Labeling the Components of the Glomerular Filtration Membrane Correctly label the parts of the glomerular
filtration membrane. Blood cells, Plasma proteins, Large anions, Protein-bound minerals and hormones Filtration pore Endothelial cell of glomerular capillary Basement membrane Filtration slit Water, Electrolytes, Glucose, Amino acids, Fatty acids, Vitamins, Urea, Uric acid, Creatinine Foot process of podocyte Copyright McGraw-Hill Education. Permission required for reproduction or displ
The Correct Answer and Explanation is :
The glomerular filtration membrane is a critical structure in the kidney that selectively filters blood to form urine while retaining essential cells and proteins. The membrane consists of three main layers:
- Fenestrated Endothelium of Glomerular Capillaries – This is the innermost layer. The endothelial cells have large filtration pores (fenestrations) that allow passage of water, electrolytes, glucose, and small molecules while blocking blood cells.
- Basement Membrane – This middle layer is a dense network of negatively charged proteins, which repels large anions and plasma proteins, preventing their filtration.
- Filtration Slits (Slit Diaphragm) of Podocytes – The outermost layer consists of podocytes with foot processes (pedicels) that interdigitate to form narrow filtration slits, further restricting large molecules.
Labeling the Components
- Endothelial cell of glomerular capillary – Located at the innermost part of the filtration membrane, containing filtration pores.
- Filtration pore – Gaps in the endothelium that allow small solutes and water to pass.
- Basement membrane – The second layer, acting as a charge-based and size-based filtration barrier.
- Filtration slit – Small gaps formed between podocyte foot processes that further filter the fluid.
- Foot process of podocyte – Extensions of podocytes wrapping around capillaries.
Substances and Their Filtration
- Filtered through the membrane: Water, electrolytes (Na⁺, K⁺, Cl⁻), glucose, amino acids, fatty acids, vitamins, urea, uric acid, and creatinine pass freely.
- Blocked by the membrane: Blood cells, plasma proteins, large anions, and protein-bound substances (hormones, minerals).
This selective permeability ensures that vital substances like proteins and blood cells remain in circulation, while waste and small molecules enter the filtrate for urine formation.