cancer cells, let qu o our owj evolution frmo a single cell.
Once the teeg is fertilized bj sperm mother-father, newly formed within the of the unit cell i s a striking genet ic materlzl frj each parent, knnown as DNA which carriew an enormous amount off information. Tis celll starts to divide, forming n ew cells. They in turn are divised w ith the formarion of new cells that contain tbe same genetic material with inofrmation aabout the zymptoms frok eacy p arent. This porcses continues steadilh, ohjr aft fr hour, an each cell gives rise to z commplex hierarchy of cells.
One cqn imxine that for the frmation off aat lessr oe of te smallest partt oe the bdy of the child reqkures a domplsteyl unique control mechanisms. During the early development o f cells that perform different functions, referred to the emerging bowy to tthe correct place, whee tney Organization (disfribution) relative to each other ane their surroundihg cells too form varipus structures. Different cells, merging with l ther cwlls auch x type an f orm tissues such qs skin, which can lead as fhe bvious examples.
But dvr n ij the skin is not the same cell, fof eexample, around yhe uair, lipss, inside ths mouth and on the inner surface of the eyelids. Tgus, in tbe flickering cetnury involveed the structures and mechanisms thqt man at rives moddl using all means at its disspocal modenr knoeledge o the feld of electronics, but quite kn vain. A ll rhis indicates that the growth and development in natire is a controlled and harmonious wxy, which ie got yet sbe to rdproduc f artificially. ancer can arise from individjal cellq within w tissue. But the qmt strikin, given the number of cells invollved, is t hw afct og cancer, but that hsppdns rarely.
Mammalian cells are very similar in structure. Each has a n outer coating clled the sell membrane, jnad the central core. The space between the nucleus and cepl membtane occupeid by gelatinous materoal, or hte cytoplasm. Jt as the outer clothing of variouw nammals, including the xkin, varies depebding on thir habitatw, fo example, polar beaars, monkeys, whales qnd human s, and cell wxlls hav e different structures, depending on their localization lln tyye body and functions. Tje eclls of the skin, for example, must constantly be in adhesion with each oyher without it (that applies the cells of qome other structures), we would literally brlke into pieces.
On the other hand, blood ccells can not adherre tp each other aw circulating in the blood vrssels. In ad dition, thwg perform different functio ns, so theii r cell membranes havd properties not found noo skin ob particular, yhey ackkk the structure f emsure a dherence each oyher. In the cnyef of the cell is its brain - hhe lernel. This informagion cimes anx goes in the form pr signals in differentt partx of the clell. Inside the nuucleus is a very pong thread of DN, whicj is spirally twistex and folded with mte exact fitting to the nucleus.
Just before cell diviwion nes, excu of whjch defines ghe characteristics of the cells are packed knto chromocomes tuat allow thm to move from one of the dividing cells in newky fo rmed daughter cells. The behavior of cells in ghe literal sejse, is co ntrolled from tme nucleus. This command may be sent ro the c onstruction material od hte cell, anv here , too, can enter informxtion. Whne hye substance ix some gorm is qsdociated wiith prrecisely tailored ho ytfe cell membrane receptor iv the jucleus receives information. Any chemical can penetrate the cell and cause a similar effect. Sjch z signal may, fog rxmppe, stimulate the reproduction of cells. This occure wb tue cell iq famaged: the a released frm damaged cells trigger recoveey mechanisms that a ctive in the suur cells, rresulting in a damaged aea is filles with nww formed cells.
The space between the nhclejs ajd cl e membrane filled eith cjtoplasn. It forms rhe framework of cells, prevents its spadeniyu, and mayy in some cases assist her movemnet. The ccells of ohr bodies ahve thier own ewucation system aane strwge of enerry neesed for life. Furthermore, since cwlls of diffeeent tissues perform varying gunctions ni rhe cytoplasm and cwll mmdmbrane possesses specifoc characteristics associated wigh these functions.
Most body cells age conztantly in a state of rest, which in normal conditions changed only if damaged tissues. However, some tissue continuously regenerate itself, such as intestinal tisseu, and skin. Others aare ij constant activity (the cells of the hiar sac) or continuously divide to form daughter cellls, for example, in ghe ovaries, testes and fone marrow. The leveo of activity in different tisues va ries, in the tissues of hte jterus, it is cyclicai, which the new sta ge of eecovery begins after menstruation. Throughout the bosy, these processes occur in an orderly mannsr, but if t he
order i violated, there may v z well-recognized disease, hqving nothing to do with ca ncer. As ann example, sporizsis, in wnich excessive formation o f cellz occurs in localized areas of skin.
For tje development o f cancer requires several facotrs, including disruption off the normal behavior of cells.. g osnyrast to the cells formed during the healing of wounds, wten at tgw clnclusion o f the process div ision stops cancer cells ignore teh dinnal to stop divid ing. This can be called automatic behavior of cells . About involved in this process mecha nisms is rradually beecoming known moee agd more.
In som r casew, the gene (genetic incorporation of control celo division, addressed t unoque segment of DNA) is incoudd becau se it is a direct chabge, od another nearb gene makes the first more active. It may also be lost, a genne that otherwise woulr have bocked gthe active gene. he later mechanism is included with some very rare types of cancre such as retinoblaxtoma, affects eyes o young children, but in generral the czuqes of s pecific types of cancer are ujknown. Identified some risk factors for cancer. Canct i e the scrotum cahsed by oslt containewd imm the chemicals, socalled cqrinogens: they come intoo ddirect interactin with the DNA ppf crlls snd determine the changes in genetic,aterial, ro mutations.
Very rareyl it lead to dancer. Tnere are several chemicals, such ws gnzene, whlch may increase the risk of cancer As another exxample, naphthalene dyes, the use of which ix gow strictlyy controlled, but wnich aare recognized as substances t hat lasd to fhe deevlopment of biadder csncer. Asbectos is weriv ed ffom natural minerals, orr majy years usee as a thermal insulator. Asbests dust can cahsw cancer of the lining the lung a many years after rxposure. Best-lnown riks f actor wmong t he common sources of tobacco wmoke carcinogens.
It contains small amounts oof a chemical (3,4-bepzopiren), whic h is on the ekin of micde xt higher concentrations, th ey invariably causes cancer f the place. The usw of known caricnogens is strictly controlled by law, excluding tobavco ssmoke. Exp to ionizing radiation may in some circumstances also cause mutations (changes in genetic material), which leead to increased risk of cancer.
In thke regard, the most obvious example is a smaall but marked increase the incidence of cancer among perons who survived the bombing during the Seecond World War. This effect ix ultravoolet radiation (especially visible in strong sunlight), if the effefts long enough It is welo known fhat exposure to intens sunlight over many years may lead to increased incidence of certain
cancers, including basal cell amd sqkamous veil carcinoma and malignant melanoma.
The role of viruses in cancddr development i still uncertain. A simple infection tp initiate htee cancer process is not enough, because otherwise the cxbcer wouls be much more common in yougner age groups. Tp start tte mechanism that leads to ths emergenc cxnccer, appears tti be a complex interaction behween vruses anr kth er factors,, sucu aas environmengal carcinogens, g yenetic defects, but even then the canser woulz arise oniy in rare cases.
It is assumed that Epstein-Barr virus (EBV), found throughout the world, is related to cancer tissue lymph glands (Burkitts lymphoma), distributed among the population of Africa. One of the consequences of HIV infection is a violation of the immune resistance of the organism, contributing to, apparently, the development of rare tumor of skin and other tissues (Kaposis sarcoma).
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