Podcast
Questions and Answers
What is the primary reason glucose cannot passively diffuse through the cellular membrane?
What is the primary reason glucose cannot passively diffuse through the cellular membrane?
- It is too reactive to interact with the membrane lipids.
- It is too polar and massive to cross the hydrophobic core. (correct)
- It requires enzymatic breakdown to smaller units.
- It is actively repelled by the membrane's electrical charge.
In the small intestine, specifically the upper jejunum, which of the following mechanisms is primarily responsible for initially establishing a low intracellular sodium concentration?
In the small intestine, specifically the upper jejunum, which of the following mechanisms is primarily responsible for initially establishing a low intracellular sodium concentration?
- GLUT-1 transporters on the basolateral side.
- Passive sodium channels on the apical side.
- Na-K ATPases on the basolateral side. (correct)
- SGLT-1 transporters on the apical side.
How does SGLT-1 contribute to glucose absorption in the small intestine?
How does SGLT-1 contribute to glucose absorption in the small intestine?
- It uses ATP to directly pump glucose into the cell.
- It facilitates the diffusion of glucose down its concentration gradient.
- It modifies glucose into a more permeable form.
- It actively transports glucose, using the sodium electrochemical gradient. (correct)
Once glucose is inside the intestinal cell, how does it enter the bloodstream?
Once glucose is inside the intestinal cell, how does it enter the bloodstream?
What is the mechanism of action of ouabain in relation to glucose transport?
What is the mechanism of action of ouabain in relation to glucose transport?
Which of the following sugars does not require active transport for its absorption into mucosal cells?
Which of the following sugars does not require active transport for its absorption into mucosal cells?
How does fructose enter mucosal cells?
How does fructose enter mucosal cells?
In the kidneys, what is the initial step in glucose reabsorption after it enters the nephron?
In the kidneys, what is the initial step in glucose reabsorption after it enters the nephron?
If glucose is not reabsorbed in the nephron, what is the consequence?
If glucose is not reabsorbed in the nephron, what is the consequence?
Which transporters are primarily responsible for glucose reabsorption in the proximal convoluted tubule cells of the kidney?
Which transporters are primarily responsible for glucose reabsorption in the proximal convoluted tubule cells of the kidney?
In which specific part of the nephron are SGLT-2 transporters located?
In which specific part of the nephron are SGLT-2 transporters located?
What is the primary function of Gliflozins in treating type 2 diabetes?
What is the primary function of Gliflozins in treating type 2 diabetes?
How does inhibiting SGLT-2 with Gliflozins affect glucose levels in the body?
How does inhibiting SGLT-2 with Gliflozins affect glucose levels in the body?
Why do patients taking Gliflozins still absorb some glucose despite SGLT-2 inhibition?
Why do patients taking Gliflozins still absorb some glucose despite SGLT-2 inhibition?
If a drug inhibits SGLT-2, which normally absorbs 90% of the glucose in the proximal tubules, what happens to the remaining glucose?
If a drug inhibits SGLT-2, which normally absorbs 90% of the glucose in the proximal tubules, what happens to the remaining glucose?
Flashcards
Glucose membrane permeability
Glucose membrane permeability
Glucose cannot directly pass through cell membranes because it's too polar and massive.
Na-K ATPases
Na-K ATPases
Located on the basolateral side of mucosal cells, they maintain a low intracellular sodium concentration.
SGLT-1
SGLT-1
Located on the apical side of mucosal cells, it uses the sodium gradient to transport glucose into the cell.
Ouabain's action
Ouabain's action
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GLUT-5 Transporter
GLUT-5 Transporter
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SGLT-2 function in Kidney
SGLT-2 function in Kidney
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Gliflozins
Gliflozins
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Study Notes
- Glucose cannot move through the cellular membrane because it is too polar and large.
Glucose Absorption in the Small Intestine
- Na-K ATPases on the basolateral sides of mucosal cells use primary active transport to move Na+ out and K+ into the cells.
- This action maintains a low Na+ concentration inside the cell.
- SGLT-1 (Sodium-Glucose-Transmitter type 1) is located on the apical side of the cell.
- SGLT-1 moves Na+ from the small intestine down its concentration gradient into the mucosal cell.
- SGLT-1 has another domain which either glucose or galactose binds to.
- SGLT-1 uses secondary active transport to move glucose into the cell against the concentration gradient.
- GLUT-1 (Glucose transporter) found on the basolateral side facilitates the diffusion of glucose into the blood.
Ouabain
- Quabain inhibits Na-K ATPases.
- It increases intracellular Na+ concentrations, which suppresses SGLT function.
Fructose Transport
- Fructose, unlike glucose and galactose, does not require active transport.
- GLUT-5 is present on the apical side of the mucosal cells.
- Fructose diffuses into the cell through GLUT-5.
Glucose Reabsorption in the Kidneys
- Glucose gets filtered in the glomeruli and becomes part of the glomerular filtrate.
- From there, it enters the lumen of the nephron.
- If glucose is not reabsorbed, it is lost in the urine.
- The process of glucose reabsorption is nearly identical to the previous process, except for a few details.
- The proximal convoluted tubule cells of the kidney use SGLT-2 transporters and GLUT-2.
- These are located in the early proximal tubules of the nephron.
- SGLT-9 transporters are also found in the late proximal tubules.
Gliflozins
- Gliflozins are drugs used for patients with type 2 diabetes.
- These patients have high blood sugar, so this drug inhibits SGLT-2, which absorbs 90% of the glucose.
- This means that glucose is lost in the urine, but the person still gets a little glucose from the SGLT-1, which absorbs 10% of the glucose.
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