Lecture 9: Renal Histology Flashcards
What is a glomerulus?
Tuft of capillaries
- afferent arteriole feeds into it
- efferent arteriole drains it
What are the two type of peritubular capillaries?
Cortical: surrounds proximal and distal convoluted tubules Long medullary (vasa recta): surrounds loop of Henle
What type of endothelium is found in the cortical peritubular capillary?
Fenestrated endothelium
What type of endothelium is found in the long medullary peritubular capillary?
Ascending: Fenestrated
Descending: Continuous
What is a renal corpuscle?
Blood filtering component of nephron
- Glomerulus (capillaries)
- Bowman’s capsule
What is the composition of Bowman’s capsule?
Visceral: layer of podocytes that cover capillaries
Glomerular space: primary filtrate
Parietal layer: simple squamous EPIthelium
Is the vascular pole of renal corpuscles endothelium or epithelium?
Endothelium
Is the urinary pole of renal corpuscles endothelium or epithelium?
Epithelium (origin of proximal convoluted tubule)
Describe mesangial cells.
- Provide structural support for capillaries/glomerulus and ECM of podocytes
- Prevent glomerular distension due to high glomerular BP
- Phagocytic cells
- Secrete growth factors and cytokines in response to injury
Describe the glomerular endothelium.
- Open fenestrations
- Thick luminal glycocalyx
- Large number of aquaporins
- Can promote vasodilation by generation NO and prostaglandins
What does the glomerular basement membrane do?
Barrier against large particles (e.g. RBC) and prevents proteins from crossing (anti-anionic)
What are podocytes?
- Visceral layer of Bowman’s capsule
- Make filtration like slits
What layers do filtrates have to cross to reach Bowman’s capsule from the capillaries?
1) Capillary endothelium
2) Basement membrane
3) Podocytes
What particles do the filtration membrane allow?
Water Ions Glucose Amino Acids Urea
*no blood or protein
What type of cells make up the parietal layer of Bowman’s capsule?
Simple squamous epithelium
Describe the histology of proximal convoluted tubule.
- Simple cuboidal to columnar epithelium
- Basal and lateral cell membranes are highly folded
- Many microvilli (brush border)
Describe the histology of the thin limb of the Loop of Henle.
- Permeable simple squamous epithelial wall
- No brush border
Describe the histology of the thick limb of the Loop of Henle.
- Simple cuboidal epithelium
- Many microvilli but no brush border
Describe the histology of distal convoluted tubule.
- Simple cuboidal epithelium
- Sparse microvilli
- Smooth luminal surface
What is the juxtaglomerular apparatus?
Specialized structure formed by the distal convoluted tubule and the glomerular afferent arteriole
What is the function of the juxtaglomerular apparatus?
Regulate blood pressure and the filtration rate of the glomerulus
-secretes renin if low BP
What is the macula densa?
Tight nuclei at distal end of thick loop of Henle near vascular pole
-monitors sodium levels and signals release of renin if low sodium levels
What type of cells are found in collecting tubules and ducts?
Principal cells: aldosterone target
Intercalated cells: involved in hydrogen and bicarbonate transport
Describe the histology of collecting ducts.
Simple cuboidal and simple columnar
