Lecture 15: Urinary System Flashcards
Kidney structure
Several lobes w/ cortex + medulla. Each lobe = multiple lobules
Hilum
Aka hilar region/hilus. Region where renal artery, vein, and ureter enter the kidney.
Renal sinus
CT space between lobes continuous with the hilus. Contains first major vessel branches and distal ureter branches (aka major/minor calyces)
Medullary pyramid
Structure shaped by epithelia-lined minor calyces. Separates renal sinus from medullae of lobes
Collecting ducts
Series of tubes extending into medulla; extension of calyx lumen. Each drains several nephrons via short tangential collecting tubules.
Ducts of Bellini
Area of collecting ducts opening up to minor calyx.
Medullary ray
Collection of collecting ducts in medulla, defines center of corticle lobule
Nephron
Basic functional unit of kidney. Contains 1 highly folded tubule and a capillary bed.
Glomerulus
Encapsulated capillary bed at distal end of nephron. Located in cortex; tube descends and returns through the medulla.
Juxtaglomerular apparatus (JGA)
Returning DCT comes in close approximation to the originating glomerulus. Set of structures for signaling filtration efficiency
JGA structures
- Macula densa
- Extraglomerular mesangial cells (lacis cells)
- Juxtaglomerular cells
Macula densa (JGA)
Concentrated nuclei of JGA on side of glomerulus. Senses filtrate salt balance at apical surface. Communicates with other JGA cells via paracrine signals.
Extraglomerular mesangial cells
Aka lacis cells. Nearby CT cells sitting between the other structures. Forms cap over glomerulus vascular pole.
Juxtaglomerular cells
First and last sm. muscle cells in a/efferent arterioles to/from glomerular capillaries. Controls GFR by vessel diameter and renin secretion.
Nephric tubule
From distal to prox (rel. to kidney): PCT -> prox. straight -> thick descend. -> thin descend./ascend. -> thick ascend. -> dist. straight -> DCT
Prox./dist. in terms is relative to glomerulus
Nephric tubule morphologies
PCT + thick descend. = large cells w/ apical brush border + basal enfoldings (ion pumps/pore proteins)
Thin tubule = near-squamous
Thick ascend. + DCT = basal strations, smaller cells vs PCT
Collecting duct = (major.) principal cells + (minor.) intercalated cells (more mito.)
Bowman’s capsule
Epithelial-lined space by which nephric tubule encapsulates its associated glomerulus. Has inner visceral and outer parietal epithelia.
Inner visceral epithelium of Bowman’s capsule
Part of glomerulus; podocytes w/ interdigitating pedicels.