Histology Flashcards
Medulla has no what
renal corpuscles
how are tubules oriented
Tubules are orientated radially, pointing from the cortex to the medulla
Whats in the medulla
There are no glomeruli in the medulla - just tubes & blood vessels
What tubular structures are in the medulla
Tubular structures; tubules of the loop of henle (A), tubules of the collecting duct (CT) & blood vessels
What happens in the pelvis
The space that urine drains into - its continuous with the collecting ductsproximallyand the uretersdistally
What is the pelvis lined by
Lined by transitional epithelium (the same that is in the bladder)
What points into the renal pelvis
The tips of the medullary pyramids project into the renal pelvis - at this point the pyramids are composed purely of collecting ducts
Cells of the glomerulus
Most of the cells that can be seen are mesangial cells and capillary endothelial cells
What stain to distinguish mesangial cells
periodic acid shift (PAS)
How does PAS distinguish mesangial cells
PAS stains glycoproteins in the glomerulus basement membrane - highlighting capillaries and allowing you to see the mesangial cells in-between
What are the 3main functions of the mesangial cell’s smooth muscle
- Structural support for the capillary and production of extracellular matrix protein
- Contraction of these muscles in the glomerulus tightens the capillaries and reduces the glomerular filtration rate (GFR) - this is important in tubuloglomerular feedback - where chemical changes in the tubules feedback to alter the GFR
- Involved in the phagocytosis of the glomerular filtration membrane breakdown products
2 components of the juxtaglomerular apparatus
afferent arteriole & distal convoluted tubule
Endothelium f the afferent arteriole
The endothelium of the afferent arteriole is expanded to form a mass of cells called GRANULAR CELLS which are able to DETECT BLOOD PRESSURE and secrete renin in response to a reduction in blood pressure
Epithelium of proximal convoluted tubule
CUBOIDAL EPITHELIUM
Why does the surface of the proximal convoluted tubule look fuzzy
Cells have microvilli that increase the surface area of the cell - why the surface looks FUZZY
why do the cells of the proximal convoluted tubule have lots of mitochondria
The cells of the proximal convoluted tubule have lots of mitochondria because they actively transportions from the glomerular filtrate including TWO THIRDS of the sodium & potassium
what does PCT reabsorb
NaCl, proteins, polypeptides, amino acids & glucose
These of the PCT cells also absorb the small protein molecules that got through the glomerulus
What do the lysosomes of the PCT do
Lysosomes are present which are involved in the degradation of small protein molecules that are reabsorbed from the urinary space
NOTE: there are more lysosomes in the proximal convoluted tubule that in the distal
What do the lysosomes of the PCT do
black dots
Thin segment of loop of henle`
simple squamous
Thick segment of loop of henle
low cuboidal
what supplies the loop of the henle
rich vasa recta
What passes out of the thin descending limb
Water but NOTionspassivelyflow out of the thin descending limb into the high osmolarity interstitium - thereby concentrating the urine
The ions the body wants back are then actively pumped out of the ascending limb - leaving water & waste products
how is the distal convoluted tubule recognised
Can be recognised since its cells DO NOT HAVE MICROVILLI meaning no “fuzzy” brush border is present
what do you see when you look at the cortex
-Much shorter than the proximal convoluted tubule - meaning when you look at a section of cortex you can see much more of the proximal convoluted tubule
What are the cells of the DCT like
Cells are CUBOIDAL and contain mitochondria
Epithelium of the Collecting duct
CUBOIDAL
Two cell types of the collecting duct
Principle cells and intercalated cells
Function of principle cells of the collecting duct
respond to aldosterone (exchanging Na+ for K+) & ADH(increasing water reabsorption by the insertion of Aquaporin-2
Function of aquaporin 2 of the collecting duct
(membrane channel for water reabsorption in the collecting duct) into the apical membrane of the cell)
A mutation in the aquaporin 2 gene can cause what
a mutation in the aquaporin 2 gene can cause diabetes insipidus
Function of intercalated cells of the collecting duct
responsible for exchangingacid FOR base (both ways)-
Alpha intercalated cells secrete ACID
Beta intercalated cells secrete BICARBONATE
Which intercalated cells secrete what
Alpha intercalated cells secrete ACID
Beta intercalated cells secrete BICARBONATE
How are the intercalated cells recognised
Can be recognised since they have a plumper epithelium that the loop of henle witha round central nuclei
What epithelium lines the renal pelvis, what is this able to do
TRANSITIONAL EPITHELIUM (urothelium) -
multilayered/stratified epithelium
that is able to stretch in three dimensions meaning that the volume of the cells stay the same but the thickness and area they cover changes
what is transition; epithelium called
urothelium
how thick is urothelium
around 5 cells thick
How does the urothelium change according to the bladders movements
Can change shape & stretch - it can become more flat as the bladder distends or more cuboidal as the bladder empties
What do the layers of (bladder) urothelium consist of
The surface layer consists of large dome-shaped UMBRELLA CELLS - large and cover several underlying intermediate cells - they have TIGHT JUNCTIONS (zona occludens) at their surface
- to prevent urine getting in-between cells,
to keep apical membrane components from diffusing to the lateral aspect of the cell & to prevent material diffusing around the cell
The basal layer consists of CUBOIDAL CELLS
Why do the cells of the (bladder) urothelium have tight junctions
to prevent urine getting in-between cells,
to keep apical membrane components from diffusing to the lateral aspect of the cell & to prevent material diffusing around the cell
What does the basal layer of (bladder) urothelium consist of
The basal layer consists of CUBOIDAL CELLS
How many layers of bladder epithelium are there and what are they
There are three layers to the bladder epithelium; surface layer, intermediate layer & basal layer
What lines the ureters
transitional epithelium
What is the ureter made of
how does this differ ti the GI tract
Spiral muscular tube; inner:longitudinal & outer:circular
NOTE: in the GI tract the inner layer is circular and the outer layer is longitudinal - OPPOSITE IN URETERS
Do ureters have serosa
NO
What other type of tissues is there
loose adventitia
5 layers of the transitional epithelium of the bladder
Layers: •Lamina propria •Muscularis mucosa •Submucosa •Muscularis propria •Subserosa & serosa
Why does the bladder have a functional valve
prevents reflux into the ureter
What are the 2 sphincters of the the urethra and what are they made up of
- Internal sphincter: smooth muscle from the bladder
- External sphincter: skeletal musclefrom the pelvic floor
how long is the female urethra
4-5cm
What lines the female urethra proximally and distally
Proximallytransitional epithelium
•Distallysquamous epithelium
how long is the male urethra
20 cm
What is the male urethra made up of and what lines it
3 parts:
- Prostatic urethra
- Membranous urethra (transitional epithelium)
- Penile urethra (pseudostratified epithelium proximally & stratifiedsquamous epithelium distally)