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Flashcards in Histology Deck (50):

What are the 3 main functions of the kidney

Maintain water and electrolyte homeostasis, body fluid osmolarity and acid-base balance
2. Excrete toxic metabolic waste products (mainly urea and creatinine)
3. Act as an endocrine gland, producing renin and erythropoietin


What covers the kidney

A thin but strong capsule of dense collagen fibres


What is the hilum

Site of entry of renal artery and exit of renal vein and ureter


What is the medulla divided into

medullary pyramids with apices (papillae) pointing toward the hilum ending on minor calyces


Where exactly does urine evolve from

The papillae


What does the renal column do

Anchors the cortex to the medulla and provides a convenient way for the vasculature to reach the cortex


What is the nephron composed of

renal corpuscle
renal tubules


What is the renal corpuscle

a know of blood vessels surrounded by a capsule (Bowman's)


How many nephrons are found within each human kidney

600,000-1million nephrons


What are podocytes

Specialised epithelium which lies on top of the glomerular capillaries


What separates the blood from the glomerular filtrate

Capillary endothelium and podocytes


What do the podocytes form

Filtration slits as the podocytes have interdigitating cell processes


What is found between the podocytes and capillary epithelium

thicker than usual basal lamina made up of GAGs


What produces the mesangium and what is it

Scattered mesangial cells produce
It is a connective tissue core


What are the functions of the mesangial cells

removal of debris


What type of cells line the Bowman's capsule

stratified squamous epithelium


Describe the walls of the renal capillaries

Fenestrated walls


What is the function of a Proximal convoluted tubule cell

Recapsures glucose, peptides, small proteins and many other items from the filtrate


What lines the proximal convoluted tubules

Stratified squamous epithelium


Describe the appearance of the Loop of Henle

Begins as a thin descending limb then changes direction like a hair pin and ascends before widening out and continue ascending


What is the main role of the loop of Henle

It creates a high osmotic pressure in the extracellular space of the medulla with salts and urea but does not actually change the volume of within the tubule


Describe the appearance of the thin limb of the loop of Henle

Thin, simple squamous lining in which the nuclei typically protrude into the lumen


Describe the appearance of the thick limb of the loop of Henle

Simple cuboidal epithelial cells with abundant mitochondria


What cells line the collecting ducts

Simple cuboidal


What tubule is the metabolically busiest cell in the Loop of Henle

Thick ascending limb


What is the Vasa Recta

Loops of blood vessels that dip down into the medulla from above and then climb back up to the cortex


Where are the distal convoluted tubules located

In the cortex


What lines the distal convoluted tubules

simple cuboidal epithelium


How are the structures of the proximal and distal convoluted tubules different

Distal lacks a brush border of extensive microvilli
Therefore they have a relatively smooth surface in comparison


What are the medullary rays

Parallel arrays of tubules that head towards the medulla from the cortex


What drugs are the collecting ducts responsive to
What do the drugs do

They can change the osmolarity of the filtrate passing through


What are the ducts of Bellini

Large excretory duct


What is the Juxtaglomerular Apparatus

The feedback unit for the nephron to allow the nephron to know what is going on and what is has produced


What 3 components is the Juxtaglomerular Apparatus made up of

Macula densa (sensory)
Juxtaglomerular cells (mostly afferent)
Extraglomerular mesangial cells


Describe the path of the distal convoluted tubule

It goes back towards its own renal corpuscle that forms part of its very own nephron


Where is the macula densa located and describe the appearance

on the side of the distal convoluted tubule nearest the afferent arteriole.
The cells are taller, crowded together and the nuclei are intensely stained


What is the function of the macula densa

Sensing ion composition in the DCT


What do the juxtaglomerular cells contain/ secrete



What type of cells are the juxtaglomerular cells

modified smooth muscle cells in wall of the afferent arteriole


Describe how urine moves from where it is produced to where it is released from the body

Produced in the renal papilla
Collected into the minor calyx
flows through major calyx, renal pelvis, ureter and then the bladder
Exits the body via the urethra on voiding


What are almost all of the conducting parts of the urinary tract lined by

a special epithelium called transitional epithelium or urothelium
It is stratified and found in 3-6 layers


What are the cells on the luminal surface called and why

umbrella cells
they are domed


Why does the epithelium have a special structure

the variability in thickness of cells represents different states of distension
The apical surface o the cells at the surface have a thickened membrane to provide a highly impermeable barrier


What lies below the epithelium in the the conducting parts of the renal system

Lamina propria and 2-3 layers of smooth muscle


Describe the flexibility of the umbrella cells

They can change their appearance at the apical membrane - they can form invaginations in the tough membrane to help products come into the cell. They increase or decrease surface area as required


Describe the histological differences between the proximal ureter and the distal ureter

A lot more smooth muscle distally compared to proximally
Less lamina propria (connective tissue in the distal ureter


What are the female urethras line with

transitional epithelium which trasition to stratified squamous near its termination


What is the male urethra lined with

Transitional epithelium.
Membranous urethra extends from the prostate to the bulb of the penis - here transitional epithelium changed to stratified columnar cells
What is the penile urethra line with


What is the penile urethra line with

stratified columnar epithelium which near the tip of the penis becomes stratified squamous


What is the prostate gland lined with

simple columnar secretory epithelium with a fibromuscular stroma