L24 - liver anatomy & function Flashcards
(52 cards)
1
Q
can the liver regenerate?
A
yes
2
Q
mass of liver
A
approx 1.5kg
3
Q
describe liver structure
A
- 4 lobes (left, right, caudate, quadrate) NOTE: opposite way on diagrams
- diaphragmatic surface superior upper surface of the liver
- visceral surface faces abdominal organs (where gallbladder is located)
4
Q
what is the liver made up of?
A
- lobules
- containing hepatocytes + kupffer cells
- blood vessels (sinusoids)
- bile caniculi
5
Q
what is the portal triad?
A
- bile duct
- hepatic portal vein
- hepatic artery
6
Q
describe liver blood flow
A
- liver receives blood from the heart & GI tract
- hepatic portal VEIN delivers deoxygenated blood from GI tract
- hepatic artery delivers oxygenated blood from heart
- the artery + vein divide into 2 and supply the left + right side of the liver
- blood flows from hepatic portal vein and hepatic artery through lobules into central vein
- bile flows in opposite direction
7
Q
what are the exocrine (digestive) functions of the liver?
A
- secretes bile salts and HCO3-
- involved in cholesterol metabolism
- organic and drug metabolism
8
Q
endocrine functions of liver
A
- secretes peptides & hormoes
- clotting and produces plasma clotting factors
- secretes plasma proteins
9
Q
where is bile synthesised and stored?
A
synthesised in liver by HMG-CoA, stored in gallbladder
10
Q
hepatocytes and their function in bile (exocrine function)
A
- create bile salts to solubilise fats
- cholesterol
- phospholipids (lectin)
- bile pigments ( extracts billirubin from rbc)
11
Q
epithelial cells and their function in bile (exocrine function)
A
- HCO3- neutralises stomach acid
- secretion is triggered by secretion from small intestine in response to fatty acids in diet
12
Q
during a meal what does the gallbladder do?
A
- contracts
- release bile into duodenum (SI)
- via Sphincter of Oddi
13
Q
what is the contraction of gallbladder stimulated by during a meal?
A
cholecytoskinin from SI which is triggered by fatty acids
14
Q
enterohepatic circulation
A
- flow of bile / bile salts
- release of bile. bile salts from gallbladder
- during fatty meal, bile salts are absorbed in SI but Na+ coupled transporters
- 95% is retired back to liver through hepatic portal vein: enterohepatic circulation
- hepatocytes absorb bile salts from blood and secrete back into the bile
- 5% lost in faeces and new bile salts synthesised from cholesterol
15
Q
what are new bile salts synthesised from?
A
cholesterol
16
Q
what does the liver do with cholesterol?
A
- extracts cholesterol from blood and secretes it into the bile and faeces
- can use to make more bile
17
Q
describe cholesterol
A
- insoluble
- froms micelles
- forms lipoproteins in plasma
18
Q
what happens when we eat dietary fibre?
A
- hides bile in SI preveting enterhepatic circulation (bile doesn’t return to liver through hepatic portal vein).
- so it removes the bile from the body and the cholesterol it contains
19
Q
can cholesterol lower drugs?
A
yes
20
Q
why do we need cholestrol?
A
- membrane + bile synthesis
- precursor to steroid hormones
- taken up by cells from blood for use
21
Q
how does the liver use bile?
A
extracts cholesterol and secretes it into bile or metabolises it into bile salts
22
Q
how are levels of cholesterol balance maintained?
A
increased dietary cholesterol suppresses HMG-CoA
23
Q
bad cholesterol (LDL)
A
saturated fatty acids
- red meat
- cheese
- whole milk
increases plasma cholesterol
24
Q
good cholesterol (HDL)
A
- polyunsaturated/ monounsaturated
- olive / peanut oil
decreases plasma conc
25
what do low density cholesterol do? (LDL)
deliver cholesterol to cells as they need a certain amount to make plasma membranes
26
what do high density cholesterol do? (HDL)
remove cholesterol from plasma and delivers to liver
27
too much cholesterol in body?
- causes deposition of cholesterol in artery walls (atherosclerotic disease)
- increased risk of heart attack
28
how to lower risk of athersosclerosis?
decrease LDL:HDL
29
what decreases HDL levels?
smoking
30
what increases HDL?
weight loss
30
what lowers LDL and raises HDL?
oestrogen
31
familial hypercholesterolaemia
decreased LDL receptors so increased circulating cholesterol
32
what are gallstones?
crystallisation of cholesterol in gallbladder
33
complications of gallstones
- can block gallbladder or bile duct, preventing fat digestion/ absorption
- decrease in absorption of fat soluble vitamins (A,D,E)
- clotting issues (K) and calcium deficiency
- bacteria acting on unabsorbed fat causes diarrhoea and fluid loss
- blocks pancreatic secretions
- causes build up of billirubin
- causes jaundice due to excess bilirubin
34
endocrine functions - synthesis of plasma proteins
most medicines are plasma protein bound
35
most abundant plasma protein?
- albumin
- made in liver
- circulate in plasma as too big to be take up into cells or filtered in kidney
- function in osmolarity of plasma
- carrier molecules for substances and drugs
36
globulins
immunoglobulins (antibodies)
37
fibrinogen
involved in blood clotting cascade
38
endocrine functions - synthesis of clotting factors
- liver makes them
- bile made by liver absorbs lipid soluble vitamin K from diet in SI
39
vitamin K
essential for production of prothrombin (precursor to thrombin) + other clotting factors
40
why can liver disease cause bleeding?
not making clotting factors and bile
41
endocrine function - liver makes peptides and hormones
- liver secretes insulin growth factor -1 (1GF-1) in response to increased levels of growth hormone (GH) from anterior pituitary
- liver hydroxylate enzymes metabolise dietary (D2) or sunlight derives (D3) vitamin D to active form
42
insulin growth factor -1 (IGF -1)
acts with grown hormone to cause bone chondrocytes for cell divison
43
what does calcitriol do?
stimulates SI absorption of calcium needed for bones
44
homeostatic function (endocrine) - peptides and hormones - angiotensinogen
- liver makes produces Angiotensinogen which is cleaved to form Angiotensin I by the action of
- renin is secreted by kidneys in response to drop in bp
- Activation of AngI to Ang II stimulates vasoconstriction and Na+/ H2O retention
45
immune function of liver
key detector of pathogens entering through GI tract.
Liver filters blood entering from hepatic portal vein
Pathogens detected by macrophage –like (Kupffer) cells
46
non-alcoholic liver disease
caused by obesity
47
hepatitis
viral infection or caused by alcohol
48
heaemochromatosis
genetic disease - build up of iron
49
cirrhosis
liver scarring and failure
50
hepatic medications
drug induced
51
liver function tests
blood test
