Cau 7 : trinh bay cac nguyen nhan tuan hoan tinh mach va UDLS

- suc bom cua tim : mau cung chay dc tronmg he thong tinh mach la nho chenh lech ap suat giua dau va cuoi tinh mach, su chenh lech nay la do tim tao ra. Luc day mau cua tim thang dc suc can cua mach nen mau chay o trong DM voi ap suat nhat dinh, ap suat nay giam tu dm den mao mach, o cuoi mao mach van con 1 ap suat, ap suat mau o dau tinh mach vao khoang 10mmHg, con o cuoi tinh mach va o tam nhi phai la 0mmHg do do mau chay dc tu tinh mach ve tim

- suc hut cua tim : trong luc tam that truong, ap suat trong tam that giam xuong, tao ra suc hut mau tu tam nhi xuong tam that va tu TM ve Tim

Mat khac, khi tam that thu bom mau vao Dm loam san van nhi that ha xuong, cung co tac dung hut mau tro ve tim

- do lonh nguc :

+) binh thuong as trong long nguc hoi thap hon so voi as khi quyen, do as am trong khoang mang phoi. Khi hit voa, the tick long nguc gi•n ra,lam as cangf am hon. AS trong long nguc giam lam cho cac tinh mach lon o day gi•n ra, as trong TM giam, hut mau tu tieu tinh mach va mao mach ve tim

+) 1 yeu to nua la: binh thuong qua tim chiem 1 the tick trong l;ong nguc, khi tam thu tim co nho lai lam khoang long nguc rong hon, AS trong long nguc cang am hon, lam cho cac tinh machtrong long nguc va tam nhi gi•n ra, tao dk hut mau ve tim

- do co co:

+) tinh mach nam xen vao cac soi co, nen khi co co bop ep vao cac mach mau, don mau cahy theo chieu van trong tinh mach

+) o chi duoi, khi cac co van dong don mau dI len tim, o o bung nho co co thang va co thanh bung ma mau dc don ve tim

- Do Dm: Dm lon va TM lon dI chung trong 1 bao xo, thg 1 dm dI kem voia 2 TM. Moi lan DM dap co tac dung don mau trong TM ve tim.

- anh huong cua trong luc: khi dung trong luc anh huong tot den viec dua mau TM phia tren ( dau, nat, co) ve tim va anh huong ko thuon loi dvoi tuan hoan tinh mach phia duoi tim. Tuy vay, cac TM o phia duoi tim co he thong van nen mau van chuyen dich dc ve tim

*) UDLS