Histology of the Urinary System Flashcards
(41 cards)
What are the main functions of the urinary system?
Excretory (removes waste), endocrine (produces hormones like erythropoietin), and metabolic (regulates electrolytes and pH).
What are the connective tissue layers surrounding the kidneys?
Renal capsule (outer collagen layer and inner myofibroblast layer).
What distinguishes the renal cortex from the medulla?
Cortex contains renal corpuscles and convoluted tubules; medulla has straight tubules, collecting ducts, and renal pyramids.
What are the components of the renal corpuscle?
Glomerulus (capillaries), Bowman’s capsule (parietal/visceral layers), capsular space, podocytes, and mesangium (mesangial cells + ECM).
What cells make up the Juxtaglomerular Apparatus (JGA) and what are their roles?
Granular cells: Mechanoreceptors secreting renin.
Macula densa: Chemoreceptors sensing NaCl.
Extraglomerular mesangial cells: Link GC and MD.
What are the segments of the nephron loop (of Henle)?
Descending limb (thin), ascending limb (thin and thick), and associated epithelia.
What are the three types of nephrons?
Cortical (subcapsular), juxtamedullary, and intermediate (midcortical).
What structures form the filtration barrier in the glomerulus?
What structures form the filtration barrier in the glomerulus?
What are the tissue layers of the ureters?
Mucosa (transitional epithelium), muscularis (smooth muscle), adventitia (connective tissue).
How does the bladder’s histology adapt to distension?
Mucosa has rugae (folds), muscularis (detrusor muscle), and adventitia.
How does the male urethra differ histologically from the female urethra?
Male urethra is longer and has prostatic, membranous, and spongy segments; female urethra is shorter and lined with stratified squamous epithelium.
What triggers micturition?
Bladder stretch receptors activate spinal reflex (infants) or voluntary control (adults), causing detrusor contraction and sphincter relaxation.
What vessels supply the nephron?
Afferent/efferent arterioles, peritubular capillaries (cortex), and vasa recta (medulla).
Why are kidneys considered endocrine organs?
They produce hormones like erythropoietin (RBC production) and renin (blood pressure regulation).
What are the two layers of the renal capsule, and what cells/fibers are in each?
Outer layer: Collagen fibers and fibroblasts.
Inner layer: Myofibroblasts (contractile cells).
How do the cortical labyrinth and medullary rays differ histologically?
Cortical labyrinth: Contains renal corpuscles and convoluted tubules (PCT/DCT).
Medullary rays: Straight tubules and collecting ducts projecting into the cortex.
What two structures compose the uriniferous tubule?
Nephron (renal corpuscle + tubules) + collecting duct.
What is the role of the vasa recta in the kidney?
Maintains the medullary osmotic gradient by countercurrent exchange (critical for urine concentration).
How can you distinguish PCT and DCT under a microscope?
PCT: Simple cuboidal with brush border (microvilli), eosinophilic cytoplasm.
DCT: Smaller cells, no brush border, less eosinophilic.
What do mesangial cells do in the glomerulus?
Phagocytose debris, regulate blood flow, and support capillary loops via ECM.
What is the function of podocytes in the glomerulus?
Wrap around capillaries; their foot processes form filtration slits to prevent protein loss.
What makes juxtamedullary nephrons unique?
Long nephron loops deep into the medulla; associated with vasa recta (key for concentrating urine).
What does the macula densa detect, and how does it respond?
Detects low NaCl in filtrate → signals granular cells to release renin (RAAS activation).
How does the ureter’s histology relate to kidney stone passage?
Muscularis contracts rhythmically (peristalsis) to move stones; pain arises from distension/spasms.
