Histo - Urinary Flashcards
What is this?
Kidney
Function:
- Regulation of volume, osmolarity, mineral composition, and acidity
- Excretion of metabolic waste products
- Excretion of foreign chemicals
- Gluconeogenesis (during fasting)
- Secretion of erythropoietin (causes RBC formation)
- Secretion of renin (cleaves angiotensinogen to
angiotensin I) - Hydroxylation of vitamin D to its active form
What is this?
-
Capsule
- Dense irregular CT
- Adipose surrounds
- Cortex & Medulla
-
Hilum
- renal a. & v. enter/leave
- ureter drains
- nerve enters
-
Renal Cortex
- outer part of kidney
- extends btw renal pyramids = renal columns
- renal corpuscles
- proximal/distal convoluted tubules
- outer part of kidney
-
Renal Medulla
- inner part of kidney
- renal pyramids
- minor calyx –> major calyx –>renal pelvis–>ureter
- collecting ducts & loops of Henle
What are the 3 things involved with Renal Function?
Basics:
- Removal of metabolic wastes and excess water & electrolytes
- makes urine
Involves:
- Filration
- water & solutes from blood –> lumen of nephron
- Secretion
- cells of tubules put substances into lumen after uptake from interstitium & capillaries
- Reabsorption
- tubular lumen –> interstitium
What is this?
Urinary Pole of Renal Corpuscle
- Bowmans’s Space
- start of convoluted tubule
What is this?
Vascular Pole of the Renal Corpuscle
- Macula densa
- lots of nuclei
- Lumen of distal convoluted tubule
What are the 4 Cells in the Glomerulus?
- Endothelial cells
- Podocytes
- make up the visceral layer of Bowman’s capsule
- Mesangial Cells
- Simple squamous cells
- making up the parietal layer of Bowman’s capsule
What is this?
Mesangial Cells
Basics:
- Resemble pericytes
- Make ECM
- Mesangium = CT area btw capillaries & podocytes
Function:
- Provide physical support & contraction
- Help regulate blood flow
- Phagocytosis
- protein aggregates
- particularly Ab-Ag complexes
- processes pass btw endothelial cells into capillary
- Secretion
- cytokines
- prostaglandins
What is this?
Podocyte
Basics:
- Long primary processes
- Branch into secondary processes or pedicels
- Interdigitate
Features:
- Separated by the filtration slits
- Diaphragm btw filtration slits
- formed by protein = nephrin + GAGs + glycoproteins
What is this?
Glomerular Filtration Barrier
Basics:
- Controls passage of molecules from the plasma in capillary –> plasma filtrate in the capsular space (urinary space)
Function:
- Size filter
- restricts some proteins
- Charge filter
- (+) or neutral more readily filtered
When things go wrong…
-
Proteinuria
- indicates kidney malfunction due to messed up barrier
What are the 3 Components of the Glomerular Filter?
-
Capillary endothelium
- Fenestrated w/ NO diaphragm
- Prevents blood cells & platelets from entering urinary space
-
Basement membrane
- fused BL
- prevents large proteins & some anions
-
Filtration slit
- Diaphragm btw pedicels
- made of the protein = nephrin
- Prevents small proteins & anions
- Diaphragm btw pedicels
What are the components of a fused Basal Lamina?
- Lamina rara of podocyte
- Lamina densa of podocyte
- Lamina densa of endothelial cell
- Lamina rara of endothelial cell
- Matrix:
- Type IV collagen
- Laminin & Entactin
- Fibronectin
- Heparan sulfate proteoglycans (Perlacan)
What is the Flow of Filtrate during Urine Formation?
Urinary space –> PCT –> descending loop of Henle –> thin loop descending/ascending –> ascending loop of Henle –> area of macula densa –> DCT –> connecting tubule –> collecting duct –> papillary duct (Bellini) –> Calyces –> renal pelvis –> ureter
What are the 2 poles of the Renal Corpuscle?
-
Urinary Pole
- start of PCT
- plasma filtrate from Bowman’s space enters PCT
-
Vascular Pole
- afferent & efferent arterioles
- macula densa w/in wall of distal tubule
- distal straight tubule becomes –> DCT
What is this?
Cortex
Glomerulus, PCT and DCT
PCT
-
Basics:
- simple cuboidal epithelium w/ brush boarder inside
- higher cuboidal than DCT
- look “filled” - prominent glycocalyx
- comes off of glomerulus @ urinary pole
- basal striations = membrane infoldings + mitochondria
- simple cuboidal epithelium w/ brush boarder inside
-
Function:
- major site of reabsorption of glomerular filtrate
DCT
-
Basics:
- simple cuboidal epithelium
- little (if any) brush border
- basal stiations/ mitochondria lining
- vascular pole (afferent + efferent arterioles)
-
Function:
-
forms macula densa at glomerulus
- part of JG apparatus
-
forms macula densa at glomerulus
What is this?
JG Apparatus
Basics:
- Macula densa
- many nuclei
- extraglomerular mesangial cells (lacis cells)
- same fxn as mesangial cells in glomerulus
- JG cells
Function of JG Cells:
- Secrete renin
- response to decreased BP
- converts angiotensinogen –> Ang I
- Intrarenal baroreceptor
Location:
- Mostly in wall of afferent arteriole
- modified SM w/ eosinophilic granules
- Few in efferent arteriole
Function of Macula Densa:
- sensitive to NaCl changes
- Affects renin release by JG cells
Location:
- Vacular pole of glomerlus
What is this?
Macula Densa
What is this?
Collecting duct or tubule
Basics:
- Simple columnar epithelium
2 Cell Types:
- Prinicple cells
- aquaporins –> reabsorption of water
- Interalated cells
- regulated acid-base
What are the important characteristics of Interstitial Cells?
Basics:
- From loops of Henle to adjacent vasa recta
- Renal cortical fibroblasts
- Medullary fibroblasts
Function:
- Secrete erythropoietin
Note:
- If activated, participate in interstitial nephritis
- Nephrotoxic drugs
- Lupus
What are the 3 common Type IV collagen pathogenesis of renal disease?
-
Goodpasture syndrome
- autoantibodies against alpha chain of Type IV collagen
-
Alport’s syndrome
- mutation in gene
-
Benign familial hematuria
- mutation in gene
- blood in urine
What is this?
Ureter
Basics:
- Connect kidneys w/ urinary bladder
- Star shaped lumen
- Lined by transitional epithelium
3 Layers:
- Mucosa
- Muscularis externa
- inner = longitudinal
- outer = circular
- helical bundles (peristaltic waves –> force urine to bladder)
- Adventitia
- ureters = retroperitoneal
What is this?
Urinary Bladder
Basics:
- Receives & stores urine from ureter
- Larger lumen/thicker LP & muscularis externa than ureter
- Adventitia (inferior)
- Serosa (superior)
3 muscle layers = interweave (Detrusor muscle)
- Longitudinal
- Circular
- Longitudinal
Note:
- Transitional epithelium w/ tight jxns btw balloon cells
- Discoidal vesicles
What is this?
Female Urethra
Basics:
- carries urine from bladder –> out of body
- btw pubic symphysis & vagina
- Short (4-5cm)
Structure:
-
Mucosa
- transitional near bladder
- SSNK w/ pseudostratified columnar distally
-
Lamina Propria
- prominent w/ venous plexi (aids in closure)
- Skene’s glands (mucous)
-
Muscularis externa
- inner = longitudinal
- outer = circular
- Adventitia
Note:
- midpart surround by sphincter urethrae = skeletal muscle
What is this?
Female Urethra
What is this?
Prostatic Urethra
Basics:
- transitional epithelium, LP, muscularis
- surrounded by prostate
Membranous:
- stratified or pseudostratified columnar w/ LP
- muscle inner longitudinal = internal sphincter
- surrounded by skeletal muscle = external sphincter
Penile (aka Spongy Urethra)
- w/in corpus spongiosum (NOT LP)
- mixed epithelium
- pseudostratified columnar/SS
- mucous-secreting glands of Littre
What is this?
Penile Urethra & Glands of Littre
Function:
- secrete mucous
What is this?
Loop of Henle
Descending thick limb
- looks like PCT
- aka proximal straight tubule
Thin limb
- SS epithelium
- more nuclei in XS than in capillaries
- no blood
Ascending thick limb
- looks like DCT
- aka distal straight tubule
- impermeable to water
