Liver Flashcards
(85 cards)
1
Q
where does the falciform ligament attach the liver to
A
anterior abdominal wall
2
Q
what does the falciform ligament contain
A
ligamentum teres
3
Q
what is the ligamentum teres a remnant of
A
umbilical vein
4
Q
what are the liver impressions (6)
A
oesophageal renal colic duodenal gastric gallbladder
5
Q
what is the dominant blood supply to the liver
A
portal system
venous drainage from GI tract to liver via hepatic portal vein
6
Q
what is the structural and functional unit of liver
A
structural - lobules
functional - acinus
7
Q
what is a liver lobule
A
hexagonal shape with central vein
8
Q
where does the portal triad lie in the lobule
A
at the corners
9
Q
what is the portal triad
A
hepatic artery
hepatic portal vein
bile duct
10
Q
what is an acinus
A
functional liver unit
localised collection of hepatocytes around portal triad
11
Q
what are sinusoids
A
discontinuous capillary
- mixes oxygenated blood from hepatic artery w nutrient rich blood from hepatic portal vein
12
Q
what is the gallbladder
A
peritoneal structure involved w storage and bile conc
13
Q
where does the common bile duct empty into the duodenum
A
major duodenal papilla (controlled by sphincter of Oddi)
14
Q
what are the fat soluble vitamims
A
A
D
E
K
15
Q
discuss vit A
A
retinal light adaptation
16
Q
what is vit A found in
A
carrots
17
Q
discuss vit D
A
increase intestinal calcium uptake
18
Q
what is vit D found in
A
milk
19
Q
discuss vit E
A
prevents RBC destruction
20
Q
what is vit E found in
A
veg oil
21
Q
discuss vit K
A
normal blood clotting
22
Q
what is vit K found in
A
spinach
23
Q
how is vit A metabolised (5)
A
- retinol absorbed by enterocytes
- retinol is esterified and incorporated into chylomicrons
- chylomicrons travel through intestinal lymph to liver
- retinol de-esterified and bound to retinol binding protein
- retinol stored in lipid droplets of sinusoidal pericytes
24
Q
what is vit A aka
A
retinol
25
what is vit B aka
folate
26
how is vit B metabolised (5)
1. vit B binds to R protein released from salivary glands n stomach (protects vit B from HCl
2. pancreatic proteases free vit B in duodenum
3. vit B binds to intrinsic factors (released from parietal cells)
4. vit B-IF complex absorbed in enterocytes of terminal ileum
5. vit B transported in blood to liver, then back to duodenum in bile (enterohepatic circulation)
27
how is vit D metabolised
1. D3 (synthesised from liver) transported to liver n converted to calcidiol (25hydroxyvitaminD)
2. intermediate travels to kidney and converted to calcitriol (1,25dihydroxyvitaminD)
3. calcitriol binds to vit D receptors in target tissues
28
how is iron metabolised (5)
1. iron is absorbed into enterocytes
2. some iron is bound in enterocytic ferritin, rest transported to blood via ferroportin
3. iron in blood bound to transferrin travels to liver
4. transferrin in hepatocytes n kupffer cells stores iron in ferritin
5. when hepatic iron stores are full, hepatocytes release hepcidin which inhibits ferroportin iron transport across enterocyte basolateral membrane
29
what is calcidiol
25 hydroxy vitamin D
30
what is calcitriol
1,25dihydroxy vitamin D
31
what are xenobiotics
foreign substances that are absorbed (skin, lungs, intestine) and are not used for energy purpose
32
what does phase 1 reaction involve
microsomal enzymes found in smooth ER
33
what does phase 2 reaction involve
non-microsomal enzymes found in cytosol
34
which enzyme is involved in phase 1 reactions
cytochrome p450
35
what happens during phase 1
oxidation
hydrolysis
small hydrophilicity increase
36
what happens during phase 2
glucoronidation - greatly increases hydrophilicity
37
what does hydrophilicity result in
water soluble = able to excrete
38
what is glucuronidation
conjugation of substance with glucuronic acid
39
where is albumin produced
hepatocytes
40
list 3 functions of albumin
1. maintains oncotic pressure (fluid distribution)
2. acts as a carrier for hormones and molecules
3. mops up free radicals
41
how do complement factors enhance immune system
by stimulating cytokine release
42
what are the 2 types of protein degradation
lysosomal
| non-lysosomal
43
describe lysosomal protein degradation
kupffer cells phagocytose unnecessary proteins
44
describe non-lysosomal protein degradation
ubiquitin binds to protein for destruction
| proteasome encases protein and destroys (aa can be recycled)
45
what are the 3 steps of the glucose/alanine cycle
1. alanine aminotransferase removes amine from glutamate and adds it to pyruvate to form alanine (transamination) and an alpha keto acid (used in Krebs)
2. alanine is transported in blood to liver and broken down into pyruvate and an ammonia group
3. pyruvate is used for gluconeogenesis, an the ammonia group is incorporated into the urea cycle
46
what removes Amine from glutamate n adds it to pyruvate to form alanine n alpha keto acid (and what is this called)
alanine aminotransferase
| - transamination
47
where is the alpha keto acid from transamination used
krebs
48
where is alanine transported to, where it is broken down
liver
49
when alanine is broken down in the liver, what is broken into
pyruvate - used in gluconeogeesis
| ammonia group - incorporated in urea cycle
50
what are the functions of the glucose alanine cycle (2)
1. provides liver w necessary ingredients for gluconeogenesis and urea cycle
2. muscles don't have to use energy to make glucose - all energy can go to muscle contraction
51
what are the 4 steps of the urea cycle
1. ammonia n carbon dioxide --> carbomyl phosphate
2. carbomyl phosphate + ornithine --> citrulline
3. citrulline --> arginine & another ammonia group added
4. arginine cleaved by arginase --> urea and ornithine
52
how many ATP does the urea cycle require
3
53
how many ammonia molecules are secreted during urea cycle
2
54
where are chylomicrons synthesised
enterocytes
55
where are VLDL's synthesised
hepatocytes
56
what is the function of chylomicrons/VLDL
transport of triglycerides from liver to tissues
57
what does lipoprotein lipase do to VLDL
strips triglyceride from VLDL
| degrades the to glycerol and 3 fatty acids
58
what are chylomicrons
lipoprotein particles that consist of triglycerides, phospholipids, cholesterol, and proteins
59
what is the diff btwn VLDL and chylomicrons
VLDL transports endogenous products, whereas chylomicrons transport exogenous (dietary) products
60
what is LDL produced by
hepatic lipase in hepatocytes
61
what do LDL do
transport cholesterol from liver to tissue cell membranes (taken up by endocytosis)
62
what does HDL do
removes excess cholesterol from cells and returns to liver
63
what happens to excess cholesterol (HDL)
converted into bile salts n excreted
| or involved in fat emulsification
64
what happens during beta oxidation
1. fatty acids diffuse across cell membranes
2. fatty acid combine with coenzyme A to form acyl coenzyme A (catalyst by acyl CoA synthase)
3. acyl coA transported across mitochondrial membrane via cartinine shuttle
4. beta oxidation - 2 carbons are removed from fatty acid --> acetyl CoA, NADH and FADH (krebs/oxidative phosphorylation)
65
what does high levels of fatty acid oxidation result in
excess acetyl CoA (too much for Krebs) --> increased ketogenesis
66
what are the 3 products of hepatic lipid metabolism
acetoacetate (converted immediately to acetone)
acetone
hydroxybutyrate
67
how is fatty acid oxidation regulated
high concentration of glycerol-3-phosphate = high levels of fatty acid oxidation
- insulin inhibits fatty acid oxidation
- glucagon activates fatty acid oxidation
68
how does insulin affect fatty acid oxidation
inhibits
69
how does glucagon affect fatty acid oxidation
activates
70
what is ketoacidosis
diabetic - low insulin
alcoholic - high glucagon
ketones = strong acids --> lower blood pH --> oxygen can't bind to Hb effectively
71
what is insulin like in a diabetic
low
72
what is glucagon like in an alcoholic
high
73
how do ketones impact pH
lower
74
what are bile salts
primarily cholesterol n waste products that need to be excreted
75
where is bile produced
hepatocytes
76
what is bile transported in
miceles
77
bile is transported in micelles through what?
canaliculi
78
why is bile transported in canaliculi
bc bile damages cell membranes
79
what helps bile move to hepatic ducts
actin filaments that contract around canaliculi
80
what is the path of bile to the gallbladder
liver - canaliculi - hepatic ducts - cystic duct - gallbladder (Sphincter of odd closed)
81
how is bile released (4)
1. food enters duodenum, CCK released
2. gallbladder contracts and sphincter of Oddi opens
3. bile enters the duodenum and emulsifies fats
4. bile salts are reabsorbed in the terminal ileum - enterohepatic circulation
82
how is bilirubin metabolised (6)
1. kupffer cells break down haem to biliverdin
2. biliverdin converted to bilirubin (catalysed by biliverdin reductase)
3. bilirubin released from kupffer cells and travels in blood bound to albumin
4. hepatocytes conjugate bilirubin with glucuronic acid (catalysed by glucuronyl transferase)
5. water soluble conjugated bilirubin is excreted in bile and unconjugated in duodenum
6. majority of bilirubin secreted as stercobilin (makes poo brown) or urobilin (makes pee yellow), some is recycled via enterohepatic circulation
83
what breaks down haem to biliverdin
kupffer cells
84
which enzyme catalyses biliverdin --> bilirubin
biliverdin reductase
85
when bilirubin is conjugated with glucuronic acid, which enzyme catalyses it
glucuronyl transferase
