II. Song dien nhanh va ngan noi len tinh hinh nao khi hoat dong X Noi len lao dong tri oc bat dau.
Nhung dieu can quan tam chung
Khi van dong, ca the ngudi van d on g p h at sinh nhting bien hoa gi ?
Dieu nay da noi trong cac b i p thit tham gia van dong, phan ting hoa hoc phtic tap tien han h m ot cach kip thdi. Nhting phan ting nay tao nen nhting san pham co acid do la acid lactic do ket qua phan ting oxy hoa san sinh ra.
Trong khi acid lactic san sinh ra thi kh oi lu gn g oxy tieu hao cu ng tang len.
M oi su tieu hao nang lugng ciia ca the, tat ca deu do phan ting oxy bu d i p lai. Khi b i p thit co lai, su
khoi phuc A.T.P da tieu hao, cac chat hoa hoc co lan giau nang luong va glycogen da phan giai khi co phan urng thieu oxy deu nhd vao nhung nang luong duoc san sinh ra trong phan ung oxy ma khoi phuc lai.
Qua trinh nghien curu da cho thay bien phap oxy hoa cung co the khu duoc phan ldn acid lactic san sinh ra khi phan giai glycogen trong dieu kien thieu oxy.
Vi vay, oxy cua co the duoc tieu hao la do nang luong cua co the da tieu hao di, con so' nang luong khac tieu hao thi can cu vao so luong van dong hoan thanh, can cti vao su chuan bi tinh than cua cong viec sap tien hanh ma co mure do khac nhau; noi mot cach khac,
so luong oxy tieu hao la do khoi lu ong van dong duoc hoan thanh quyet dinh; khoi luong van dong cang nhieu thi thong thudng khoi luong oxy tieu hao cang ldn.
So' luong oxy can thiet de cho m ot cong viec hoac tien hanh van dong, sinh ly hoc goi la “tong so oxy can thiet” . So' luong oxy can thiet it hay nhieu thi phai can cu vao cudng do, tinh chat van dong ma co the rat khac nhau; noi chung so'luon g oxy can thiet trong m ot phut co luc rat it, co luc nhieu tdi 10ml hay hon ntia.
Nhu da neu d tren, bo m ay ho hap khong the mot lan hut vao duoc nhieu oxy nhu the, phoi ngudi ta moi phut hut vao nhieu nhat la ± 5ml oxy. Vi vay khi tien hanh van dong ma moi phut b i p thit can hon 5ml oxy, thi ngay tti luc b i t dau, bo m ay ho hap phai hoat dong vdi cudng do ldn nhat mdi gan du hoac du.
Trong thai gian van dong, tong so oxy khong the bu dap lai dirge het. Mot phan so lugng oxy can thiet dirge bu d i p lai trong thai gian nghi, do do nang lugng tieu hao trong thgi gian van dong khong nhung lay trong phan ung oxy hoa ma con lay trong phan Ung yem khi. M ot phan so lugng oxy can thiet dugc bu dap lai trong thai gian nghi goi la “ ng ox y ” .
Tat nhien, khong phai la trong bat cU mon van dong nao, so lugng oxy do phoi hut vao cu ng co the dat tai han do dap ung lan nhat. Du la co dat tai han do ldn nhat, cung khong phai la trong m ot luc; vi the cho nen bat cU luc nao ngudi van dong tien hanh v an don g co phan cang t h i n g la co the co “ ng ox y ” it hay nhieu.
H oat dong cang cang t h in g , thai gian ca n g n g in . cucng do van dong (so lugng van dong hoan thanh trong mot dan vi thai gian) cang ldn, thi se co mot phan kha ldn “tong sd oxy can th ie t” bien thanh “ ng o x y ” .
Ty le sa do sau day se cho chung ta thay ro : SO DO NO OXY Thai gian van dong C6ng suat kilo/m et Tdng s6 luong oxy hit vao
No oxy (cm 3)
Su bad! phdr gua no ory
va tang s5 ory ht vao
30’ 1215 1432 1090 75 0 2* 1215 5345 2170 4 0 7 5* 1215 13290 2910 21.9 15' 1215 41940 5055 12.1 SO 2740 3810 3090 81.0 SO' 3430 5585 4875 87.2
Co nhiing nghe lao dong phuc tap nang nhoc hay nhiing mon the thao van dong, khi tien hanh, toan bo so luong can thiet deu duoc bu d i p lai trong thai gian nghi. Thi du chay 100 thudc hay danh m ot tran cau long (danh doi) mot ben qua manh ve ky thuat, the luc... va mot ben qua yeu do do tran dau ket thuc nhanh trong thai gian ngan chi can 5 den 10% hoac 10 den 15% oxy can thiet dugc bu dap lai, con 90 hay 95% hoac 85 den 90% oxy bien thanh “ ng oxy” chi dugc bu d i p lai sau khi da hoat dong xong.
Do do de chung ta hieu r i n g , van dong ciia bap thit co yeu cau rat cao vai bo may ho hap. N eu muon thoa man yeu cau do, chi co cach tang khoi lugng khong khi thay doi trong phoi. So' lugng khong khi thay doi trong phoi la so lugng khong khi hit vao va thd ra trong thai gian van dong va trong m ot thgi gian ngan sau khi van dong da ket thiic (de khoi phuc “ng ox y ” ).
Muon cho so lugng khong khi moi lan hit vao va thd ra dugc nhieu han thi chi can hit tha cho sau va tang so lan thd.
Do thd sau va so lan thd phai dinh theo su van dong ciia bap thit ho hap. B i p thit ho hap co b i p thit d sudn, bap thit bun g va b i p thit hoanh cach mo. T ru ng khu ho hap tu don g truyen kich thich than kinh v an dong den b i p thit ho hap. Dong thdi hoat don g ciia trung khu ho hap phai dua vao qua trinh kich thich than
kinh truyen tdi; kich thich than kinh nay truyen tdi la nhd co nhung kich thich dau than kinh ciia te bao phoi, m ang quanh long nguc va bap thit ho hap nhan duoc moi khi ho hap. Ngoai ra hoat dong ciia trung khu ho hap con dua vao su phan tich hoa hoc ciia mau. Thi du C 0 2 hoac cac san pham co acid khac (nhu acid lactic) san sinh ra khi b i p thit van don g tang len nhieu trong mau cung co the lam cho trung khu ho hap hung phan; do do lam cho ho hap cang sau ca n g nhanh.
Trung khu ho hap va vo nao co m oi lien he rat khoa hoc m at thiet vdi nhau; chinh vi nhu the ma chiing ta co the thay doi tan so ho hap theo y muon, m uon nhanh hay muon cham cu ng duoc. Cuoi cu n g tru n g khu ho hap ciing co lien he mot cach phan xa vdi bap thit (bap thit d tu chi va bap thit lung).
C a c nha kh oa h o c d V ie n n g h ie n c u u sin h ly Leningrat va cac vien nghien cuu d cac nude Trung Quoc, Due, ... da tung tien hanh m ot sd thuc nghiem ; de nghj mot ngudi van dong vien dap xe dap tren mot m ay do. Luc mdi bat dau, van dong vac m ot khdi s i t nang tu do ho hap; nhung roi trong thdi gian vac do, de nghi ngudi van dong liic thd sau va nhanh, luc thd cham va nong. Ket qua chiing ta thay ra n g khi thd sau va nhanh ngudi van don g da tang toe do udn len m ot cach ro ret; den khi thd cham , ngudi van d o n g do da giam toe do sue udn hoac don g ta c di.
Giua mure do cang t h in g , tam trang van dong va khoi lugng khong khi thay doi trong phoi tang len, co moi lien he co dieu kien voi nhau va dua den hinh thanh nhu sau : trong mot hai cai do duoc lap lai, tuy r i n g thoat dau su lap lai do cua cai nay la ket qua, cua cai kia la nguyen nhan (vi du khoi luong khong khi thay doi trong phoi tang len) van co the lam dieu kien cho cai kia xuat hien (van dong tang cudng).
Nhung neu chi co tang khoi luong khong khi thay doi trong phoi van chua du de dam bao cung cap khoi luong ldn oxy cho co the van dong nang, khi van dong nhung dieu kien cang thang hay trong thi dau. Oxy trong khoi luong khong khi thd vao phai di qua nhiing huyet quan nho nhat (vi huyet quan) ciia te bao phoi lien he vdi chat nhuom ciia hong cau (sac to mau). Mau di tu phoi ra mang nhieu oxy de di vao tam nhi trai, vao tam that trai, roi theo moi lan tim bop phun ra cac dong mach van chuyen den cac bo phan trong than the.
Khi mau qua cac vi huyet quan d cac to chiic va khi quan, mau cung cap oxy cho cac to chiic dong thdi lai mang ra ngoai C 0 2 va cac san pham khac do cac to chiic ciia co the bai tiet.
Mau thieu oxy nhung giau C 0 2 (m au trong tinh mach) theo m ach mau lai trd ve tim (ve tam nhi phai ciia tim). Tu tam nhi phai di vao tam that phai roi di vao mach m au ciia phoi, trong m ach m au ciia phoi nha
C 0 2 ra. Khi ngucri van dong thai C 0 2 ra ngoai; sau do mau lai hut oxy vao phoi roi vao mau.
Trong phoi, qua trinh m au mang oxy co lien quan m at thiet vdi ap lire khong khi hut vao. Vi vay, khi ap lire khong khi thap, vi nhu d m ien nui cao do ap luc oxy thap, sir hit oxy vao ciing kem (d nui cao, su hit oxy vao kem con nhieu nguyen nhan khac nua quyet dinh) nhu co the bai tiet qua nhieu C 0 2, do do lam cho ho hap trao doi phufc tap hoac do thanh phan hoa hoc bien hoa trong mau). Khi hit khong khi co it oxy, dii la trong dieu kien ap lire khong khi binh thudng ciing phat sinh tinh hinh oxy vao mau kem.
Do la m ot trong nhting nguyen nhan lam cho nhting ngudi khong d mien nui de bi gap kho khan khi bap thit van dong.
Can cu vao cac diem noi tren, chiing ta xem co the hieu mot cach ro rang : cung cap oxy cho khi quan va to chuc co the khong phai chi co khdi lugng khong khi thay doi trong phoi quyet dinh ma con do su van dong cua bo may tuan hoan quyet dinh, con do tinh chat bien hoa m au quyet dinh, dong thdi ciing do ca ap luc khong khi va thanh phan khong khi hit vao quyet dinh.
Neu moi lan tim bop vao co the phun ra m ot khdi lugng m au cang nhieu “ khdi lugng m au tim phun ra" co the tang len, thi duong nhien su cung cap oxy cho khi quan va to chtic dugc cai tien. N eu khoi lu g n g mau
or tim phun len, tan so bop tim cua tim cu ng tang len thi sir cung cap oxy do ciing tang len, do do khoi lugng mau tim phun ra trong mot phut (tire la trong mot don vi thai gian) ciing tang len. Cuoi cung sir cung cap oxy cho khi quan va to chtic ca the con do nang lire mau tiep xuc vai oxy va do so lirgng s i c to' trong mau quyet dinh. Bori vi s i c to' mau n i m trong hong huyet cau cho nen sir cung cap oxy con do so' lirqrng hong huyet cau quyet dinh. S o'lugng hong huyet cau cang nhieu va so lugng s i c to' mau cang lorn thi oxy cung cap cho cac khi quan va cac to chuc cang dugc nhieu, ciing nhu bieu hien ciia mot nguori thich ting vai m ien niii cao la su tang hong huyet cau trong mau. H ong huyet cau tang len, mau trong phoi nhan dugc nhieu oxy han, do do oxy chuyen tai cac khi quan va to chtic ca the cung nhieu han.
So lugng mau tim phun ra tang len va tim lam viec nhanh han la do anh huorng ciia than kinh. A n h huang do truyen tti he thong than kinh trung uang den tim doc theo hai loai than kinh : than kinh giao cam va than kinh pho giao cam.
Than kinh pho giao cam , co the lam cho tan so bop ciia tim cham di, giam siit su hung p h a n ciia bap thit, giam bat nang luc truyen hung p h an ciia b i p thit tim va stic bop ciia b i p thit tim, co n th a n kinh giao cam thi ngu gc lai co the lam tang tan so b op ciia
tim, co the phat huy va nang cao moi tinh nang dang co cua tim.
Cac cong trinh nghien curu ve tac dung ciia hai loai than kinh nay, phan lan la cong lao cua Paplop. Tac dung ciia hai loai than kinh nay khong doi k hang vai nhau, cung khong trai ngugc nhau ma la th on g nhat bo sung lan cho nhau. Neu than kinh pho giao cam co m ot tac dung dac biet khi bap thit tim bop vao, thi than kinh giao cam ciing co tac d u n g d a c b ie t khi bap thit tim nd ra. Trong hai loai th a n kinh do dii chi la m ot loai bi ton thuang ciing giam siit nan g lu c ciia tim va cuoi ciing cu n g co the dua den h ien tu g n g la tim se bi suy y e u va k iet sue khi dam nh an m o t khoi luo'ng tuan hoan lan han.
Tac dung ciia than kinh giao cam va than kinh pho giao cam doi vai tim co quan he m at thiet vai hoat dong than kinh cao cap (chiing ta co the thay su quan he nay trong thi du ve hoat dong ciia tri tudng tugng da noi d phan tren). D ong thdi co quan he rat nhieu tac dung phan xa true tiep va don gian. Thi du, phan ung mau bien hoa nang ve m at axit thi co anh hudng true tiep doi vdi su co bop ciia tim. Tim day m au va do keo dai thd thit tim ciing anh hudng den van han h cua tim, co the lam tang sue bop cua tim, v.v...
So lugng mau tim phun ra trong m ot phut tang len. Sd di tang len la vi tan so bop cu a tim nhanh len, sUc
nor ra cua tim tang len, boi vi mau d m ach mau vao tim vdi mot khoi luomg lorn lam cho tim trong thai gian tam chtfcmg day dii mau. Mau or cac mach mau sd di chay ve tim vdi khdi luang ldn la vi bap thit co ho’n vao lam tang to'c do luu thong mau d tinh mach (con mau d dong mach luu thong la nhd tim bop vao). Ho hap manh va sau thi khac nao nhu ong borm dac biet hut mau vao trong mach mau (la vi khi hut khong khi vao, ap lire trong long nguc thap horn ap lire khong khi ben ngoai). Khi van dong, mach mau trong bap thit nd
ra cung co the lam cho mau liru thong nhanh.
Co hien tirang mach mau nd ra trong b i p thit khi tien hanh van dong la vi co anh hirdng cua phan xa he thong trung iromg than kinh, dong thdi cung la b i p thit thai acid ra, phat sinh tac dung kich thich ddi vdi dau than kinh cua mach mau. Mach mau nd ra, duong nhien la the tich cua mach mau cung theo do tang len.
He thong tim va mach mau la mot to chdc thanh mot he thong vong tuan hoan. Vi vay chung ta co the hieu mot cach ro r in g , the tich tang len (mach mau nd ra) vi khdi luung mau tang len. Neu mot doan mach mau tirorng doi khong to nd ra, mau d doan mach mau nay tang len thi lam cho doan mach mau khac co lai (the tich be di). Do la “phan phoi lai m au” ; loai phan phoi lai mau nay noi chung la hay phat sinh ra khi tieu hoa thurc an. Luc do mach mau bung nd ra va mach mau bap thit
co lai. Khi bap thit van dong, thi nguqrc lai mach mau bap thit no ra, con mach mau or khi quan bung co lai. Nhiing bien hoa cua tuan hoan mau la mot trong nhiing nguyen nhan tai sao sau khi an no khong nen tien hanh van dong ngay va khi van dong cung khong nen an corm no.
Khi mach mau nor kha to, su phan phoi lai mau khong du, nen can phai dap ung cho viec tang cudrng luu thong mau. Nhung lam the nao mui tang cuomg duorc luu thong mau.
Cac cong trinh khoa hoc nghien cuu da chung minh, trong trang thai tinh, ngirdi ta chi co 55 den 75% mau tham gia tuan hoan, con lai 45 den 25% mau khong tham gia tuan hoan dUng lai or cac to chuc va khi quan (tuc la mau du tru).
Kho du trii mau nay chinh la gan 25%, la lach (toan bo mau du tru a la lach dat tori 15%), cuoi cung la da 10%.
Khi bap thit van dong, mau bo sung vao tuan hoan de tang khoi luong mau cho tuan hoan; do do co the chuyen cang nhieu oxy den cac to chuc va khi quan.
Khi khoi luomg mau tuan hoan tang bang cach mau tii cac kho du trii, tham gia tuan hoan khong nhung chi phat sinh ra khi bap thit van dong ma ca sau khi m6i biia an, khi ap luc khong khi xuong thap (or tren cao) va khi bi kich thich bdi xuc dong da mat do h i n len (phan khoi hay buc tuc). Hien tuomg sau cung tuc la hien tuomg