Lecture 28: THE NEPHRON Flashcards
How many nephrons per kidney?
Approximately 1 million
What is the nephron responsible for?
Urine formation
What are the two types of nephrons?
Cortical and juxtamedullary
What portion of nephrons are cortical?
85%
Where are cortical nephrons found?
Lie mainly in the cortex
Where are juxtamedullary nephrons found?
Extend deep into the medulla
What are juxtamedullary nephrons important for?
The formation of concentrated urine
What are the functions of the nephron and its associated structures?
Selectively filter blood, return to blood anything to be kept and carry waste away for storage and expulsion
What is each nephron comprised of?
A glomerular capsule, renal tubules and a collecting duct
What is each nephron associated with?
A glomerulus and peritubular capillaries
What are glomerular capillaries specialised for?
Filtration
What is the structure of glomerular capillaries?
Thin walled single layer of fenestrated endothelial cells
What are glomerular capillaries fed and drained by?
Arterioles
What is tightly regulated at the glomerular capillaries?
Blood pressure
What are peritubular capillaries specialised for?
Absoprtion
Where are peritubular capillaries found?
Wrapped around the renal tubules (proximal and distal)
What do the peritubular capillaries receive?
Filtered blood from the glomerulus via efferent arterioles
What can pass from the peritubular capillaries into the nephron?
Some non-filtered solutes that need to be excreted
What are vasa recta?
Extensions that follow the nephron loop deep into the medulla
Where are vasa recta found?
Only with juxtamedullary nephrons
What is the renal corpuscle?
The glomerulus enclosed by the glomerular capsule
What meets at the renal corpuscle?
The capillary and nephron
What is the renal corpuscle the site of?
The filtration barrier
What is the first part of the nephron?
The glomerular capsule
How many layers of the glomerular capsule?
Two
What is the layers of the glomerular capsule?
Outer parietal layer of simple squamous cells and inner visceral layer of podocytes
What is between the layers of the glomerular capsule?
The capsular space which receives the filtrate (primary urine)
Where are podocytes found?
Surrounding the glomerular capillaries
What is the structure of podocytes?
very branched, very specialised epithelium
What do the branches of podocytes form?
Intertwining foot processes called pedicels