Liver

Question 1

Where is the liver located?

Answer 1

Located in the upper right quadrant of the abdomen, beneath the diaphragm and above the stomach.

Question 2

Where does the blood supply to the liver come from?

Answer 2

The GI tract via the hepatic portal vein

Also lesser amount of (oxygenated) blood from hepatic artery

Question 3

Name the two places in the body that have a portal blood system

Answer 3

Liver

Hypothalamo-hypophyseal system (supplies anterior pituitary)

Question 4

What is a portal system?

Answer 4

Two capillary systems in series (in liver has the hepatic portal vein in between)

Question 5

What is contained in the hepatic portal blood?

Answer 5

Water
Water soluble vitamins
Electrolytes
Toxins (e.g. Ammonia)
Carbohydrates
Proteins
Hormones

Question 6

What is urea (krebs) cycle and where does it take place?

Answer 6

The liver only.

CO2 + 2NH3 -> H2O + CO(NH2)2

Produces urea - soluble - excreted in urine

Question 7

What are there none of in the hepatic portal vein?

Answer 7

Lipid and lipid soluble vitamins (A, D, E, K)

Question 8

Why are there no lipids in the hepatic portal vein?

Answer 8

They are digested by lipases (requires bile acids) to form micelles which are taken up by cells, processed into chylomicrons. Released into lymphatics (called lacteals) and eventually drain into thoracic duct to join the venous system.

Question 9

What are the six key functions of the liver?

Answer 9

Storage - of iron, vitamin A, B12, D, K and glycogen
Production - of albumin, glycogen, coagulation factors, complement components
Breakdown - of drugs, haemoglobin, hormones, poisons
Filtering - kupffer cells (macrophages)
Exocrine function - secretes bile
Endocrine function

Question 10

Discuss the endocrine function of the liver

Answer 10

Produces angiotensin, Thrombopoietin, and insulin like growth factor 1 (IGF1)

Modifies and activates vitamin D and thyroxine

Breaks down insulin, glucagon, oestrogen and progesterone

Question 11

What enzymes in the liver function in drug metabolism?

Answer 11

Cytochrome p450 - haem containing isoenzymes

Question 12

What are the main cells of the liver ?

Answer 12

Hepatocytes

Question 13

What are some key features of hepatocytes?

Answer 13

Lots of mitochondria
Lots of peroxisomes
Lots of RER, SER, ribosomes, Golgi
Glycogen deposits

Question 14

What three things make up the portal triad?

Answer 14

Hepatic arteriole
Portal venule
Bile canaliculus

Question 15

What are sinusoids?

Answer 15

Like a wide capillary vessel - for passage of blood into central canal. (Takes place of capillaries and venules in liver, spleen and bone marrow).
Surrounded by simple squamous epithelium with large gaps

Question 16

What is the periportal space of Mall?

Answer 16

The space between the stroma of the portal canal and the outermost hepatocytes in the hepatic lobule.

Where lymphatic vessels arise from in the liver

Question 17

What is a liver lobule?

Answer 17

Polygonal shaped, repeating structures of the liver

Question 18

What is a liver acinus?

Answer 18

The functional unit of the liver

Question 19

What is the space of disse?

Answer 19

Located between hepatocytes and a sinusoid (contains blood plasma). Microvilli of hepatocytes extend into space - allows proteins/plasma components from sinusoids to be absorbed into hepatocytes

Question 20

What is a kupffer cells?

Answer 20

Specialist macrophages that line sinusoids. Make up ~80% macrophages of the body. Constantly exposed to gut derived bacteria and toxins

Question 21

What are stellate (Ito) cells?

Answer 21

Cells in the liver - full of vacuoles containing vitamin A

Question 22

What happens to stellate cells in liver cirrhosis?

Answer 22

Stellate cells lose vitamin A storage capability and differentiate into myofibroblasts which deposit collagen in perisinusoidal space (fibrosis)