For each of the following descriptions of a structure, find the matching name in the question key:
location of macula densa
capillary specialized for filtration
capillary specialized for reabsorption
primary site of tubular reabsorption
receives urine from many nephrons
cuplike part of the renal corpuscle
The correct answer and explanation is :
Here are the correct answers for each description along with a 300-word explanation of each structure:
- Location of Macula Densa: Distal Convoluted Tubule (DCT)
The macula densa is a group of specialized cells located in the distal convoluted tubule (DCT), where it passes by the glomerulus. These cells detect the concentration of sodium chloride (NaCl) in the filtrate and play a crucial role in regulating glomerular filtration rate (GFR) via the tubuloglomerular feedback mechanism. If the NaCl concentration is too low, it signals the juxtaglomerular cells to release renin, which activates the renin-angiotensin-aldosterone system to increase GFR. - Capillary Specialized for Filtration: Glomerulus
The glomerulus is a network of capillaries located within the renal corpuscle, where blood filtration begins. It is specialized for filtration due to its fenestrated endothelium, which allows small molecules such as water, ions, glucose, and urea to pass into the Bowman’s capsule, while larger molecules like proteins and blood cells are retained in the bloodstream. - Capillary Specialized for Reabsorption: Peritubular Capillaries
The peritubular capillaries surround the renal tubules (proximal and distal convoluted tubules and loop of Henle) and are specialized for reabsorption. After filtration in the glomerulus, essential substances such as water, glucose, and ions are reabsorbed from the renal tubules into the bloodstream via these capillaries. - Primary Site of Tubular Reabsorption: Proximal Convoluted Tubule (PCT)
The proximal convoluted tubule is the primary site for tubular reabsorption. The majority of reabsorption (about 65-70% of filtrate) occurs here, including glucose, amino acids, ions, and water. The PCT has a dense network of microvilli that increase its surface area for efficient reabsorption. - Receives Urine from Many Nephrons: Collecting Duct
The collecting duct receives urine from multiple nephrons. It plays a role in the final concentration of urine through processes like water reabsorption, influenced by hormones like ADH. The collecting duct channels urine into the renal pelvis for eventual excretion. - Cuplike Part of the Renal Corpuscle: Bowman’s Capsule
The Bowman’s capsule is a cuplike structure that encases the glomerulus. It is part of the renal corpuscle and serves as the site where filtration occurs. The filtrate passes from the glomerulus into the Bowman’s capsule before moving into the proximal convoluted tubule for further processing.