Excretion and liver structure

Question 1

What is excretion?

Answer 1

The process of an organism removing waste metabolic products

Question 2

What’s the importance of excretion?

Answer 2

Waste is removed from cells as it would be harmful if allowed to accumulate and it has no value to organism

Question 3

What are waste products of vertebrate animals?

Answer 3

Gases (CO2), nitrogenous waste and bile pigments from breakdown of RC

Question 4

What are methods of excretion?

Answer 4

Passive diffusion and internal excretory organisms

Question 5

What is passive diffusion as a method of excretion?

Answer 5

Through normal body surface or specialised structure with large surface area (lungs,gills)

Question 6

What is internal excretory organs as a method of excretion?

Answer 6

Assist removal of metabolic products from interstitial fluid (lymph, blood plasma)

Question 7

What are routes of excretion in vertebrates?

Answer 7

Kidney, lungs, sweat and bile

Question 8

How are the kidneys a route of excretion?

Answer 8

They work by filtration and selective reabsorption but also involved in osmoregulation

Question 9

How are waste products excreted from the kidneys?

Answer 9

Nitrogenous waste products are excreted as urine

Question 10

How are the lungs a route of excretion?

Answer 10

Excrete carbon dioxide by diffusion

Question 11

What is excreted by sweat?

Answer 11

Ammonia, urea, uric acid, amino acids, salts, lactic acid and hydrogen carbonate ions

Question 12

How is sweat a method of excretion?

Answer 12

It is continuous and rate can increase if cooling needed

Question 13

How is bile a method of excretion?

Answer 13

Hydrogen carbonate ions are released into the bile, as well as pancreatic and intestinal juices

Question 14

What is the function of bile as a route of excretion?

Answer 14

It regulates intestinal pH and excretory CO2

Question 15

Why does CO2 need to be excreted?

Answer 15

It is a waste products of cellular respiration

Question 16

How is CO2 carried in the blood?

Answer 16

Dissolved in plasma, in carbaminohaemoglobin and converted into HCO3- ions

Question 17

What percentage of CO2 is dissolved in plasma?

Answer 17

5%

Question 18

What percentage of CO2 is converted into carbaminohaemoglobin?

Answer 18

25%

Question 19

What percentage of CO2 is converted into HCO3- ions?

Answer 19

705

Question 20

How is CO2 dissolved in plasma?

Answer 20

Can form carbonic acid when combined with water

Question 21

How is CO2 converted into carbaminohaemoglobin?

Answer 21

It diffuses into red blood cells

Question 22

How is CO2 converted into HCO3- ions?

Answer 22

Converted in red blood cells which passes back to plasma to transport, and H+ lowers blood pH

Question 23

What are the types of nitrogenous waste products?

Answer 23

Ammonia, urea and uric acid

Question 24

What does the type of nitrogenous waste products depends on?

Answer 24

Water availability

Question 25

What is the solubility and toxicity of ammonia?

Answer 25

High

Question 26

What is the solubility and toxicity of urea?

Answer 26

Middle

Question 27

What is the solubility and toxicity of uric acid?

Answer 27

Low

Question 28

What type of organism produces ammonia?

Answer 28

Freshwater animals since there is plentiful water supply

Question 29

What type of animals produce urea?

Answer 29

Marine animals and many terrestrial animals where water can be gained in adequate amounts

Question 30

What type of organism produces urea?

Answer 30

Reptiles and birds as can be stored (in eggs) and eliminated with little water (adults)

Question 31

What is the energetic cost of ammonia?

Answer 31

Low cost but toxic so need a lot of water

Question 32

What is the energetic cost of urea?

Answer 32

Medium, as less toxic so can store but needs water to excrete

Question 33

What is the energetic cost of uric acid?

Answer 33

Expensive to make, but little water needed

Question 34

What is deamination?

Answer 34

Amino acids from the diet or unwanted proteins once hydrolysed are transported in the blood

Question 35

Why is deamination is important?

Answer 35

Excess levels of amino acids are toxic and cannot be stored so are broken down

Question 36

Why are excess amino acids toxic?

Answer 36

The amino group

Question 37

Where does break down of amino acids occur?

Answer 37

In hepatocytes in the liver

Question 38

How are amino acids initially broken down?

Answer 38

Amino acids are broken down with oxygen to form a keto acid and ammonia

Question 39

How is keto acid broken down?

Answer 39

Either enters the Krebs cycle and produce ATP or converted to carbohydrate/fat and stored

Question 40

How is ammonia broken down?

Answer 40

It is instantly converted to urea in the ornithine cycle which is filtered out the blood by kidneys

Question 41

What is the ornithine cycle?

Answer 41

Ammonia + CO2 -> Water + Urea (using ATP)

Question 42

Why is ammonia broken down into urea?

Answer 42

Ammonia is very toxic, whereas urea is less toxic and less soluble

Question 43

What are functions of the liver?

Answer 43

Deamination, homeostatic control of blood glucose (glycogen), storage of iron and glycogen, breakdown by detoxification, synthesis of plasma proteins and formation of bile

Question 44

What is the importance of detoxification?

Answer 44

Ingested drugs or naturally occurring hydrogen peroxide produced in the body can damage cells

Question 45

What is detoxification?

Answer 45

Making toxins harmless

Question 46

What do liver cells contain?

Answer 46

Enzymes which detoxify molecules

Question 47

What are methods of detoxification?

Answer 47

Combining with other molecules, oxidation, reduction and methylation

Question 49

Why does alcohol need to be broken down?

Answer 49

It contains ethanol ,which is lipid soluble so moves through cells easily and depresses nerve activity

Question 50

How is ethanol broken down?

Answer 50

Using alcohol dehydrogenase and oxidised NAD to form ethanal

Question 51

How is ethanal broken down?

Answer 51

Using ethanal dehydrogenase and oxidised NAD to form ethanoic acid, which can be used in the link cycle

Question 52

What happens if you drink too much alcohol?

Answer 52

Reduced NAD builds up and oxidised NAD becomes low, fatty acid builds up and a condition called fatty liver develops

Question 53

What is the result of fatty liver?

Answer 53

Hepatocytes are destroyed, reduced blood supply to lobules, Nh3 builds up so liver cannot function and can lead to death