(5) Excretion

Question 1

Excretion

Answer 1

Removal of metabolic waste form the body.
The kidney excretes urea and is responsible for osmoregulation - control of water and salt levels.
The liver turns ammonia into urea which can be excreted in the urine.

Question 2

Structure of the liver

Answer 2

Bile is made and secreted by the liver, then transported by the bile duct to the gall bladder for storage.

Hepatic portal vein (inter lobular) - connects the liver to the kidney.
Hepatic artery (inter lobular) -blood flow into the liver.
Hepatic vein (intra lobular) - blood flow away from the liver (bottom)

Sinusoids - blood from the hepatic artery and hepatic portal vein is mixed here.
Kupffer cell - recycles old red blood cells and breaks down haemoglobin into bilirubin which is secreted in bile.
Hepatocytes - remove substances from blood in sinusoids and secrete waste back into it. Microvilli - large surface area for absorption/secretion. Lots of ribosomes for protein synthesis and mitochondria for energy.

Question 3

Storage of glycogen

Answer 3

Made form alpha glucose. Highly branched, making it good for storage and insoluble. Enzymes can break down glycogen into glucose when the body needs energy.