Toj.su
Sistemai asabi odam
dar muqoisa az sistemai
asabi tamomi mavjudo-
ti digar mukammaltar buda, shaklhoi olii inikosi psi-
khologi va sistemai murakkabi amalu raftorro dar namu-
di faoliyati boshuurona imkonpazir megardonad.
Sokhtori murakkabi on, ki az shabakai nakhho va girehhoi
ziyodi asabi, inchunin retseptorhoi ba shaklhoi mukhtali-
fi tasiroti muhit mutobiqshuda tarkib yoftaast, aksu-
lamalhoi zud va daqiq, mekhanizmi soddai hosilshavii
aloqahoi muvaqqatii asabi, ki azkhudnamoii tajribahoi
navi hayoti bo onho aloqamand ast, inchunin tahlili
amiqi tasiroti muhit va raftori murattabu murakka-
bro tamin menamoyad.
Tamomi tashkilahoi
asabi az hujayrahoi asabi
tarkib yoftaand. Hujayrai
asabi neyron nom dorad.
Miqdori neyronho tanho dar
magzi sari odam ba 1012 (yak
trillion) merasad.
Hujayrai asabi sokhtori mu-
rakkab dorad. On az tana yo
soma, yadro va shokhahoi
kutohu daroz iborat ast.
SHokhai daroz dar yak neyron
odatan yakto buda akson nom
dorad. SHokhahoi kutohi
hujayrai asabi yakchandto bu-
da, dendrit nomida meshavand. Akson va dendrithoi yak
hujayrai asabi bo hujayrai digar tavassuti sinapsho
payvast shuda, baroi intiqoli impulshoi asabi az yak
neyron ba neyroni digar khidmat mekunand. Sinapsho
tashkilahoi makhsusi asabie meboshand, ki aloqai
muvaqqati yo tuloniyu ustuvori baynihamii hujayrahoi
asabiro tamin mekunad.
Payvasti milliardho neyron tashkilahoi murakka-
bi asabi va shabakai sershokhai robitai bayni onhoro ba
vujud ovardaast, sistemai asab no-
mida meshavad.
Sistemai asabi odam az du
qismat iborat ast: qismi markazi va
qismi kanori (periferi,. Rasmi 7.
Qismi markazii asab yo sistemai
markazii asab (SMA) az harommagz
va magzi sar iborat ast. Magzi sari
odam, ki 1/50 hissai vazni badani
uro tashkil medihad, tashkilai mu-
rakkabtarini biologi donista me-
shavad. Vazni in uzv dar navzodi
taqriban 350g, va dar odami bolig ba hisobi miyona 1400g
– ro tashkil medihad. On dar sinni 18 – 30 solagi vazni
maksimalii khudro sohib gardida, pas az 50 – solagi mun-
tazam khurd va sabuk shudan megirad, ki sababash pirshavii
boftahoi asabi va atrofiya (khushkshavi) – i magz meboshad.
Magzi sar dar navbati khud, az magzi darozruya, magzi
miyona, magzi mobayni, magzcha va magzi pesh tarkib yofta-
ast. Rasmi 8.
Harommagz. Mo peshtar qayd kardem, ki dar sistemai
asabi girehshakl girehhoi alohida vazifahoi khudro ba
tavri mustaqilona ijro mekunand. Dar baze namoyanda-
goni sistemai asabi mutamarkaz niz in chiz dar shakli
mukhtoriyati nisbii harommagz boqi mondaast. Masalan
tajribahoi fiziologi rus I.P.Pavlov nishon dodand, ki
dar surati dur kardani magzi sari qurboqa ham on meta-
vonad bo panjaash baroi az khud dur sokhtani angezandai
noguvor (kislotai ba pusti vay chakonidashuda) kushish
kunad. In imkoniyatro ba vay faoliyati avtanomii
harommagz faroham meovarad. Harommagzi inson az
mukhtoriyat mahrum ast, vale dar natijai hamkori bo digar
sokhtorhoi sistemai asab funksiyahoi muhimi psikhikiro
ijro menamoyad.
Harommagzi odam dar kovokii sutunmuhra joygir
shuda, bevosita ham bo magzi sar va ham bo sistemai asabi
kanori payvasta ast. Vobasta ba mavqei joygirshaviash
on, dar ijroishi faoliyati psikhiki yake az vazifahoi
muhimro ijro mekunad, ki on ham boshad, tamini robita
dar bayni «shtab» – magzi sar va uzvhoi kanorii organizm
meboshad. Vazifai digari muhimi in uzv az faoliyati
reflektorii on barmeoyad. Dar harommagz markazi bisyor
reflekshoi muhim joygirand.
Magzi darozruya avvalin barjastagi dar kanori bo-
loii harommagz ast, vale barjastagi dar in qismati si-
stemai asab tagyiroti yagona nest, dar in joy sokhtori
tarkibii magz niz tagyir meyobad. Hamai in nishonai on
ast, ki harommagz ba okhir rasida, uzvi digar – magzi sar
ogoz meyobad. Mahdudshavii baze vazifaho dar in min-
taqa imkoniyat medihad, ki onro hamchun qismi alohidai
magzi sar baho dihem.
Dar magzi daroz-
ruya markazhoi bisyor
reflekshoi gayri-
sharti joygirand (dar
borai refleksho niga-
red ba zermavzui
badi). Az on jumla
markazi refleks-hoi
tappishi dil, nafas-
kashi, furubari, judo-
shavii obi dahon, araq-
judokuni, atsazani,
sulfa-zani, hikakzani,
qay-kuni, judoshavii obi dahon, reflekshoi mavqei badan
dar fazo va gayra. Ijroishi vazifahoi in markazho az
shubahoi olii (qishrii) magzi sar idora karda mesha-
vand.
Magzi miyona dar boloi magzi darozruya joygir
shuda, davomi onro tashkil medihad. Dar on hujayrahoi
ziyodi asabi jam omada, markazhoero ba vujud meovarand,
ki az rui vazifaashon ba du guruh judo karda meshavand:
markazhoi hissi va effektori (harakati). Markazhoi
hissi ba shiddati mushakii tamomi badan va ba in vasila
ba tamomi harakathoi odam yo hayvonot tasir meraso-
nand. Vazifahoi markazhoi hissi boshad, bo funksiyahoi
binoi va shunavoi aloqamandand. Markazi ba nom «start –
refleksho» niz dar magzi miyona joygir ast. In refleksho
vazifai ehtiyotkunanda doshta, dar on zohir meshavand, ki
odam yo mavjudoti digar hangomi tasiroti nogahoni yak-
bora va be sarfahm raftan ba hodisa magurezad, khudashro
panah mesozad, chashmashro mepushad va monandi inho. In-
chunin dar magzi miyona reflekshoi tarzi ist, nigoh dosha-
ni muvozinati badan hangomi rost roh raftan, harakat ba
balandi va nishebi, charkhzani va g. joygirand.
Magzi mobayni dar qismi markazii magzi sar joy-
gir buda, az se taraf bo magzi miyona, magzcha va nimkur-
rahoi magzi pesh pushonida shudaast. Magzi miyonaro mar-
kazi ehsos menomand, zero hama rohhoi asabii az uzvhoi
his ba sohai qishrii magz ravanda tavassuti on meguza-
rand. Markazhoi muhimi hissiyot va emotsiyaho niz mahz
dar in sokhtori magz joygirand. Tavassuti tasiroti
barqi ba baze nuqtahoi on dar hayvonot va inson hissiyo-
ti gazab, qanoatmandi yo tarsro ba vujud ovardan mumkin
ast. Dar magzi mobayni inchunin markazhoi fiziologii
tanzimi harorati badan va ishtiho niz joygirand. Han-
gomi tasiri suni ba qitai muayyani on ishtihoi bar-
tarafnashavanda ba vujud meoyad va hangomi tasir ba
qitai digar boshad, novobasta az gurusnagii chandruza
hayvon ba khurok etibor namedihad.
