II. Song dien nhanh va ngan noi len tinh hinh nao khi hoat dong X Noi len lao dong tri oc bat dau.
TRONG COTHE
Cor the con nguori nhir mot bo may khong lo tinh vi, luon luon dien bien nhung qua trinh phuc tap. Bo tieu hoa khong ngung tieu hoa thuc an. Qua duong mau, oxy duorc cung cap cho cor the va khi carbonic la san pham ho hap trong cac cor quan bi thai tru. Trai tim co bop dua mau vao he thong cac mach, phan phoi chat dinh duong va oxy cho toan cor the.
Than loc tu mau nhung chat can ba co hai. He cor co th it tao kha nang van dong cua cor the va cac bo phan. Cu quan cam giac tiep nhan nhiing tac dong cua the giori ben ngoai roi truyen cac tin hieu len bo oc. He than kinh tiep nhan cac tin hieu do, bao dam nhiing phan ung tuong ling, gnip cho cor the thich nghi nhip nhang mot cach chinh xac voi ngoai canh ciia moi truong.
Chiic nang cua moi cor quan trong cor the duorc phan phoi that phuc tap va chinh xac.
Khi chiing ta nghi ngoi hay lao dong, thuong thiic am nhac hay vui dua the thao, tap trung tu tuong giai dap mot bai toan kho hay van hanh may moc voi nhiing dong tac quen thuoc, cac cor quan trong cor the hoat dong het siic an y va phu hqrp voi mot nhiem vu hoan chinh.
Cac ca quan do ton tai doc lap. Qua cac thi nghiem a
mot co the moi chet, cua con meo chang han ta lay rieng trai tim va cho chay qua do mot dung dich dinh duomg bao hoa oxy ham nong 38o thi trai tim do con dap dirge hang gig. Dung nhting moi trudng dinh dudng nhan tao thich hgp khong nhung chi trai tim ma ca gan, than co lap deu tiep tuc song va hoat dong.
Tuy nhien, su song cua co the khong phai la phep cong don gian nhting hoat dong cua cac co quan, ma la mot chinh the phuc tap, mot khoi thong nhat gitia cac co quan, thudng xuyen ton tai vdi nhting tac dong qua lai trong cac dieu kien tinh va co the van dong.
Cai gi da xac lap moi lien he tuong tac ay gitia cac bo phan co the. Qua nhieu cong trinh ciia cac nha khoa hoc da cho thay : trudc het co quan toi cao dieu hoa cac qua trinh song d con ngudi la he than kinh. Nhd he than kinh co the da bao toan dugc tinh on dinh cua qua trinh song d chinh minh vdi ngoai canh thudng xuyen thay doi. No dap ting rat nhay ben vdi nhting tac dong ben ngoai.
Tuy nhien, bo trgcho he than kinh con ton tai mot he thong khac khong kem phan quan trong do la he thong te bao.
Moi te bao, moi mo, moi co quan, co mot su chuyen hoa (su trao doi cac chat trong co the) dac thu. San pham chuyen hoa tuan hoan trong co the va anh hudng tdi cac ca quan va cac mo khac. Do la hinh thtic don gian nhat ciia quan he tuong tac hoa hoc gitia cac bo phan cor the nhu cac thirc
nghiem cua I.V. Mitsurin da kh in g dinh y nghia to ldn cua cac san pham chuyen hoa cua cac co quan trong su dieu hoa cac chuc phan. Nhd phuong phap ghep cay, mot sd tinh chat cay coi nhu tinh chiu lanh, tinh thu phan, pham chat qua da bien doi. Phuong phap nay lam cho cac san pham chuyen hoa d cay nay xam nhap va anh hudng ldn den cay kia.
Co the con ngudi phuc tap hon, thi vai tro chi dao cua he than kinh tren hoat dong cua cac co quan cang co y nghia to ldn. Vdi toe do rat ldn, nhung tin hieu than kinh d in truyen rat nhanh ve co quan va anh hudng tdi chuc phan cua no.
Khac vdi cac tac nhan hoa hoc tuan hoan trong the dich, cac tin hieu than kinh do nao truyen di dinh hudng chinh xac ve mot co quan nhat dinh. Gitia nao va co quan co lien he hai chieu : qua day than kinh, nhting tin hieu di tu nao den co quan va nguoc lai. Nao xac dinh nhting diem dang hoat dong d cac bo phan co the khac nhau. No bao quat va chi dinh cac chtic phan dieu tiet, bao dam tac dung qua lai gitia cac co quan.
Tuy nhien, su phat trien cua he than kinh nhat thiet phai co su tham gia cua he thong dieu hoa hoa hoc va noi tiet.
Dudi tac dung cua cac dich tieu hoa, bo may tieu hoa thuc an, chinh ruot lai la anh hudng tich cuc tdi cac tuyen tieu hoa khac. Noi ro hon, la thanh ta trang va ruot non tham gia san xuat mot chat dac biet, tham vao mau, tang cudng chtic phan cua mot tuyen tieu hoa quan trong. Do la tuyen tuy.
Than la co quan bai tiet nude tieu, song than lai tiet th in g vao mau mot san pham dac biet, lam tang huyet ap.
Chung ta deu biet tuyen nude bot tiet ra nude bot, tao mot chat dem, hoa tron theo thuc an va tham gia vao viec tieu hoa hydrat carbon (cac chat loai dudng bot). Nhung, qua nhting nghien ctiu d cac nam gan day lai phat hien r in g tuyen nude bot eon tiet ra cac chat chi phoi luong dudng huyet (ty le dudng glucose trong mau), su phat trien cua tu cung, buong trting va tinh hoan.
Nhting thi du tren cho thay rang, trong cac sinh vat cao cap va trong con ngudi ton tai mdi lien he the dich gitia cac co quan. Hon the, trong lich trinh tien hoa cua gidi sinh vat, lai phat sinh nhting hinh thtic mdi cua su tuong tac the dich gitia cac bo phan co the ma trong nhieu trudng hop co tuyen noi tiet phai tham gia.