DISEASES AND IMMUNITY: Module 4 Flashcards
what is a pathogen
an organism which causes diseases
infectious (communicable) diseases
caused by pathogens
spread between people, infecting each other
non infectious (non-communicable) diseases
are not caused by pathogens
they cannot be spread person to person
usually happen due to genetics or lifestyle
4 types of pathogens
bacteria
viruses
protoctists
fungi
2 example of bacterial diseases in humans
myobacterium tuberculosis
bacterial meningitis
an example of a bacterial disease affecting plants
ring rot
treatment for bacterial disease
and how do they work
antibiotics
break down bacterial cell wall (peptidoglycan)
2 viruses affecting humans
Human immunodeficiency virus (HIV)
covid-19
virus affecting plant
tobacco mosaic virus (TMV)
protoctist disease in humans
plasmodium causes malaria
protoctist disease affecting plants
blight
fungal disease affecting humans
ringworm
athletes foot
fungal diseases affecting plants
black sigatoka
ways of transmitting communicable diseases
droplet transmission like sneezing
vectors like anopheles mosquitoes
fungal spores in wind
what factors affect transmissions of diseases
social factors: HIV underdiagnosed
living conditions: TB spread fast in overcrowding
climate: vectors live in different climates like mosquitoes in warmer ones
how does our body openings (e.g. eyes) act as a defensive barrier
cavities lined w mucus membrane
with lysozyme enzymes which kills bacteria by damaging their cell walls making them burst
how does our skin act as a defensive barrier
physical barrier preventing pathogens from entering
but when cut or wounded, wound clotted by platelets
how does our breathing system have defensive barriers
goblet cells secrete mucus
trapping pathogens
sweeping them by cilia to stomach acid
how does our stomach have defensive barriers
stomach acid is acidic
denaturing proteins and killing pathogens
how does our intestines have defense mechanisms
has its own helpful and harmless bacteria
which compete with other pathogens
how does inflammation help as a non specific response
damaged tissues triggers release of histamines
vasodilation happens near area
increased blood flow causes the redness
more blood flow delivers nutrients for repair
expulsive reflexes
coughing / sneezing
expels or removes harmful pathogens from body
plant physical defences
waxy cuticle on surface traps pathogens, not letting them enter leaf
cell wall prevents pathogens entering plant cell
pathogens enter plants: triggers callose (polysaccharide) to be released between cell wall and plasma membrane, so pathogens cant enter
plant chemical defences
some plant produce antimicrobial compounds that kill pathogens
plants have tannins which stops vectors as they bind to saliva to deactivate insect enzymes
what do pathogens have on their surface
specific antigens
3 types of phagocytes
macrophage
monocyte
neutrophils
how to tell apart phagocytes
neutrophils have multi lobed nucleus and are usually smaller
macrophages have kidney shaped nucleus and are larger
specific immune response: step 1 with phagocytes
until APC formed
- opsonin coats pathogen
- phagocyte recognises foreign pathogen and engulfs it (endocytosis)
- inside phagocyte it vesicles into a phagosome that lysosomes fuse to form phagolysosome
- hydrolytic enzymes digest pathogen
- pathogen removed from cell (exocytosis)
- phagocyte keeps some antigens from pathogen to present on its surface (becomes antigen presenting cell)
Specific immune response: step 2
T lymphocytes and their role
- T lymphocyte has specific receptor binding to the antigen presenting cell
- this activates T cell (clonal selection) causing mitosis of T cells (clonal expansion)
- T helper cells releases cytokines (interleukin) to activate B lymphocytes
- T killer cells destroy cells infected by pathogen
- T regulartory cells suppress immune response to protect host cells
- T memory remains in bloodstream for a quicker secondary response incase of reinfection
specific immune response: step 3
B lymphocytes and their role
- cytokines from T helper trigger B lymphocytes
- B lymphocytes with antibody on surface specific to the antigen from pathogen are activated
- they divide by mitosis and differentiate into plasma cells and B memory
- plasma cells release many antibodies into plasma specific to pathogen antigen
- B memory remains in bloodstream to divide in case of reinfection
antibody structure
- quaternary protein (two heavy, two light chains)
- polypeptides held together by disulfide bonds
- they have a variable region that is different between antibodies as it has specific antigen binding site
- constant region is the same for all antibodies
- hinge region allows flexibility of antibody
3 roles of antibodies
- neutralisation (anti-toxin)
- agglutination
- opsonisation
neutralisation; antibody
neutralises toxins to make them harmless
so u feel less ill
agglutination; antibody
clumps pathogens
to be engulfed by phagocytes easier
and to make them too big to invade host cells
opsonisation; antibody
coats and marks pathogen for phagocytosis
why is your secondary immune response quick
- T and B memory cells from initial infection remain
- divide by mitosis to mass produce cells
- to fight off disease
active immunity:
when your body makes its own antibodies
natural active immunity
getting sick
active artificial immunity
vaccination using weakened pathogen
passive immunity
you get antibodies from elsewhere
natural passive immunity
breastmilk
artificial passive
antibody injection
autoimmune diseases
how and tell me two
persons immune system fails to distinguish self antigens and foreign antigens
effectively attacking and killing normal cells
- lupus
- rheumatoid arthiritis
vaccines
- dead or weakened (atenuated) pathogen injected into host
- to trigger less harmful specific immune response
- producing T and B memory cells for the disease in case of infection
why cant antibiotics help viruses
viruses have no cell structure (no cell walls)
so antibiotics cannot work
why dont antibiotics harm host cells
animal cells have no cell wall
to be targeted by antibiotics
antibiotic resistance explained
- a random mutation in pathogenic bacteria
- protects the bacteria from antibiotics
- bacteria survive and reproduce more bacteria with antibiotic-resistance characteristic
what is causing antibiotic resistance to be widespread
over-prescription
not completing the course
Why should biodiversity be protected in terms of diseases and immunity
many medicinal drugs from plants have not yet been discovered
so you would not want these undiscovered species of plants to go extinct
personalised medicine
medicine being tailored to your genetics to make the treatment more effective
