Histology of the renal system Flashcards
what does the urinary system consist of
2 kidneys
2 ureters
bladder
urethra
pathway of urinary system
urine produced in kidneys
flows down utters to bladder where it is stored
until voided by urethra
which parts of urinary tract are retroperitoneal
kidneys
ureters
where is urinary bladder located
anterior part of the pelvis
blood supply to the kidney
renal arteries
arise from the aorta
venous drainage of kidney
renal veins
to the inferior vena cava
kidney filtration rate
filter the entire blood supply of the individual every 5 minutes
urine formation rate
1mL urine per minute
what is removed from blood for urine formation
urea
other toxins
what is conserved in the blood in urine production
water
salts
glucose
proteins
kidney anatomy
retroperitoneal organ
covered by thin fibrous capsule
outer renal cortex (darker)
and inner renal medulla
concave medial border (hilum) for structures entering and exiting
10-12 cm
location of the kidney
between T12 and L3
where do nephrons arise form in kidney
cortex
loop down the medulla and return to the cortex
ten drain into the collecting ducts
descend again into the medulla to discharge urine from apex of medullary pyramid
medullary pyramid
cone shaped
renal papilla
apical part of the medullary pyramid
enveloped by funnel shaped pelvis
represents the dilated proximal part of ureter
surrounded by branch of renal pelvis called calyx
how many lobes in kidney
10-18
how many lobes in kidney
w10-18
how many lobes in kidney
w10-18
what is the whole urinary collecting system in the kidney described as
pelvicalyceal system
renal sinus
space between branches of pelvvicalyceal system
filled with fatty supporting tissue
what is the kidney covered in
capsule
thick layer of perinephric fat
to protect against trauma
major calyx
minor calyx collects urine from papilla
they join in renal sinus to form major calyx
that then forms Renal pelvis
functions of the kidney
regulation of balance between water and electrolytes and the acid base balance
excretion of metabolic wastes with excess water and electrolytes in the urine
excretion of many bioactive substances including many drugs
secretion of renin, for blood pressure regulation
secretion of erythropoietin, stimulating erythrocyte production in red marrow when blood o2 level is low
conversion of steroid pro hormone vitamin D initially produced in the skin to active form calcitriol
what is the basic functional unit of the kidney
urineferous tubule
composition of urineferous tubule
nephron and collecting tubule
divisions of the nephron
renal corpuscle
proximal tubule
loop of hence
distal tubule
connecting tubule
renal corpuscle
initial dilated part comprised of capsule of bowman and glomerulus
always in the cortex
proximal tube
long convoluted part
located in the cortex
shorter straight part that enters the medulla
loop of henle
in the medulla
thin descending and thin and thick ascending
distal tubule
consisting of thick straight part ascending rom the loop of henle
back into the Cortex
convoluted part completely in the cortex
connecting tubule
short minor part
linking nephron to collecting ducts
reabsorption of water takes place
label the functional unit of the kidney
uniniferous tubule
nephron and collecting tubule/duct
cell type proximal convoluted tubule
simple cuboidal
with microvilli
cell type distal convoluted tubule
simple cuboidal
wider lumen
no microvilli
thick loop cell type
simple cuboidal
thin loop cell type
simple squamous
collecting tubule cell type
simple cuboidal to columnar
2 types of nephrons
cortical
juxtamedullary
cortical nephrons
upper cortex of the kidney
juxtamedullary cortex
near the junction of the cortex and medullar of the kidney
have long loops of henle
what is renal corpuscle composed of
glomerular capillaries and Bowmans capsule
image of renal corpuscle
what are podocytes
modified epithelial cells
assist in filtration
what is the glomerular filter
filtration barrier (between blood in glomerular capillary and space of Bowmans capsule)
3 parts of the glomerular filter
fenestrated endothelium of glomerular capillary
thick fused basal laminae of podocytes (visceral layer of BC) and glomerular endothelial cells (restrict large proteins)
slit diaphragms between pedicles of visceral layer of epithelium to restrict small proteins
image of the glomerular filter
when is filtrate produced in the corpuscle
when blood plasma is forced under pressure
through capillary fenestrations
across filtration membrane or GBM surrounding the capillary
through filtration slit diaphragms located between podocyte pedicles
glomerular filtration barrier, specialisation
displays high conductance to small and midsized solutes in plasma
retains relative impermeabiliy oto macromolecules
label the image, what is it
renal corpuscle
PCT – Stained darker than DCT
Lumen of DCT is wider than PCT
Nucleus is more prominent in DCT than PCT
CD – cells are more columnar than DCT and PCT (cuboidal)
Water reabsorption takes place in CD under the influence of ADH
ADH action in distal convoluted tubule
secreted by posterior pituitary
acts on last part of DCT
increase permeability of the tubule
permits absorption of water to produce more concentrated urine
in permanent absence of ADH
vast quantities of diet urine are formed
because of failure of water reabsorption in DCT and collecting ducts
renal corpuscle summary
PL – parietal layer of BC
CS – capsular space
G - Glomerulus
Visceral layer of BC you can’t see. Why?
Between PCT and DCT, which one has wider lumen?
MD – macula densa
juxtaglomerular apparatus
located at the vascular pole
where you have afferent and efferent arterioles
have macula dense cells and juxtaglomerular cells
macula densa cells
chemoreceptors
Cluster of modified cells in the wall of DCT adjacent to the juxtaglomerular cells. They monitor sodium concentration.
juxtaglomerular cells
Modified smooth muscle cells in wall of an afferent arteriole. They release renin to regulate blood pressure.
mesangial cells
remove trapped residues and aggregated protein from the basement membrane thus keeping the filter free of debris.
2 groups of mesangial cells
smooth muscle origin
extraglomerular mesangial cells
pericyte-like intraglomerular mesangial cells
Extraglomerular mesangial cells
located at vascular pole
pericyte-like intraglomerular mesangial cells
within the renal corpuscle
blood pressure regulation is controlled by what
RAAS system
RAAS system
juxtaglomerular apparatus
specialisation of glomerular afferent arteriole and distal convoluted tubule of same nephron
involved in RAAS
made up of:
1. macula densa
2. juxtaglomerular cells of AA
3. extraglomerular mesangial cells (help remove debris)
what are cells of macula densa sensitive to
concentration of sodium ions in fluid in DCT
decrease in systemic blood pressure results in decreased production of glomerular filtrate and hence decreased concentration of sodium ions in distal tubular fluid
label the Renal cortex
P – PCT
D – DCT
G – Glomerulus
U – Urinary space/capsular
TP – Tubular pole
why do simple cuboidal cells of distal tubules differ from proximal tubules
smaller
no brush border
more empty lumens
flatter
more nucleus typically seen in sections of distal than proximal
what is in the image and label
medulla
HT – Thick Loop of Henle
HL – Think Loop of Henle
IC – Interstitial cells
CD – Collecting duct
VR – Vasa recta
direction of tubules, ducts and vessels in medulla
towards papillary tip
what is in the image and label
lumen of ureter
longitudinal mucosal folds
formed by lmucusla contractions
wall of ureter
mucosa
muscularis
adventitia
ureter mucosa
transitional epithelium
wide lamina propria
layers of transitional epithelium in ureter
outermost is characterised by large cuboidal cells
intermediate cells are polyhedral in shape
basal cells are low columnar or cuboidal
lamina propria ureter
fibroelastic connective tissue denser
more fibroblasts under epithelium
looser nearer muscularis
muscular layers in upper ureter
inner longitudinal smooth muscle layer
middle circular smooth muscle layers
not always distinct
muscular layers in lower ureter
inner longitudinal smooth muscle layer
middle circular smooth muscle layers
additional third outer longitudinal layer of smooth muscle
what are the ureters
muscular tubes that carry irine form the kidneys to the bladder
urinary bladder
in bladder what does the interstitial connective tissue merge with
connective tissue of serosa
what lines the surface of the bladder
serosa for superior surface
adventitia for inferior surface which merges with connective tissue of adjacent structures
mucosa of empty bladder
mucosal folds
disappear during bladder distention
what is mesothelium
highly specialised epithelia that protects underlying tissues from mechanism stress and seal them from overlying fluid space
urinary bladder
superficial are low cuboidal or columnar, appear dome shaped
some may be binucleate
outer plasma membrane is prominent
deeper cells are round
basal cells more columnar
superficial LP contains connective tissue fibers, numeros fibroblasts and blood vessels
renal tubule summary
how do you differentiate from collecting tubular and loop of henle
medulla displays simple cuboidal of Ct
simple squamous of HL
endothelial cells of vasa recta
label image
