Health and disease
Introduction
Pathogen- disease-causing organism that cause communicable diseases
A disease is a condition where part of the organism does not function correctly. Disease is often
responsible for ill health, but being healthy is not just about being free from disease.
Health (defined by WHO) – complete physical, social and mental wellbeing
WHO co-ordinates ways to improve health across the world
Antigen – protein on surface of cells to trigger immune response
Antibody – protein produced by plasma cells in specific immune response to kill specific pathogens
B lymphocyte – cell of immune system, specific to antigen
Lytic – viral replication, host cell burst when new viruses leave
Lysogenic – virus remains dormant, not cause infection, virus replicated when host cell replicated
Plasma – short lived cells producing antibodies by protein synthesis
Memory B cell – long lived cell of immune system occur after primary immune response, provide
rapid response if infection happen again
Susceptibility
The presence of one disease can lead to a higher susceptibility to other diseases. This is because the
immune system can be compromised in some way e.g. individuals infected with HIV have reduced
numbers of lymphocytes circulating around the body which reduces the ability of the immune
system to fight opportunistic infections like pneumonia
Viruses living in cells can trigger cancers – HPV virus infects cells of cervix causing cervical cancer,
some strains of hepatitis virus cause liver cancer
Immune reactions caused by pathogens can trigger allergies like skin rashes and asthma – overactive
immune response
Sever physical ill health lead to depression and other mental illness – this can also impact immune
system and lifestyle choices
Communicable vs non-communicable
Communicable – spread between individuals like bacteria, fungi, viruses and parasites. They are also
known as contagious or infectious diseases.
Non-communicable – cannot be spread between individuals, they last for a long time and get worse
slowly
Communicable Non-communicable
COVID, common cold Asthma
Malaria Coronary heart disease
meningitis Cancer
Diabetes
, If you are affected by one disease, you are also more susceptible to others as your body becomes
weakened so less able to fight off other diseases.
Direct vs indirect contact
direct Indirect
Bodily fluids Airborne transmission
Touching, sex Contaminated objects
Sneezing Animal to person contact
coughing Contaminated food or water
Vectors like malaria
Bacteria – very small cells that reproduce rapidly, they produce toxins that damage cells and tissues
Viruses – not cells, can reproduce rapidly, live inside cells and replicate using cells’ machinery to
produce many copies of itself, the cell will burst to release all the new viruses and make you ill
Protists – all eukaryotes, most single celled, some protists are parasites
Fungi – some are single celled, others have a body made of hyphae (thread like structures), hyphae
grow and penetrate human skin and surface of plant, causing disease, hyphae produce spores that
spread to other animals and plants
Disease pathogen type transmission symptoms Reduc spread
cholera Vibrio cholerae bacterium Infected, Severe very Good hygiene,
untreated watery access clean
water, poor diarrhoea water, boil
hygiene and cover
food (flies)
HIV Human Virus Sex, breast Initially, mild Male and
Immunodeficiency feeding, flu, then female
Virus contaminated asymptomatic, condoms, not
needles, virus repeated share needles,
invades WBC infection, die, abstinence,
destroying lead to onset isolate
them, lead to of AIDS individuals,
AIDS sterilise
Malaria Plasmodium Protoctista Animal damage RBC/ Bed nets,
falciparum vectors, blood and insecticide,
infected liver, fever, fume areas,
female weakness, remove
mosquito bite illness, standing
human and water where
transfer they breed,
Protoctista
into blood
vessels, infect
liver and RBC
tuberculosis Mycobacterium bacterium Airborne, Lung damage, Physical
tuberculosis Inhaled bloody mucus, distancing,
Introduction
Pathogen- disease-causing organism that cause communicable diseases
A disease is a condition where part of the organism does not function correctly. Disease is often
responsible for ill health, but being healthy is not just about being free from disease.
Health (defined by WHO) – complete physical, social and mental wellbeing
WHO co-ordinates ways to improve health across the world
Antigen – protein on surface of cells to trigger immune response
Antibody – protein produced by plasma cells in specific immune response to kill specific pathogens
B lymphocyte – cell of immune system, specific to antigen
Lytic – viral replication, host cell burst when new viruses leave
Lysogenic – virus remains dormant, not cause infection, virus replicated when host cell replicated
Plasma – short lived cells producing antibodies by protein synthesis
Memory B cell – long lived cell of immune system occur after primary immune response, provide
rapid response if infection happen again
Susceptibility
The presence of one disease can lead to a higher susceptibility to other diseases. This is because the
immune system can be compromised in some way e.g. individuals infected with HIV have reduced
numbers of lymphocytes circulating around the body which reduces the ability of the immune
system to fight opportunistic infections like pneumonia
Viruses living in cells can trigger cancers – HPV virus infects cells of cervix causing cervical cancer,
some strains of hepatitis virus cause liver cancer
Immune reactions caused by pathogens can trigger allergies like skin rashes and asthma – overactive
immune response
Sever physical ill health lead to depression and other mental illness – this can also impact immune
system and lifestyle choices
Communicable vs non-communicable
Communicable – spread between individuals like bacteria, fungi, viruses and parasites. They are also
known as contagious or infectious diseases.
Non-communicable – cannot be spread between individuals, they last for a long time and get worse
slowly
Communicable Non-communicable
COVID, common cold Asthma
Malaria Coronary heart disease
meningitis Cancer
Diabetes
, If you are affected by one disease, you are also more susceptible to others as your body becomes
weakened so less able to fight off other diseases.
Direct vs indirect contact
direct Indirect
Bodily fluids Airborne transmission
Touching, sex Contaminated objects
Sneezing Animal to person contact
coughing Contaminated food or water
Vectors like malaria
Bacteria – very small cells that reproduce rapidly, they produce toxins that damage cells and tissues
Viruses – not cells, can reproduce rapidly, live inside cells and replicate using cells’ machinery to
produce many copies of itself, the cell will burst to release all the new viruses and make you ill
Protists – all eukaryotes, most single celled, some protists are parasites
Fungi – some are single celled, others have a body made of hyphae (thread like structures), hyphae
grow and penetrate human skin and surface of plant, causing disease, hyphae produce spores that
spread to other animals and plants
Disease pathogen type transmission symptoms Reduc spread
cholera Vibrio cholerae bacterium Infected, Severe very Good hygiene,
untreated watery access clean
water, poor diarrhoea water, boil
hygiene and cover
food (flies)
HIV Human Virus Sex, breast Initially, mild Male and
Immunodeficiency feeding, flu, then female
Virus contaminated asymptomatic, condoms, not
needles, virus repeated share needles,
invades WBC infection, die, abstinence,
destroying lead to onset isolate
them, lead to of AIDS individuals,
AIDS sterilise
Malaria Plasmodium Protoctista Animal damage RBC/ Bed nets,
falciparum vectors, blood and insecticide,
infected liver, fever, fume areas,
female weakness, remove
mosquito bite illness, standing
human and water where
transfer they breed,
Protoctista
into blood
vessels, infect
liver and RBC
tuberculosis Mycobacterium bacterium Airborne, Lung damage, Physical
tuberculosis Inhaled bloody mucus, distancing,
