Renal Anatomy 2: The Nephron Flashcards
This is the microscopic functional unit of the kidney and is responsible for urine formation.
Nephron
What are the 2 types of nephrons?
Cortical and juxtamedullary nephrons
These nephrons make up most of the nephrons and lie mainly in the cortex.
Cortical nephrons
These nephrons extend deep into the medulla. It is important for the formation of concentrated urine.
Juxtamedullary nephrons
Each nephron is comprised of what 3 structures?
Glomerular capsule, renal tubules (PCT and DCT) and collecting duct
Each nephron is associated with what 2 structures?
Glomerulus and peritubular capillaries
These are specialised for filtration. It is fed and drained by arterioles. Blood pressure is also tightly regulated here.
Glomerular capillaries
These are specialised for absorption and reabsorption. It receives filtered blood from the glomerular capillaries (via efferent arterioles) and reabsorbed filtrate from the nephron.
Peritubular capillaries
These are extensions that follow the nephron loops deep into the medulla. Thee are only found in juxtamedullary nephrons.
Vasa recta
This is the term for when a glomerulus is enclosed by a glomerular capsule. It is the site of filtration barrier.
Renal corpuscle
Where is the site of the filtration barrier?
Renal corpuscle - where nephron and capillary meet
This is the first part of a nephron and is responsible for receiving filtrate.
Capsular space
What are the 2 layers of epithelia in the glomerular capsule?
Inner visceral layer of podocytes
Outer parietal layer of simple squamous epithelium
This is the specific place in the glomerular capsule that receives the filtrate.
Capsular space
These are specialised epithelia that surround the glomerular capillaries.
Additional question:
Its branches form intertwining foot processes known as _________.
Podocytes; pedicels
These form in between pedicels and is where filtered blood passes through into the capsular space.
Filtration slits
This lies between the blood and capsular space. It allows free passage of water and small molecules, but restricts passage of most proteins.
Filtration barrier/blood-urine barrier
True or false. RBCs are filtered into the nephron.
False. They’re proteins - and too big to be filtered into the nephron.
What are the 3 layers of the filtration barrier?
Fenestrated endothelium of glomerular capillary
Fused basement membrane
Filtration slits
What kind of endothelium lines the glomerular capillary?
Fenestrated epithelium (simple squamous)
This renal tube is responsible for the bulk reabsorption of substances from the nephron. It is surrounded by peritubular capillaries.
Proximal convoluted tube
The proximal convoluted tube has what kind of epithelium?
Cuboidal epithelial cells, but leaky and has microvilli
Why does proximal convoluted tube have a lot of mitochondria?
Because ATP is needed to carryout lots of reabsorption (active transport)
What are the 3 main structures found in the proximal convoluted tube?
- cuboidal epithelium
- dense microvilli (brushborder enzymes)
- highly folded basolateral membrane (for high SA)
This is surrounded by vasa recta and is responsible for dipping down into the medulla. (absorption and reabsorption of different substances is reflected by changes in epithelium)
Nephron loop
This renal tube is responsible for fine tuning of reabsorption using hormones like aldosterone. It is made of cuboidal epithelium but has no brush border and has fewer mitochondria.
Distal convoluted tube
This is where the filtrate from several DCTs drains into.
Collecting ducts
What are the 2 cells found in the collecting duct? What are their functions?
Principal cells - reabsorption
Intercalated cells - acid/base balance
The reabsorption at this structure is influenced by both aldosterone and ADH.
Collecting duct
What kind of epithelium is in the distal convoluted tube?
Simple cuboidal epithelium
In histology, how do you distinguish between the proximal convoluted tube and the distal convoluted tube?
PCT = has a fuzzy lumen (due to microvilli brush border)
DCT = has a clear lumen (because no microvilli)
What type of epithelial cells would you find in the nephron loop?
- nephron loop is composed of PCT and DCT
PCT => simple cuboidal epithelia with microvilli brush border & lots of mitochondria
DCT => simple cuboidal with no microvilli brush border & no mitochondria
Ascending and descending limb of nephron loop => simple squamous epithelium
