Liver and Kidney Flashcards
1
Q
Liver
A
- largest organ, largest mass of glandular tissue in body.
- plays an important role in the uptake, storage and distribution of nutrients
- produces the majority of circulating plasma proteins (e.g. albumins), stores iron, converts vitamins and degrades drugs and toxins
- acts as an exocrine organ (produces bile) and performs endocrine-like functions.
- remarkable capacity for regeneration after either surgical removal or after chemical injury, 51% of the original liver can regenerate back to its full size.
2
Q
Dual blood supply in the liver
A
- a venous supply via the hepatic portal vein
- an arterial supply via the hepatic artery.
3
Q
Structural components of the liver
A
- parenchyma (P) (plates of hepatocytes)
- connective tissue stroma (CT)
- sinusoidal capillaries (hepatic sinusoids)
- perisinusoidal spaces (of Disse).
4
Q
Unit structure of the liver
A
- classic lobule (polygonal shape)
- portal lobule (triangular in shape)
- liver acinus (a diamond-shaped area that has three zones and best correlates to blood perfusion, metabolic activity and liver pathology)
5
Q
Classical lobule
A
- the unit drained by a central vein
6
Q
Portal lobule
A
- the unit supplied and drained by portal triad
7
Q
Liver acinus
A
- the unit supplied and drained by terminal branches of portal triad vessels
8
Q
Hepatocytes in classic lobule
A
- organized into irregular anastomosing plates that radiate towards a central vein
9
Q
Portal triad
A
- occupy corners of polygonal classic tobule
- contains branches of portal vein (PV), hepatic artery, (HA), bile ducts (BD) and small lymphatic vessels
10
Q
Hepatocytes
A
- constitute 80% of the liver and are large, polygonal cells with spherical nuclei (often binucleated) and acidophilic cytoplasm containing sER, rER, numerous mitochondria, peroxisomes and multiple small Golgi complexes
- basal surface has contact with the perisinusoidal space (of Disse), whereas the apical surface is connected to the adjacent hepatocyte to form a bile canaliculus.
11
Q
Bile flow
A
- Bile canaliculi drain into the short canals of Hering, which are partially lined with hepatocytes and cuboidal cholangiocytes (cells lining the biliary tree)
- Canals of Hering harbour specific hepatic stem cells
- Flow of bile: bile canaliculi → canals of Hering → intrahepatic bile ductule → interlobular bile ducts (which is port of the portal triad) → right and left hepatic ducts → common hepatic duct → gallbladder → bile duct → duodenum
12
Q
Hepatic sinusoids
A
- sinusoids form irregular vascular channels that run parallel and between the plates of hepatocytes
- receive mixed blood (~75%) from venous portal circulation and arterial blood (~25%) from systemic circulation.
13
Q
Discontinuous sinusoidal endothelium
A
- large fenestrae, large gaps between neighbouring endothelial cells
- Blood cells are unable to pass through fenestrae and gaps, fluid and protein can pass
14
Q
(Perisinusoidal) Space of Disse
A
- lies between hepatocytes and the endothelium
- site of exchange of materials between blood and liver cells
15
Q
Kupffer cells
A
- aka stellate sinusoidal macrophages
- remove senile red blood cells and recycle iron molecules
16
Q
Hepatic stellate cells
A
- reside in the perisinusoidal spaces and are loaded with lipid droplets for storage of vitamin A
- In pathologic conditions, Ito cells have the potential to differentiate into myofibroblasts (go from quiescent to activated state).
17
Q
Causes of cirrhosis
A
- most common: alcohol,hepatitis B,hepatitis C andnon-alcoholic fatty liver disease
- less common: autoimmune hepatitis,primary biliary cholangitis,haemochromatosis, certain medications andgallstones.
18
Q
Cirrhosis
A
- Healthy liver cells are slowly replaced by scar tissue
- progressive disease which can take years to develop due to long-term damage
- Can develop into liver failure were the liver has lost too many hepatocytes and is no longer to coupe with the demand
- 2 hallmarks: Thick bands of mature fibrous tissue (fibrosis) + nodules of ‘regenerative’ hepatocytes
19
Q
Hepatocellular carcinoma
A
- mostly occurs in people withcirrhosis of the liver, and so risk factors generally include factors which cause chronic liver disease that may lead to cirrhosis
- liver is most frequent site of secondary tumours (most noticeably from GIT).
- Surgical resection (only 5-15% of patients are suitable), liver transplantation (need donor and immunosuppressive medication)
20
Q
Obstructive jaundice (or icterus)
A
- Due to narrowed or blocked bile/pancreatic duct, preventing normal drainage of bile from the bloodstream into the intestines
- Bile accumulation in bile duct (can progress and induce necrosis of hepatocytes in portal areas)
21
Q
Liver diseases
A
- Alcohol-related liver disease
- Non-alcoholic fatty liver disease
- Infection (Tuberculosis, Spirochaetes)
- Haemochromatosis
22
Q
Laboratory investigations
A
- Liver Function Tests (LFT’s) (biochemistry)
- Biopsy - special stains: Ferric Iron (haemosiderin), Retic (reticulin fibres), Van Gieson (collagen, bile), PAS/D.PAS (glycogen)
23
Q
Role of the kidney
A
- eliminate waste products
- maintain normal acid-base balance
- conserve fluid, electrolytes and other essential substances
24
Q
Structure of the kidney
A
- Capsule: dense irregular collagenous connective tissue, plus occasional fibroblasts and blood vessels
- Cortex: parts of nephrons: collecting tubules (arranged in cortical labyrinths) and medullary rays; blood vessels; connective tissue
- Medulla: renal pyramids containing part of nephron
- Pelvis: beginning of main excretory duct
25
External anatomy of kidney
- retroperitoneal
- bean‑shaped, hilum faces medially
- renal artery, renal vein, ureter in renal sinus
- calyces
- medulla
26
Internal morphology of kidney
- kidney capsule
- cortex: medullary rays
- medulla: renal pyramid, renal column, renal papilla, minor calyx, major calyx
- renal pelvis
27
Renal Corpuscle (Glomerulus, Bowman’s capsule)
- afferent and efferent arterioles
- juxtaglomerular apparatus
- glomerulus
- fenestration (pore)
- proximal convoluted tubule
- glomerular capillary
- podocyte
- filtration slit
- bowman's capsule
- distal convoluted tubule
28
Nephron
- Proximal convoluted tubule: active reabsorption
- Loop of Henle: descending, ascending
- Distal convoluted tubule
- Juxtaglomerular apparatus /Macula densa: renin production (blood pressure control, influences rate of renal blood flow)
- Glomerulus: (filtration unit) (250 µm) - afferent/efferent arterioles, Bowman’s capsule, Podocytes
29
Urine drainage
- renal corpuscle
- proximal convoluted tubule
- thick descending limb
- thin loop (of Henle)
- thick ascending limb
- distal convoluted tubule
- cortical collecting tubules
- medullary collecting ducts
- papillary collecting ducts (of Bellini) ‑ area cribrosa
- renal papilla
30
Proximal convoluted tubule (& thick descending tubule)
- simple cuboidal epithelium
- intensely eosinophilic
- prominent brush border - narrow lumen
- numerous lateral folds & basal striations
31
Thin loop of Henle
- simple squamous epithelium
- nuclei bulge into the lumen
- highly permeable to water, urea, ions
32
Distal convoluted tubule (thick descending tubule)
- simple cuboidal epithelium
- weakly eosinophilic
- low brush border ‑ wide lumen
- impermeable to water / urea
33
Collecting tubules/ducts
- simple cuboidal epithelium
- pale cytoplasm
- prominent lateral cell boundaries
- luminal (apical) surface may be scalloped
34
Juxtaglomerular cells
- Secrete renin in response to low blood pressure or low blood sodium
35
Macula densa
-Senses decreased salt concentration in the filtrate and signals juxtaglomerular cells to release renin
36
Arterial supply in kidneys
- Renal artery
- Segmental arteries
- Lobar arteries
- Interlobar arteries
- Arcuate artery (corticomedullary junction)
- Interlobular arteries
- Afferent arterioles
- Glomerular capillaries
- Efferent arterioles
37
Venous drainage
- stellate veins
- interlobular veins
- arcuate veins
38
Clinical issues of kidney
- Nephritis
- Acute glomerulonephritis
- Congenital (polycystic)
- Tumours
39
Laboratory investigations
- Biopsy:
- Electron Microscopy
- Immunofluorescence
- IgA, M, G, Fibrinogen, C3, C4
- Paraffin wax
- special stains:
- PAS (basement membrane)
- PA Silver (basement membrane + spikes)
- MSB - connective tissue, fibrin
- Sirius/Congo Red - amyloid
