Histology Flashcards
What is the histological Structure of the kidneys :
1) Stroma : Fibrous Capsule and Interstitium
2) Parenchyma : Uriniferous Tubules
Describe the anatomy of Uriniferous Tubules :
It consists of two structures :
1) Nephron. 2) Collecting Duct.
Nephron consists of :
1) Renal corpuscle = Malpighian Corpuscle
2) Renal tubules
A.Proximal convoluted tubules ( PCT )
B.Loop of Henle
C.Distal convoluted tubules ( DCT )
Renal Corpuscle is where ……………………. & Renal tubules where ……………………
Blood plasma is filtered , filtered fluid passes
Types of Nephrons :
A) Short nephrons = Cortical nephrons ( MAJORITY )
B) Long nephrons = Juxtamedullary nephrons
About Short nephrons OR Cortical Nephrons :
Short = their loop of Henley is short
Cortical = their renal corpuscle in outer portion of cortex
About Long nephrons OR Juxtamedullary nephrons :
Long = their loop of Henle is long
Juxtamedullary = Their renal corpuscle lie deep in cortex close to medulla
Number of nephrons in the kidneys :
1 million
Function of long nephrons :
Excretion of very concentrated urine
Each corpuscle has two poles :
A) Vascular Pole
B) Urinary Pole
How to differentiate btwn The two poles of Renal corpuscle :
Vascular Pole : where afferent arteriolar enters and efferent arteriole leaves
Urinary Pole : where the proximal convoluted tubule begins
Components of renal corpuscle :
A) Glomerulus
B) Bowman’s Capsule
Glomerulus is formed of :
1) Glomerular Capillaries
2) Mesangial Cells
Glomerular capillaries arise from ……………… and drain into ……………………..
Afferent arteriole , Efferent arteriole
Endothelium of Glomerular capillaries :
Fenestrated simple squamous epithelium; these fenestrae are numerous ,large and not closed by diaphragm
Define Mesangial Cells :
Contractile connective tissue cells that occupy the spaces between the glomerular capillaries AND help regulate glomerular filtration
Define Bowman’s capsule:
Epithelial Capsule that surrounds the glomerulus
Layers of Bowman’s Capsule :
Two layers :
Outer layer AND Inner layer
* Outer layer= Parietal layer
Simple squamous epithelium
- Inner layer = Visceral layer ( Envelops the glomerular capillaries )
Special cells called Podocytes
Between the two layers : Bowman’s Space ; urinary space where the fluid filtered through the capillary wall is recieved
Define Podocytes :
Modified simple squamous epithelial cells of visceral layer of Bowman’s capsule
Podocytes structure :
Each one has CELL BODY and PRIMARY PROCESSES , these processes give rise to SECONDARY PROCESSES which rises the PEDICLES , these Pedicles are separated by FILTERATION SLITS which are covered by FILTERATION-SLIT DIAPHRAGM…
Define blood renal barrier ?
Structures that separate blood in glomerular capillaries from the filterate in Bowman’s space
Renal blood barrier function ?
1)PERMITS the passage of water, ions and small molecules from the blood to bowman’s space
2)PREVENTS the passage of large molecules such as Blood cells and proteins
What are the structures involved in renal blood barrier ?
1) Fenestrated endothelium of blood capillaries
2) Glomerular basement membrane ( formed from both Podocytes and endothelial basement membrane )
3)Filteration slit
Compare btwn PCT and DCT :
Attached in tables app
Function of loop of Henle:
1) It connects PCT with DCT
2) it concentrates urine
Henle’s loop consists of :
1) Descending limb ( thick part which is similar structurally to PCT and thin part )
2) Ascending limb ( thick part which is similar structurally to DCT and thin part )
The thin segment of Henle loop is lined with …………………….
Squamous epithelial cells
Define connecting tubules :
Short segments between DCT and the beginning of cortical collecting ducts
Types of Collecting ducts :
Cortical , medullary and papillary ducts
Functions of collecting ducts :
1) CONDUCT urine
2) CONCENTRATE urine
Common characteristics btwn all Types of collecting ducts :
1) the lumen is relatively wide
2) they are lined with simple cuboidal epithelium
3) the cytoplasm contains few organelles
Define Papillary Collecting ducts ?
Ducts formed by the union of several medullary collecting ducts
Papillary Collecting ducts open into :
Area cribrosa of renal papilla
Define Medullary rays :
Medullary projections that enter the Cortex
Medullary rays components :
Single cortical collecting duct and the straight portions of several nephrons that drains into it
What is the renal lobe ?
Renal pyramid and the corresponding covering of the cortical tissue
What is the renal lobule ?
Group of nephrons that open into branches of the same collecting duct
Site of Juxtamedullary complex :
At the vascular Pole of the renal corpuscle , Where the DCT fits btwn afferent and efferent arteriole
Define Juxtamedullary complex :
Complex of vascular and tubular components of the nephron
Juxtamedullary complex components:
1) Macula dense
2) Juxtaglomerular cells
3) Extra-glomerular mesangial cells
Define Macula Densa :
Special type of cells that line of the DCT that facing the glomerulus
Histology of Histology of macular densa :
Closely packed columnar cells :
A.deeply stained packed nuclei
B.Numerous Microvilli
C.Thin basement membrane
D. They have cell processes, which extend through the lacking basement membrane towards the juxtaglomerular cells.
Macula densa is in direct contact with ……………… & ……………….. .
Juxtaglomerular cells , lacis cells
define JG cells :
Special modified smooth muscle cells that present in tunica media of afferent arteriole and few in efferent arteriole
JG cells function :
Secretion of renin
Cytoplasm of JG cells contain :
Large secretory granules ( formed from both renin secretion )
Effect of JG cells on the afferent arteriole?
Internal elastic lamina of the afferent arteriole is absent ; then these cells are in close contact with intima and blood in lumen
Define EG mesangial cells : Q
Group of cells present in the area between the afferent arteriole , efferent arteriole and macula densa
Extra-glomerular mesangial cells communicate with ……………. .
Intra-glomerular mesangial cells
Function of EG mesangial cells :
Support and coordination
Mention the general arrangement of blood vessels within the kidneys :
Renal artery > Segmental branch > interlobar artery > Arcuate artery > Interlobular artery > afferent arteriole > Glomerulus > efferent arteriole > peritubular network capillaries > Vasa recta > Interlobular veins > Arcuate veins > interlobar veins > single renal vein
Interlobar arteries way :
Run in interval , between the two adjacent pyramids toward the cortex
Arcuate arteries are located at ……………………………. .
Junction of Cortex and medulla
Afferent arterioles arises from :
Interlobular arteries
Peritubular network of capillaries surrounds :
Tubular parts of the nephron in the renal cortex
