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Questions and Answers
Mesangial cells are primarily located in which part of the glomerulus?
Mesangial cells are primarily located in which part of the glomerulus?
What is the primary function of the mesangial cells in the glomerulus?
What is the primary function of the mesangial cells in the glomerulus?
Which of the following components of the blood renal barrier prevents the passage of red blood cells?
Which of the following components of the blood renal barrier prevents the passage of red blood cells?
What is the composition of the slit diaphragms in the filtration slits?
What is the composition of the slit diaphragms in the filtration slits?
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What is the function of the lamina rara interna in the glomerular basement membrane?
What is the function of the lamina rara interna in the glomerular basement membrane?
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What is the ultimate function of the mesangial cell contractions in response to blood pressure changes?
What is the ultimate function of the mesangial cell contractions in response to blood pressure changes?
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What is the primary function of the glomerular basement membrane in the filtration barrier?
What is the primary function of the glomerular basement membrane in the filtration barrier?
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In which region of the nephron are the cells smaller than in the PCT, with short microvilli and basolateral folds?
In which region of the nephron are the cells smaller than in the PCT, with short microvilli and basolateral folds?
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What is the main function of Principal cells in the collecting ducts?
What is the main function of Principal cells in the collecting ducts?
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What is the characteristic feature of the glomerular filter in diabetes mellitus and glomerulonephritis?
What is the characteristic feature of the glomerular filter in diabetes mellitus and glomerulonephritis?
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Which type of cells in the collecting ducts are responsible for maintaining acid-base balance?
Which type of cells in the collecting ducts are responsible for maintaining acid-base balance?
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What is the name of the duct that forms at the apex of each renal pyramid, where several medullary collecting ducts merge?
What is the name of the duct that forms at the apex of each renal pyramid, where several medullary collecting ducts merge?
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Study Notes
Mesangial Cells
- Located within the stalk of the capillary tuft (intraglomerular mesangium) and the vascular pole (extraglomerular mesangium)
- Participate in maintaining the basement membrane through phagocytosis and structural support
- Provide physical support to capillaries within the glomerulus
- Involved in immune defense and repair in the glomerulus
- Adjust contractions in response to blood pressure changes to maintain an optimal filtration rate
Blood Renal Barrier (Filtration Barrier)
- Separates blood in glomerular capillaries from the capsular space of Bowman's capsule
- Composed of: • Pores in the capillary endothelium • Continuous basement membrane of glomerular capillaries fused with the basal lamina of podocytes
- Has three layers: lamina rara externa, lamina rara interna, and an intermediate zone
- Slit diaphragms are modified occluding or tight junctions composed of nephrins, proteins, glycoproteins, and proteoglycans
- Restricts passage of proteins larger than 70 kDa
Function of the Filtration Barrier
- Filters blood plasma
- Allows water, ions, and small molecules to enter the capsular space
- Prevents large plasma protein molecules from entering the capsular space
Renal Tubules
- Consist of: • PCT (Proximal Convoluted Tubule) • Loop of Henle • DCT (Distal Convoluted Tubule)
- Histological features of each region: • PCT: Simple cuboidal epithelium, cells well-stained, numerous mitochondria, prominent basal folds, and long microvilli • Loop of Henle (Thick limbs): Simple cuboidal epithelium, no microvilli, but many mitochondria • Loop of Henle (Thin limbs): Simple squamous epithelium, few mitochondria • DCT: Simple cuboidal epithelium, cells smaller than in PCT, short microvilli and basolateral folds
Collecting System
- Composed of: • Principal cells: Cuboidal to columnar, pale-staining, distinct cell membranes • Intercalated cells: Few and scattered, slightly darker staining
- Connecting tubules extend from each nephron and join together to form collecting ducts
- Cortical collecting ducts: Lined by simple cuboidal epithelium, pass through cortical medullary rays
- Medullary collecting ducts: Lined by columnar cells, larger and straighter, run parallel to descending and ascending limbs of the loops of Henle and vasa recta
- Papillary duct (or duct of Bellini): Several medullary collecting ducts merge to form Papillary duct at the apex of each renal pyramid
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Description
Learn about the location, functions, and importance of mesangial cells in the glomerulus. Understand their role in maintaining the basement membrane, physical support, immune defense, and adjust to blood pressure changes. Test your knowledge of these cells and their significance in the kidney.
