Nephron Structure And Function — a labelled NEET Biology diagram with a definitions lexicon.
Nephron Structure and Function Labelled parts: Nephron structure and function, Bowman's capsule, Afferent arteriole, Efferent arteriole, Glomerulus, Filtration, Plasma filtered from glomerulus into Bowman's capsule, Proximal convoluted tubule (PCT), Reabsorption, Glucose, amino acids, Na+, H2O (and more), Loop of Henle, Descending limb, Water reabsorption, Osmosis, Ascending limb, Na+Cl- transport, Condition reabsorption, Na+, Cl-, HCO3-, and water (as needed), Distal convoluted tubule (DCT), Collecting duct, Vasa recta, Osmolarity (mOsm), Countercurrent gradient, ADH-dependent water reabsorption, Cortex, Medulla, Outer medulla, Inner medulla, 300 mOsm, 1200 mOsm. This small blood vessel carries blood into the glomerulus within the kidney's nephron. It has a relatively high blood pressure. FYI: The afferent arteriole regulates the blood flow into the glomerulus, thereby controlling the glomerular filtration rate (GFR). This small blood vessel carries blood away from the glomerulus. It has a lower blood pressure compared to the afferent arteriole. FYI: The resistance offered by the efferent arteriole helps maintain the high hydrostatic pressure necessary for filtration in the glomerulus. This segment is the primary site for the reabsorption of essential substances from the filtrate. It reabsorbs the majority of filtered glucose, amino acids, and sodium ions. FYI: Approximately 65-80% of filtered sodium and water, along with nearly all filtered glucose, are reabsorbed here. This segment of the Loop of Henle is impermeable to water but highly permeable to solutes (salts). It actively concentrates the filtrate by allowing salts to leak out into the surrounding interstitial fluid. FYI: The descending limb's permeability to water is high, causing water to exit by osmosis, thus concentrating the filtrate. This segment of the Loop of Henle is impermeable to water but actively pumps out solutes (Na+, K+, Cl-) into the interstitium. This process creates the osmotic gradient. FYI: The ascending limb is responsible for generating the hyperosmotic gradient in the renal medulla, which is essential for water reabsorption. This segment is involved in fine-tuning the electrolyte balance of the blood. It regulates the reabsorption of Na+ and Cl- under hormonal control (e.g., aldosterone). FYI: The DCT is the site where the final adjustments to urine concentration and electrolyte balance occur, responding to hormonal signals. This duct collects filtrate from multiple nephrons and is the final site for water and electrolyte regulation. Its permeability is highly regulated by ADH. FYI: The permeability of the collecting duct to water is directly controlled by Antidiuretic Hormone (ADH); high ADH means high water reabsorption. This is the osmotic gradient established by the Loop of Henle, where the ascending limb actively pumps solutes out, creating a high salt concentration in the renal medulla. FYI: The countercurrent mechanism is vital because it allows the kidney to concentrate urine up to 1200 mOsm/L, far exceeding plasma concentration. Antidiuretic Hormone (ADH) stimulates the insertion of aquaporin channels into the membranes of the collecting duct and late DCT. This increases the permeability to water, allowing it to be reabsorbed into the blood. FYI: Low plasma osmolarity (dilute blood) triggers ADH release, leading to maximum water reabsorption and concentrated urine. The net movement of water molecules across a semipermeable membrane from a region of higher water potential (lower solute concentration) to a region of lower water potential (higher solute concentration). FYI: Osmosis is the fundamental process governing water movement in the kidney, ensuring that water moves down its concentration gradient.