Topic 1.4
What happens when homeostasis fails?
Homeostasis continuously works to maintain stable conditions in the human body. Sometimes, however, the mechanisms fail. When they do, cells may not get everything they need, or toxic wastes may accumulate. This can lead to disease or even death.
Disease
Disease occurs when the body can’t work properly. This is usually because something stops homeostasis from working.
There are two main types of disease:
Infectious or Communicable Disease: An illness that can spread pathogens from one person to another by:
- contact with blood or saliva
- coughing and sneezing
- another animal (e.g. mosquito or rat)
- by eating contaminated foods
Non-Infectious Disease: Diseases that aren’t passed from person to person. They can progress slowly or result in rapid decline and death.
For example:
- most cancers
- diabetes
- hypertension
- rheumatoid arthritis
- sickle cell anaemia
Understanding Pathogens
Pathogens that can cause disease include viruses, bacteria, fungi, and parasites. Infectious diseases are one of the leading causes of death worldwide.
Virus
Small infectious agents that can only replicate inside the living cells of an organism. Examples include influenza and COVID-19.
Toxins
Poisonous substances produced by living organisms, often harmful to the body. Examples include bacterial toxins like botulinum.
Carcinogen
Substances that cause cancer, such as tobacco smoke or UV radiation.
Pollution
Contaminants in the environment that can cause harm, like air pollution from industrial activities.
Germs
Microorganisms, including bacteria and viruses, that can cause infections.
Fungus
Spore-producing organisms that can infect skin and tissues, like athlete’s foot or yeast infections.
Bacteria
Microscopic organisms, some of which can cause diseases such as strep throat or tuberculosis.
Parasites
Organisms that live in or on a host, causing harm, like tapeworms or malaria.
Discussion
- How do you think the different types of pathogens affect the way diseases spread in a population?
- Can you identify any measures we can take to prevent the spread of these pathogens in our daily lives?