Communicable diseases Flashcards
Primary immune system
Phagocytosis - non-specific response
What is the first process of phagocytosis
toxins produced by pathogen attract phagocyte which travels down a concentration gradient to pathogen
step 2 and 3 of phagocytosis
pathogen attaches to phagocyte
phagocyte starts to engulfs pathogen -forms phagosome (pathogen binding site to vesicle)
step 4 process for phagocytosis
lysosomes bind to the vesicle
lysosomes contain lysozymes (enzymes needed to digest the pathogen)
step 5 process of phagocytosis
breakdown products of the pathogen are absorbed by phagocyte
Physical barriers to infection include :
• Skin is a tough physical barrier consisting of keratin
• Stomach acid (hydrochloric acid) which kills bacteria
• Gut and skin flora – natural bacterial flora compete with pathogens for food and space
Non-specific responses of the body to infection include:
• Inflammation
• Lysozyme action
• Interferon
• Phagocytosis
• Blood clotting
second line of defence - specific cellular response
main product cytotoxins T cells
Step 1 for T cells
Some phagocytes become antigen presenting cell (APC)
After digesting the pathogen, the phagocyte can present the antigen on its own cell membrane.
Memory cells
cells which replicate themselves when exposed to an invading
pathogen and remain in the lymph nodes searching for the same antigen thus resulting
in a much faster immune response
B effector/plasma cells
antibody producing cells
T helper cell
stimulate B cells and T killer cells to divide
T killer cells
destroy pathogen infected cells
neutralisation
Antibodies are
complementary in shape to a specific antigen, to which they attach and subsequently
inhibit its action
agglutination process
where
several antibodies bind together
antibodies structure
-composed of four polypeptide chains
-linked together by
disulphide bridges
- constant region which is
involved in phagocyte interaction to stimulate phagocytosis
-variable constant which responsible for the specificity of antibody for one particular antigen
- hinge regions - flexible for the binding of multiple pathogens
Pathogen
is an organism that can cause a disease
Direct transmission
When a disease transmits directly from one organism to another e.g HIV
Indirect transmission
When a disease is transmitted from one another via an intermediate e.g air , food , water
Factors increases chances of diseases
Overcrowded increases transmission e.g TB direct transmission by air droplet
Climate can also affect spread of communicable diseases
e.g potato blight
Accessibility of healthcare
Education - people being informed or how to avoid/ treatment
