Lecture 6 The Liver & Metabolic Homeostasis Flashcards
What are the liver functions (7)
- Phagocytosis
- Synthesis of Bile salts & excretion of haem
- Synthesis of serum proteins
- Processing of drugs & hormones
- Activation of Vitamin D
- Storage e.g. glycogen/ Vitamin A (retinol)
- Metabolism
- carbohydrate metabolism
- lipid metabolism
- protein metabolism
How much does the liver weigh?
About 1.4Kg
What 3 blood vessels are involved in in liver blood supply ?
- Hepatic portal vein - nutrients
(Not a true vein as conducts blood from capillary bed of GI tract to capillary bed of liver & does not go directly to heart) - Hepatic artery - oxygen
- Inferior vena cava - to heart
Gross anatomy of liver
- Right lobe of liver
- Right hepatic duct
- Left lobe of liver
- Left hepatic duct
- Cystic duct
- Common hepatic duct
- Common bile duct
What is a liver lobule ?
The functional unit of the liver
Overview of a single liver lobule (3)
- Portal triad:
- branch of hepatic artery
- branch of hepatic vein
- bile duct - Central vein
- Liver lobule
Details of single liver lobule (5)
- Connective tissue
- Sinusoids
- Hepatocytes
- Central vein
- Portal triad (3)
What are Kupffer cells? (3)
- Within sinusoids
- Fixed bacteria cells
- Remove these Bacteria & old blood cells
Where is bile stored?
Gall bladder
Features of bile (3)
- 800ml-1 litre per day
- Yellow/green
- pH 7.6-8.6
What does bile contain? (6)
- Water
- Bile salts
- Cholesterol
- Phospholipids
- Bile pigments
- Ions
What are bile slats & what do they do? (4)
- Based on the structure of cholesterol (e.g. sodium glyocholate)
- Emulsify fat
- Allow pancreatic lipase (catalyses hydrolysis of lipids) to break down fats more easily
- Aid absorption of lipids
What are bile pigments & what do they do? (3)
- When red blood cells broken down they recycle the iron present in haemoglobin and break down haem
- Bilirubin (yellow) breakdown product of haem
- Bilirubin metabolised by bacteria to give stercobilin (brown) - faeces
Bilirubin
Glycogenesis
Food -> plasma glucose increases -> insulin which converts glucose to glycogen
- absorptive state
- within hepatocytes
Glycogenolysis
Glucagon & adrenaline convert glycogen to glucose
Glycolysis - postabsorptive state
Gluconeogenesis
3 carbon chain molecules used in gluconeogenesis (3)
- Lactic acid
- Pyruvic acid
- Glyceraldehyde
Lipid metabolism in Hepatocytes (3)
- Make triglycerides (lipogenesis)
- Triglycerides broken down to fatty acids & glycerol (lipolysis)
- Make cholesterol (a lipid) + bile salts
Lipogenesis
- in absorptive state
- glucose & amino acids converted to glycerol & fatty acids by insulin
- triglycerides ( triacylglycerols)
What happens in lipolysis (6)
- post absorptive state
( adrenaline, noradrenaline & cortisol)
- Triglycerides -> fatty acids + glycerol
- Glycerol -> Pyruvate -> Acetyl CoA
- Fatty acid catabolism (beta oxidation) -> Acetyl CoA
- Acetyl CoA -> acetoacetic acid -> beta hydroxybutyric acid + acetone
- Ketone bodies -> ATP in Kreb’s cycle
Protein metabolism: catabolism (2)
- for energy production
- Deamination of amino acids
Organic acid + NH4+ -> Urea -> Urine - Amino acids -> glucose or ketone bodies or fatty acids-> Acetyl CoA- Kreb’s cycle - ATP
Protein metabolism: Anabolism
Hepatocytes make plasma proteins (e.g. albumin & fibrinogen)
What happens in absorptive state (2)
- Glycogenesis
- Lipogenesis
What happens in post-absorptive state (3)
- Glycogenolysis
- Gluconeogenesis
- Lipolysis
