終於要講下內分泌,見到血糖都知今次係講胰島素。
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Insulin & Glucagon are both synthesized in the pancreas, by the beta cell & the alpha cell respectively in the pancreatic islet.
降糖素 (或者胰島素 insulin) 是由降糖細胞 (或者貝塔細胞 beta cell) 分泌,而升糖素 (或者抗胰島素 glucagon) 則是由升糖細胞 (或者阿爾法細胞 alpha cell) 分泌,兩種細胞都可以在胰島找到。{參閱:「基本的胰臟介紹」}
They are 2 peptide hormones responsible for regulating blood glucose level, by signaling cells to intake or release glucose.
升糖素和降糖素都是荷爾蒙,屬於胜肽 (peptide),所謂胜肽就是組成蛋白質的材料,所以你可以想像成小塊的蛋白質 (protein)。升糖素和降糖素要求細胞處理葡萄糖 (glucose),以此管理血液裡葡萄糖的數量,也就是「血糖」。
As the cell needs some follow-ups on alteration of the glucose level inside the cell, Insulin & Glucagon are also responsible in the regulation of energy-related molecules inside the cell.
既然是要求細胞處理葡萄糖,那荷爾蒙總不能射後不理,至少也得幫一下忙吧。所以升糖素和降糖素也會負責管理細胞內有關能量的物質。
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(i) Insulin 降糖素
Insulin is responsible for decreasing the blood glucose level. It binds to the insulin receptor on body cells, especially on hepatocytes, muscle cells and adipose cells.
降糖素透過啟動細胞上專門的受體,尤其是肝臟細胞、肌肉細胞和脂肪細胞來降低血糖。
There are 2 main roles of the activated Insulin receptor.
(i) Recruit glucose channels to the cell membrane so that the glucose in the bloodstream can enter the cell.
(ii) Promote storage of energy through the glycolysis, and also glycogens & VLDLs formation in the hepatocyte.
基本上如果降糖素的受體啟動的話主要會出現2個反應。
(一) 在細胞膜上安裝讓葡萄糖通過的通道。因為正常來說葡萄糖是無法穿透細胞膜,有了通道血液裡的葡萄糖就可以從通道走進細胞。
(二) 促進細胞裡葡萄糖的分解 (glycolysis)。而且特別會促進在肝臟細胞裡進行的脂蛋白 (lipoprotein) 和醣類 (glycogens) 的合成,簡單來說就是把葡萄糖合成大一點,方便儲存。
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(ii) Glucagon 升糖素
Glucagon is responsible for increasing the blood glucose level. It binds to the Glucagon receptor on hepatocytes and adipose cells.
升糖素透過啟動肝臟細胞、脂肪細胞上專門的受體來提升血糖。
There are 2 main roles of the activated Glucagon receptor.
(i) Promote the break-down of stored energy sources like glycogens, fatty acids and release glucose into the bloodstream.
(ii) In the urgent case of starvation, Glucagon promotes fatty acids to be transferred into ketone bodies (acetone, acetoacetate, beta-hydroxybutyrate) for the heart and the brain.
基本上如果升糖素的受體啟動的話主要也是會出現2個反應。
(一) 促進脂類、醣類的分解,再把分解出來的葡萄糖送進血液。
(二) 在極度缺少能量,或者葡萄糖,的情況下,升糖素促進脂類轉成酮體 (ketone bodies),作為腦部和心臟的能量臨時代替品。
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以前既文章,有興趣既可以參考下
「基本的器官介紹」系列
目錄:lihkg.com/t/785268/
唔想睇文既可以睇片:rebrand.ly/basic_anatomy_and_physiology
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