Excretion

Question 1

Why must waste be removed from the body?

Answer 1

Waste products can become toxic if they are not removed.

Question 2

What are the two key examples of waste products?

Answer 2

Carbon dioxide and nitrogenous waste

Question 3

How is carbon dioxide produced and removed from the body?

Answer 3

Waste product from respiration and is expired from the body

Question 4

How is nitrogenous waste produced and removed?

Answer 4

Nitrogenous waste is produced through the filteration of the blood which removes excess amino acids and is removed from the body through excretion.

Question 5

What is the function of the liver?

Answer 5

Glycogen storage
Detoxification
Formation of urea

Question 6

What blood vessels are found in the liver and what are their roles?

Answer 6

Hepatic artery - provides the liver with oxygenated blood
Hepatic vein - Carries blood away from the liver
Hepatic portal vein - Supplies the liver with blood coming from the digestive system which is rich with nutrients

Question 7

What are the cells found in the liver?

Answer 7

Hepatocytes - contain many mitochondria, a nuclei and a large golgi apparatus
- this is because they require high levels of metabolic energy

Question 8

What are kupfer cells?

Answer 8

Kupfer cells are immune cells found in the sinusoids which protect the liver against disease
Act like macrophages, engulfing any foreign particles

Question 9

Where is bile produced and transported to?

Answer 9

Produced by hepatocytes using old dead blood cells.
The bile is first secreted into spaces called canaliculi, and then it passes through bile ducts to the gall bladder, where it is stored

Question 10

How do liver cells response to insulin?

Answer 10

Absorb excess glucose from the blood and convert it to glycogen (glycogenolysis).

Question 11

How do hepatocytes respond to glucagon?

Answer 11

In response to glucagon, hepatocytes hydrolyse glycogen back into glucose and release into the blood (gluconeogenesis)

Question 12

What is detoxification?

Answer 12

The neutralisation and breakdown of unwanted chemicals such as alcohol, drugs, hormones and toxins produced in chemical reactions in the body.
Many metabolic reactions produce toxins, and the liver contains enzymes to break these down into non toxic substances

Question 13

What is deamination?

Answer 13

Deamintion is when the amine group is removed from amino acids, converting it to ammonia.
Ammonia is highly toxic so it must be converted to urea before being transported in the blood.

Question 14

What is the ornithine cycle?

Answer 14

The ornithine cycle is how urea is produced from ammonia, ready to be transported to the kidneys and excreted.

Question 15

Function of the kidney

Answer 15

The excretion of nitrogenous waste and osmoregulation.

Question 16

Structure of the kidney

Answer 16

Three distinct layers: Cortex, Medulla and Pelvis
Blood vessels: Renal artery and Renal vein
Nephrons: Bowmans capsule, Glomerulus, Proximal convoluted tubule (PCT), Descending limb, Ascending limb, Distal tubule and Collecting duct

Question 17

Where does ultrafiltration occur?

Answer 17

At the Bowmans capsule where solutes are filtered from the glomerulus through the bowmans capsule into the PCT
Solutes: amino acids, water, glucose, urea and inorganic ions)
- small molecules
This forms glomerular filtrate

Question 18

Where does selective reabsorption occur?

Answer 18

Primarily in the PCT and along the rest of the nephron