Cau 1: trinh bay tinh chat sinh ly cua co tim va UDLS

Co tim co chuc nang co tu dong, ko theo y muon va co nhip nhang de thuc hien cnang bom mau. De hoan thanh cnang nay co tim co 4 dac tinh sinh ly:

*) Tinh hung phan:

- Tinh hung phan la knang dap ung voi kick thick cua tim, the hien = co tim phat sinh dien the hoat dong, dien the nay lam co co tim.

* Dac diem ve knang dap ung voi kthick cua co tim: co tim dap ung voi kick thick = co co nhu co van, nhung co dac tinh rieng la dap ung theo quy luat "tat ca or ko"

- Thi nghiem: kick thick 1 mang co tim ech bang dong dien cam ung co cuong do tang dan va ghi do thi co co

co tim ko dap ung(ko co)?+) Voi cuong do kick thick duoi nguong

co tim co co toi da?+) Voi cuong do lon hon or = nguong

Co tim dap ung theop quy luat " tat ca or ko"?

- giaI thich: co tim ctao la 1 hop bao, co cac cau dan truyen hung phan hoat dong cua co tim nhu la 1 dong nhat. Khi kick thick?giua cac Tb tat ca?toi cuong do toi nguong thi toan bo cac soi co tim hung phan cac soi co tim deu co. do vay co tim co la co toi da.

- tinh hung phan cua co tim khac co van: co van gom nhieu soi co rieng biet, giua cac TB co ko co cau dan truyen hung phan nen khi bi kick thick thi tuy theo cuong do kick thick manh hay yeu ma so soi co tham gia nhieu hay it. Khi cuong do kick thick tang dan thi so soi co tim bien do co co tang cho den khi toan bo cac?tham gia dap ung tang dan soi co tham gia dap ung thi co co manh nhat

* Dac diem ve dien the hoat dong cua co tim

- hien tuong keo dai dien the dinh o co tim dc goi la cao nguyen

- dien the hd cua co tim co giai doan cao nguyen la do;

+) nguyen nhan: do kenh calci cham o mang TB co tim: o mang Tb co tim co chu yeu la kenh cham (kenh ca cham hay kenh Ca-Na) va cung co kenh Na nhanh. Thoi gian mo kenh Ca cham keo dai toi vai phan muoi giay, lam cho duy tri lau dai trang?1 luong lon ion Ca va Na dI vao trong Tb co tim tao dg cao nguyen cua dien the hd?thaI khu cuc

+) Nguyen nhan do mang co tim giam tinh tham voi ion K+: khi xhien dthe ko tao dc giai? K+ ko ra khoi TB ?hd tinh tham cua mang voi K+ giam doan taI cuc lam cho trang thaI khu cuc keo dai gop phan tao dg cao nguyen cua dien the hd.

Nguyen nhan nay chi co owr co tim ko co o co van.

*) Tinh tro co chu ky

- tinh tro co chu ky la tinh ko dap ung voi kthick co chu ky cua co tim

- thi nghiem: ghi do thi hoat dong cua tim ech, ta thay tim ech hoat dong co chu ky, gom cac giai doan co va d•n

?- neu kthick vao giai doan tim dang co( tam thu): tim ko co them nua khi tim dang co co, tim ko dap ung voi kthick gla giai doan tro cua tim

- neu kick thick vao luc co tim dang gi•n thi tim dap ung = 1 co bop phu goi la ngoai tam thu. Sau ngoai tam thu tim gi•n ra va nghi keo dai, goi la ghi bu.

+) tim nghi bu la do xung dong tu nut xoang toi tam that roI vao gd tro cua co bop phu, nen co bop binh thuong ko xay ra cho den khi xung dong tiep theo cua nut xoang thi lai xhien co bop binh thuong

+) Tong thoi gian chu ky ngoai tam thu + chu ky tiep sau do = tong thoi gian cua 2 chu ky tiom binh thuong.

- trong giai doan tam thu tim co tinh tro, ma tim hdong co tinh chu ky nen gd tro cung lap dI lap lai 1 cach deu dan do do tim co tinh tro co tim chiu kthick lien tiep, tim ko bi co cung phu hop voi chu ky?chu ky bom mau cua tim

*) Tinh nhip dieu cua co tim.

- tinh nhip dieu la kha nang tu phat sinh ra cac xung dong nhip nhang cho tim hd, dc thuc hien boi he thong nut tu dong

- do su do ri ion Na vao Tb nut xoang lam nut nay tu hung phan va hung phan phat sinh deu dan, nhip nhang

- ngoai nut xoang co knang tu phat xung dong, cac phan khac cua he thong nut cung co knang tu phat xung dong: nut nhi - that, bo his, mang purkinze. Khi tim dap theo nhip phat xung cua cac phan nay goi la dan nhip lac cho.

*) tinh dan truyen cua co tim:

- tinh dan truyen lad kha nang dan tryenn xung dong cua soi co tim va he thong nut. Co tim va he thong nut co knang dan truyen xung dong voi van toc khac nhau.

=> nho tinh hung phan, tinh nhip dieu va tinh dan truyen xung dong ma tim du o trong co the hay tach khoi co the va dc nuoI duong day du thi tim van tu co bop deu dan, nhip nhang. nho tinh tro co chu ky ma tim ko bi co cung khi chiu cac kick thick lien tuc.

*) UDLS:

- trong 1 so TH tinh hung phan ptrien qua -> thuoc an than

- dtri ngoai tam thu la giam tinh hung phan