ANATOMY - Nephron Flashcards
What is the nephron?
The nephron is the microscopic functional unit of the kidney
What are the two main functional components of the nephron?
Renal corpuscle
Renal tubule
(T/F) The number of nephrons varies between breeds
FALSE. The number of nephrons does not differ between breeds however the size of the renal corpuscles does vary
What is the cortical labyrinth?
The cortical labyrinth is the arrangement of the renal corpuscles and coiled proximal convoluted tubules (PCT) and coiled distal convoluted tubules (DCT)
What are medullary rays?
Medullary rays are the arrangement of straight proximal convoluted tubules (PCT) and straight distal convoluted tubules (DCT) and origins of the collecting ducts
What are renal corpuscles?
The renal corpuscles are the blood-filtering components of the nephron consisting of the glomerulus and Bowman’s capsule
What is Bowman’s capsule?
Bowman’s capsule is the blind ending origin of the nephron surrounding the glomerulus
Describe the two poles of Bowman’s capsule
Vascular pole: the afferent and efferent arterioles enter and exit the glomerulus
Urinary pole: the proximal convoluted tubule (PCT) arises
What are the two layers of Bowman’s capsule?
Parietal layer
Visceral layer
What is the name of the space between the parietal and visceral layer of Bowman’s capsule?
Urinary space
What is the function of the urinary space?
The urinary space is where filtrate is collected before passing into the proximal convoluted tubule (PCT)
Which layer of Bowman’s capsule is in direct contact with the glomerulus?
The visceral layer of Bowman’s capsule is in direct contact with the glomerulus
What are the components of glomerular filtration barrier?
Fenestrated glomerular endothelium
Glomerular basement membrane
Podocytes of the visceral layer of Bowman’s capsule
What is the function of the glomerular filtration barrier?
The glomerular filtration barrier acts to filter components of the blood based on particle size and charge to produce a filtrate
Histologically, what type of cells are the glomerular endothelial cells?
Fenestrated, simple squamous endothelial cells
What is the glomerular basement membrane?
The glomerular basement membrane is the modified, combined basement membrane of the podocyte cells and the glomerular endothelial cells
What is the function of the mesangial cells?
The mesangial cells produce a matrix which permeates the glomerular basement membrane to phagocytose any debris retained during filtration
What are pedicels?
Pedicels are extensions of the podocyte cells which are directly in contact with the glomerular basement membrane
What is the name and function of the spaces between the pedicles of the podocytes?
The spaces between the pedicels are known as filtration slits which are covered by a thin membrane known as the slit diaphragm. These filtration slits are where blood components are filtered
Describe the histological appearance of the proximal convoluted tubules (PCTs)
Simple cuboidal epithelium, microvillous brush border, indistinct cell boundaries, basal nuclei
What are the three specialised structures of the proximal convoluted tubule (PCT) epithelium which allows for reabsorption?
Microvilli
Leaky junctions
Cell wall interdigitations
What are the methods of reabsorption by the proximal convoluted tubules (PCTs)?
- Paracellular reabsorption
- Passive or active trans-cellular reabsorption
What is the function of the counter current multiplier system in the medulla?
The counter current multiplier system creates the concentration gradient in the medulla required to concentrate the urine
Which structures make up the counter current multiplier system in the medulla?
The loop of Henle and the Vasa recta
Which structures make up the juxtaglomerular apparatus?
Macula densa
Extraglomerular mesangial cells
Juxtaglomerular cells
What is the function of the juxtaglomerular cells?
The juxtaglomerular cells synthesise and secrete renin
What is the function of the macula densa?
The macula densa regulates blood pressure through the renin-angiotensin-aldosterone mechanism
Where are the macula densa cells located in the nephron?
The macula densa cells are located at the vascular pole of the glomerulus within the distal convoluted tubule (DCT)
Describe the histological appearance of the distal convoluted tubules (DCTs)
Simple cuboidal epithelium, distinct cell boundaries
Describe the histological appearance of the collecting ducts/papillary ducts
The collecting ducts/papillary ducts are pale staining with a simple cuboidal/columnar epithelium with distinct cell boundaries
What are the papillary ducts?
The papillary ducts are the most distal region of the collecting duct system where the collecting ducts have fused
Where do the papillary ducts terminate in the unilobar kidney?
The papillary ducts terminate at the renal crest of the unilobar kidney
What type of epithelium lines the renal pelvis?
Transitional epithelium/urothelium
