Skip to content
    • Ico Human Biology Human biology
    • 16+
    • 45

Pathogens and the immune system

4  of  10

Fungi

The fungi are eukaryoticeukaryotic
Cells that make up animals, plants, fungi and protista. They are three-dimensional, membrane-bound sacs containing cytoplasm, a nucleus and a range of membrane-bound organelles.
organisms. The best known fungi are the mushrooms and toadstools that are such important decomposers and the yeast used in baking and brewing.

The fungi we eat, and the fungi we find decomposing fallen trees in our woodlands, do not cause communicable human diseases – although if we eat the wrong type, they may poison us.

Structure of fungi

There are many different forms of fungi but they have a number of common characteristics:

  • cell walls made of chitin and glucansglucans
    Complex carbohydrates found specifically in fungal cell walls.
  • cannot photosynthesise so they are all saprophytes or parasiteparasite
    Organism that feeds off another living host and causes it some damage. An example of a parasite is a tapeworm that lives in the digestive system of a host organism.
    s
  • many fungi (with the exception of the yeasts) are multicellularmulticellular
    Made up of more than one, usually many cells.
  • reproduce using spores which they usually produce in enormous quantities

The structure of fungal hyphae

Fungi and disease

Fungi do not cause many human diseases. There are a number of fungal skin conditions, where the fungus digests away the skin and causes irritation. These include athlete’s foot and ringworm.

Ringworm is a fungal infection of the skin, unpleasant but not serious (Photo credit: CDC/ Dr Lucille K. Georg)

Aspergillosisaspergillosis
A serious type of fungal infection that can affect the lungs, the brain and other organs of people who are already ill or have a compromised immune system.
 is one very serious type of fungal infection that can affect the lungs, the brain and other organs. It often affects people who are already ill or have suppressed immune systemimmune system
The body's natural defence mechanism against infectious diseases.
s – for example people affected by HIV/AIDSHIV/AIDS
The acquired immunodeficiency syndrome (AIDS) is a condition caused by the infection by the human immune deficiency virus (HIV). It attacks and destroys the immune system, leaving the patient defenceless and unprotected from any pathogens and threats.
. A healthy immune system can usually destroy the fungus.

The main way that fungal pathogens affect people is by the damage they cause our crops. There are around 10,000 fungal pathogens that affect crop plants around the world, causing malnutritionmalnutrition
The result of any imbalance in the diet, which may be too much food, too little food or the lack of one element of the diet.
 and even starvation as they destroy the food people need to eat.