-dose response-

hye...i'm Ida..emm...adawiah share with you about the dose-response curve right???

i have new information to you..i hope what i share to this entry will help you to understand about dose response curve...

Five centuries ago, the physician and alchemist Paracelsus said that:

“All substances are poisons: there is none which is not a poison.

The right dose differentiates a poison and a remedy.”

Paracelsus (1493-1541)

By this, he meant essentially that a substance in too great an amount can be dangerous, yet in an extremely small amount can be relatively harmless. Every chemical element has a spectrum of possible effects on a particular organism. For example, selenium is required in small amounts by living things but may be toxic or increase the probability of cancer in cattle and wildlife when it is present in high concentrations in the soil. Copper, Chromium and manganese are other chemical elements required in small amounts by animals but toxic in higher amounts.

DOSE RESPONSE

From these, we can know the effect of a certain chemical on an individual depends on the dose. This concept is termed dose response. Dose dependency can be represented by a generalized dose-response curve such as that shown in Figure 1.

When various concentrations of a chemical present in a biological system are plotted against the effects on the organism, two things are apparent:

· Relatively large concentrations are toxic and even lethal (points D, E and F in Figure 1).

· Trace concentrations may be beneficial for life (between points A and D); and the dose-response curve forms a plateau of optimal concentration and maximum benefit between two points (B and C). Points A, B, C, D, E and F in Figure 1 are important thresholds in the dose-response curve. Unfortunately, the amounts at which points E and F occur are known only for a few substances, for a few organisms, including people; and the very important point D is all but unknown. Doses that are beneficial, harmful, or lethal may differ widely for different organisms and are difficult to characterize.

Source :

http://www.dose-response.com/

http://aquaticpath.umd.edu/appliedtox/dose-response.pdf

http://www.eoearth.org/article/Dose-response.pfd
prepared by : * ieda 4-ever*

TOxiC????

Do you know what is toxic ??

Do you know toxic is very dangerous to our body??

Toxicity is the degree to which a substance is able to
damage an exposed organism.
Toxicity can refer to the
effect on a whole organism, such as an animal, bacterium,
or plant, as well as the effect on a substructure of the organism, such as a cell (Cytotoxicity) or an organ (organotoxicity), such as the liver (hepatotoxicity).
By extension, the word may be metaphorically used to describe toxic effects on larger and more complex groups, such as the family unit or society at large.

A central concept of toxicology is that effects are dose-dependent; even water can lead to water intoxication when taken in large enough doses, whereas for even a very toxic substance such as snake venom there is a dose below which there is no detectable toxic effect.

resource: www.wikipedia.com

by:*esyahzul*

DOSE-RESPONSE RELATIONSHIP

Hye….adawiah come back with new information. I hope you all enjoy with entry in this blog…for this tyme I will share to you…about…about what ya…about DOSE-RESPONSE RELATIONSHIP…

Did you know about that???NNNOOO???oh…so sad…BUT..its ok..i will share with you.dont worry la...but you must finish to read my entry..hahhaa…ok..

emm…maybe now you are thinking what it’s DOSE-RESPONSE RELATIONSHIP…I will tell you about the definition about DOSE-RESPONSE RELATIONSHIP..

"DOSE-RESPONSE RELATIONSHIP describes the change in effect on an organism caused by differing levels of doses to a stressor after a certain exposure time. This may apply to or to populations. For your information DOSE-RESPONSE RELATIONSHIP known as exposure-response relationship".

Studying dose response, and developing dose response models, is central to determining "safe" and "hazardous" levels and dosages for drugs, potential pollutants, and other substances to which humans or other organisms are exposed. These conclusions are often the basis for public policy

Did you know what is DOSE-RESPONSE MODEL??

This is the DOSE RESPONSE MODEL

It should be realised that dose-response relationships will generally depend on the exposure time. The quantifying the response after a different exposure time leads to a different relationship and possibly different conclusions on the effects of the stressor under consideration. This limitation is caused by the descriptive nature of the approach.

O0oppsS…guy I have to go to class now…emm…i hope the simple information above can make you understand about DOSE-RESPONSE CURVE..I will share to next tyme k??maybe after my class..hehhe..wait for my entry for next episode…hahaha…

Bubye~

references :

http://en.wikipedia.org/wiki/Dose-response_relationship,http://www.curvefit.com/introduction89.htm

by : *adawiah*

wow....threshold effect again!!!

Not enough to understand about threshold effect?? Here, I come to let you see a ‘picture’ that I promised to show..Ectually,the picture is just a picture of graph..Interesting right??Haha..

Knowledge of the slope is important in comparing the toxicity of various substances ( Figure above). For some toxicants a small increase in dose causes a large increase in response (toxicant A, steep slope). For other toxicants a much larger increase in dose is required to cause the same increase in response (toxicant B, shallow slope).

A threshold for toxic effects occurs at the point where the body's ability to detoxify a xenobiotic or repair toxic injury has been exceeded. For most organs there is a reserve capacity so that loss of some organ function does not cause decreased performance. For example, the development of cirrhosis in the liver may not result in a clinical effect until over 50% of the liver has been replaced by fibrous tissue.

Pen off.Tata

Resources :

Turk J. & Turk A.(1988).Environmental Science.4^th Edition.United States of Amerika.Saunders College Publishing.

by : *eizzah*

Let’s get knowledge about threshold effect

Did everyone know about threshold effect?or never heard about it? ...Don’t worry friends... In this section i will give information about threshold effect...Hope all of you will enjoy reading this article below..=)

Threshold effect that we will learn together are relating to the environmental and human health

What is a threshold effect ?

Threshold effect is a level below which no effect occurs and above which effects begin to occur.

Did you know about dose?

Dose can be defined as amount of toxic material that enters in our body.

How threshold dose of a chemical can be related to our health effect?

If a threshold dose of a chemical exists, then a concentration of that chemical in the environment below the threshold is safe. If there is no threshold dose, then even the smallest amount of the chemical has some negative toxic effect. For example, taking aspirin is therapeutic and not dangerous up to a contain dose, but above that dose it can cause nausea, brain damage, bleeding, and, eventually, death. Sulfuric acid is not dangerous when only small amounts of it get on a person's skin, but if the amount gets too high, it burns. Thresholds for toxicity exist because, up to a certain point, the body can repair damage and detoxify chemicals to which it is exposed. If the exposures get too high, however, the detoxification and repair mechanisms are overwhelmed and toxicity starts to occur.

Now, do you understand what threshold effect about??To be more understand and exciting about this,let see some ‘picture’...But wait and see it on the next entry..To be continued

Resources :

http://www.answers.com/topic/threshold

Botkin D. & Keller E.(2007).Environmental Science.Sixth Edition:Earth as a Living Planet.United State.John Wiley & Sons.Inc.

by : *eizzah*

-the safe environment-

by : *adawiah*

....welcome...welcome....

Assalammualaikum...

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by : ada,ida,na,izah,esyah n nita