Lecture 29: The Nephrons Flashcards
What is a nephron?
A microscopic functional unit of the kidney
Approximately how many nephrons are there per kidney?
1 million
What are nephrons responsible for the formation of?
Urine
What are the 2 types of nephrons?
- Cortical nephrons
- Juxtamedullary nephrons
What % of nephrons are cortical nephrons?
85%
Where do cortical nephrons lie?
In the cortex
Where do Juxtamedullary nephrons extend?
Deep into the medulla
What are Juxtamedullary nephrons important for?
Formation of concentrated urine
What are the 3 functions of the nephron?
- Selectively filter blood
- Return to blood anything to be kept
- Carry waste away for expulsion
What is each nephron comprised of?
5
- Renal corpuscle
- Proximal convoluted tubule
- Nephron loop
- Distal convoluted tubule
- Collecting duct
What is each nephron associated with?
2
- A glomerulus
- Peritubular capillaries
What are glomerular capillaries specialised for?
Filtration
What are glomerular capillaries?
Thin walled single layer of fenestrated endothelial cells
What are glomerular capillaries fed/drained by?
Arterioles
What is tightly regulated around glomerular capillaries?
Blood pressure
What are peritubular capillaries specialised for?
Absorption
What do peritubular capillaries wrap around?
Renal tubules
What do peritubular capillaries receive blood from/via?
From the glomerulus via efferent arterioles
What do the peritubular capillaries receive reabsorbed filtrate from?
Nephron
Some non-filtered solutes that need to be excreted can pass from the peritubular capillaries to where?
Into the nephron
What are vasa recta?
Extensions of pertibular capillaries that follow nephron loops deep into the medulla
Where are vasa recta found?
Only with juxtamedullary nephrons
What are renal corpuscles?
A glomerulus enclosed by the glomerular capsule
The renal corpuscle is where what meet?
The capillary and nephron
The renal corpuscle is the site of what?
The filtration barrier
What is the glomerular capsule?
The first part of the nephron
What 2 layers make the glomerular capsule?
- Outer parietal layer
- Inner visceral layer
What is the parietal layer of the glomerular capsule made from?
Simple squamous cells
What is the visceral layer of the glomerular capsule made from?
Podocytes
What is between the outer parietal layer and the inner visceral layer of the glomerular capsule?
Capsular space
What does the capsular space receive?
Filtrate
What do podocytes surround?
The glomerular capillaries