Renal Anatomy and Histo Flashcards
What are the points of constriction on the ureter?
- uretopelvic junction
- Over common/external iliac
- Uretovesical junction
List the vessels from renal artery to renal vein.
- Renal artery
- Segmental
- Interlobar arteries
- Arcuate arteries
- Interlobular arteries
- Afferent arterioles
- Glomerular capillareis
- Efferent arterioles
- Peritubular capillaries
- Interlobular veins
- Arcuate veins
- Interlobar veins
- Renal vein
What makes up the sympathetic renal plexus?
- Lesser splanchnic
- Least splanchnic
- Lumbar splanchinic
Where does the renal plexus synapse?
Aorticorenal ganglion
What is a defining feature of the renal cortex?
Renal corpuscles
What are cortical labyrinth?
- Between medullary rays contains the RC + convoluted tubules + collecting tubules
What makes up the medulla?
- consists of renal columns and cone shaped masses called renal pyramids
What is a uriniferous tubule?
- Nephron + Collecting tubule
Where is erythropoietin produced from?
Fibroblasts in the renal interstitium
Whats responsible for final concentration of urines?
Cortical and medullary collecting ducts
What makes up the renal corpuscle and what are the components made of?
- Glomerular capillary tuft, which are fenestrated with open pores
- Bowman’s Capsule composed of:
- Parietal layer-simple squamous
- Visceral layer- podocytes
- Glomerular space- primary filtrate
What is the red line and blue line?
- Red is the vascular pole where afferent arteriole comes in
- Blue is the urinary pole where urine enters proximal convoluted tubule
What is secreted by glomerular endothelium?
- AQP-1 water channels
- NO and PGE2
- Contains plasma membrane bound glycocalyx
arrows are glomeruluar endothelium
Where are podocytes found and what do they do?
- Found on the visceral layer of bowmans capsule
- They wrap around glomerular endotheliuim and give off primary and secondary foot processes
- secondary create filtration slits
- size selective and charge selective
- Nephrin is part of the diaphragm that covers podocytes and repels positively charged proteins
- secondary create filtration slits
Describe the glomerular basement membrane and its function?
- Physical and ion selective filter made up of multiple collagens, laminin, fibronectin, and heparin sulfate
- Restricts large protiens such as albumin and hemoglobin
- albuminuria or hematuria indicates damage to GBM
- Negative charge restricts movement of anions
If protein leaks through the GBM, what usually happens to it?
Gets reabsorbed by proximal convoluted tubule
What makes up the filtration apparatus of the kidney?
- Glomerular endothelium
- GBM
- Visceral layer of bowmans capsule
All are contained within the renal corpuscle
What is bowmans space, what does it contain, and what is it continuous with?
- Space btw visceral and parietal layers of bowmans capsule
- contains the glomerular ultrafiltrate aka primary urine
- Continuous with proximal convoluted tubule at the urinary pole of the renal corpuscle
What are mesangial cells?
- Function in phagocytosis and endocytosis, structural support, secrete IL-1, PGE2, PDGF and modulate glomerular distension via contraction
- Located in the renal corpuscle most obvious near the vascular stalk
Where is the only place that proximal convoluted tubules can be found?
Renal cortex
What does the PCT do?
- Recieves ultrafiltrate from bowmans space and reabsorbs about 65% of it
- Made of simple cuboidal to columnar with apical brush border (gives foggy appearance inside the PCT)
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What does the PCT reabsorb and how?
- Na/K/ATPase actively reabsorb Na
- Cl passively diffuses
- H2O follows via AQP-1
- AA sugars and polypeptides reabsorbed via SGLT2
- Proteins and large peptides are endocytosed
What is the proximal straight tubule? (P)
- aka thick descending limb of the loop of henle
- shorter than PCT
- Less brush border
- Contains SGLT1 high affinity sodium glucose co transporter
What makes up the thin descending limb and its functions?
- highly permeable to water less permeable to NaCl and urea
- Water diffuses out
- Simple squamous without brush broder
- (tL on picture)
Distal straight tubule (thick ascending limb of LOH)?
- Simple cuboidal with microvili but no visible bruch border
- Cortical and medullary
- Na K and Cl diffuse out of filtrate into the interstitium
- NO water movement
- Nucleus is in the apical section and cells buldge into the lumen
- D and TAL
Distal convoluted tubule?
- Simple cuboidal epi no brush border, smoother and larger lumen
- Shorter than PCT cells
- Reabsorbs Na and bicarb
- Secretes K and NH4
- DCT exchanges Na for K under aldosterone regulation
What are the collecting tubules/ducts?
- simple squamous to cuboidal epithelium
- As you move to medulla they become simple cuboidal to columnar
- See cell broders in histo
what is this
Collecting duct, there are identifiable cell borders
What are the two cell types found in collecting ducts/tubules?
- Light cells (Principal cells): with a single cilium
- target of adh regulated AQP2 channels
- Dark cells (intercalated cells):
- alpha intercalated secretes H
- Beta intercalated secretes bicarb
What is the primary function of the collecting duct?
- water reabsorption via aldosterone regualtion
What are vasa recta?
- vasculature that surrounds the LOH from efferent arterioles
- Participate in countercurrent exchange and concentration of urine
- Descending is continuous endothelium but ascending has fenestrations
What are peritubule capillaries?
- From efferent arterioles surround CT
- Fenestrated endothelium
- Re uptake of water and salt
- Gives off vasa recta
What is the Juxtaglomerular apparatus?
- located near vascular pole of renal corpuscle and terminal portion of straight tubule
- Regulates BP via activation of RAAS at times of low sodium/BV
- Macula densa cells “sensa” low sodium
- Triggers release of renin from JG cells
Left vs right?
- empty bladder made of transitional epi
- Full bladder made of transitional epi
Where can transitional epitheium be found? What is it impermeable to?
- lines calyces, ureters, bladder, and intial segment of the urethra
- Impermeable to salts and waters
what are the three layers to the transitional epithelium?
- Superifical- stretches/relaxes
- Intermediate- slides
- Basal- stem cells
What allows for the unique properties of transitional epithelium?
- Modified areas of plasma membrane called Plauqes made of uroplakin proteins
- give areas more thickness and prevents diffusion of urine into cells
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- give areas more thickness and prevents diffusion of urine into cells
What is the significance of fusiform vesicles?
- uroplakin proteins housed in fusiform vesicles
- As the bladder fills and distends the vesicles are brought to the surface and release uroplakin proteins to insert more plasma membrane
- As bladder empties uroplakin are endocytosed back to vesicles
Describe the layers of ureters
- luminal transitional epithelium
- Sm mm layers:
- inner longitudinal
- middle circular
- outer longitudinal
- Embedded in adipose tissue where vessels and nerves form adventitia
What prevents urine reflux?
- Bladder distends and compresses ureters
- Contractrion of sm mm of bladder wall compresses ureters
- Ureters enter bladder obliquely
what is this
ureter
what is this
bladder
what epithelium makes up the origin of the urethra?
Transitional
What makes up majority of epitheliuim in urethra?
Psuedostratified columnar
What makes up distal end epithelium of urethra?
stratified squamous epi
Female urethera?
- Terminates posterior to clitoris
- Membranous part of urethrea penetrates urogenital diaphragm forming external urethral sphincter
Describe prostatic urethra?
- Transitional epithelium
- 2-4 cm from neck of bladder through prostate
- ejaculatory ducts enter posteriorly
Membranous urethra?
- Urothelium ends here and is made of psuedostratified columnar now
- passes through deep perineal pouch forms external urethral sphincter
- Extends 1cm from prostate to bulb of penis
Penile (spongy) urethra?
- 15 cm through length of penis opens at glans penis
- surrounded by corpus spongiosum lined with PSCT and transitions to stratified squamous epi at the end
- Cowpers and urethral glands empty here
