15.4 The Liver Flashcards

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1
Q

define excretion

A

the removal of waste products of metabolism from the body

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2
Q

what are the 3 main metabolic waste products in mammals

A
  • CO2
  • bile pigments
  • nitrogenous waste products (urea)
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3
Q

what is CO2 a waste product of

A

cellular respiration which is excreted from the lungs

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4
Q

how are bile pigments formed

A

from the breakdown of haemoglobin from old RBCs in the liver

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5
Q

where are bile pigments excreted from and into

A

the liver into the small intestine via the gall bladder and bile duct

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6
Q

how are nitrogenous waste products formed

A

from the breakdown of excess amino acids by the liver

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7
Q

what is the nitrogenous waste product in mammals

A

urea

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8
Q

what is the nitrogenous waste product in fish

A

ammonia

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9
Q

what is the nitrogenous waste product in birds and insects

A

uric acid

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10
Q

explain the blood supply to the liver

A
  • oxygenated blood is supplied by the hepatic artery and removed by the hepatic vein
  • the hepatic portal vein carries blood with products from digestion from the intestine to the liver
  • 75% comes via the hepatic portal vein
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11
Q

explain the characteristics of hepatocytes

A
  • large nuclei
  • prominent Golgi apparatus
  • lots of mitochondria
  • divide and replicate very quickly
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12
Q

what are sinusoids

A

spaces where blood from the hepatic artery and the hepatic portal vein get mixed (increases oxygen content of blood from the HPV)

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13
Q

what do sinusoids contain

A

Kupffer cells

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14
Q

what do Kupffer cells do

A

act as resident macrophages by ingesting foreign particles and protecting it against disease

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15
Q

what do the hepatocytes secrete

A
  • bile from the breakdown of blood into spaces called canaliculi
  • then bile drains into the bile ductule which go to the gall bladder
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16
Q

what are the 3 main function of the liver

A
  • carbohydrate metabolism
  • deamination of excess amino acids
  • detoxification
17
Q

explain carbohydrate metabolism (blood glucose rises)

A
  • blood glucose levels rise = insulin levels rise = hepatocytes convert glucose –> glycogen (storage)
18
Q

what is transamination

A

conversion of one amino acid into another

19
Q

why is transamination important

A

overcomes the problems of the diet which doesn’t always contain the required balance of amino acids

20
Q

what is deamination

A

the removal of an amine group from a molecule

21
Q

explain the process of deamination

A
  • hepatocytes remove the amino group and convert amino acids –> ammonia –> urea
22
Q

what happens to the remaining amino acids after deamination

A
  • fed into cellular respiration

- converted into lipids for storage

23
Q

what does the ornithine cycle do

A

convert ammonia into urea

24
Q

how is hydrogen peroxide broken down

A

hepatocytes contain catalase which splits the hydrogen peroxide into oxygen+water

25
Q

how does the liver detoxify ethanol

A
  • hepatocytes contain alcohol dehydrogenase that breaks down ethanol –> ethanal
  • ethanal is converted to ethanoate (used to build up fatty acids/in cellular respiration)
26
Q

what is cirrhosis

A

a disease where normal liver tissue is replaced by fibrous scar tissue

27
Q

what are the causes of cirrhosis

A
  • genetic conditions
  • hepatitis C
  • excessive amounts of alcohol
28
Q

explain the 3 stages of alcoholic Iiver disease

A
  1. alcoholic fatty liver disease (big fat-filled vesicles displace nuclei of hepatocytes and liver gets bigger)
  2. alcoholic hepatitis (fatty liver, damaged hepatocytes, sinusoids and hepatic veins become narrow)
  3. liver cirrhosis (hepatocytes die and are replaced by fibrous tissue so liver shrinks)
29
Q

explain carbohydrate metabolism (blood glucose falls)

A
  • blood glucose levels fall = hepatocytes convert glycogen –> glucose under influence of the hormone glucagon