An infectious disease is caused by a pathogen that can be passed from one organism to another through various means of transmission. Non-infectious diseases are not caused by pathogens but can be genetic or related to lifestyle/environment. Pathogens are organisms that cause disease by multiplying and spreading under the right conditions. The body has multiple lines of defense against pathogens, including physical barriers, non-specific immune responses like inflammation, and a specific adaptive immune response that recognizes foreign antigens.

1. http://www.huffingtonpost.com/2014/01/13
Disease
Sarah Jones

2. What is a healthy organism?
Health is the wellbeing of the organism. All our
body functions, which are under the control of
our genes, work together to maintain health.
karmajello.com

3. Disease is any condition that adversely affects
the function of any part of a living thing.
commons.wikimedia.org

4. An infectious disease is one that is caused by
an organism and that can be transferred from
one person to another. The transfer may be
directly from person to person, or it may be
carried out by a vector, such as a blood-sucking
insect.
keysmosquito.org

5. Examples of infectious diseases are colds,
influenza, chicken pox, herpes and measles.
http://www.huffingtonpost.com/2014/01/13
Hepatitis C Virus

6. Non-infectious diseases are diseases that are
not due to disease-causing organisms. They
include genetic diseases, such as Down
syndrome, haemophilia, and those that are
related to lifestyle or environment, such as
cardiovascular disease and skin cancer.

7. Agents of Disease

8. Pathogens
Organisms are called pathogens when they
cause disease. To cause disease, organisms
need the right conditions to multiply and be
transmitted.
Ebola

9. An infectious disease is caused by a pathogen and
can be passed from one organism to another.

10. How are diseases spread?
• Airborne
• Contact
• Faeces
• By other organisms
• The Asian tiger mosquito is responsible for the
transmission of dengue and yellow fever plus
20 other viral diseases.

11. Pathogens and Epidemics
During the Middle Ages waves of infectious
diseases such as cholera and plague swept
through Europe.
Plague victims being blessed by a priest

12. Macroparasites
Macroparasites are large parasites that can be
seen with the naked eye. They may be internal
or external parasites. Examples of internal
include, tapeworms, roundworms and
flukes. External parasites include lice, ticks and
fleas.
sph.unc.edu

14. Immune Response – The Body's
Response to Micro-Organisms
Flu Pneumonia German Measles

15. Bodies Defence
1. Physical (skin and mucous)
2. Nonspecific defensive cells (phagocytes,
white blood cells, inflammation and fever)
3. Immune Response (lymphatic system-recognition
of foreign cells)
www.just-health.net

16. Our bodies contain very large numbers of
bacteria (approximately 15% of your body
weight) and many of those in the intestine are
essential for our wellbeing (microflora).
nutritionresearchcenter.org

17. Defence Barriers
• Skin
• Mucous membranes
• Cilia
• Chemical barriers
• Specific response -
Immune response

18. Defence Adaptations - Non-specific responses
• Inflammation response
• Phagocytosis
• Sealing off the pathogen
Electron Micrograph of a Macrophage Phagocytosis of E. coli

19. The Immune Response
The key to a healthy immune system is its
remarkable ability to distinguish between the
body’s own cells (self) and foreign cells
(nonself).
www.niaid.nih.gov

20. The body’s immune defenses normally coexist
peacefully with cells that carry distinctive "self"
marker molecules. But when immune defenders
encounter cells or organisms carrying markers
that say "foreign," they quickly launch an attack.

21. Anything that can trigger this immune response
is called an antigen. An antigen can be a microbe
such as a virus, or even a part of a microbe.
http://www.huffingtonpost.com/2014/01/13

22. Tissues or cells from another person (except an
identical twin) also carry non-self markers and
act as antigens. This explains why tissue
transplants may be rejected.
spectrum.ieee.org