Cau 31: cac hormon tuy noi tiet: ban chat, tac dung, dieu hoa bai tiet va UDLS

a) Hormon insulin

*) b/c: insulin la 1 pr nho voi trong lg ptu 5.808. no dc ctao boi 2 chuoi a.a co noi voi nhau = nhung cau noi disulfua. Khi 2 chuoi a.a nay bi tach ra thi hoat tinh se mat.

*) t/d:

- tac dung len chuyen hoa glucid;

+ tang thoaI hoa glucose o co: mang TB thuong chi cho glucose khuyech tan rat it tru khi co td kick thick cua insulin. Ngoai bua an lg insulin bai tiet rat it nen glucose kho khuyech tan qua mang Tb co. tuy nhien khi ld nang or luyen tap thi TB co co the sd mot lg lon glucose ma ko can 1 lg insulin tuong ung vi khi do mot ly do nao do chua ro d• lam cho mang Tb co dang vd tang tinh tham dvoi glucose.

. truong hop thu 2 TB su dung nhieu glucose do la trong thoi gian vai gio sau bua an. luc nay nong do glucose trong mau tang cao, tuyen tuy bai tiet 1 lg lon insulin. Nong do insulin tang d• lam vc glucose vao TB

+ tang du tru glycogen o co: neu sau bua an co ko vd thi glucose van dc vc vao TB co. luong glucose dc sd se dc tick tru lai duoi dang glycogen va dc dung khi can

+ tang thu nhap, du tru va su dung glucose o gan:

. hau het glucose dc hap thu tu ruot vao mau sau bua an tro thanh dang glycogen du tru hau nhu ngay tuc khac tai gan. Khi doi nong do glucose giam trong mau, tuyen tuy se bai tiet insulin, luc nay glycogen cua gan se dc phan giaI thanh glucose lam cho nong do glucose trong mau ko giam xuong qua thap.

. khi lg glucose dc dua vao mau qua nhieu thi or la chung dc du tru duoi dang glycogen or la duoi tac dung cua insulin, lg glucose thua nay se dc chuyen thanh acid beo va dc chuyen den cac mo mo duoi dang ptu lipoprotein ty trong thap va lang dong duoi cac mo mo du tru.

+ uc che qua trinh tao duong moi:

. insulin lam giam hoat tinh va so lg cua enzym tham gia vao qua trinh tao duong moi

. insulin lam giam giaI phong a.a tu cac co va tu cac mo khac vao gan do do lam giam nguyen lieu cua qua trinh tao duong moi

-> lam giam Cm glucose trong mau

- tac dung len chuyen hoa lipid

+ tang tong hop acid beo va vc acid beo den mo mo: duoi td cua insulin 1 mat lg glucose dc su dung nhieu cho muc dich sinh nang lg nen tiet kiem dc lipid, mat khac lg glucose ko dc su dung het se dc tong hop thanh acid beo o gan va dc vc den mo mo

+ tang tong hop triglycerid tu acid beo de tang du tru lipid o mo mo

- t/d len chuyen hoa pr va su tang truong

+ tang vc tich cuc cac a.a vao trong TB

+ tang sao chep chon loc ptu ADN moi o nhan TB dich de tao thanh ARN thong tin

+ tang dich m• ARN thong tin tai cac ribosom de tao thanh cac ptu pr moi.

-.> insulin co td tang tong hop va du tru pr va do vay tgia lam phat trien co the.

*) Dieu hao bai tiet insulin:

+) co che the dich

- [glucose]: o [glucose] trong mau la 80 - 90 mg/dl, lg insulin dc bai tiet rat it. Nuu [glucose] dot ngot tang len 2- 3 lan cao hon binh thuong va giu o muc nay thi insulin dc bai tiet nhieu. [glucose] tang tren 100 mg/dl, insulin co the dc bai tiet tang tu 10 - 25 lan so voi muc co so. day la 1 co che dhoa rat quan trong nham dieu hoa [glucose] cua co the.

- [a.a]: mot so a.a db arginin, lysin cung co td khick thik bai tiet insulin. Khi nong do cac a,a nay tang len thi insulin cung dc bai tiet nhieu tuy nhien neu chi don thuon a.a thi td kick thick bai tiet insulin yeu hon so voi glucose or phoi hop voi glucose.

- [hormon] do thanh ong tieu hoa bai tiet nhu gastrin, secretin, cholecystokinin cung co td bai tiet insulin. Nhung hormon nay thg dc bai tiet sau bua an va nho co td lam tang bai tiet insulin ma chung tgia lam cho glucose va a.a dc hap thu de dang hon

+) co che TK: duoi nhung dk nhat dinh, kick thick TK giao cam va pho giao cam co the lam tang bai tiet insulin. Tuy nhien he TK tu chu it co vai tro dhoa baio tiet insulin trong Th binh thg.

b) hormon glucagon:

*) b/c hoa hoc: glucagon dc bai tiet tu TB anpha cua tieu dao langerhans khi nong do glucose giam trong mau. glucagon co nhieu tac dung ngc voi td cua insulin

- Glucagon la 1 polypeptid co 29 a.a voi trong lg ptu la 3485

*) t/d:

- tac dung len chuyen hoa glucid

+ tang phan giaI glycogen o gan: glucagon co knang lam tang phan giaI glycogen o gan do do lam tang Cm glucose trong mau sau vai phut

+ tang tao duong moi o gan: ngay ca khi glycogen o gan d• b9i phan giaI het, neu tiep tuc truyen glucose vao co the thi [glucose] mau van tiep tuc tang -> do glucagon lam tang vc a.a vao Tb gan roi sau do lai tang chuyen a.a thanh glucose

- cac td khac cua glucagon

Cac td ngoai td tang Cm glucose trong mau cua glucagon chi xhien khi glucagon dc bai tiet qua muc

+ tang phan giaI lipid o mo mo du tru thanh acid beo de tao nang lg do hoat hoa lipase o mo mo du tru

+ uc che tong hop triglycerid o gan va uc che vc acid beo tu mau vao gan. chinh td nay cung gop phan lam tang lg acid beo cung cap cho cac mo khac de tao nang lg.

*) dieu hoa bai tiet:

- [glucagon] huyet tg bthuong k\la 50- 100pg/ml. su bai tiet glucagon phu thuoc chu yeu vao [glucose] trong mau, ngaoi ra [a.a] trong mau or 1 so yeu to khac cung anh huong den bai tiet glucagon

- anh huong cua [glucose] mau: td cau [glucose] mau len su bai tiet glucagon thi hoan toan ngc voi insulin. [glucose] mau giam xuong duoi 70mg/dl se kick thick Tb alpha cua tieu dao langerhans tang bai tiet glucagon len nhieu lan so voi bthg. Ngc lai [glucose] tang su lam giam bai tiet glucagon

- anh huong cua [a.a] mau: [a.a] tang cao trong mau db alanin va arginin se kick thick tang bai tiet gkucagon

- anh huong cua vd: luyen tap va ld nang, [glucagon] co the tang tu 4 -5 lan