Introduction Flashcards
what is the need for an immune system?
Protection against infectious organisms
Name some types of infectious organisms.
- Bacteria
- Viruses
- Fungi
- Protozoans
- worms
what are the 2 major systems of immunity ?
- innate immunity
- adaptive immunity
what are the features of innate immunity?
- “A first line of defence”
- Present at birth
- Responds rapidly
- Has no specificity
- Has no memory
what factors make up innate immunity?
Barriers, cells, soluble factors
What are the two types of barriers?
- Physical
- Chemical
Name 2 physical barriers of innate immunity.
- Impermeable outer surface
e. g. skin,epithelial cell layer lining mucosal surfaces - Cilia in nasal passages and bronchi
Describe the physical barrier in the nasal passages.
- airborne bacteria are trapped on mucus secreted by goblet cells
- cilia waft the bacteria towards mouth and nose
Name 3 chemical barriers of innate immunity.
- Acidity in stomach
- Alkaline secretions
- Lysozyme in tears
Name a biological barrier of innate immunity.
Competition with commensal organisms
Describe the mechanisms of innate immunity in the gastrointestinal tract.
- most pathogens are destroyed by the low pH of the stomach
- the few pathogens that reach the large bowel must compete with billions of harmless gut bacteria
What are the 3 types of cells in innate immunity?
- Phagocytes
- NK cells
- Eosinophils
Name 3 types of phagocytes.
Monocytes,macrophages and neutrophils
Give a simple description of phagocytosis.
A phagocyte binds to bacterium. The bacterium is engulfed in the phagocyte. The bacterium is inside a membrane bound vescicle which fuses with a lysosome which degrades the bacteria.
What is the role of NK cells ?
Kill tumour cells and virally-infected cells
What is the role of eosinophils?
Attack and kill parasites
what are the innate immunity soluble factors?
- Lysozyme
- Complement
- Cytokines particularly Interferons
- Acute phase proteins (concentration goes up during infection)
How do components of the innate system act together?
They cooperate together and also cooperate with the adaptive immune system
what are the features the adaptive immune system?
-Slow to start
-Adaptive
-Highly specific
-Has memory
-Recognition of self and non-self
-Humoral and cellular components
that work in concert
In humoral immunity , what are antibodies?
- Specific proteins produced against pathogens
- Produced by B lymphocytes
Describe cellular immunity..
Mediated by lymphocytes which recognise specific pathogenic structures called antigens
What cells are involved in cellular immunity?
- B lymphocytes
- T lymphocytes
- Helper T cells
- Cytotoxic T cells
What is the role of Helper T cells?
help B cells produce antibodies
What is the role of cytotoxic T cells?
destroy own cells which have been infected eg with virus
