Structure and function of the liver

Question 1

Main metabolic waste products in mammals are:

Answer 1

-carbon dioxide= one of the waste products of cellular respiration which is excreted from the lungs
-bile pigments= formed from breakdown of haemoglobin from old red blood cells in the liver
-fish produce ammonia
-birds and insects produce uric acid

Question 2

The liver

Answer 2

-5% tot body mass
-largest internal organ of body
-just below diaphragm and made of several lobes
-fast growing (metabolically active)
-rich blood supply
-supplied with blood by a second vessel (hepatic portal vein)

Question 3

Structure of the liver

Answer 3

-hepatocytes (liver cells)=
-large nuclei,
-prominent Golgi apparatus
-lots of mitochondria
-blood from hepatic artery and hepatic portal vein mixed in spaces called sinusoids surrounded by hepatocytes
-increases oxygen content of blood from hepatic portal vein, supplying hepatocytes with enough oxygen
-sinusoids contain Kupffer cells=act as resident macrophages of liver=ingesting foreign particles
-secrete bile from breakdown of blood into spaces called canaliculi and from these the bile drains into the bile ductulus which take it to the gall bladder

Question 4

Functions of the liver

Answer 4

-carbohydrate metabolism
-deamination of excess amino acids
-detoxification

Question 5

Carbohydrate metabolism

Answer 5

-blood glucose levels rise, insulin levels rise and stimulate hepatocytes to convert glucose to storage carbohydrate glycogen (100g stored)
-blood glucose levels fall, hepatocytes convert glycogen back to glucose under influence glucagon

Question 6

Deamination of excess amino acids

Question 7

Detoxification

Answer 7

-breakdown of hydrogen peroxide (by-product of various metabolic pathways)
-splits hydrogen peroxide into oxygen and water
-ethan via alcohol dehydrogenase that breaks down ethanol to ethanal then converted to ethanoate may be used to build up fatty acids or used in cellular respiration