excretion

Question 1

definition of excretion

Answer 1

the removal of metabolic waste

Question 2

describe the process of urea being formed

Answer 2

• amino acids are filtered into the liver via the hepatic artery
• they are broken down into carbohydrates and then ammonia
• ammonia is very toxic so it is broken down further into urea
• urea and excess amino acids are released back into the hepatic vein

Question 3

renal artery

Answer 3

blood vessel that leads to the kidney, high concentration of urea

Question 4

kidney

Answer 4

organ that contains 1000s of Nephrons that filter the blood

Question 5

ureter

Answer 5

tube that carries urine to the bladder from the kidney

Question 6

bladder

Answer 6

organ that can hold up to 500ml of urine

Question 7

urethra

Answer 7

tube that carries urine from bladder to outside the body

Question 8

renal vein

Answer 8

blood vessel that exits the kidney, low concentration of urea

Question 9

bowmans capsule

Answer 9

where ultrafiltration occurs

Question 10

PCT

Answer 10

where selective reabsorption occurs

Question 11

loop of Henle

Answer 11

concentration of urine

Question 12

collecting duct

Answer 12

water reabsorption

Question 13

afferent arteriole

Answer 13

tube that enters the glomerulus, has a wider diameter than efferent arteriole, creating a build up of pressure

Question 14

efferent arteriole

Answer 14

tube that exits the glomerulus, has a narrower diameter than afferent arteriole, creating a build up of pressure

Question 15

stages of ultrafiltration

Answer 15

• large pressure in glomerulus forces small molecules into the bowmans capsule, forming the glomerular filtrate
• larger molecules like proteins are too big to fit through so stay in the blood

Question 16

name the small molecules that are able to pass into the bowmans capsule

Answer 16

glucose, urea, amino acids, salts

Question 17

basement membrane

Answer 17

surrounds the capillaries and controls which molecules can pass through

Question 18

stages of selective reabsorption

Answer 18

• filtrate moves along the PCT

- useful molecules such as glucose are reabsorbed back in blood via active transport

Question 19

how is the PCT adapted for selective reabsorption

Answer 19

• brush border with micro villi, increases SA

- lots of mitochondria provides energy for active transport

Question 20

stages of water reabsorption

Answer 20

• loop of Henle concentrates the urine by actively transporting salts out
• causes water to diffuse into the blood
• collecting duct responds to hormone ADH which makes collecting duct more permeable and can reabsorb more water if you are dehydrated

Question 21

osmoregulation

Answer 21

process of maintaining salt and water balance