Glucose Uptake and Storage Flashcards
(14 cards)
What is the Km of GLUT1 compared to normal blood glucose levels?
Below normal range, so it functions efficiently even when fasting
What does teh high Km of GLUT2 allow?
Increased glucose uptake post-meal in liver and pancreatic β-cells
Where is GLUT4 found?
In adipose and muscle tissues
How is GLUT4 regulated?
By insulin, which stimulates its translocation to the plasma membrane
How does secondary active transport work for glucose uptake?
SGLTs use the Na+ gradient to tranposrt glucose into cells
Where fo SGLT and GLUT2 operate in epithelial cells?
SGLT on apical membrane
GLUT2 on basolateral membrane
What is glycogen?
A branched polymer of glucose used for storage in liver and muscles
Whhy store glucsoe as glycogen?
To reduce osmotic preassure and allow high-density stroage
What are the key steps of glycogen syntehsis?
Formation of UDP-glucose
Initiation by glycogenin
Branchin
Elongation
How is glycogen breakdown intiiated?
By phosphorylase (linear chians) and debranchinf enzymes (branches)
What hormones regulate glycogen metabolism?
Insulin and glucagon/epinephrine via phosphorylation cascades
How does phosphorylation affect glycogen enzymes?
Activates phosphorylase, inactivates synthase
What is Vin Gierke’s disease?
Type Ia GSD due to glucose-6-phosphate deficiency
What is McArdle’s disease?
Type V GSD due to muscle phosphorylase deficiency
