#Biochemistery
#Carbohydrate_metabolism
#بوست_رقم 3
Absorption
🌼الحاجات اللي ح نتكلم عنها في البوست دا :-
📌Definition of absorption.
📌Factors influencing rate of absorption.
📌 Mechanisms that responsible for absorption.
آخر حاجه عرفناها في البوست الفات انه
End products of carbohydrate digestion are: monosaccharides ; glucose, galactose, fructose.
وهي دي اللي بيحصل ليها ال absorption دا
🌸 Definition of absorption:-
Transport of the end products of CHO digestion from the jejunum to portal veins to the liver and finally to the blood or lymph .
📌لكن طبعاً لازم galactose و fructose يتحولوا لي ل glucose .
🌺 Factors influencing rate of absorption:-
1. State of mucous membrane and length of time of contact.
2. Hormones :-
A. Thyroid hormons
B. Adrenal cortex , absorption decrease in adrenocortical deficiency ,manily due to decrease concentration of sodium in body fluids
C. Anterior pituitary
دا بتأثر علي ال absorption بإنه بتأثر في thyroids
D. Insulin ,this has no effect on absorption of glucose.
3. Vitamins:-
B- vitamins , thiamine, pyridoxine and pantothenic acid.
🌸 Mechanisms that responsible for absorption :-
1. Active transport ( against concentration gradient i.e. from low to high concentration) and using energy .
2. Passive transport (down the concentration i.e. from high to low concentration) by facilitated diffusion (use carrier) not use energy .
🔥لكن عشان يحصل ال active transport في شروط لازم تتوفر لي في structure of suger
1. Hexose ring
2. OH group at position 2 at the right side
3. Methyl or a substituted methyl group should present at carbon number 5 .
🔥الشروط موضحة في الصورة 👇 رقم "١"
🌸الشروط الذكرناهم ديل متوفرين في glucose و galactose بس
طيب وال fructose؟!!
🌟 Does not contain -OH group to right at position 2 , so the absorped more slowly than glucose and galactose by passive diffusion . 😢
🔥وبكدا نعرف انه :-
Acive transport is much more faster than passive.
🌺Passive process called "slow process"
🌸طيب نبدأ نتكلم عن Mechanisms بالتفصيل :-
1. Active transport :-
🔥Mechanism of active transport:
🌺 In the cell membrane of the intestinal cells , there is a mobile carrier protein called sodium - dependant glucose transporter ( SGLT-1) . it transport glucose to inside the cell using energy.
طيب ال energy دي بنجيبها من وين؟!🤔
From sodium potassium pump .
🌸 نتكلم عن ال transporter دا شوية 👐
* Has 2 separate sites, one for sodium and the other for glucose.
* it transports them from the intestinal lumen across cell membrane to the cytosol.
* Then both glucose and sodium are released into cytosol allowing the carrier to return for more transport of glucose and sodium.
🌺 The sodium is transport from high to low concentration ( with concentration gradient ) and at the same time causes the carrier to transport glucose against its concentration gradient.
🌸 The Na+ is expelled outside the cell by sodium potassium pump , which needs ATP as source of energy catalyzed by enzyme called Adenosine triphosphatase ( ATPase )
🍁طييب شنو اللي بحفز لي ال transport دا ويزيد لي ال transporter؟!!
☘ insulin increase the number of glucose transporters in tissues containing insulin receptors e.g. muscles and adipose tissue.
☘ زي مافي activetor كمان فيInhibitors🏼 طيب نشوفها
Inhibitors of active transport:-
1. Quabin ( cardiac glycoside ) :
بعمل inhibits ل ATPase اللي محتاجنو في انتاج ال energy لل sodium potassium pump
2. Phlorhizin :
ودا بعمل inhibits ل binding of sodium in the carrier protein .
كمان في صورة تحت 👇 ح توضح كل الكلام الفوق دا وبتلخصو لينا ✊ تابع مع الصورة ولخص الكلام القريتو كلو 👋 رقم" 2"
طيب نشوف ال Mechanism التاني
2. Passive transport ( facilitated diffusion ) :-
🍁 it occurs by means of sodium independent facilitative transporter ( GLUT-5)
طيب منو من ال suger بيستخدموا الطريقة دي؟!!
1. Fructose
2. Pentoses
🌸 عشان م مستوفيين شروط ال active فما عندهم حل غير passive .
* ال fructose عرفناهو ليه
* وال pentoses م ينفع لانه نحن قلنا لازم يكون hexose .
لكن برضو ممكن glucose و galactose يحصلوا ب passive اذا كان concentration gra
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