Lecture 1: Renal histology Flashcards
What are the functions of the kidneys?
- Filter blood to remove waste as urine
- Regulate salt, water and acid base balance
- Regulate blood pressure
- Produce enzymes/hormones
Parts of a nephron?
- Renal corpuscle
- PCT
- Proximal straight tubule
- Thin decscending limb
- Thin ascending limb
- Thich ascending limb
- DCT
- Connecting tubule
- Collecting duct
What are the features of a renal corpuscle?
- Contains capillary tuft
- Podocytes surround capillaries - they envelope them
- Parietal epithelial cells form outside of the corpuscle
- Outside of podocytes is urinary space which drains into proximal tubule
What are the layers of the glomerular filtartion barrier?
- Fenestrated capillary with negatively charged glyococaylx along surface of holes
- Basement membrane made up from collagen and negatively charged proteoglycans
- Podocytes form slit diaphragm between secondary foot processes which is also covered in glycocaylx
What do the mesangial cells do wand where are they found?
- They are SM cells packed into capillary tuft that maintain tuft shape:
- They have supportive and contractile role
- They secrete ECM
When does glomerularsclerosis occur?
- When mesangial cells over produce ECM which –> scarring
What are the constituants of the juxtaglomerular apparatus and what does it do?
- Comprised of :
- JG cells: specialised smooth muscle cells in the afferent arterioles
- Macula densa cells: specialised cells in wall of TAL which detect salt conc.
- Extraglomerular mesangial cells
- Major functions are inducing afferent arteriole vasoconstriction of TAL [NaCl] is high, and inducing renin release from JG cells if [NaCl] is low.
What are the features of proximal tubule cells?
What are their functions?
- Cuboidal epithelium
- Microvilli on apical surface (increase SA on apical surface)
- Lateral processes and infoldings on basolateral surface which (Increase SA on basal surafce)
- Function to bulk reabsorb
- Diffusion
- Pinocytosis
What are the features of thin limb cells and what are their functions?
- Thin squamous epithelium
- Nuclei buldge in lumen
- Role in water reabsorption
What are the features of TAL & distal tubule cells and what are their functions?
- Cubodial cells
- Basolateral processes
- Short microvilli
- Functions:
- Fine tuning of salt, pH and urine conc
- Dont do pinocytosis
Features & functions of cells of collecting duct cells?
- Cuboidal –> columnar epithelium
- Final modifiers of water, salt, and pH of the urine
What are the features of a kidney lobe?
- Defined by lobular arteries
- Cortex made up of lobules and contains renal corpuscles and portions of the PCT and DCT
- Medulla makes a cone/pyramid and contains collecting ducts and loops of henle
What are the histological features of a kidney lobule?
- Defined by interlobular Blood vessels
- Centre is medullary ray (which can be seen in cross section in the cortext)
- All of the straight portions of the nephrons in that region (straight sections of PCT, DCT and collecting duct
- Either side of medullary rays are convoluted tubes and renal corpuscles
What are the blood vessels within the kidney?
- Renal artery –> interlobar vessels –> arcuate arteries at base (nearest to cortext) of pyramid as arteries curve over –> send off branching interlobular arteries: (2 paths)
- –> afferent arterioles of corpuscles in cortex –> efferent –> peritubular capillaries –> interlobular vein –> arcuate vein –> interlobar vein
- –> afferent arterioles of corpuscels in medulla –> efferent –> aterial vasa recta (track with LoH) –> venous vasa recta –> arcuate vein –> interlobar vein
What are the histological feartures of the ureter and bladder?
- Transition epithelium allowing expansion
- Mucous membrane
- Elastic LP
- SM layers alllowing contraction (inner long, outter circular)
- outside layer of adventitia
