Excretion

Question 1

What are the liver cells called?

Answer 1

Hepatocytes

Question 2

How is the liver supplied with blood?

Answer 2

Via the hepatic artery and the hepatic portal vein

Question 3

What is the function of the hepatic artery?

Answer 3

Oxygenated blood is supplied from the aorta via this artery. Supplies oxygen for aerobic respiration.

Question 4

What is the function of hepatic portal vein?

Answer 4

Deoxygenated blood from the digestive system enters here from the intestine. This blood is rich in the products of digestion. The blood may also contain toxic compounds. The concentrations in the blood here will be uncontrolled

Question 5

Where does blood leave the liver and go?

Answer 5

Blood leaves via the hepatic vein and rejoins the vena cava.

Question 6

What is the fourth vessel connected to the liver?

Answer 6

The bile duct

Question 7

What is the function of the bile duct?

Answer 7

Bile is secreted from the liver to be used in digestion and excretion. The bile duct carries the bile to the gall bladder.

Question 8

Why does bile go to the gall bladder?

Answer 8

To be stored until required to aid digestion of fats in the small intestine.

Question 9

What does bile contain?

Answer 9

Excretory products such as bile pigments like bilirubin which will leave the body with faeces

Question 10

How is the liver divided?

Answer 10

Into lobes which are dither divided into lobules.

Question 11

What are the 3 structures to label in a microscopic image of the liver lobules?

Answer 11

Inter lobular vessel
Intra-lobular vessel
Liver lobule

Question 12

What are the inter-lobular vessels?

Answer 12

The smaller vessels that the hepatic artery and hepatic portal vein split into where they enter the liver. They run between and parallel to the lobules.

Question 13

What is the sinusoid?

Answer 13

Lined with liver cells

The blood from both the hepatic portal vein and hepatic artery flows along here in close contact with liver cells.

Question 14

What can the liver cells in contact with the sinusoid do?

Answer 14

They can remove substances from the blood and return other substances to the blood.

Question 15

What are kupffer cells?

Answer 15

Specialised macrophages that can move about with the sinusoids?

Question 16

What is the function of kupffer cells?

Answer 16

To breakdown and recycle old red blood cells.

Question 17

What is the product of haemoglobin?

Answer 17

Bilirubin

Question 18

What forms the bile duct?

Answer 18

The bile canaliculi

Question 19

What has happened to the blood by the end of the sinusoid?

Answer 19

The concentrations of the blood components have been modified and regulated.

Question 20

What is found at the centre of each lobule?

Answer 20

A branch of the hepatic vein known as the intra-lobular vessel.

Question 21

Describe hepatocytes?

Answer 21

Cuboidal shape
Have many microvilli on the surface
Dense cytoplasm

Question 22

Metabolic functions that occur in hepatocytes?

Answer 22

Protein synthesis
Transformation and storage of carbohydrates
Synthesis of cholesterol and bile salts
Detoxification

Question 23

Liver functions?

Answer 23

Detoxification of alcohol and drugs
Breakdown of hormone
Destruction of red blood cells

Question 24

What levels are controlled by the liver?

Answer 24

Glucose levels
Amino acid levels
Lipid levels

Question 25

What does the liver synthesise?

Answer 25

Bile Plasma proteins Cholesterol Red blood cells in the fetus

Question 26

What does the liver store?

Answer 26

Vitamins A, D and B12 Iron Glycogen

Question 27

Enzymes contained by liver?

Answer 27

Catalase | Cytochrome P450

Question 28

Where is alcohol broken down?

Answer 28

In the hepatocytes

Question 29

Which enzyme action is involved in the detoxification of ethanol?

Answer 29

Ethanol dehydrogenase.

Question 30

How is ethanol dehydrogenated further?

Answer 30

By the enzyme ethanal dehydrogenase

Question 31

What is the final compound produced in the detoxification of ethanol?

Answer 31

Ethanoate acetate | This acetate is combined with coenzyme A to form acetyl coenzyme A

Question 32

What atoms are released from the alcohol?

Answer 32

2H (hydrogen)

Question 33

What happens to the hydrogen released from the alcohol detoxification?

Answer 33

It combines with a Coenzyme called NAD to then form reduced NAD

Question 34

Why can't amino acids be stored?

Answer 34

As the amine group makes them toxic

Question 35

What is NAD also used for?

Answer 35

The breakdown of fatty acids

Question 36

Why can drinking to much alcohol cause the liver to become enlarged?

Answer 36

As the liver will have insufficient stores of NAD to break down the fatty acids. The fatty acids will therefore be converted back to lipids and stored as fat in the hepatocytes

Question 37

Why aren't amino acids excreted as a whole molecule?

Answer 37

As they contain a lot of energy

Question 38

What are the two processes to remove and excrete the amino component called?

Answer 38

Deamination followed by the ornithine cycle

Question 39

What is the process of deamination?

Answer 39

Removes the amino group and produces ammonia.

Question 40

Describe ammonia?

Answer 40

Very soluble and highly toxic | Must not be allowed to accumulate.

Question 41

What does deamination produce?

Answer 41

Ammonia and a Keto acid

Question 42

What can a Keto acid do?

Answer 42

Enter respiration directly to release its energy

Question 43

What is the structure of an amino acid?

Answer 43

A carbon in the middle Carboxyl group to the right 2NH2 to the left Hydrogen below

Question 44

What gets added to an amino acid in deamination?

Answer 44

Oxygen

Question 45

What is the structure of a Keto acid?

Answer 45

2 Carbon in the middle Double bond downwards to oxygen Carboxyl group to the right

Question 46

What is the formula for ammonia?

Answer 46

2NH3

Question 47

What are the 3 parts of a kidney?

Answer 47

Outer- cortex Inner- medulla Centre- Pelvis which leads to the ureter

Question 48

How does ammonia produce urea?

Answer 48

By combining with carbon dioxide

Question 49

What do ammonia, carbon dioxide combined with the amino acid produce?

Answer 49

Citrulline

Question 50

What is converted by the further addition?

Answer 50

Arginine

Question 51

What is arginine re-converted to and how?

Answer 51

To orthinine by the removal of urea

Question 52

Word equation for deamination?

Answer 52

Amino acid plus oxygen | Equals Keto acid plus ammonia

Question 53

External kidney structures?

Answer 53

Cortex Medulla Pelvis

Question 54

Where does the pelvis lead to?

Answer 54

Ureter

Question 55

What is at the start of the nephron?

Answer 55

The Bowmans Capsule

Question 56

How does blood enter the kidney?

Answer 56

Via the renal artery | Splits to form many afferent arterioles

Question 57

Describe the glomerulus?

Answer 57

A knot of capillaries Blood enters the glomerulus via the afferent arterioles and leaves via the efferent arteriole Surrounded by the Bowmans capsule

Question 58

Where does ultrafiltration occur?

Answer 58

Barrier between capillary and lumen of Bowmans capsule

Question 59

What are the 3 layers of ultrafiltration?

Answer 59

Endothelium of capillary Basement membrane The epithelial cells of Bowman's capsule

Question 60

What is the basement membrane made up of?

Answer 60

Colleges fibres and glycoproteins

Question 61

How does the blood pass through the endothelium of the capillary?

Answer 61

The gaps between the endothelium cells | The pores within the endothelium cells

Question 62

Role of basement membrane?

Answer 62

Prevents the passage of molecules of a larger relative molecular mass

Question 63

What can't pass through the basement membrane?

Answer 63

Most proteins | All blood cells

Question 64

What are the cells called than line the Bowmans capsule?

Answer 64

Podocytes

Question 65

Describe podocytes?

Answer 65

Contain many finger like projections- major processes | On each major process are foot processes

Question 66

Role of foot processes?

Answer 66

Ensure that there are gaps between the endothelium cells of the capillary

Question 67

What are the 3 parts of the tubule?

Answer 67

Proximal convoluted tubule Loop of henle Distal convoluted tubule

Question 68

Describe the mechanism of reabsorption?

Answer 68

Sodium ions are pumped out of the cell Sodium ions diffuse back in cotransporting amino acids or glucose This decreases water potential so water moves in by osmosis