The immune system Flashcards
Understand the anatomy and function of the immune system Describe the response to different pathogens Understand the function and differences between innate and acquired immunity
What does the immune system protect us from? (3)
Pathogens and foreign molecules such as:
Parasites
Bacteria
Viruses
What are the 3 main functions of the immune system?
Protects from pathogens and foreign molecules
Removes dead or damaged cells
Attempts to recognise and remove abnormal cells
What are the 2 lines of body defences?
Physical and chemical barriers
Immune defences
What are physical and chemical barriers? (2)
Skin, epithelial linings and cilia
Acids, mucous and lysozymes
What is an immune defence? (2)
Innate, non-specific, immediate response
Acquired - specific attack on pathogen
What is the lymphatic system comprised of? (4)
Primary tissues (bone marrow and thymus)
Encapsulated tissues (lymph nodes and spleen)
Lymph vessels
Diffuse tissues
What are the 6 key cells of the immune system?
Basophils - release chemicals that cause inflammation
Neutrophils - ingest and destroy invaders
Eosinophils - destroy invaders
Monocytes and macrophages - ingest and destroy
Lymphocytes and plasma cells - specific
Dendritic cells - recognise pathogens
What is the definition of innate immunity?
The body’s nonspecific immune response to. invasion - present from birth
How does innate immunity work? (4)
Physical and chemical barriers
Phagocytosis: macrophages and neutrophils
Engulf and digest
Inflammatory response
How do phagosomes work with lysosomes? (2)
- Phagosome engulfs pathogen
2. Lysosomal enzymes digest pathogen
What are the roles of macrophages? (3)
- Macrophage engulfs antigen
- Macrophage digests antigen in lysosome
- Antigen presenting macrophage displays antigen fragments on surface receptors
How do natural killer cells work? (4)
They eliminate virus-infected and tumour cells
- secrete interferons (interferon alpha and beta)
- Prevent viral replication
- Interferon gamma is released - actives immune cells
Describe the inflammatory response role: (3)
- Attract immune cells and chemical mediators to site of infection
- Produce physical barrier to proven the infection form spreading
- Promote tissue repair
Name the 4 players in the inflammatory response:
- Histamines from mast cells - swelling
- Interleukins - allows more WBC to enter
- Bradykinin - pain and swelling
- Complement cascade - membrane attack complex
Describe the membrane attack complex: (complement cascade)
- Complement proteins insert themselves in to the pathogen membrane
- Water and ions freely enter the cell
- Cell swells and lyses - death
What is the definition of acquired immunity?
Directed at specific invaders and is the bodies SPECIFIC immune response - adaptive immunity
What are the 3 players in acquired immunity?
T lymphocytes - helper T cells, cytotoxic T cells
B lymphocytes - plasma and memory cells
NK cells
What is a B lymphocyte?
A lymphocyte clone that has a specific antigen
What is the primary immune response? (4)
- Correct antigen is found
- Clonal expansion
- Memory cells are long lived and reproduce
- Short lived effector cells carry out the immediate response
What is the secondary immune response?
When memory cells are re-exposed to the appropriate antigen, the clone expands more rapidly to produce effector and memory cells
How many classes of antibodies are there and what are their names?
- IgG
- IgA
- IgE
- IgM
- IgD
What are the key structural details about antibodies: (4)
Heavy chain and light chain
Fab region is top half, Fc region is bottom half
Hinge region allows movement
Linked by disulphide bonds
What is the most common anti body?
IgG - 75%
What are T lymphocytes?
T cell receptors - activated by antigen
Bind to antigen presenting cell
What is involved in the major histocompatibility complex? (2)
Cytotoxic T cells
Helper T cells
What is involved in a defence against bacteria? (4)
Skin - initial barrier
Phagocytes, B lymphocytes, Mast cells and lyses
Antibodies
Plasma proteins and leukocytes release antibodies
What is involved in a defence against a virus? (5)
Cytotoxic T cells, NK cells, macrophages and cytokines, B lymphocytes
