histology of urinary system Flashcards
describe the shape of outer cortex?
granular in appearance
what does the outer cortex consist of?
Cortical arches
Renal columns
what is cortical arche ?
space between the base of the pyramids ( of the medulla ) and the surface of the kidneys
what does the cortical arch consists of ?
Medullary / cortical rays
plain convoluted part
describe medullary/ cortical rays?
rays that appear radiating from the pyramid
they are collecting tubules and collecting ducts
located in the CORTEX but heading towards medulla
describe plain convoluted part?
Consists of :
renal corpuscle
Proximal convoluted tubule (PCT)
Distal convoluted tubule ( DCT)
FOUND IN THE CORTEX
what is renal column?
area between the adjacent cortical arches
Extends into the medulla between 2 pyramids
Contain few/nil renal corpuscles ( like medullary arches-plain convoluted part ) + inter lobar vessels
describe blood vessel course inside the kidney parenchyma?
Renal artery enters the hilum
Breaks into segmental/lobar artery
Become interLOBAR as they head to the renal column ( renal column = interlobar )
Once it reaches the base of the pyramid it FORMS THE ARCUATE ARTERY
interLOBULAR arteries arise from arcuate
interlobular arteries give raise to AFFERENT arterioles
Branch into tuft of capillaries beds inside the glomerulus
join together again to form EFFERENT arterioles
as they go down and branch into capillaries around HENELES LOOP called —> VASA RECTA
renal artery —> segmental/lobular—-> interlobar —> arcuate —> interlobular —> afferent —> capillary bed —> efferent —> vasa recta
describe how the veins form inside the kidney?
Interlobular veins —> arcuate vein —> interlobar vein —> segmental/lobar vein —-> Renal vein
what is cortical glomerulus ?
glomerulus seen in the cortex
what juxtamedullary glomerulus?
Glomerulus seen between the base of the pyramid and the cortex
what is lobule of kidney?
area of cortical arch bounded on either side by :
Inter lobular Blood vessels
1 medullary ray in the center
what is the functional unit of kidney?
uriniferous tubules
what forms the functional unit of the kidneys ( uriniferous tubules )?
Nephrons
collecting duct
what forms a nephron?
renal corpuscle —> for filtration
Renal tubules —-> selective reabsorption and secretion
what forms a renal corpuscle ?
Glomerulus —> TUFT OF CAPILLARIES
Glomerular capsule —> bowmans capsule :
Has inner layer ( visceral layer ) and outer parietal layer
between them u have bowmans space
what type of cells is the bowmans capsule ?
simple squamous epithelium
what are the components of the renal tubules of the nephron ?
proximal convoluted tubule PCT
Loop of henle :
Thick of descending portion
Thin descending portion
thin ascending portion
thick ascending portion
Distal convoluted tubule ( DCT )
Collecting tubule
what happens to collecting tubules?
collecting tubules in the cortex join together to form portion of the COLLECTING DUCTS in the cortex
which is known as medullary rays ( cortical arch)
as you go down in them medulla , the collecting ducts become larger and wider —-> become ducts of bellini ( which is the other second part of the functional unit of kidney)
what are the parts of the functional unit found in the cortex?
Renal corpuscles
Proximal convoluted tubules ( MOST ABUNDUNAT )
Distal convoluted tubules
Medullary rays —> bundles of collecting tubules and ducts that radiates towards the medulla
what are the parts of the functional unit found in the renal medulla?
Loop of henle
Collecting ducts
Ducts of bellini ( collecting papillary ducts ) —> represent most distal portion of collecting duct
what is the area cribrosa?
area of the apex of the pyramid where the ducts of bellini opens
since the ducts open there, the area appears porous
what are 2 types of nephrons ?
based of the location of the renal corpuscles in the cortex?
Cortical nephrons —> 85% , located in cortex
Juxtamedullary nephrons —-> closer to renal medulla , loops of henle extends deep into renal pyramids
in cortical nephrons —> henles loop is short
in juxtamedullary nephrons —> henles loop is LONG
what are the components of renal corpuscle ?
Glomerulus
Bowmans space
Vascular pole
Urinary pole
describe glomerulus?
Rounded structure formed of TUFT OF CAPILLARIES
describe bowmans space?
Narrow space surrounding the glomerulus
describe the vascular pole ??
afferent arterioles enters the corpuscle to supply the glomerulus
describe the urinary pole?
Substances which leave the capillaries to enter the RENAL TUBLE
what are the nucleus found in the glomerulus?
nucleus of 3 cells :
Capillary endothelial cells
Mesangeal cells of the supporting mesangium —> ( cell between capillaries that are used for cushioning and support )
Podcytes —> (cells on top of the capillaries that have spider like appearance )
WE HAVE RBCS IN THE GLOMERULUS BUT THEY DONT HAVE NUCLEIS
what are the nucleus found in lining of bowmans capsule ?
Flattened nulcei of the squamous cells
What are the components of glomerulus ?
Glomerular capillaries
Mesangium
Podocytes
describe glomerular capillaries ?
capillaries are fenestrated but the basement membrane of the endothelium is continuous
May contain erythrocytes ( NO NUCLEUS)
Have prominent basement membrane
endothelial cells nuclei may bulge into capillary lumen
describe mesangium ?
Specialized connective tissue
Mesangial cells
Mesangial substance —> densely stained extracellular substances provides support for the capillary loops
describe podocytes?
Invest the surface of the glomerular capillary loops exposed to bowmans space
Have extensive branching cytoplasm
describe capillary endothelium ?
Fenestrated to permit the passage of all NON CELLULAR elements of blood
describe capillary basement membrane ?
Non fenestrated layer that act as glomerular ultra filter
smaller molecules pass freely
larger molecules are retained
describe podocytes?
Envelope the glomerular capillaries
Long cytoplasmic primary processes give rise to short secondary foot processes ( PEDICLES )
which interdigitate and are directly applied to the glomerular basement membrane
Slit pores —–> the gaps between the interdigitation ( pedicles ) —> restrict the passage of large molecules
Plasma from glomerular capillaries filtrates into bowmans space through :
Capillary endothelium —-> basement membrane —–> slit pores of the podocytes
Phagocytic function of the podocytes is REMOVE ANY LARGE MOLECULES WHICH BECOME TRAPPED IN OUTER LAYER OF THE FILTER
Molecules trapped in the endothelial side are PHAGOCYTOSED BY MESENGIAL CELLS
where is the location proximal convoluted tubule ?
cortex
LONGEST AND MOST CONVOLUTED PART OF THE NEPHRON —> CONSTITUTES THE BULK OF RENAL CORTEX
what are the components of proximal convoluted tubule epithelial lining ?
Simple, tall cuboidal epithelium
Prominent brush border –> increase the surface area of plasma membrane for reabsorption of glomerular filtrate
Deeply stained cytoplasm : high content of organelles , principally mitochondria
These reflect the re-absorptive function of PCT
what is the location of distal convoluted tubule ?
cortex
how to differentiate between PCT and DCT?
Absence of brush border
LARGER MORE CLREARLY DEFINE LUMEN
more nuclei are seen in transverse section since the cells of DCT are smaller than those of PCT
less affinity to cytoplasmic stains due to smaller content of organelles
Sections of DCT are much less frequent that sections of PCT since the DCT is a much shorter than PCT
PCT –> irrugular lumen due to brush border, narrower lumen, not prominent due to bipolar staining
DCT —> smooth border, larger lumen, prominent well spaced nulcei
what is the location of loop of henle?
Mainly found in renal medulla
some found in cortex
what type of cell is the thin segment of loop of henle?
Simple squamous epithelium
how do we differentiated between thin segment of loop of henle and vasa recta since both have simple squamous ?
by their :
Regular , rounded shape
when seen in transverse section
Absence of erythrocytes
what type of cells is the thick segment of loop of henle?
low cuboidal epithelium
Round in cross section
no brush border found in loop of henle
NEITHER THIN OR THICK
how do we differentiate bewteen PCT and thick segment since both have simple cuboidal?
PCT –> tall cuboidal , brush border
Thick segment —> low cuboidal , no brush border
describe collecting tubules?
Similar epithelial lining to the thick segment of the loop ( LOW CUBOIDAL )
WIDER AND LESS REGULAR DIAMETER THAN ASCENDING LIMB ( LOOP OF HENLE )
describe collecting ducts?
COLUMNAR ( TALL )
pale stained epithelial lining cytoplasm
LARGE DIAMETER
ABSENCE OF BRUSH BORDER
compare collecting ducts and collecting tubules?
Collecting duct —> columnar lining, larger lumen
collecting tubule —> cuboidal lining, narrower lumen
What is the location of collecting ducts?
Medulla
what is the location of juxtaglomerular apparatus ?
rounded
adjacent to the renal corpuscles and DISTAL CONVOLUATED TUBE
what are the type of cells found in the juxtaglomerular apparatus?
Juxtaglomerular cells
Macula densa
juxtaglomerular cells + macula densa = juxtaglomerular apparatus
what are the juxtaglomerular cells?
Modified smooth muscle cells of afferent arterioles in the vascular pole of renal corpuscle
Contain SECRETORY GRANULES OF RENIN
CELLS OF AFFERENT ARTERIOLE THAT TOUCH DCT undergo changes —> juxtaglomerular cells
what are macula densa?
Modified DCT CELLS
taller cells with more prominent nuclei towards luminal surface
cells of DCT that touches arteriole under goes changes —> macula densa
what is the function of juxtaglomerular apparatus?
Regulation of systemic blood pressure via renin angiotensin aldosterone mechanism
describe the urinary tract course?
Minor calyx
major calyx
renal pelvis
ureter
urinary bladder
Urethra
which part of the excretory passage that doesnt have the same general structures?
urethra
all of them have transitional epithelium except urethra
mucosa
muscularis
adventitia/serosa
describe the mucosa of urinary tract epithelium ?
LINED by transitional epithelium ( UROTHELIUM )
Stratified epithelium :
Begins in the minor calyces as two cell layer and increases as many as six tor more layers in the empty bladder
DISTENSIBLE :
When relaxed –> surface epithelial cells are cuboidal and bulge into lumen ( Dome shaped cells ) —> interdigitating cell junctions permit great distention of the epithelium without damage to the surface integrity
Impermeable :
Doesnt modify urine but it is specialized for its storage and passage to the exterior , thick plasma membrane
what is ureter?
transport the urine from the kidney to the bladder
stellate lumen —> STAR SHAPED
how does the rune flow through ureter?
peristalsis can pump urine from the kidney into bladder only at relatively low means rate of urine of flow is low
under these circumstances isolated boluses of urine are propelled steadily through ureter ( assumed uniform ) by contraction waves
describe the mucosa of ureter?
start shaped lumen due to folding
transitional epithelium
lamina propria –> firboelastic connective tissues
describe the muscularis layer of ureter?
INNER LONGITUDINAL
OUTER CIRCULAR
opposite to GIT
in the distal part of the ureter
We have a third outer layer —> longitudinal layer peristaltic contractions —> these contractions create the folding of the mucosa –> Star shapes )
describe the adventitia of urter?
loose connective tissue containing blood vessels , lymphatic and nerves
what the difference between urinary bladder and ureter?
structures of the wall similar to ureter
lamina propria may contain mucous glands at the neck of the bladder
3 ill defined layer of smooth muscles —> detrusor muscles
Inner longitudinal , middle circular ( INTERNAL SPHINCTER ) , outer longitudinal
Serosa or adventitia
describe the mucosa of urinary bladder?
Transitional epithelium thrown into folds in relaxed states
lamina propria
describe the muscularis of urinary bladder?
smooth muscles irregularly arranged into layers
Irregular arrangement allows mass contraction —> EMPTYING BUT NO PERISTALSIS
describe the epithelium of urethra?
starts off as transitional cells as it exit the bladder
Along the urethra —> stratified columnar cells
Stratified squamous cells —-> near the external urethral orifice
Gradual changes
transitional epithelial –> stratified columnar —> stratified squamous
what lines the prostatic urethra?
transitional epithelium
what surrounds the prostatic urethra?
Prostate glands which contain :
Tubulo alveolar
Alveoli are wid, irregular , epithelial folds
Contain :
Secretory product
Lamellated glycoprotein masses ( corpora amylacea CA ) with increasing age
Prostatic concretion : CALCIFICATION OF CORPORA AMYLECAE
describe the fibromuscular stroma?
Dense collagen
Fibroblast
irregularly arranged smooth muscle fibers
