Histology Flashcards
Describe an average kidney
bean shaped organ
Approximately 10-12cm long
5-6cm wide
What types of fibres make up the renal capsule?
Collagen
What is the functional unit of the kidney?
The nephron
How many nephron are present per medullary pyramid?
50,000
What is the average length of a nephron?
45-65mm
How long would all of the nephron in your body be when added together end to end?
60km (slightly more than Dundee to Edinburgh apparently…)
What is the renal corpuscle?
A tuft of capillaries called the glomerulus and a cup of simple squamous epithelium called the bowman’s capsule
Which is larger the afferent or efferent arteriole in the renal corpuscle?
The afferent - bottle necks and produces an increased pressure for filtration.
What two layers separate the blood and glomerular filtrate?
the capillary endothelium
the podocytes
The endothelium is fenestrated with pores approximately ______ in diameter.
70-90nm in diameter
the podocytes have interdigitating cell processes that form pores approximately ____in diameter
25nm
the basal lamina between the podocytes and the endothelium is thicker/thinner than usual by ____x; approximately ______microns
The basal lamina between the podocytes and endothelium is thicker than usual by 6x; approximately 0.3microns (as opposed to 0.05microns).
Scatter cells which produce connective tissue for support and debris removal is called the ______
Mesangial cells (form the mesangium)
How much more urinary filtrate is produced than urine?
120x.
What cells make up the proximal convoluted tubule?
Simple cuboidal epithelium with a microvilli brush border at the apical membrane
The cells of the proximal convoluted tubule are very busy/not very busy cells and so have many/few mitochondria
Very busy
Many mitochondria
Glucose and protein is filtered out of the blood and then reclaimed in the proximal tubule - true/false
True for glucose
not true for all proteins just small ones
The glomerulus and proximal tubule lie in the medulla - true/false
false - they lie in the cortex.
The loop of henlé lies in the medulla - true/false
true
the loop of henlé is made up of what type(s) of cells?
descending - simple squamous epithelium with nuclei projecting into the lumen
Ascending - cuboidal epithelium
the ascending limb of the loop of henlé has many/few mitochondria
Many
What is the purpose of the loop of henlé?
It establishes a large solute gradient and allows a large osmotic pressure to be maintained in the medulla.
Where do the vasa recta run?
The vasa recta run from the cortex and dive into the medulla before turning on a hairpin and exiting again.
Why is the course of the vasa recta important?
If it penetrated deeper it would have water drawn out and dilute the solute potential in the medulla.
After the loop of henlé is the ______ which is made of _____________ epithelium. How does this compare to its proximal counterpart?
Distal convoluted tubule made up of stratified squamous epithelium. like the proximal tubule it is highly metabolically active and has lots of mitochondria but very few microvilla.
What cells line the collecting tubules and collecting ducts?
Simple columnar epithelium.
What is the juxtaglomerular apparatus?
specialized tissue where the distal tubule passes adjacent to the vascular pole of its own renal corpuscle.
Three parts of the of the juxtaglomerular apparatus are the ______, _______ & ________.
Macula densa
Juxtaglomerular cells
Extraglomerular mesangial cells
What is the macula densa?
DCT cells are taller, crowded together and with incredibly staining nuclei on the side closest to the arteriole.
What is the function of the macula densa
Unsure but believed to be sensing ionic concentrations
What are the juxtaglomerular cells?
Modified smooth muscle cells in the walls of the afferent arteriole which secrete/contain renin.
What is the extraglomerular mesangial cell?
A modified mesangial cell type that extends outside the corpuscle. its exact purpose is unknown.
What epithelium lines almost all of the conducting pathway for urine?
Urothelium AKA transitional epithelium.
Urothelium is stratified - true/false
True
Urothelium is found in 8 layers - true/false
False - found in 3-6 layers
What are umbrella cells?
they are domed cells that lie at the surface of the urothelium and are so called because of their shape.
What lies below the urothelium?
A thickened membrane to provide a complete impermeability.
What is distal to the membrane which lies below the urothelium?
Lamina propria and 2-3 layers of smooth muscle.
Length of an average female urethra =
Length of an average male urethra =
3-5cm
20-21cm
what lines the female urethra?
Transitional epithelium
Changes to simple stratified near its termination
What parts are there to the male urethra? What lines each of them?
Prostatic - transitional epithelium
Membranous - stratified columnar epithelium
Penile - stratified columnar epithelium then changes near its termination to simple stratified.
the prostate is formed from…?
Tubule-alveolar glands
The prostate is lined by _______
simple columnar secretory epithelium with fibromuscular stroma.
What percent of seminal fluid volume is made of the prostatic secretions?
~50%
