Biochemistry LE 4: Renal Metabolism, Water, Sodium, and Potassium

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What is the primary source of energy for the renal medulla?

Oxidation of FFAs (correct)

Oxidation of glucose

Glycolysis

Breakdown of proteins

Where is gluconeogenesis primarily located in the kidneys?

Renal medulla

Renal cortex (correct)

Collecting ducts

Nephrons

What percentage of glucose production during fasting is attributed to the kidneys?

20%-25% (correct)

60%-70%

5%-10%

40%-50%

What is the role of phosphofructokinase in the kidneys?

Glycolysis Signup and view all the answers

What is the function of glucose 6-phosphatase in the renal cortex?

Synthesis of glucose Signup and view all the answers

What is the effect of meals on renal gluconeogenesis?

It increases by 2-fold Signup and view all the answers

What are the preferential gluconeogenic precursors in the kidneys?

Glutamine and lactate Signup and view all the answers

Where is hexokinase primarily located in the kidneys?

Renal medulla Signup and view all the answers

What is the rate of gluconeogenesis dependent on in the kidneys?

Biochemistry Signup and view all the answers

What triggers the release of renin in the juxtaglomerular apparatus?

Decreased renal perfusion pressure Signup and view all the answers

What is the substrate for the enzyme renin?

Circulating angiotensinogen Signup and view all the answers

What type of protein is angiotensinogen?

Glycoprotein Signup and view all the answers

What is the primary function of the Renin-Angiotensin-Aldosterone System (RAAS)?

Regulation of body sodium Signup and view all the answers

Which hormone increases sodium reabsorption in the kidneys?

Cortisol Signup and view all the answers

What is the location of angiotensinogen synthesis?

Liver Signup and view all the answers

What stimulates the secretion of renin?

Prostaglandin E2 and norepinephrine Signup and view all the answers

What is the effect of prostaglandins and kinins on sodium reabsorption?

Decreases sodium reabsorption Signup and view all the answers

What is the role of adenylate cyclase in renin regulation?

Regulates renin secretion through pathways involving PKA and cAMP-responsive binding protein (CREB) Signup and view all the answers

What is the primary driving force behind sodium reabsorption in the tubular cells?

Electrochemical gradient generated by the Na+/K+-ATPase Signup and view all the answers

In the proximal tubule, sodium enters the tubular cells via which of the following mechanisms?

Na-H exchanger and glucose cotransporter Signup and view all the answers

What percentage of filtered sodium is reabsorbed in the ascending limb of the loop of Henle?

25% Signup and view all the answers

Which of the following diuretics acts on the proximal tubule?

Acetazolamide Signup and view all the answers

What is the mechanism of action of loop diuretics, such as furosemide?

Block Na+K+2Cl cotransporter Signup and view all the answers

In the collecting duct, sodium is reabsorbed via which of the following channels?

Amiloride-sensitive epithelial Na channels Signup and view all the answers

What is the effect of spironolactone on sodium reabsorption and potassium secretion?

Decrease sodium reabsorption and potassium secretion Signup and view all the answers

What is the result of inhibiting NaHCO3 cotransporter in the proximal tubule?

Decrease sodium and HCO3 reabsorption Signup and view all the answers

What is the effect of natriuretic hormones on sodium reabsorption and glomerular filtration rate?

Decrease sodium reabsorption and increase GFR Signup and view all the answers

What is a characteristic of an ideal marker of GFR?

Must be freely filterable Signup and view all the answers

Why are new markers not widely available?

They are more expensive than creatinine Signup and view all the answers

What is the function of NGAL in tissue remodeling?

It promotes heterodimerization with metalloproteinase 9 Signup and view all the answers

In which cells is NGAL produced?

In various epithelial cells and myelocytes Signup and view all the answers

What happens to NGAL after tissue damage?

Its synthesis and secretion into the bloodstream is immediately released Signup and view all the answers

What is the molecular weight of NGAL?

25 kD Signup and view all the answers

What is the function of NGAL in innate immunity?

It plays a role Signup and view all the answers

What happens to NGAL in the proximal tubules?

It is freely filtered and reabsorbed Signup and view all the answers

What is the relationship between cellular stress and NGAL excretion?

There is a quantitative link Signup and view all the answers

What is the most likely explanation for glucosuria?

Exceeds maximal reabsorptive capacity for glucose Signup and view all the answers

Where does sodium reabsorption not occur in the renal tubules?

Thin ascending limb Signup and view all the answers

Which hormone inhibits renal gluconeogenesis?

Insulin Signup and view all the answers

Which part of the kidney has the highest ATP consumption?

Proximal Signup and view all the answers

Who has the highest amount of total body water relative to sex?

Males Signup and view all the answers

What is the function of the proximal tubule in the kidney?

All of the above Signup and view all the answers

What is the primary function of the thick ascending limb?

Sodium reabsorption Signup and view all the answers

Which of the following is NOT a site of sodium reabsorption?