers to microbes?
Skin
Cilia
What are some biochemical barriers to microbes?
Lysozyme in tears,
HCl in stomach
What are commensal organisms and what is their purpose?
- Organisms that live in harmony with its host.
- bacteria in gut, vagina
- compete with foreign microbes for resources so they don’t survive
- component of innate immunity
What does the innate system do when surface barriers are breeches?
- local innate immune factors (phagocytes and complement system) will inhibit microbe multiplication
- attempt to limit damage it causes
What are phagocytes ?
- Neutrophils
- sometimes called polymorphonuclear leukocyte s
- ingest and digest foreign material
- have surface receptors that recognise common cell wall components of many types of bacteria
Explain phagocytosis
- the process of phagocyte ingesting and digesting foreign material
- Neutrophil comes into contact with bacteria and adheres to it
- Adherence activates neutrophil to fold membrane around bacterium
- Bacterium is taken into a vesicle inside neutrophil
- Phagosome is formed
- Neutrophil releases packets of digest enzymes
- Bacteria is digested
- Neutrophil releases degraded products
What is the complement system?
- component of innate immunity
- a series of ~20 blood proteins which can diffuse out of the bloodstream into tissue spaces of our bodies to limit infections (particularly bacterial)
Describe the process of the complement system
- First complement components bind to bacterial antigen
- Activates other complement components
- Other complement components increase vascular permeability, opsonate bacteria, lyse bacterial cell walls, and release chemicals
All which aim to facilitate phagocytosis