The urinary system

Question 1

What does the urinary system do?

Answer 1

maintains water balance

removes excess substances absorbed from food

removes waste products from metabolism such as urea from the breakdown of proteins

Question 2

renal veins

Answer 2

carry cleaned blood back to the body

on the left of a diagram

Question 3

renal arteries

Answer 3

carry blood from the body to the kidneys

on the right of a diagram

Question 4

ureters

Answer 4

carry urine from the kidneys to the bladder

Question 5

bladder

Answer 5

stores urine

Question 6

kidneys

Answer 6

remove substances including urea from the blood and make urine

Question 7

uretha

Answer 7

urine flows through the urethra to the outside of the body

a muscle keeps the exit from the bladder closed until we decide to urinate

Question 8

urea

Answer 8

produced from the breakdown of excess amino acids in the liver

toxic

Question 9

urine

Answer 9

contains waste substances, water, urea, mineral ions

Question 10

What does a kidney contain?

Answer 10

around a million tiny tubules called nephrons which make urine

Question 11

stage 1

Answer 11

filtration

blood from renal artery passes into:
GLOMERULUS - network of capillaries

blood is under high pressure

small molecules are squeezed out and pass into the BOWMAN’S CAPSULE

urea, mineral ions and glucose move by diffusion
water moves by osmosis

larger molecules remain in the blood

Question 12

stage 2

Answer 12

selective reabsorption

filtrate passes into the FIRST CONVOLUTED TUBULE

molecules which are needed need to be reabsorbed, while others can form urine

the kidneys reabsorb only what is needed

• all of the glucose is reabsorbed
• as much water as is needed
• some mineral ions

molecules are pumped by active transport through proteins in the cell wall of the tubule

Question 13

stage 3

Answer 13

formation of urine

filtrate passes into the LOOP OF HENLE

more water is absorbed by osmosis, as well as some mineral ions

rest of the filtrate passes into the COLLECTING DUCT

what is now called urine passes through the ureter to the bladder, where it is stored

it contains urea, excess water, and some mineral ions

the filtered blood is taken away to the renal vein

Question 14

adaptations

Answer 14

first convoluted tubule is curved to increase surface area
capillaries have increased surface area as well as they are smaller

folds in the cell membrane called microvilli increase surface area so more selective reabsorption can take place

contains lots of mitochondrian to provide energy for active transport so more can take place

lots of protein molecules for more active transport

loop of henle is long to increase surface area

Question 15

List the structures of the urinary system that urea passes through, in order, starting with blood in the renal artey.

Answer 15

(-blood in renal artery

• bowman’s capsule
• first convoluted tubule
• loop of henle
• second convoluted tubule
• collecting duct)
• kidney
• ureter
• bladder
• uretha

Question 16

Explain why a patient will die if they have kidney failure which is not treated.

Answer 16

body processes make waste products such as urea

if too much urea builds up in the blood, it becomes toxic, which will damage the body