II. Song dien nhanh va ngan noi len tinh hinh nao khi hoat dong X Noi len lao dong tri oc bat dau.
BIEN HOA HOA HOC BAP THIT KHI VAN DONG
KHI VAN DONG
Tieng trong, tieng coi, khau lenh cua ngudi phu trach va thay giao, phao lenh kich thich thinh giac truyen vao vo nao va duoc ngudi lao dong va ngudi van dong vien tiep thu la tin hieu bat dau van dong ciia vo nao. Dong thdi cor the sinh ly phuc tap bat dau phat sinh tac dung. Luong hung phan do truyen den b i p thit do than kinh nao tuy di qua cac nhanh than kinh ciia tuy song. Khi hung phan truyen den bap thit thi b i p thit co vao hoac dan ra. Bap thit co vao la bieu hien trang thai bien hoa cua albumin cor.
Su bien hoa trang thai ciia albumin co bieu hien b i n g soi co co lai va co het co. Hoat dong co tinh chat nguyen t i c tu dong ciia soi co co lai do la hinh thanh qua trinh tu dong chuyen tiep lay nang luong can thiet trong su phan giai cac chat hoa hqfp co lan d trong mau. Dung dau cac chat hoa hop lan co du trU nang luong Ion la A.T.P (acide adenosin triphosphorique).
Bat cii bap thit d vi tri nao co vao cung kem theo su phan giai A.T.P Do do co the thay ring khi b ip thit co vao thi trong b ip thit sinh ra qua trinh bien hoa nang thanh co nang. Co che sinh ly ciia qua trinh bien hoa nang thanh co nang phat sinh trong bap thit ve co ban da duoc nha sinh vat hoc Ankailicot giai thich vao thdi ky hon 60 nam qua.
Nang lu ong can thiet de tien hanh h o a t don g bap thit do sir phan giai A.T. P cung cap. Do do chung ta thay rang bap thit co vao la do khdi lu ong A.T. P trong b i p thit quyet dinh. Neu A.T.P trong bap thit it hon miic can thiet thi b i p thit khong co kha nang hoat dong (co) binh thudng. B i p thit nao thieu chat A.T.P thi khi co vao khong duoi ra duoc hoac khong duoi t h i n g hoan toan nhu khi b i t dau duoi ra. Chi co khi nao b i p thit van dong khoi phuc lai duoc A .T .P b i n g miic co the lam cho b i p thit hoat dong duoc thi b i p thit mdi khoi phuc lai duqrc trang thai binh thudng. C h u n g ta biet duoc hien tu on g nay la qua nhieu cong trinh nghien cuu nghiem tuc thuc hanh thuc nghiem doi vdi sue vat. Cung nhu hien tuong do thudng thay d nhiing ngudi van dong vien mdi tap chay cu ly n g i n ; van don g vien thay mot cam giac kho chiu khi b i p thit “ciing” ra, hoac mot ngudi dang lao dong chan tay cang t h i n g bong nghi thdi gian dai thi khi lao dong lai cu ng thay hien tuqrng nhu tren ( b i p thit “ciing” ra).
Neu khi bap thit co vao, chat A.T.P phan giai trong thdi gian cach quang giiia luc b i p thit co vao phat sinh ra tac dung hoa hoc lam khoi phuc A.T. P da tieu hao khi van dong. Ve m at nay, b i p thit khac nao nhu mot binh i c quy hay m ot cai pin, khi ph at hien ra pin du trii dien m at di va chi co khi nao bap thit co(n h u sac de)nap lai vao roi thi mdi thay nguon dien lu c co nhu
cu. Tinh hinh sac de dien nay cung giong nhu tinh hinh trong thoi gian b i p thit nghi hoac thai gian bap thit duoi ra hoan toan.
Tac dung hoa hoc de ra nang luong de khoi phuc A.T.P co oxy tham gia (tac dung oxy hoa hoac tac dung phan giai can oxy) cung co the khong oxy tham gia (tac dung phan gia yem khi). Thu nhat : chu yeu la phan ung oxy hoa cua hydratcarbon, mot phan chat m o \ nhung loai chat tuong tu mo, albumin; hai la : bien hoa phat sinh ra theo kieu len men ciia hoa hop lan va hydratcarbon, C 0 2 va nuoc bai tiet trong co the ra la san pham cuoi ciing cua tac dung oxy hoa. Acid lactic va acid cetonic la san pham cuoi cung ciia tac dung phan giai yem khi cua hydratcarbon. Acid lactic va acid cetonic tich lai trong co the de sau se oxy hoa hoac theo nuoc tieu va mo hoi ra ngoai. Phuong thuc phan ung oxy hoa la phuong thuc tuong doi ngan nhat bdi vi luc do co the loi dung vdi han do ldn nhat nang luong cua chat bi oxy hoa. Con phan ling thieu oxy co the su dung nang lu on g nhanh hon phan ting oxy hoa, nhung khong rut gon hon bdi vi san pham ciia no la nhting chat chua duoc oxy hoa day dii nhu acid lactic.
Hai phuong thtic bien hoa hoa hoc ke tren tuy theo mtic do nao do ma co the coi la bien doi (dot chay) hoan toan va bien doi (dot chay) khong hoan toan. Ai cung ro r i n g khi oxy day dii, nhiet lu on g san sinh ra
do su dot chay hoan toan cua chat dot thi nhieu hon nhiet lu on g san sinh ra bdi su dot chay do dang cua chat dot; bdi chat dot chay do dang sau nay lai co the dot chay duoc nua.
H ydratcarbon va chat md oxy hoa thanh C 0 2 va nude, do la hai chat hoan toan chay het va acid lactic hinh thanh khi phan giai hydratcarbon trong trudng hop thieu oxy vdi mure do nao thi lai co the bien thanh chat dot.
Tai sao khi b i p thit van dong, trong b i p thit da co tac dung oxy hoa tiet kiem va co loi cho co the ve mat cung cap nang luong, dong thdi lai co phan urng khong tiet kiem thieu oxy, do do khong co loi cho c o the ? Nguyen nhan la vi khi b i p thit hoat dong, nang luong tieu hao nhieu gap nhieu lan khi bap thjt trong trang thai tinh. Thi du khi di bo vdi toe do 48 thudc mot phut, co the lam cac chat thay cu doi mdi tang 82%. Vdi toe do 148 thudc mot phut thi cac chat thay cu doi mdi tang 1762% vdi toe do 228 thudc mot p h ut.T rong mon chay bien toe thi cac chat thay cu doi mdi tang len 1420% nhung vdi toe do chay 400 thudc mot phut, cac chat thay cu doi mdi tang len 8500%. Do do co the thay rang trong khi thi chay, co the van dong can so luong oxy tang gap 8500 lan. Nhung (phan dudi se noi den) cai do kho co the co duoc bdi vi so lu on g oxy can thiet cho co the bi quy luat cua he ho hap va he tuan hoan
han che; vi the cho nen khong nhd den oxy giup cho phan ung thieu oxy. Khi bap thit bat dau hoat dong, phan ung thieu oxy co the bao dam qua trinh tu dong thay cu doi moi ciia cac chat co tinh tich cuc cao do. Hon nua chi khi so' luong oxy ciia bap thit tham gia van dong dat toi muc do can thiet, thi qua trinh phan urng thieu oxy moi co the bang qua trinh oxy hoa. Muc dich va tac dung thay cu doi mdi ciia cac chat la kh« phuc A.T.P phan giai thanh nang luong.
Su nhin nhan cho thay r in g , phan urng thieu oxy ma ngudi ta tien hanh hoat dong b i p thit nhu trong dieu kien “thieu h u t” , bdi vi san pham hinh thanh day dii chua oxy hoa do thieu oxy va chu yeu la sau khi hoat dong ket thiic hien tuong oxy hoa trong gid nghi duoc bu lai. Hon nUa trong mot so trudng hop so luong oxy can thiet luc nghi van cao hon so vdi luc van dong (do goi la hien tu on g “no oxy” , (ve diem nay se noi tdi d phan sau).
Tom lai, nguon nang luong ciia b i p thit co vao la do A.T.P phan giai va khoi phuc trong qua trinh b i p thit van dong, nguon dam bao san sinh ra nang lu ong de khoi phuc A.T.P la hydratcarbon, md, cac chat tuong tu md va cac chat khac. A.T.P d trong b i p thit khong ngiing bi phan giai va mot phan nao co the theo quy luat tu nhien bi co the lam m at di, nhung co the tu hoan toan du oc khoi phuc lai. Khi hydratcarbon phan
giai thieu oxy thi mot phan cua san pham cuoi cung cua no la acid lactic lai co the dung de che thanh hydratcarbon.
Hieu qua cuoi cung sau khi qua trinh oxy hoa hoan toan hinh thanh roi, co the bai tiet ra ngoai C 0 2 va nuoc, do do ma gay ra hien tuong thieu nguon nang luong cho co the (hydratcarbon, mo, albumin) va doi hoi phai lay 0 ben ngoai de bo sung cho co the. Qua trinh bo sung nguon nang lu on g cho co the giai quyet b i n g cach dung nap dinh duOng an uon g h an g ngay. Vay qua trinh bo sung dinh duOng de cho du trti nang lu ong tien hanh nhu the nao ?
Trong b i p thit ngoai A.T.P va nhiing ch at hoa hop lan giau nang luong con co du trii hydratcarbon duoi hinh thuc glycogen va con co du tru mo duoi hinh thuc chat mo co lan NO oxy hoa mot cach de dang. Khi bap thit van dong, nhung du tru nay bi tieu hao truOc, theo do la du tru nang luong tieu hao gom nhung nang luong hau bj d cac bo may khac chuyen tOi bap thit de bo sung. Noi chua hydratcarbon (ve m at sinh ly hoc goi la kho du tru hydratcarbon) la gan. Cu 100 gam trong lu ong gan thi co 4-5 gam dudng; con “ kho du tru mO” la m ang m o duoi da, m o bung va m ang ruot.
Qua t n n h b i p thit van dong, dac biet la nhting van dong m anh, cuc m anh nhu th o m o, nong dan ca y btia, cong nhan khuan vac, nhting van dong vien ca c mon
the thao : quyen anh, bong da, truot tuyet, quan vqrt va trong mot thOi gian dai gan se tiet glycogen tao thanh glucose. Glucose nay tham vao mau qua te bao gan, roi tti mau tham vao bap thit; khi da tham vao b i p thit roi, hoac la bi xam nhap vao qua trinh phan giai oxy hoa, hoac la bien thanh duong roi moi gap phan giai thieu oxy hay phan giai oxy hoa.
Phan giai chat lipid no co phan khac, chat lipid kl di tii kho du trU vao mau trudc het bi gan giti lai; gan cai tao chat lipid “trung tinh” tham gia phan ting hoa hoc thanh lipid photphoric (lipitdephosphorique). Lipid photphoric vao mau oxy hoa m ot cach de dang; m au van chuyen den cac b i p thit; b i p thit cung cap cho su tieu hao mat di.
Do do, chung ta co the thay rang : trong qua trinh lay nang luong cung cap cho b i p thit tham gia vao van dong, gan co tac dung vo cung quan trong va cu the. Bo sung du trti nang luong va qua trinh chat lipid ton tai “ kho du trti” la nhd an tham qua mao ruot vao mau.
Dting ve quan diem hoa hoc sinh vat ma suy nghi, kha nang van dong cua b i p thit rieng chi do du trti nang ItiOng it hay nhieu quyet dinh ma m oi b ien hoa hoa hoc ph at sinh ra trong co sd con co su tham gia ciia m ot loai v a t chat khac vdi so lu on g nho nh ung co tinh tich cuc dac bi<?t n i m trong ba t cut khi quan va to chtic nao. Loai vat chat nay bam sinh che tao ra trong
ca the cua con nguoi, nhieu cong trinh cac nha khoa hoc da nghien curu (ca the dong vat va vi sinh ciing co the che tao ra duoc); no bao dam cho phan ung thay cu doi mori ciia chat nay hay chat khac no luon tien hanh rat nhay cam va tien trien theo mot quy luat nhat dinh b i n g toe do nhanh hay cham cho cuoc thay cu doi mui noi tren. Nhung trong qua trinh phan ung no khong co tieu hao gi ca, dong thdi cung khong phai la thanh phan ciia mot san pham nao true tiep tham gia phan ung do; chat do la chat men, m ot tap doan men tu nhien vinh curu.
Sd luorng cac loai men trong cor the co rat nhieu loai, vi moi loai phan ung deu co mot loai men rieng biet tham gia. Thi du, co rat nhieu men la men oxy hoa, mot so luong lOn la men bao dam tac dung phan giai hydratcarbon thieu oxy, cung co men phan giai chat lipid hay phan giai chat albumin v.v... khi co the co tin hieu thay cu doi mdi la no tu dong xuat hien.
Men cang co sure nhay ben thi cang m anh, ca n g lam cho phan ung co lien quan den chat men do tien hanh cang nhanh. Nhu the no co y nghia gi ddi vdi c o the ? Do tat ca nhung diem noi tren, ch un g ta co the thay rang du tru A.T.P cang nhieu, nang luc van d on g ciia bap thit cang ldn; nhung nang luc hoat don g ciia b i p thit co the nang cao len duoc du la so lu on g A.T.P trong bap thit khong tang len. Men co the bao dam cho qua
trinh oxy hoa hay qua trinh thieu oxy tien hanh de khoi phuc A.T.P. Vi neu su nhay ben tich cuc tinh cua men duoc nang cao, thi khoi phuc A.T.P tien hanh duoc nhanh, b i p thit co the hoan thanh van dong duoc vOi mot khoi luong nho A.T.P hoac nguoc lai A.T.P van bi tieu hao nhu thuOng (co khi it hon), ma bap thit van tien hanh van dong duoc nhieu hon. Cho nen, n h o co anh huong ciia van dong lao dong va tap luyen, bie hoa trong b i p thit phat sinh tot hon, (se noi ro hon o phan sau) ma sir hinh thanh qua trinh dien bien va khoi phuc cac yeu to' van tot.
Co mot dac diem can phai nhan m anh la cong tac nghien curu tien hanh doi voi van dong, sire van dong khac nhau va thirc nghiem tien hanh tren don g vat deu chung minh no dam nhiem vdi m ot nhiem vu sinh ly khac nhau, tinh chat bien hoa hoa hoc sinh vat phat sinh ra trong b i p thit hoac trong toan bo co the deu khac nhau.
De bao dam nhiem vu sinh ly hoan thanh voi to'c do nhanh trong thoi gian n g i n ciia cac van don g co bap dac biet la van dong vien thi dau dung sire manh va toe do circ nhanh nhir cau long, quan vot, b o n g da, dien kinh... qua trinh hoa hoc dam bao khoi phuc A.T.P mang theo tinh chat ciia m ot qua trinh phan giai thieu oxy, chii yeu la tac dung phan giai thieu oxy ciia dirong b i p thit, san sinh ra acid lactic. D ong th oi ciing la loai
bien hoa cua chat hoa hoc co lan khong can oxy (acid creatinique, phosphorique- chat hoa hap co lan nay toa nang lugng cua minh ra va nhiing thanh phan khac acid photphoric de gop phan khoi phuc A.T.P).
Co the chung ta so sanh cong suat hoan thanh lao dong van dong vai thai gian can thiet cho van dong, chung ta se hieu ro r i n g qua trinh phan giai thieu oxy chiem uu the lan trong khi hoan thanh van don g toe do manh, nhanh. Thi du : chay 100 thuorc la mon van hinh nhu phai su dung het ca nang sinh ly. C ong suat binh quan ciia mot van dong vien chay 100 thtrac trong 1 giay dong ho het 3,5 ma luc, co nguai co the d a t tai 374 kilogam met trong 1 giay (hoac binh quan trong mot giay thi tii 3-4m. Han niia phai hoan thanh trong' thai gian ngan tii 11 giay den 13 giay. Thai gian do se khong dii de mau va phoi lam viec trong m ot chu ky. Chung ta cung de thay rang trong luc bap thit phai gang het siic de van dong trong dieu kien khong duac cung cap vai mot so lugng oxy lan ma phai dai cho den khi m au duac cap dii oxy binh thuang tai tron g m au thi cuoc thi dua chay da ket thiic.
Trong khi tien hanh van dong vai toe do trung binh trong m ot thai gian kha dai, giai doan b i t d au van dong la “giai doan phat d on g ” co tinh chua du oxy, tinh tich cue ciia qua trinh thay cu doi mdri tron g b i p thit cu ng duac tu don g nang cao len m ot cach tifen qu y et,
chua dat tai m ac cung cap oxy vdi so lugng lan. Theo vai thdi gian van dong cua van dong lien tuc so lugng oxy cung cap cho bap thit hoat dong dugc tang len nhanh, binh thuang, cham la vi do bo m ay ho hap lam viec nhieu hay it va hit sau hay nong; tim hoat dong binh thuang hay tang cudng. Ngoai ra cung vi vi huyet quan nd ra, do do su cung cap mau cho b i p thit cung tuy muc do dugc cai tao, oxy cung cap cho b i p thit tang len lam cho qua trinh phan giai thieu oxy bien thanh qua trinh oxy hoa va luc do di vao “trang thai on dinh” . Trang thai on dinh” la trang thai ma qua trinh sinh ly bien hoa hoa hoc sinh vat bien doi co the lam cho b ip thit van dong trong mot thdi gian kha dai dugc.
“Trang thai on dinh” la trang thai cung cap oxy thoa man nhu cau cho mau va ca bap; ket qua lam cho