Q.Identify the following structures and explain their significance in renal physiology?
a. Juxtaglomerular apparatus
b. Podocytes
c. Sphincters in the bladder
d. Renal cortex

The kidney's microscopic working unit

Each human kidney contains close to a million nephrons, and every nephron has two parts: a filtering renal corpuscle and a long renal tubule.

Renal corpuscle

The renal corpuscle pairs a double-walled cup, Bowman's capsule, with a tuft of capillaries it encloses, the glomerulus. The capillary walls have pores (fenestrae); the inner (visceral) layer of Bowman's capsule is made of podocytes, cells with branching foot processes that wrap the capillaries and leave narrow filtration slits between them, while the outer (parietal) layer is simple squamous epithelium. Together the fenestrated endothelium, basement membrane and podocyte foot processes form a three-layered filter that holds back blood cells and large plasma proteins.

Renal tubule

From Bowman's capsule, the tubule runs on as the proximal convoluted tubule (PCT), then forms the U-shaped loop of Henle (thin descending limb, thick ascending limb), then coils again as the distal convoluted tubule (DCT), and finally opens into a straight collecting duct that carries urine through the medulla toward the calyces.

Cortical vs juxtamedullary nephrons …