The most significant biological consequences of radiation result from the The severity of the effects depends on the density of ionisation in the medium. All these processes lead to the final radiobiological effect of the radiation on the human body. Ionizing radiation can, apart from causing. In summary, radiation can affect cells. High doses of radiation affect many cells, which can result in tissue/organ damage, which ultimately yields one of the Acute Radiation Syndromes. The next few pages will discuss the biological effects of low doses of radiation.


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Following this, physicochemical processes take place, such as intramolecular energy transfers, excitation and ionization of atoms.

What are the biological effects of ionizing radiation?

The time length of this is about s. Then the chemical processes start.

At this point primary damage to biological structures begins at the time length of about seconds. Following the chemical processes, biological processes starts to occur. In this phase the damaged biological structures can be either repaired or irreversibly damaged.

Biological effects of ionizing radiation

Biological damage can lead to cellular death, which can occur over time periods from seconds and up to years.

All these processes lead to the final radiobiological effect of the radiation on the human body.


Ionizing radiation can, apart from causing damage, also lead to activation of adaptive and protective mechanisms. The pathogenesis of ionizing radiation damage starts at with the physicochemical processes.

These processes give origin to reactive compounds that act on molecular level and cause radiation cellular changes. This causes cells to losing their specific properties. At the subcellular biological effects of radiation there are irregularities happening to the biochemical processes: The activity of enzymes changes phosphorylation mechanisms are disrupted the synthesis of nucleic acid specific proteins do no longer work.

The cellular level of damage first manifests itself with a decrease in the number of proliferating cellular populations. The loss of specialized cells causes the biochemical biological effects of radiation to intensify. The changes starts to interfere with the functions of vitally important biological effects of radiation such as hematopoietic tissues, intestinal epithelium etc.

The resulting organ and systemic changes to the whole organism initiates the development of radiation sickness. There are also latent somatic and genetic damages, which can be seen on a population level.

Biological effects of the same doses of ionizing radiation can differ greatly.

Radioactivity : Biological Effects

These effects depend on the linear energy transfer and on the spatial biological effects of radiation of a given dose. DNA molecules are the most critical cellular structures that can be affected by ionizing radiation.

Ionizing radiation can induce a number of changes in the size, structure and shape of these molecules. Understanding of how the ionizing radiation affects the cell is an essential prerequisite to understand the pathogenic mechanisms that causes somatic and genetic damage to human tissues.

One of the most important properties of cells is the ability to divide and create identical daughter cells. The cell cycle consists of 4 phases: The first post-mitotic G1 phase starts immediately after the cell division and is characterized by the synthesis of RNA, proteins and DNA precursors. G1 lasts up to tens of hours.

In this phase it is decided whether the cell is going to continue in the cell cycle, differentiate, die or enter the resting G0 phase. In G0, the cells stop dividing. At the end of the G1 phase the cell is the most radiosensitive, and is biological effects of radiation to enter the S phase, which lasts hours.

Biological Effects of Radiation | Teach Nuclear

This phase is characterized by the lowest radio sensitivity. The DNA in the nucleus is duplicated, and a number of specific proteins are synthesized.


Following the S-phase, the cell enters the G2 phase. G2 phase is rather short; it lasts approximately hours.