BL S8 The Liver Flashcards
What are the 6 main functions of the liver?
- Storage
- Catabolism
- Anabolism
- Filtering
- Endocrine
- Exocrine
What does the liver store?
Iron
Vitamins A, D, K and B12.
Glycogen
What is the livers role in anabolism?
Produces:
- Albumin and other plasma proteins
- Glycogen
- Coagulation factors
- Haematopoiesis - in fetus but this function can be revived if bone marrow is failing.
What is the livers role in catabolism?
Breaks down:
- Drugs via CYP450s
- Posions vis CYP450s
- Hormones
- Haemoglobin
- Can take over removal of aged or abnormal red blood cells post splenectomy.
How does the liver filter the blood?
Action of kuppfer cells.
What is the exocrine function of the liver?
Bile secretion - 1L per day.
What are the vast endocrine functions of the liver?
Produces:
- Angiotensin - causes vasoconstriction and BP increase.
- Thrombopoetin - glycoprotein - regulates platelet production.
- Insulin-like growth factor - IGF-1.
Modifies:
- Vitamin D to active form
- Thyroxine to active from
Breaks down
- Oestrogen
- Progesterone
- Glucagon
- Insulin
What is thyroxine important in?
Muscle control Heart function Digestive function Brain development Metabolism Bone health
What are some comparisons that can be made of hepatocytes to other cells?
- Regenerate remarkably
- More mitochondria
- More peroxisomes - strong oxidising agents contained within.
- More free ribosomes
- More RER and SER
- More Golgi complexes
- Large glycogen deposits
What vein feeds blood to the liver?
Hepatic portal vein
What does the superior mesenteric vein drain?
Small intestine
Caecum
Transverse and ascending colon.
What does the splenic vein drain?
Spleen
Pancreas
Stomach
What does the splenic vein receive blood from?
Inferior mesenteric vein
What does the inferior mesenteric vein drain?
Rectum, sigmoid colon and descending colon.
What does the falciform ligament do?
It is a fold of peritoneum attaching the liber to the anterior abdominal wall and diaphragm.
What travels in the hepatic portal vein?
- Water
- Water soluble vitamins
- Electrolytes
- Carbohydrates - glucose, galactose, fructose etc.
- Proteins - AAs - di/ tripeptides
- Intestinal hormones - pancreatic hormones
- Toxins ie ammonia.
What does not travel in the hepatic portal vein?
Lipids.
Fat soluble vitamins - ADEK
What are the main dietary lipids?
Triacylglycerols
Cholesterol
Phospholipids
Why do lipases work in conjunction with bile?
Bile emulsifies lipids
Forms lipid droplets called micelles.
Increasing surface area for digestion by lipases.
After lipids are digested by lipases what happens?
Taken into cells and processed into chylomicrons.
What is a chylomicron?
A globular molecule made of triglyceride, embedded apolipoproteins and phospholipids.
What is the function of a chylomicron?
Carry lipids from the intestine to adipose, cardiac and skeletal muscle tissue where they can be metabolised or stored.
Where do chylomicrons travel?
In the lymphatics.
Where are chylomicrons taken up?
Lacteals found in the villi of the small intestine.
What is the milky fluid that drains from lacteals?
Chyle
What do lacteals drain into?
Abdominal lymphatics that drain into the thoracic duct, joins the venous System and the junction between the left jugular and subclavian veins.
How do chylomicrons enter the liver?
Hepatic artery
What is the space of disse aka the perisinusoidal space?
Space between a hepatocytes and the sinusoid.
What is a sinusoid?
A small blood vessel that is a type of capillary similar to fenestrated endothelium.
What continues a hepatic triad?
Hepatic artery, hepatic portal vein branch and bile duct
What is a kuppfer cell and describe its function?
A kuppfer cell is a monocytes derived macrophage which forms part of the sinusoid lining.
Exposed to gut derived bacteria, microbial debris and bacterial endotoxins which it can phagocytose.
Also has a role in recycle old blood cells.
Migrates to sites of inflammation in the liver through fenestration in the endothelium of the sinusoids.
What is the role of a stellate cell?
Have vacuoles/ lipid droplets storing vitamin A.
When liver becomes damaged they activate - losing their vitamin A storage capacityan differentiate into myofibroblasts - begin to secrete collagen form scar tissue.
Leads to liver fibrosis.
What is the role of liver fibrosis and portal hypertension?
Deposition of scar tissue within the space of disse causes constriction in the space of Disse. Leads to portal hypertension.