B5 Communicable Diseases

CGP 81-87

Define pathogen

microorganism which enters body and causes disease

what type of disease do pathogens cause

communicable (infectious)

What are the 4 main types of pathogen

bacteria, viruses, protists, fungi

What do bacteria do? How big are they?

very small, way smaller than body cell. produce toxins which damage cells and tissues

What is virus? is it a cell?

tiny thing much smaller than cell

uses cell’s mechanics to reproduce so much that the cell bursts and then all the viruses escape to go around body

what’s a protist? and a parasite?

Protists come in lots of different types. Always eukaryotes. most single-cell.

Parasites are a type of protist which live in or on an organism causing it harm, but can be transferred by a vector

How can fungi harm organisms?

their body, made of hyphae can split off and penetrate human skin

Give 3 ways pathogens spread

water

air

direct contact (touching contaminated surfaces)

Give the 3 viral diseases

measles, HIV, TMV

Measles:

• How is it spread?

• Symptoms

• Preventing

spread by air droplets from sneeze or cough

red skin rash, fever

vaccine at young age (MMR)

HIV:

• How is it spread?

• Symptoms

• Preventing

• sexual contact or exchanging bodily fluids (sharing needles etc.)

• initially flu-like symptoms, then no sign for a few years. Then attacks immune system

• antiretroviral drugs to prevent HIV replicating in body

• contraception

Tobacco Mosaic Virus:

• How is it spread?

• Symptoms

• Preventing

• Humans are vector, our hands spread it when we touch plant.

• discoloured leaf, can’t carry out photosynthesis

• Digging up and destroying infected plants, hand washing

Which disease is Fungal?

rose black spot

Rose black spot:

• How is it spread?

• Symptoms

• Preventing

• water or wind

• purple or black spots on leaves, can cause leaves to turn yellow and drop off - less photosynthesis so plant might die

• fungicides, destroying infected leaves

which disease is caused by a Protist?

malaria

Malaria:

• How is it spread?

• Symptoms

• Preventing

• mosquito vector

• repeating fever, can be fatal

• insecticides, mosquito nets

what are the 2 bacterial diseases?

salmonella and gonorrhoea

Gonorrhoea:

• How is it spread?

• Symptoms

• Preventing

• sexual contact

• painful to urinate, thick yellow or green discharge from penis or vagina

• antibiotics and contraceptive barriers like condoms.

Salmonella:

• How is it spread?

• Symptoms

• Preventing

• contaminated food

• fever, vomiting, diarrhoea

• Good food hygiene

Give the 4 main ways we prevent disease

• being hygienic

• destroying vectors

• isolating infected individuals

• vaccination

What is WBC phagocytosis

engulfing and digesting pathogen

WBC Lymphocytosis: What is an antibody?

WBCs produce antibodies to lock onto antigens of unrecognised things. This means they can be found and destroyed by other WBCs

Can an antibody be used for any antigen?

no. antibodies are specific to 1 antigen type

What do memory WBCs do?

remember the shape of the pathogens’ antigen so antibodies can be produced faster next time.

This is why you don’t get chicken pox twice - your body can fight it off really quickly the second time.

WBC Lymphocytosis: What do antitoxins do?

antitoxins bind to the toxins produced by invading bacteria and neutralise them.