Viruses!

What are Viruses VIDEO

(3:35)

It did not take doctors long to find out that the medicines that are usually used to fight bacterial

diseases did not work on all illnesses. They figured that something other than bacteria and protists must be causing diseases in humans as well.

This led to the discovery of viruses.

Viruses are microscopic

particles that invade the cells of

plant, animals, fungi, and

bacteria. Viruses often destroy the cells they invade.

AIDS Virus

A virus is not a cell. A typical virus is composed of a core of genetic material surrounded by a protein

coat. The protein coat protects the virus and enables it to invade its host cell.

In many viruses, DNA is the genetic material.

Other viruses have RNA.

Viruses are parasitic and can reproduce only

inside the cells of their host. This makes viruses

very different from bacteria and protists.

Viral genetic material has room for only a few genes. Usually they are only genes that code for the protein coat and for enzymes that enable to virus to take over the cell.

There has been an ongoing debate among scientists as to whether or not viruses are alive or not alive. Viruses lack three essential features of living things:

1. They are not made of cells2. They cannot make proteins by themselves3. They cannot use energy

Even though viruses can reproduce they are only able to so when inside living cells.

Because they cannot reproduce on their own most

scientists classify them as non - living things.

Virus Reproduction

All viruses reproduce by taking over the reproductive machinery of a cell.

The following is a story to help you visualize what it is like for a virus to reproduce…

How Viruses Work Video(2:25)

Once upon a time there was a factory that made cars and trucks.

Everyone who worked in the factory was very happy making cars and

trucks.

One day a crazy man came to the factory with an army tank! He told all the workers in the factory that they would not be allowed to make cars and trucks anymore.

They were only allowed to make tanks! The crazy man had the blue prints for the tanks and he forced the workers in the factory to make tanks instead of cars and trucks.

Once the crazy man had enough tanks he would send them out to find and take over other

factories and make them produce tanks too.

In the story the virus is represented by the crazy man in the tank. The virus takes over the healthy cell (like the tank took over the factory) and force the cell to make viruses

instead of making other cells. Once the cell is full of new viruses it bursts open and all the

new viruses take over new healthy cells.

Our mainline of defense against

viruses are the white blood cells in our

bloodstream.

These white blood cells seek out viruses

and attack them. Killing them as

quickly as possible before they can take

over other cells.

Some Infection-Fighting White Blood Cells

Vaccines Video (3:22)

The illustration is an electron micrograph of a mixture of erythrocytes (red blood cells) and leucocytes (white blood cells) The erythrocytes are the flattened, donut-shaped cells. They lack nuclei and possess millions of hemoglobin molecules whose function is to transport oxygen throughout the body. The leucocytes (white blood cells) are the round cells with a spiked appearance. They function to identify and remove foreign proteins (bacteria, viruses, toxins, etc.) from the body. This is the body's main disease fighting mechanism.

This is an actual picture of White Blood Cells, in with some red blood cells. The platelets are stained purple, a T-

Lymphocyte white cell is stained green, and a Monocyte white cell is stained gold as seen through a scanning

electron microscope.

The reason HIV is such a dangerous virus is because it has the ability to take over the

white blood cells!

HIV waits for a white blood cell to attack it, then it takes over the white blood cell and

makes it into a virus making factory.

The effect of this is that other viruses can now take over your body and kill you because your

defenses have been taken down

by the HIV.

Viruses cause serious human diseases in addition to AIDS, such as measles and influenza.

Viral diseases are much more difficult to treat than bacterial diseases. This is true for a few reasons.

#1 most antibiotics that are used on bacteria disrupt the bacteria’s cell wall or proteins inside the bacteria.

Since a virus has no cell wall or inner proteins it is immune to those medicines.

#2 since viruses actually enter healthy cells, it is hard to find them.

Not only is it difficult to find them but it is hard to kill them without also killing the cells they are living in.

The most effect defenses we have against viral diseases is

vaccination.

When you receive a vaccination your body is able to ‘learn’ how to find the virus and then if you

ever catch it your body will know how to kill it.

Vaccines have helped wipe out diseases like small pox that used to kill millions of people every year.

However, vaccines are not available for all viruses. There are many viruses that we do not have any

defense against and even if we do sometimes the viruses will mutate which can make the vaccine

ineffective.

Symptoms Cold Flu

Fever RareCharacteristically, high (102-104oF)

Cough,Chest Discomfort Hacking

Nonproductive, common; can become severe

Headache Rare Prominent

General Aches, Pains Slight Usual; often

severe

Fatigue, Weakness Very mild Can last up to 2 -

3 weeks

Extreme Exhaustion Never Early and

prominent

Stuffy nose Common Sometimes

Sneezing Usual Sometimes

Sore Throat Common Sometimes    

Cold vs. Flu How to know what you have.

Herpeshttp://www.contemporarypediatrics.com/contpeds/article/articleDetail.jsp?id=108010