Histological Structure of the Kidney

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  • Created by: Becca
  • Created on: 26-12-13 21:07
What are the main functions of the kidney?
Urine production: filtration of blood, modification of filtrate (composition & volume), unwanted residue excreted as urine. Endocrine: renin (BP), erythropoetin (stimulates erythrocyte production). Synthetic: active metabolite of vit D
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What is the structure of the cortex?
Outer shell with columns of Bertin lying between individual units of medulla
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What is the structure of the medulla?
Series of conical medullary pyramids, base on cortex & tip onto urine collecting system (calyceal system) towards hilum of kidney. Apex terminates into papilla -> minor calyx. Walls of calyces & ureter contain smooth muscle for propulsion of urine
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What type of epithelium is there near the basement membrane & lining the lumen? What special features are there?
Basement membrane: stratified cuboidal. Lumen: squamous transitional epithelium (urothelium), surface specialisations resist toxins & acidic pH of urine, impermeable so urine can't leak out or water be drawn in by osmotic pressure
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What are the capillary systems in the kidney?
Arterial & venous separated by glomerular & peritubular capillaries (allows discharge of waste). 1st system: affterent arteriole -> glomerular capillary bed -> sit of filtration. 2nd system: efferent arteriole -> peritubular -> secretion/absorption
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What happens at the cortico-medullary junction?
Efferent arterioles give rise to vasa recta which run straight down to medulla & are in close proximity to the loop of Henle -> drain interlobular & arcuate veins
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What is between afferent & efferent arterioles?
A segment of tube called the macula densa
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What is the role of mesangial cells?
Supporting tissue of glomerus/capillary loop system, involved in inflammatory response (phagoytosis), contract/regulate blood flow, secrete prostaglandins & angiotensin II
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What cells are found in the juxtaglomerular apparatus? What is their role?
Renin producing granular cells: myoepithelial cells, regulate plasma volume & BP. Lacis cells: extra-glomerular mesangial cells, regulate lumen size of arterioles to alter pressure difference & filtration capacity
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What is the histology of the macula densa? What is their function?
Lumenally placed nuclei with Golgi facing vascular pole of glomerulus, act as sensors of sodium & chloride levels in fluid -> active maintenance of BP & volume
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What is the histology of the Loop of Henle?
Begins/ends with thick walls but central U-shaped portion has thin walls. Lining cells form simple squamous epithelium with little cytoplasmic specifications
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What is the histology of he distal tubule? What is its function?
Cuboidal with sparse microvilli (lumen appears empty), nuclei more centrally located, rich in mitochondria. Function: acid/base balance, pumps ions against concentration gradient
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What is the histology of the collecting duct? What is its function?
Collecting tubules are lined with cuboidl epithelial cells -> taller & columnar in ducts. Water absorbed along osmotic gradient into interstitium -> concentration of urine
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What is the histology of the bladder? What happens as the bladder fills?
Transitional epithelium (urothelium, cell shape changes as bladder fills), detrusor muscle has 3 layers - outer longitudinal, circular tight spiral, long loose spiral. As bladder fills, criss-cross arrangement appears
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What is the histology of the urethra? What are the gender difference?
Stratified squamous epithelium, external sphincter striated muscle under voluntary control. Male: 4 portions, longer & partly external to the body. Female: short, end of urinary tract
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Card 2

Front

What is the structure of the cortex?

Back

Outer shell with columns of Bertin lying between individual units of medulla

Card 3

Front

What is the structure of the medulla?

Back

Preview of the front of card 3

Card 4

Front

What type of epithelium is there near the basement membrane & lining the lumen? What special features are there?

Back

Preview of the front of card 4

Card 5

Front

What are the capillary systems in the kidney?

Back

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