the amazing nephron workshop Flashcards
what is the functional unit of the kidney
the nephron
how many nephrons are in the canine kidney
400,000 - 600,000
in basic terms (in/out) what does the nephron do
filter plasma and produce urine
can the body regenerate nephrons
no - damages due to normal ageing loss, renal injury or renal disease
the medulla is composed of
entirely of straight tubules - appears striated in transverse section
what are the classifications of nephrons
by their location of their glomeruli in the cortex:
- superficial (near the capsule)
- cortical
- juxtamedullary (near medulla)
the cortex of the kidney is made up of
glomeruli as well as straight and convoluted tubule segments
what are juxtamedullary nephrons
long and due to this are adapted to resorb a lot of water back into the blood. this is really useful in animals that need to minimise the amount of water that they lose in urine
the ability to produce very concentrated urine is associated with
a greater percentage of juxtamedullary nephrons
a filtrate is formed when:
blood passes through the glomerulus which acts like a sieve
outline the journey of blood through the kidney to make urine
- glomerulus
- proximal convoluted tubule
- loop of henle
- distal convoluted tubule
- collecting duct
what is the function of the tubular components of the nephron
adjust the make up of the urine by moving things in or out
the renal corpuscle is made up of
made up of a ball of capillaries (glomerulus) where blood flows in and is filtered towards a double walled capsule (bowmans capsule)
what structures are included in the nephron
- glomerulus
- bowmans capsule
- efferent and afferent arterioles
- proximal convoluted and straight tubule
- loop of henle
- distal convoluted tubule
what is the venous supply/drainage of the glomerulus
The glomerulus is formed by an afferent arteriole that divides into looping capillaries in a ball, which then join back up on the opposite side to make the efferent arteriole carrying the blood away. Intraglomerular mesangial cells and matrix occupy the spaces between capillary loops within the glomerulus.
The arterioles (afferent and efferent) enter and exit at one end of the ball of the glomerulus (the “vascular pole”) and the ultrafiltrate is created and enters the Bowman’s capsule at the other end (the ‘urinary pole”).
what happens to blood entering the glomerulus through the afferent arteriole
pushed through the walls of the glomerular capillaries with a filtration effect towards bowmans capsule. the capsule is cup shaed with inner and outer laters separated by a cavity (urinary space)
the renal filter is made up of
- Endothelial cells of the glomerulus
Endothelial cells have large fenestrations (pores) which allow many products to pass through. However, a lot of the material that makes up the pores is negatively charged and so there is a charge-barrier as well as a physical space restriction when passing through.
Blood cells and most proteins are too large to pass through this layer. - Glomerular Basement Membrane (GBM)
This is the main filtration barrier to cells and large molecules. It is also negatively charged. - Podocytes of the visceral layer of Bowman’s capsule
The podocyte projections don’t completely cover the GBM as there are some gaps. They therefore make a discontinuous layer on the urinary space side of the GBM.
The spaces between the foot projections are called filtration slits. Filtration of smaller molecules is blocked by the presence of a thin negatively charged membrane within the filtration slits.
passage through the renal filter is dependent on
molecular size and charge
Blood cells and most proteins are stopped at the endothelial fenestrations and negatively charged macromolecules are repelled by the negatively charged components of all layers of the filter.
which is wider: the afferent of efferent arteriole
afferent, but both are regulated to maintain GFR