Question

1. describe the structure of a nephron, label on a diagram. glomerulus, bowman’s capsule, proximal and distal tubule, loop of henle, collecting duct

Explanation:

1. Nephron Structure Overview: The nephron is the functional unit of the kidney, responsible for filtering blood and forming urine. It consists of a renal corpuscle (glomerulus + Bowman’s capsule) and a renal tubule (proximal convoluted tubule, loop of Henle, distal convoluted tubule, and collecting duct).
2. Renal Corpuscle:

• Glomerulus: A tuft of capillaries (fenestrated) where blood filtration occurs. It is supplied by an afferent arteriole and drained by an efferent arteriole.
• Bowman’s Capsule: A double - walled (parietal and visceral layers) cup - shaped structure that encloses the glomerulus. The space between the two layers is the capsular space, where the filtrate (ultrafiltrate) collects.

1. Renal Tubule:

• Proximal Convoluted Tubule (PCT): The first coiled segment of the tubule, located in the renal cortex. It has a brush border (microvilli) to increase surface area for reabsorption of nutrients (e.g., glucose, amino acids), ions (e.g., $Na^+$, $Cl^-$), and water.
• Loop of Henle: A U - shaped tubule with a descending limb and an ascending limb. The descending limb is permeable to water (facilitating water reabsorption, making the filtrate more concentrated), and the ascending limb (thin and thick segments) is impermeable to water but actively transports ions (e.g., $Na^+$, $Cl^-$) out, creating a concentration gradient in the medulla.
• Distal Convoluted Tubule (DCT): A coiled segment in the cortex, involved in fine - tuning electrolyte balance (e.g., reabsorption of $Ca^{2+}$, secretion of $K^+$) and acid - base balance (secretion of $H^+$ or $HCO_3^-$) under hormonal control (e.g., aldosterone, parathyroid hormone).
• Collecting Duct: Receives filtrate from multiple nephrons. It runs through the medulla and is responsible for final water reabsorption (under ADH control) and further ion regulation, concentrating the urine before it is transported to the renal pelvis.

For labeling a diagram:

• Identify the glomerulus (tuft of capillaries) and label it.
• Label Bowman’s capsule around the glomerulus.
• Trace the tubule from Bowman’s capsule to the PCT, then the loop of Henle (mark descending and ascending limbs), followed by the DCT, and finally the collecting duct (which merges with other collecting ducts).

Answer:

The nephron has a renal corpuscle (glomerulus + Bowman’s capsule) and a renal tubule (proximal tubule, loop of Henle, distal tubule, collecting duct). The glomerulus is a capillary tuft; Bowman’s capsule encloses it. The proximal tubule reabsorbs solutes/water. The loop of Henle (descending/ascending limbs) creates a concentration gradient. The distal tubule fine - tunes ion/acid - base balance. The collecting duct concentrates urine. For a diagram, label the glomerulus (capillary tuft), Bowman’s capsule (around glomerulus), proximal tubule (after capsule), loop of Henle (U - shaped), distal tubule (after loop), and collecting duct (connecting to renal pelvis).