Histology of urinary Flashcards
Functions of urinary system
Removal of metabolic waste by-products
Regulation of body fluid composition & volume
Endocrine function (renin, erythropoietin)
COvering of kidney
renal capsule, perirenal fat, renal (GErota’s) fascia
Renal capsule
thin fibrous CT layer
Perirenal fat
thick layer of adipose tissue
Renal (Gerota’s) fascia
dense fibrous CT layer
Kidney has
cortex, medulla, corticol column
Cortex
cortical arch
medulla
- renal pyramids, 2. corical columns
renal pyramids
- Base
- Apex (~ renal papilla)
- Pointing towards hilum
Openings at area cribrosa
cortical column
extension of cortex
RENAL PELVIS
= Funnel-shaped expansion of proximal ureter
Excretory passage of urine
Openings at renal papilla → minor calyces → major calyces → renal pelvis → ureter
Mucosa lined by
transitional epithelium
Ducts of Bellini
largest collecting ducts opens at area cribrosa in renal papilla
Nephron
- Renal or Malphigian corpuscle
2. Renal tubules
Renal or Malphigian corpuscle
Bowman’s capsule, glomerulus
Renal tubules
proximal tubule, loop of henle, distal tubule
2 types of nephrons
cortial nephron, juztamedullary nephron
cortical nephron (85%)
Shorter
Renal corpuscle in superficial cortex & mid-cortical
Tubular part extends into outer medulla
Have peritubular capillaries
juxtamedullary nephron (15%)
Longer
Renal corpuscle near cortico-medullary junction
Tubular part extends into inner medulla
Have vasa recta capillaries
Renal or malphigian corpuscle
Oval to round structure in renal cortex
Renal or malphigian corpuscle composed of
glomerulus and bowman’s capsule
GLOMERULUS (network of fenestrated capillaries)
Afferent arteriole (incoming) Efferent arteriole (outgoing) Wall lined by endothelium
BOWMAN’S CAPSULE
= dilated (pouch-like) part of nephron
INNER VISCERAL LAYER - Podocytes
OUTER PARIETAL LAYER
- Simple squamous epithelial cells
Vascular pole
Blood vessels enter & exit Bowman’s capsule
Urinary pole
Connects Bowman’s capsule to proximal tubule
PODOCYTE
Modified epithelial cells lining visceral layer of bowman’s capsule
Filtration slits or slit pores
- in between pedicels
- covered by thin slit diaphragm / slit membrane
GLOMERULAR FILTRATION BARRIER component
Components:
1. Fenestrae of glomerular endothelial wall 2. Glomerular basal lamina 3. Slit diaphragm of filtration slits
MESANGIAL CELLS
= Specialised connective tissue cells
Mesangial cells groups
a.k.a Lacis cells, intraglomerular
Extraglomerular
At vascular pole, As a component of juxtaglomerular apparatus
intraglomerular
Within renal corpuscle, Support capillary loops of glomerulus
renal tubule
pt, dct, loh
pt
pctt, descending thick limb
dt
ascending thick limb , dct, macula densa
proximal tubule = renal cortex
Lined by simple cuboidal epithelium
More eosinophilic cytoplasm
Long microvilli (brush border)
proximal tubule fx
Resorption of water, sodium, chloride,
amino acids & glucose
Eliminates waste, drugs & toxins
;loh where
Renal cortex & medulla
loh structure
Lined by simple squamous epithelium
No microvilli
loh fx
Resorption of mainly water
descending limb > ascending limb
distal tubule = renal cortex structure
Lined by simple cuboidal epithelium
Less eosinophilic cytoplasm
Only few short microvilli
distal tubule fx
[*in response to aldosterone]
Resorption of sodium & chloride
Secretion of hydrogen & potassium
collecting tubules and duct got 3 parts
3 parts:
Cortical
Medullary
Papillary
collecting tubules and duct what
Each tubule drains several DCT
Short connecting tubule
→ collecting tubule (CT) → collecting ducts (CD)
→ opens at area cribrosa of renal papilla
→ minor calyx
collecting tubules and duct structure
Lined by simple cuboidal to columnar epithelium
pale- stained cytoplasm
well defined cellular outlines
- no microvilli
collecting tubules and duct fx
Resorption of water
[*ONLY in presence of Anti diuretic hormone (ADH) ]
cortical labyrinth
Renal corpuscles
Convoluted part of renal tubules
- PCT
- DCT
medullary rays
Straight part of renal tubules
- Pars recta of PT & DT
- Thin limbs of LOH
Collecting tubules
JUXTAGLOMERULAR APPARATUS component
Macula densa cells of DCT
Juxtaglomerular cells of afferent arteriole
Extraglomerular mesangial cells
JUXTAGLOMERULAR APPARATUS fx
Regulate blood pressure
& filtration rate of glomerulus
JUXTAGLOMERULAR APPARATUS where
near vascular pole
JUXTAGLOMERULAR APPARATUS formed by
dct and glomerular afferent arteriole
MACULA DENSA CELLS
= modified epithelial cells of DCT
MACULA DENSA CELLS structure
Tall, narrow, pale cells with prominent central nuclei
macula densa acting as
chemooreceptors, Sensitive to sodium ions concentration in DCT
[Low sodium concentration → renin production]
URETERS (ureters)
folded mucosa, smooth muscle layer, 3 layers in lower 1/3, adventitia, stellate shaped lumen
Folded mucosa
ureters
- Transitional epithelium & lamina propria
Smooth muscle layer:
ureters
- 2 layers in upper 2/3
Inner longitudinal
Outer circular - 3 layers in lower 1/3
Inner longitudinal
Middle circular
Outer longitudinal
Adventitia (ureters)
- Loose CT containing
blood vessels, lymphatic vessels & nerves
URINARY BLADDER got
mucosa, smooth muscle, adventitia/serosa , transitional epithelium and lamina propria
mucosa urinary bladder
- Folded except at trigone
- Transitional epithelium & lamina propria
ub
Mucus gland in lamina propria near urethral orifice
Smooth muscle (~ detrusor muscle) (ub)
- 3 layers:
Inner longitudinal
Middle circular
Outer longitudinal.
Middle layer forms internal sphincter at internal orifice of urethra
Adventitia/ serosa (UB)
- Dense irregular collagenous CT
with elastic fibers
MALE URETHRA
mucosa , lamina propria, smooth muscle
mucosa (male urethra)
- Transitional epithelium for prostatic urethra
Pseudostratified/ stratified columnar epithelium
for membranous & spongy urethra
Stratified squamous nonkeratinised epithelium
for glans penis area
Lamina propria (male uretha)
Loose fibroelastic CT with glands of Littre
Smooth muscle (male urethra)
Inner longitudinal & outer circular
External urethral sphincter
in urogenital diaphragm
- skeletal muscle (voluntary control)
Female urethra
elongated mucosal folds, Inner longitudinal & outer circular smooth muscle
,
Female urethra lined by
Transitional epithelium (near bladder) Stratified squamous nonkeratinized epithelium (near external orifice)
female urethra has lamina propria
Loose fibroelastic CT with glands of Littre