6.3 Defence Against Infectious Disease Flashcards
The first line of defense against infectious disease
Surface Barriers; intact skin & mucous membrane
Skin protects…
External structures (outer body areas)
The second line of defense
Innate immune system (Non specific response)
Difference between 2nd and 3rd line of defense
2nd is non-specific in response, 3rd is specific
Role of white blood cells in the 2nd line of defense
Engulf and digest forgiven bodies
Other components of innate immune system
Inflammation, fever and anti microbial chemicals (complement proteins)
Two key properties of innate immune system
- Does not differentiate between different types of pathogens (non specific)
- Responds to infections the same way every time (non-adaptive)
Phagocytes
Type of white blood cell, provide no specific immunity
Phagocytosis
Process by which solid materials(I.e pathogens) are ingested by cells (‘eaten’ via endocytosis)
Process of Phagocytosis
- In response to infection; phagocytes leukocytes circulate in blood and move into body tissue
- Damaged tissues release chemicals to draw blood cells to site of infection
- Cellular extensions surround and engulf Pathogens, then fuse to form internal vesicle
- Vesicle fuses to lysosome and pathogen is digested
- Pathogen fragments (antigens) may present on surface of phagocyte to stimulate 3rd line of defense
Structure of Virus
Antigens on the surface outside casing called envelope, once it enters body - uses as host to replicate itself
Third line of defense
Adaptive immune system (specific response)
Characteristics of adaptive immune system
Can differentiate between particular pathogens and target specific response.
Can respond rapidly up re-exposure to specific pathogen to prevent symptoms from developing (memory cell)
Adaptive immune system are coordinated by
Lymphocytes
Effect of HIV on the immune system
Decrease in number of active lymphocytes
What occurs as a result of a cut in the skin
Clotting factors are released from red blood cells
Why isn’t penicillin used against HIV
Penicillin is an antibiotic. antibiotics do not affect viruses
What is the reason for the faster rise in antibody concentration after the second infection
Lymphocytes rapidly reproduced to form plasma cells
What is a feature of phagocytic white blood cells
Form part of non-specific immunity
What is a non-specific immunity defense to disease
Endocytosis of pathogens by white blood cells
Characteristic of antigens
They stimulate the production of antibodies
Why is using a combination of antibiotics and bioengineered antibodies to treat infections more effective than antibiotics alone
Bacteria becomes more noticeable to phagocytes
Reasons antibiotics aren’t always effective against pathogens
- Antibiotics interrupt processes found in some but not all pathogen cells
- Some pathogens have no metabolic processes to interrupt
- Some pathogens have developed genetic resistance to specific antibiotics
Explain the formation of a blood clot
- Platelets are recruited to site of injury (chemical signal)
- Cologne activates platelets, platelets change size
- More platelets come to the site. (Positive feedback)
- Platelets release thrombin.(prothrombin that turns into thrombin)
- Thrombin catalase turns fibrinogen into fibrin
- Fibrin forms web, holding the platelets together
