Liver and kidney system Flashcards
What are the functions of the liver?
- Uptake, stores and distributes nutrients
- Produces majority of circulating plasma proteins
- Stores iron
- Converts vitamins
- Degraded drugs and toxins
- Acts as an exocrine organ (produces bile) and performs endocrine-like functions
How does the liver receive blood?
Dual blood supply
Hepatic portal vein
Hepatic artery
State four structural components of the liver
- Parenchyma (plates of hepatocytes)
- Connective tissue stroma
- Sinusoidal capillaries
- Perisinusoidal spaces (of disse)
What three ways are used to describe the unit structure of the liver?
Classic lobule (polygonal shape)
Portal lobule (triangular shape)
Liver acinus (diamond shape, three zones)
How does each functional unit supply/drin?
‘Classic’ lovule: drained by a central vein
Portal lobule: by a portal triad
Liver acinus: by terminal branches of portal triad vessels
Where does the portal triad sit?
On the corners of the polygonal classic lobule
Outline hepatocytes
- 80% of the liver
- Large, polygonal cells
- Spherical nuclei, often binucleate
- Acidophilic cytoplasm
- Numerous mitochondria, peroxisomes and small golgi complexes
What does hepatocyte cytoplasm contain?
sER and rER
What are the two surfaces on hepatocytes and where do they contact?
Basal surface: contact with Perisinusoidal space of disse
Apical surface: connected to adjacent hepatocyte to form a bile canaliculus
Where do bile canaliculi drain?
Into the short canals of Hering
Then the intrahepatic bile ductule
Interlobular bile ducts (portal triad)
Right/left hepatic ducts
Common hepatic duct
Gallbladder
Bile duct
Duodenum
What form irregular vascular channels running parallel to the plates of hepatocytes?
Hepatic sinusoids
What is the space of disse?
Lies between hepatocytes and epithelium.
The site of exchange of materials between blood and liver cells.
What specialised sinusoidal macrophage-like cells are found in the sinusoidal epithelium?
Kuppfer cells, remove senile RBCs and recycle iron molecules
What do hepatic stellate cells do?
Reside in perisinusoidal spaces, loaded with lipid droplets for vitamin A storage
What does the urinary system contain?
2 Kidneys
2 Ureters
Bladder
Urethra
What are the functions of the kidney?
- Control acid-base balance
- Eliminate waste products of metabolism
- Excrete excess water
- Endocrine organ (renin (BP control) and erythropoietin (erythrocyte production))
Outline the structure of a kidney
- Capsule (collagenous connective tissue)
- Cortex (contains parts of the nephron: collectibg thbules, medullary rays)
- Medulla (renal pyramids containing part of the nephron)
- Pelvis (beginning of main excretory duct)
What are the features of a nephron?
- Proximal convoluted tubule (active reabsorption)
- Loop of Henle (ascending, descending)
- Juxtaglomerular apparatus (renin production)
- Glomerulus (filtration unit, bowman’s capsule)
What are the features of the proximal convoluted tubule?
Simple cuboidal epithelium
Intensely eosinophilic
Prominent brush border (narrow lumen)
Numerous lateral folds and basal striations
What are the features of the thin loop of henle?
Simple squamous epithelium
Nuclei bulge into the lumen
Highly permeable to water, urea, ions
What are the features of the distal convoluted tubule?
Simple cuboidal epithelium
Weakly eosinophilic
Low brush border (wide lumen)
Impermeable to water/urea
What are the features of the collecting tubules/ducts?
Simple cuboidal epithelium
Pale cytoplasm
Prominent lateral cell boundaries
Luminal (apical) surface, may be scalloped
What is found in the cortex and upper medulla?
Rebal corpuscle
Proximal convoluted tubules
Straight segment of descending proximal tube
Thin segments of loop of henle
Straight ascending segment of distal tube
Distal convolute tubules
Collecting tubules
What do the macula densa do?
Sense a decreased salt concentration in filtrate and signal the juxtaglomerular cells to release renin
What staining techniques can be done on kidney and related tissue?
H&E
PAS
PA silver
Immunofluorescence
Electron Microscopy
What laboratory investigations are done using kidney samples?
IgA, M, G, fibrinogen, C3 and C4 levels
Paraffin wax
What clinical complications relate to the kidney?
Nephritis
Acute glomerulonrphritis
Congenital
Tumours
