Kidneys

cvonck@zeelandnet.nl
URINARY System
It is formed of :
1- 2 Kidneys
2- 2 Ureters.
3- Urinary bladder
4-Urethra.
Histological Structure:
Stroma:
•
•
Capsule (Fibrous C.T.) which is loosely
attached to the underlying kidney substance.
It is surrounded by peri-renal fat.
Reticular tissue: is delicate and extends
between the parenchyma.
Parenchyma:
Uriniferous tubule:
•
It is the structural and functional unit of the
kidney.
•
It consists of nephron + collecting tubule.
The Nephron is the active part and subdivided
into
•
Renal corpuscle.
•
Proximal convoluted tubule (P.C.T.).
•
Loop of Henle.
•
Distal convoluted tubule (D.C.T.)
Kidney Organization
Kidney
Lobe
Capsule
Cortex
Renal
Pelvis
Medullary
Pyramid
Ureter
The renal corpuscle (Malpighian corpuscle)
. ١
The renal corpuscle (Malpighian corpuscle)
. ١
EM of the glomerulus
-The glomerular endothelium:
Fenestrated endothelium 60-100 nm
(open fenestrae).Hold back the blood
cells.
-The basement membranes:
Continuous and thick 100 nm.Hold
back the plasma protein (albumin).
-The filtration slit diaphragms
(membranes) which cover the
filtration slits 30 nm. It holds back the
large molecules
Length
Convolutions
Diameter
Lumen
Lining Cells
Number
Shape
Nucleus
Side Border
Luminal Border
Base of cell
Cytoplasm
Function
Proximal Convoluted
Tubules
Distal Convoluted
Tubules
About 15 mm
More
Large(60 um)
Narrow
about 5 mm
Less
Small(30-50)
Wide
3-5 cells
Cubical
Basal & Rounded
Not clear
Brush border(due to
microvilli)
Show basal mitochondrial
striation
Deeply acidophilic &
granular
5-8 cells
Less cubical
Central & Rounded
Clear
Few & Short Microvilli
1-Reabsorption of Na, water,
glucose, amino acids and
Plasma Proteins
2-Excretion of some
metabolites(dyes &
Penicillin)
1-Reabsorption of more Na ,
water>>>under the effect of
ADH
2-Reabsorption of Na >>
under the effect of
Aldosterone
Show basal mitochondrial
striation
Pale acidophilic & non
granular
Kidney
Kidney
Cortex
Medullary
Rays
DCT
PCT
The juxtaglomerular cells
The juxtaglomerular cells
Lacis cells (polar cushion)
The juxtaglomerular cells
The juxtaglomerular cells