L24 - Liver Anatomy And Function Flashcards
What are the four lobes in the liver?
- left
- right
- caudate
- quadrate
What is the superios upper face of the liver called?
Diahphragmatic surface
Where is the gallbladder located?
Visceral surface
- faces adj abdominal organs (downwards)
What is the liver made up of? What does it contain?
Lobules
- hepatocytes, blood vessels, bile canliculi
What is the portal triad?
- bile duct
- portal vein
- hepatic artery
Where does liver receive blood from? (2)
- heart
- GI tract
What does the hepatic portal vein deliver?
Poorly oxygenatwd blood from the GI tract
What does the hepatic artery deliver?
Oxygenated blood from the heart
Why does the hepatic portal vein and the hepatic artery divide into two?
To supply left and right side of the liver
Where does blood flow? And where does bile flow?
Blood - hepatic portal vein and hepatic artery to central vein
Bile - opposite direction
What are the hepatic functions of the liver? (6)
- exocrine (digestive, bile salts and HCO3-)
- cholesterol metabolism
- organic and drug metabolism
- endocrine (peptides and hormones)
- clotting (plasma cf)
- secretes plasma proteins
What is bile synthesised by? Where is it stored?
- liver
- in the gallbladder
What are the components produced by? (2)
- hepatocytes
- epithelial cells
What do hepatocytes produce in the exocrine function? (4)
- bile salts (solubilise fats)
- cholesterol
- phospholipids
- bile pigments
What do epithelial cells produce in the exocrine function?
- HCO3- (neutralises stomach acid
= secretion triggered by secretin from SI in response to FA in diet
During a meal, what does the gall bladder do? What is it stimulated by?
- contracts and releases bile into duodenum via sphincter of oddi
- stimulated by cholecystokinin from SI (triggered by FA)
What is the enterohepatic circulation?
Flow and release of bile/bile salts
What happens to bile salts during a fatty meal?
Absorbed into SI by Na+ coupled transporters
What do hepatocytes absorb?
Bile salts from the blood
- secrete back into bile
What are new bile salts synthesised from?
cholesterol
Where does the liver extract salts cholesterol from? What does it secrete it into?
- from the blood
- into bile/faeces
What is cholesterol like?
Insoluble but forms micelles
What does the sequestering of bile in SI by dietary fibres prevent?
Enterohepatic recirculation
What is cholesterol required for? Where is it synthesised in the body?
- membrane, bile synthesis, precursoe to steroid hormones
- liver by HMG-CoA
How are cholesterol level maintained in normal range?
Increased dietary cholesterol supressing HMG-CoA
Where are saturated fatty acids found in? What does it do to plasma cholesterol?
- red meat/cheese/whole milk
- increases plasma cholesterol
Where are polyunsaturated/monounsaturated fatty acids found in? What does it do to plasma cholesterol?
- olive/peanut oil
- decrease plasma cholesterol
How does cholesterol circulate?
Lipoprotein complexes (chylomicrons, etc.)
What do low density lipoprotein cholesterol carriers do?
Deliver cholesterol to cells
What do high density lipoproteins do?
Remove cholesterol from plasma and deliver to liver
What is atherosclerotic disease?
Deposition of cholesterol in arter walls
= increased risk of heart attack
What are important factors for atherosclerotic disease?
Ratio of LDL to HDL
- smoking dec HDL, wl inc it
- oestrogen lowers LDL, raises HDL
What is familial hypercholesterolaemia?
decreased LDL receptors
- inc circulating cholesterols
What are gallstones?
Crystallisation of cholesterol in gallbladder
What do gallstones lead to? (4)
- blocked gallbladder/bile duct = prevents fat digestion/absorption)
- dec in absorption of fat soluble vitamins (ADE), clotting problems
- bacteria acting on unabsorbed fat = diarrhoea, fluid loss
- blocked pancreatic secretions = build up of bilirubin
What is jaundice?
Excess bilirubin
(Can occur in liver disease and haemolytic anaemia)
What are the plasma proteins? (3)
- albumin
- globulins (immunoglobuling/abods)
- fibrinogen (blood clotting cascade)
Where is albumin synthesised, circulate and its function? (3)
- liver
- plasma
- osmolarity of plasma, carrier molecule for substances/drugs
What is the bile in the liver essential in the absorption of?
Lipid soluble vitamin K in SI
What is vitamin K essential for?
Production of prothrombin (cf)
What does the liver secrete in response to inc levels of GH?
Insuling-like growth factor -1 (IGF-1)
What does IGF-1 do?
Act in synergy with GH
= bone choncdrocytes to undergo cell div
What does liver hydroxylase enzymes metabolise?
Dietary (D2), sunlight-derived (D3) vit D to 1,25-(OH)2D-calcitriol (actiive form)
What does calcitrol stimulate?
SI absorption of calcium required for bones
What does the liver do in the homeostatic function? (3)
- produce angiotensinogen (cleaved = angiotensin I by the action of renin)
- renin secreted by kidneys (drop in BP)
- activation og AngI to AngII = vasoconstriction and Na+/H2O retention
What is does the liver do in the immune function? (3)
- key detector of pathogens through GI tract
- filets blood from hepatic portal vein
- pathogens detected by macrophage-like (kupffer) cells
What are liver diseases and what are they caused by? (6)
- alcoholic liver disease (exc alc)
- non-alcoholic liver disease (obesity)
- hepatitis (viral infection, exc alc)
- haemochromatosis (gen disease, build of Fe)
- cirrhosis (liver scarring, failure//viral, alc,drugs, metabolic factors)
- hepatotoxic medications (drug induced)
