“Effects of radiation on living tissues”

Radiation may come from either an external source like fallout from bombs, melt down from nuclear power plant melt downs  given off into the environment both air, water and food, x-ray machine, or an internal source, such as an injected radioisotope.

How does radiation effect living tissues?
The impact of radiation on living tissue is complicated by the type of radiation and the variety of tissues.

What effect can ionizing radiation have on the cells’ chemical bonds?
The functions of living tissue are carried out by molecules, that is, combinations of different types of atoms united by chemical bonds. Some of these molecules can be quite large. The proper functioning of these molecules depends upon their composition and also their structure (shape). Altering chemical bonds may change composition or structure.

Ionizing radiation is powerful enough disrupt chemical bonding. For example, a typical ionization releases six to seven times the energy needed to break the chemical bond between two carbon atoms.[91] This ability to disrupt chemical bonds means that ionizing radiation focuses its impact in a very small but crucial area, a bit like a karate master focusing energy to break a brick. The same amount of raw energy, distributed more broadly in nonionizing form, would have much less effect. For example, the amount of energy in a lethal dose of ionizing radiation is roughly equal to the amount of thermal energy in a single sip of hot coffee.[92] The crucial difference is that the coffee’s energy is broadly distributed in the form of nonionizing heat, while the radiation’s energy is concentrated in a form that can ionize.

What is DNA?
Of all the molecules in the body, the most crucial is DNA (deoxyribose nucleic acid), the fundamental blueprint for all of the body’s structures. The DNA blueprint is encoded in each cell as a long sequence of small molecules, linked together into a chain, much like the letters in a telegram. DNA molecules are enormously long chains of atoms wound around proteins and packed into structures called chromosomes within the cell nucleus. Only a small part of this DNA needs to be read at any one time to build a specific molecule. Each cell is continually reading various parts of its own DNA as it constructs fresh molecules to perform a variety of tasks.

What effect can ionizing radiation have on DNA?
Ionizing radiation, by definition, “ionizes,” that is, it pushes an electron out of its orbit around an atomic nucleus, causing the formation of electrical charges on atoms or molecules. If this electron comes from the DNA itself or from a neighboring molecule and directly strikes and disrupts the DNA molecule, the effect is called direct action. This initial ionization takes place very quickly, in about 0.000000000000001 of a second. However, today it is estimated that about two-thirds of the damage caused by x rays is due to indirect action. This occurs when the liberated electron does not directly strike the DNA, but instead strikes an ordinary water molecule. This ionizes the water molecule, eventually producing what is known as a free radical.

A free radical reacts very strongly with other molecules as it seeks to restore a stable configuration of electrons. A free radical may drift about up to 10,000,000,000 times longer than the time needed for the initial ionization (this is still a very short time, about 0.00001 of a second), increasing the chance of it disrupting the crucial DNA molecule. This also increases the possibility that other substances could be introduced that would neutralize free radicals before they do damage.
What immediate effects can ionizing radiation have on living cells?
All of these collisions and ionizations take place very quickly, in less than a second. It takes much longer for the biological effects to become apparent. If the damage is sufficient to kill the cell, the effect may become noticeable in hours or days. Cell “death” can be of two types. First, the cell may no longer perform its function due to internal ionization; or “reproductive death” (mitotic inhibition) may occur when a cell can no longer reproduce, but still performs its other functions.
Death may also result if cell reproduction ceases in parts of the body where cells are continuously being replaced at a high rate (such as the blood cell-forming tissues and the lining of the intestinal tract).

What long-term effects can radiation have?
The effect of the radiation may not be to kill the cell, but to alter its DNA code in a way that leaves the cell alive but with an error in the DNA blueprint. The effect of this mutation will depend on the nature of the error and when it is read. Since this is a random process, such effects are now called stochastic.[100] Two important stochastic effects of radiation are cancer, which results from mutations in nongerm cells (termed somatic cells), and heritable changes, which result from mutations in germ cells (eggs and sperm).

How can ionizing radiation cause cancer?
Cancer is can be produced if radiation does not kill the cell but creates an error in the DNA blueprint. Different cells have different sensitivities to radiation thus some take longer to show its effects like bone marrow is more sensitive than skin cells to radiation-induced cancer.  If the cell’s DNA mutates it can lose control of cell division, and begins dividing uncontrollably which produces the phenomena known as cancer. This effect might not appear for many years.
Cancers induced by radiation do not differ from cancers due to other causes, so there is no simple way to measure the rate of cancer induced by radiation.

Because the cancers can occur anytime in the exposed person’s lifetime,
How can ionizing radiation produce genetic mutations?
The risk of genetic mutation is expressed in terms of the doubling dose: the amount of radiation that would cause additional mutations equal in number to those that already occur naturally from all causes, thereby doubling the naturally occurring rate of mutation.
Well, on the one hand radiation can cause genetic mutation (cell death or cancer)… it can cause illness due to mutated proteins and whatnot that cause cellular function and processes to become messed up (radiation sickness). That is radiation, by itself. Radioactive material gives off radiation. If consumed or ingested, the source of radiation would be inside the body, providing a continuous dose.

Most radioactive materials are poisonous by its very chemical nature… like uranium, cesium, which is a heavy metal… and is poisonous regardless of its isotopic properties.

And chemical isotope that has one chemical property can be consumed and utilized by the body, naturally… like the formation of cell membranes or calcium for bones. If those chemicals themselves were radioactive then when they decay, they will convert to alternative chemicals. The radiation or material itself is irrelevant in this case, but the problem arises in the fact that essential components of the body are no longer built using the proper materials.

Should we be concerned for our health after the Japanese nuclear plant melt downs? See next article

 

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Excerpts courtesy of  http://1.usa.gov/fK4YiO

Excerpts courtesy of  http://yhoo.it/hjVRBu

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