L29 The Nephron

These flashcards cover key terms and concepts related to the nephron and its functions as discussed in the HUBS192 lecture notes.

Glomerular Capsule

Aka Bowman’s capsule, first part of the nephron, encloses glomerulus. Two layers, outer parietal (simple squamous), and inner visceral (podocytes). Capsular space between layers.

Nephron function

Selectively filter blood, return to blood anything to be kept, carry away waste for storage and expulsion.

Cortical Nephrons

85% of nephrons and lie mainly in the cortex.

Juxtamedullary Nephrons

15 % of nephrons that extend deep into the medulla and are important for the formation of concentrated urine.

Nephron components

Glomerular capsule, renal tubules (PCT, nephron loop, DCT), collecting duct. Each nephron associated with a glomerulus and peritubular capillaries.

Glomerulus

Network of capillaries specialized for filtration (thin walled single layer of fenestrated endothelial cells). Fed and drained by afferent and efferent arterioles, tightly regulate BP. Enclosed by glomerular capsule.

Filtration Barrier

Blood-urine barrier that lies between blood and capsular space. Allows free passage of water and small molecules while restricting most proteins and RBCs.

Filtration barrier components (3 layers)

Fenestrated endothelium of glomerular capillary, fused basement membrane, filtration slits between pedicels of podocytes.

Podocytes

Specialized epithelial with branches that form foot processes (pedicels), which form filtration slits where filtered blood passes into capsular space. Wrap around glomerular capillaries.

Urine= Filtered - Reabsorbed + secreted

Urine is waste fluid and solutes filtered from blood, some filtrate reabsorbed, some of what wasn’t filtered is secreted into nephron.

Proximal Convoluted Tubule (PCT)

Bulk reabsorption, surrounded by peritubular capillaries. Cuboidal epethelium (leaky), dense microvilli on luminal membrane, highly folded baseolateral membrane, lots of mitochondria fro active transport.

Nephron loop

Thick descending limb (similar PCT), thin descending limb (simple squamous), thin ascending limb (simple squamous), thick ascending limb (similar DCT).

Distal Convoluted Tubule (DCT)

Fine-tuning reabsorption with hormone influence. Cuboidal epithelium but thinner than PCT with less mitochondria and few microvilli (no brush border).

Collecting Duct

Receives filtrate from several DCTs and empty into papilla. Hormone influenced fine tuning, simple cuboidal with principle cells (reabsorption) and intercalated cells (acid/base balance).

Peritubular Capillaries

Specialised for absorption, receives filtered blood from glomerulus via efferent arteriole, and reabsorbed filtrate from nephron.

Vasa Recta

Extensions of peritubular capillaries that follow nephron loops deep into the medulla (juxtamedullary).

Filtration Slits

Narrow gaps formed between the pedicels of podocytes that allow filtered blood (filtrate) to pass into the capsular space.

Renal Corpuscle

Glomerulus enclosed by glomerular capsule, where capillary and nephron meet and site of filtration barrier.