3.2 Innate Immune System Flashcards
What is infectious disease?
When a pathogen succeeds in evading the host’s immune defences
What are the 4 roles of the immune system?
Pathogen recognition
Eliminating the infection
Recognising itself to reduce damage
Remembering pathogens to prevent recurring infections
Give 3 features of innate immunity
Fast
Non-specific
No memory
Same intensity of responce
Give an example of a physical barrier against infection
The skin
Mucous membranes
Bronchial cilia
Give an example of a physiological barrier against infection
Vomiting, diarrhoea, coughing, sneezing
Give an example of a chemical barrier against infection
Low pH, antimicrobial molecules
Give an example of a biological barrier against infection
Normal flora in the body keep bacteria at a low level as they are all competing to live in that environment
What can happen when the skin barrier is breached?
Normal flora on the skin enters the body and infects an area where it does not belong.
How can antibiotics be the cause of an infection?
If 1 type of normal flora is depleted by antibiotics, the other types of flora can grow to an extent that they produce symptoms and spread to other areas.
Give 3 types of phagocytes
Macrophage Neutrophil Monocytes Basophil Eosinophil
How is a phagocyte able to recognise a pathogen?
On pathogen:
Pathogen-associated molecular patterns (PAMPs)
Carbohydrates, lipids, proteins, nucleic acids
On phagocyte:
Pathogen recognition receptors (PRRs)
Describe opsonisation of microbes
Coating proteins called opsonins attach to the microbial surface leading to enhanced attachment of phagocytes
Give examples of opsonins
Complement proteins (C3b)
Antibodies (IgG)
Acute phase proteins (CRP)
Give 2 ways in which phagocytes can kill bacteria
Oxygen dependent- toxic O2 products
Oxygen independent- lysozymes, hydrolytic enzymes
What is a cytokine?
Chemical produced by macrophages to kill microorganisms, activate phagocytes and start inflammation
