Immunity & Disease Flashcards
Define innate and adaptive immunity
Innate: non-specific eg. skin and mucous membranes, phagocytic cells (neutrophils, macrophages), inflammation, fever
Adaptive: cell mediated immunity, humoral immunity
Name 2 defences of innate immunity
SKIN
outer layer of keratin (mechanical barrier)
dead skin cells sloughed off = hard for bacteria to colonise
sweat + oils contain anti-microbial chemicals
MUCOUS MEMBRANES
washes away bacteria and viruses
cilia
acid (stomach & vaginal)
enzymes (saliva & eye)
What are the chemical barriers in innate immunity?
Proteins - interferons which inhibit the replication of many viruses
What are the cellular defences in innate immunity?
Granulocytes - basophils, eosinophils, neutrophils attracted by inflammatory response of damaged cells, remove dead cells and microorganisms
Monocytes - macrophages live longer than granulocytes, stimulate a specific immune reponse
Adaptive immunity
LYMPHOCYTES
produced in the bone marrow
B cells mature in bone marrow then concentrate in lymph nodes and spleen
T cells mature in thymus
B&T cells circulate in blood and lymph to ensure they come into contact with pathogens
What is the role of B cells and what do they secrete?
Secrete antibodies = glycoproteins, specific, IgG, IgM, IgA, IgE, IgD
- Humoral immunity
- Recognise pathogens outside cells
- can bind to antigen on cell or free = plasma cells = more antibody
- can become memory B cells which remain in the blood for secondary invasion
What is the role of T cells?
Don’t recognise free antigen only antigen presenting cells
Directly attack invaders (killer T, CD8)
- cell-mediated immunity
- recognise pathogens that have entered cells
Help B cells
What are the 2 types of T cells?
Cytotoxic:
seek and destroy any antigens in system, destroy microbes tagged by antibodies
some can recognise and destroy cancer cells
Helper:
stimulate B cells
activate cytotoxic
detect antigen by macrophage brought to helper T cells for identification
What happens to T cells in HIV?
HIV destroys helper T cells = no B cells division = immune response diminished
What causes a deficient and hyperactive immune system?
Deficient = chemo/drugs, HIV, splenectomy, bone marrow dysfunction Hyperactive = allergy, auto-immunity, overreaction to pthogen
Causes of secondary immunodeficiency
Malnutrition, burns, uraemia, diabetes mellitus, immunotoxic medications, self-medication of recreational drugs and alcohol, AIDS
Hypersensitivity (hyperactive immune reaction)
Excessive immune reaction against harmless antigen
Type 1 = anaphylaxis/allergy eg asthma, rhinitis (hayfever)
Overreaction to pathogen = Systemic Inflammatory Response Syndrome
Autoimmunity (hyperactive immune reaction)
Failure of organism in recognising its own constituent parts as self, leading to immune response against its own tissues/cells
Self-reactive lymphocytes are deleted centrally
eg type 1 diabetes mellitus, coeliac disease, MS, rheumatoid arthritis
Name 3 manipulations of the immune system
Suppress eg. organ transplant (increases risk of infection)
Cancer - immunotherapy
Vaccination
What are the 4 types of vaccines?
Live - live weakened pathogen eg. MMR
Inactivated - part of pathogen eg. Hep B
Toxoid - bacterial toxin eg. diphtheria
Conjugated - antigen linked to protein carrier eg. Pneumococcal
