The Nephron- structural and functional considerations Flashcards
list the components of the nephron
Renal corpuscles
PCT and DCT
Peritubular capillary network
Interstitium
Loops of henle
vasa recta
collecting ducts /papillary ducts
diagram on anki
filtration takes place in what structures in the nephron
bowmans capsule and glomerulus
the renal corpuscle is made up of what structures wihtin nephron
glomerulus + bowmans capsule
number of nephrons found in kidney varies between…
species
approx how many nephrons are found in the;
elephant
man
dog
cat
mouse
Elephant: approx.. 7 million per kidney
Man: approx.. 1 million per kidney
Dog : approx.. 0.5 million per kidney (adult 12 kg dog).
Cat: approx.. 200,000 per kidney (adult)
Mouse: approx..11,000 per kidney
do additional nephrons develop once kideny is fully deveoped?
no
name the functional roles of the nephron
Filtration
Reabsorption
Setting up concentration gradient
Secretion
Collecting duct- concentration of urine
function of parts of nephron is refelcted in… and influeced by what substances?
Function is reflected in histological structure
Function varies under influence of Aldosterone and ADH
which strcutures are found in the cortex region and which in the medulla region
on anki
where are the medullary rays located
in the cortex
what are the medullary rays comprised of
comprised of arrangemnts of renal corpuscles (central area) which are surrounded by straigh parts of proximal distal tubules and collecting tubules
function of the renal corpuscle
filtration barrier
type of epithelium in PCT and bowmans capsule
pct= simple cuboidal
bowmans= simple squamous
describe the formation of the renal corpuscle
glomerulus makes contact with bowmans capsule
glomerulus starts pushing inwards till the renal corpuscle is formed
diagram on anki
renal corpuscle terms;
-what is the term which describes the region where the glomerulus and bowmans capsule make contact?
-term describing outer surface layer of balloon formed
-term describing space between both other layers
-visceral layer
-parietal layer
-urinary space
term given to filtrate which ultimately forms the urin in the renal corpuscle
2 types of poles in renal corpuscle
urinary pole
Urinary & Vascular poles
what are the mesangial cells
-function
cells that sit in the convulutuions of other structures within renal corpuscle.
-produce a supporting matrix and togetehr with globelular basement membrane; phagocytose any debris retained by filtration barrier -like a hoover!
FILTRATION occuring in renal corpuscle resultsin…
removal of nitrogenous wastes (plus lots of good stuff too)
filtration is based on…
particle size and charge (-vely charged particles are repelled)
desrcibe what structures the filtrate passes into in renal corpuscle.
blood exits through…
passes into the urinary space and then on into the PCT (proximal convuluted tubule)
-through glomerulus via efferent arteriole
function of proximal convoluted tubule
reabsorption of around 70% of glomerular filtrate
what can be seen on a histological section when looking at PCT )proximal convoluted tubule)
what does PCT consist of
PCT forms part of the…
Abrupt change in epithelium at the ‘urinary pole ‘ of bowman’s capsule (simple squamous to cuboidal epithelium with ‘brush border’)
Microvilli can be seen
The proximal tubule consists of a convoluted part and a straight part
cortical labyrinth
what structures does the PCT contain within that allow for reabsorption to occur
microvilli, leaky intercellular junctions, inter-digitations in cell wall
2 types of cellular pathways that occur within PCT
trans-cellular pathways- passive and active
features of PCT in a H&E section
Basal nuclei (towards base of cell), microvillus (brush) border- pink-fluffy border, lack of cell boundaries.
name the structures found in a histological section of the medulla which make up the counter current multiplier system
- thin descending loop of henle (from PST)
- thin ascending loop (to DST)
- descending vasa recta (efferent arterioles)
- ascending vesa recta (similar to venules)
- Collecting duct- concentration of urine
what is the function of the juxtaglomerular cells
production of renin (also known as an angiotensinogenase)
juxtaglomerular cells store renin until they are told to release it
name the 3 cells found in the juxtaglomerular apparatus
juxtaglomerular cells
macula densa cells
Mesangial cells (Lacis cells)
function of the macula densa cells
Sense sodium chloride concentration in the lumen and stimulate the juxtaglomerular cells to synthesize and release renin into the bloodstream
-blood pressure regulation
function of the distal convoluted tubule (DCT)
-Re-absorption sodium, chloride, calcium and magnesium (actively)
-Tubular Secretion (H+, K+(aldosterone))
mai nhistological differences between DCT and PCT
-PCT has that fluffy brush border which is thr microvilli, DCT does not have this
-fewer DCT in number compared to PCT
-DCT have more lumen in the middle in general
-DCT much paler and more columnar than PCT
collecting ducts in kidney fuse to form what
large papillary ducts
