Non-Specific Response Flashcards
Briefly describe the two defence mechanisms to infection
Non-specific = immediate response, same for all pathogens
Specific = Slower response, provides lifelong immunity + is pathogen specific
Describe the lines of defence for infection
1st - Barriers preventing entry
2nd - Non specific responses
3rd - Specific responses
Describe barriers to infection
- Skin —> contains keratin, not easily digested; impermeable, acts as protective barrier; outer layer of cells shed, removing bacteria
- Mucociliary escalator —> airways containing mucus and cilia
- Reflexes —> coughing, sneezing, blinking
Stomach acid —> contains gastric acid
Gut and skin flora —> intestines and skin naturally covered in billions of microorganisms, compete w pathogens for nutrients and space
How does inflammation occur?
Histamine is released by mast cells when pathogens invade
- cause vasodilation of blood vessels
- raised temps reducing pathogen reproduction
- wall of capillaries made permeable, forces out WBCs and antibodies, causing swelling
- releases cytokines, triggering immune response in infected area, and phagocytes which engulf foreign particles
- redness from increased blood flow + swelling from dilation
What are interferons and how do they prevent infection?
Anti-viral proteins produced by infected cells
- inhibit production of viral proteins, preventing virus from replicating
- activate WBCs in specific immune response to kill infected cells
- activate other mechanisms of non specific immune response
How does fever prevent infection?
Cytokines released when pathogens invade, hypothalamus detects this and sets higher body temperature
- reduces pathogens ability to reproduce quickly
- specific immune system works better at higher temps
How do lysozymes prevent infection?
Damages bacterial cell walls, found in bodily secretions (e.g. mucus, tears, etc.)
Describe differences in B and T lymphocytes
~ B cells are involved in humoral immunity whilst T cell are involved in both humoral and cell-mediated immunity
~ B cells respond to foreign material outside of the body cells, whilst T cells work inside
~ B cells mature in bone marrow whilst T cells mature in thymus gland
~ B cells respond to bacteria and viruses whilst T cells respond to own cells altered by viruses or cancers
Name the two types of B cells
Plasma and memory B cells
How do plasma cells work?
- Directly secrete antibodies
- survive for a few days
- responsible for primary immune response
How do memory B-cells work?
Circulate in blood + tissue fluid
- Responsible for secondary immune response
- Rapidly divide when in contact with antigen, develop into more plasma and memory cells
Name the two types of specific response
Humoral and cell-mediated response
What is the role of memory cells?
Remain in blood, prepared to respond quickly to the same pathogen; have specific complementary receptor proteins to a certain pathogen
What are phagocytes and how do these respond to infection?
Type of WBC responsible for removing dead cells and invasive microorganisms by engulfing them
- chemicals released by pathogens as well as body cells (e.g. histamines) attract phagocyte to site
- recognise antigens on surface of pathogens as non self
- cell membrane of phagocyte extends around pathogen, engulfing it and trapping pathogen in vesicle called phagosome
- digestive enzymes + lysosomes released by phagocytic vacuole break down cell wall, vesicle becomes phagolysosome
- antigens of bacteria form MHC complex, now projects antigens on outer membrane —> becomes antigen presenting cell, initiates specific response
Describe difference between two types of phagocytes
Whilst macrophages become antigen-presenting cells, neutrophils do not
