Microbe and disease. immune system

Glossary
antibiotics – Chemicals prescribed as medicine to kill bacteria inside the body.
antibodies – Chemicals produced by white blood cells to fight microbes that cause disease.
bacteria – The type of microbes that are single-celled organisms.
fungi – The type of microbes that feed off other living things.
immune – Resistance to infection caused by a microbe.
microbe – A very small living thing.
transmission – The spread of a disease from person to person.
viruses – The type of microbes that can only grow and reproduce within other living things.

Microbes are very small living things and are sometimes called micro-organisms.There are three types of microbes:
Different types of microbes
bacteria
viruses
fungi
microbes

Bacteria fact file
size: 1/1000 mm
shape: Bacteria can be spherical, rod-shaped or comma-shaped.
structure: Bacteria are single-celled organisms, which do not completely have a nucleus. Some cause disease, but many
are useful.
reproduction: Bacteria reproduce very quickly. Two can very quickly become four, then eight and so on.
The time of reproduction depends on how desirable the conditions are.
Bacteria can rapidly reproduce themselves in warm, dark, and moist conditions
Some can reproduce every 20 minutes
Example: flu, measles, chickenpox, smallpox
Bacteria e.g. Salmonella and Streptococcus

Viruses fact file
size: 1/1,000,000 mm
shape: Viruses have regular and geometric shapes.
structure: A virus is a simple organism which does not display ALL the characteristics of living things. They are made up of a protein coating and some genetic material.
reproduction: Viruses can only grow and reproduce within other living things.
Example: cholera, sore throat, food poisoning
Viruses e.g. flu virus and HIV (the AIDS virus)

Fungi fact file
size: Some fungi can actually be seen with the naked eye, others are slightly bigger than bacterial cells.
shape: Fungi come in many different shapes.
structure: Fungi have the
most complex structures of
all the microbes. They feed
off other living things.
Example : fungal sinusitis
Fungi e.g. Penicillium and yeast

Microbes have many uses that are based on the fact that microbes can be grown.
Bacteria grow in milk to make it ‘go off’.
This type of bacterial growth is used to make milk into yoghurt.
Cheese is another product that is made from milk.
Yeast is a type of fungus and carries out respiration. The respiration of this microbe can be used in different ways in baking bread and in brewing.
The anaerobic respiration of yeast is used to make beer and wine.
Using microbes – bacteria and fungi

Microbes can enter the body in many different places.
How do microbes enter the body?
How are the diseases caused by microbes spread?

How are microbes spread ? The spreading of microbes and disease is known as transmission.

How are microbes spread?

The spread of disease can be prevented by making sure that good hygiene is used in key places such as bathrooms and kitchens.
How is the spread of disease stopped?

Fighting microbes
How does the body fight off microbes that cause disease?

The body’s defense against disease causing organisms, malfunctioning cells, and foreign particles
What is the immune system?

The dead, outer layer of skin, known as the epidermis, forms a shield against invaders and secretes chemicals that kill potential invaders
You shed between 40 – 50 thousand skin cells every day!
The First Line of Defense
~Skin~

The First Line of Defense
~Saliva~~Stomach Acid~
What’s the first thing you do when you cut your finger?

The food is digested within the hole in the tube, but it never actually enters into the solid plastic material.
Think of the human body as a hollow plastic tube…
Tube inner surface ~Digestive System~
Plastic interior ~Body~
Tube outer surface ~Skin~

If invaders actually get within the body, then your white blood cells (WBCs) begin their attack
WBCs normally circulate throughout the blood, but will enter the body’s tissues if invaders are detected
The Second Line of Defense
~White Blood Cells~
Video

What do white blood cells do?
The human body has a number of natural defences against microbes.
Some white blood cells can destroy microbes by engulfing them.
Some white blood cells are able to produce chemicals called antibodies. These pairing with matching antigens on the surfaces of microbes and so help the white blood cells to engulf microbes.
The body also produces white blood cells to help defend it from microbes.

Viruses enter body cells, hijack their organelles, and turn the cell into a virus making-factory. The cell will eventually burst, releasing thousands of viruses to infect new cells.
Viruses

Virus-infected body cells release interferon when an invasion occurs
Interferon – chemical that interferes with the ability to viruses to attack other body cells
The Second Line of Defense
~Interferon~
What happens to already infected cells?

Injured body cells release chemicals called histamines, which begin inflammatory response
Capillaries dilate
Pyrogens released, reach hypothalamus, and temperature rises
Pain receptors activate
WBCs flock to infected area like sharks to blood
The Second Line of Defense
~The Inflammatory Response~

Most infections never make it past the first and second levels of defense
Those that do trigger the production and release of antibodies
Proteins that latch onto, damage, clump, and slow foreign particles
Each antibody binds only to one specific binding site, known as an antigen
The Third Line of Defense
~Antibodies~

Resistance to a disease causing organism or harmful substance
Two types
Active Immunity
Passive Immunity
What is immunity?

You produce the antibodies
Your body has been exposed to the antigen in
the past either through:
Exposure to the actual disease causing antigen – You fought it, you won, you remember it
Planned exposure to a form of the antigen that has been killed or weakened – You detected it, eliminated it, and remember it
Vaccine : Antigens are deliberately introduced into the immune system to produce immunity
Because the bacteria has been killed or weakened, minimal symptoms occur
Have eradicated or severely limited several diseases from the face of the Earth, such as polio and smallpox
Active Immunity

You don’t produce the antibodies
A mother will pass immunities on to her baby during pregnancy - through what organ? PLACENTA
These antibodies will protect the baby for a short period of time following birth while its immune system develops. What endocrine gland is responsible for this? THYMUS
Lasts until antibodies die
Passive Immunity

Immune system mistakenly recognizes harmless foreign particles as serious threats
Launches immune response, which causes sneezing, runny nose, and watery eyes
Anti-histamines block effect of histamines and bring relief to allergy sufferers
Immune Disorders
~Allergies~

Caused by the Human Immunodeficiency Virus
Discovered in 1983
Specifically targets and kills T-cells
Because normal body cells are unaffected, immune response is not launched
AIDS
~The Modern Plague
The HIV virus doesn’t kill you – it cripples your immune system
With your immune system shut down, common diseases that your immune system normally could defeat become life-threatening
Can show no effects for several months all the way up to 10 years
Acquired Immune Deficiency Syndrome

The problem of preventing diseases caused by germs is an exceedingly difficult one and no solution for all diseases has yet been found. One's chances of avoiding such diseases, however, may be greatly enhanced:
1. By strengthening the body through hygienic living so that it offers greater resistance to the invasions of germs.
2. By living as far as possible under conditions that are unfavorable to germ life.
3. By understanding the agencies through which disease germs are spread from person to person.
Avoidance of Germ Diseases

Habits of living must harmonize with the plan of the body
1. Of exercise: Exercise daily the important groups of muscles.
2. Of form: Preserve the natural form of the body.
3. Of energy: Observe regular periods of rest and exercise and avoid exhaustion.
4. Of nutriment: Eat moderately of a well-cooked and well-balanced diet and drink freely of pure water.
5. Of respiration: Breathe freely and deeply of pure air and spend a part of each day out of doors.
6. Of nervous poise: Suppress wasteful and useless forms of nervous activity, avoid nervous strain, and practice cheerfulness.
7. Of cleanliness: Keep the body and its immediate surroundings clean.
8. Of restraint: Abstain from the unnecessary use of drugs as well as from the practice of any form of activity known to be harmful to the body.
9. Of elimination: Observe all the conditions that favor the regular discharge of waste materials from the body.
Hygienic living