Question

Draw a labelled diagram of a nephron. State the functions of glomerulitis, distal convoluted tubule and descending limb of Henle's loop

Answer 1

• The glomerulus is a capillary tuft that receives its blood supply from an afferent arteriole of the renal circulation. Here, fluid and solutes are filtered out of the blood and into the space made by Bowman’s capsule. The glomerulus is the site in the nephron where fluid and solutes are filtered out of the blood to form a glomerular filtrate.
• The distal convoluted tubule's permeability to water is variable depending on a hormone stimulus to enable regulation of blood osmolarity, volume, pressure, and pH. Normally, it is impermeable to water and permeable to ions, driving the osmolarity of fluid even lower. However, anti-diuretic hormone (secreted from the pituitary gland as a part of homeostasis) will act on the distal convoluted tubule to increase the permeability of the tubule to water to increase water reabsorption. This example results in increased blood volume and increased blood pressure. Many other hormones will induce other important changes in the distal convoluted tubule that fulfil the other homeostatic functions of the kidney.
• The loop of Henle consists of a descending limb and ascending limb. It transfers fluid from the proximal to the distal tubule. The descending limb is highly permeable to water but completely impermeable to ions, causing a large amount of water to be reabsorbed, which increases fluid osmolarity to about 1200 mOSm/L.