The Kidneys

Question 1

vena cava :

Answer 1

main vein returning blood to the heart

Question 2

renal vein :

Answer 2

takes “cleaned” blood away from kidneys

Question 3

aorta :

Answer 3

main artery supplying oxygenated blood to body

Question 4

renal artery :

Answer 4

brings blood containing “waste” to the kidneys

Question 5

urethra :

Answer 5

carries urine out of the body

Question 6

ureter :

Answer 6

carry urine to the bladder

Question 7

bladder :

Answer 7

muscular sac that stores urine (~ 700 cm)

Question 8

sphincter muscle :

Answer 8

keeps bladder close

Question 9

medulla :

Answer 9

lighter middle layer of kidney

Question 10

pelvis :

Answer 10

central cavity which collects urine

Question 11

cortex :

Answer 11

darker outer layer

Question 12

nephron :

Answer 12

filtration unit (where the urine is produced)

Question 13

The main function of the kidney is to ….

Answer 13

get rid of waste such as:
• Urea
• Excess water
• Excess salt (mineral ions)

Question 14

Substances found in uncleaned blood :

Answer 14

urea, proteins, cells, glucose, amino acids, salt and water

Question 15

Substances found in urine :

Answer 15

urea and some salt and water

Question 16

Substances found in cleaned blood :

Answer 16

proteins, cells, glucose, amino acids, some salt and water and very little urea

Question 17

It is important to remove urea because …

Answer 17

it is toxic

Question 18

It is important to remove excess water because …

Answer 18

of its osmotic effect

Question 19

It is important to remove excess salt because …

Answer 19

of its osmotic effect

Question 20

When you compare the composition of blood and urine, you can see that some substances are ….

Answer 20

more abundant in urine than in blood

Question 21

The substances more abundant in urine than in blood are …

Answer 21

waste substances, such as urea, which the body doesn’t want

Question 22

There is about 60 times more urea …

Answer 22

in urine than in blood

Question 23

The explanation is that as the blood passes through the kidney …

Answer 23

urea is taken out of it and passed into the urine.

Question 24

However, the kidneys do more than simply …

Answer 24

cleanse the blood of urea

Question 25

. They also regulate the …

Answer 25

amount of water and salt in the blood and also make sure that the pH of the blood is constant

Question 26

The concentration of water and salt in our blood changes depending on …

Answer 26

what you eat and drink

Question 27

If you drink a lot of water …

Answer 27

it is absorbed from your gut into the bloodstream and it has a diluting effect on the blood. The diluted blood reaches the kidney, which takes out more water than usual and pass it into the urine, thereby producing more urine, which is dilute.

Question 28

If you eat a lot of salt,

Answer 28

the solute concentration in your blood increases. To counteract this, the kidneys take out less water from the blood and pass it into the urine, therefore producing less urine

Question 29

By regulating the water and salt concentrations …

Answer 29

the kidneys make sure that the concentration of the blood stays more or less the same all the time

Question 30

Regulating the water and salt concentration is important …

Answer 30

so that also the solute concentration in our body cell is constant. Otherwise, osmosis would occur and our cells would not function properly

Question 31

Regulating the water and salt concentration is known as ….

Answer 31

osmoregulation and is an example of homeostasis.

Question 32

Explain what happen when some food (chicken) is eaten.

Answer 32

o mechanically broken by mouth from chicken to protein
o in the digestive system protein is chemically broken down into amino by protease
o most of the amino acids are absorbed into blood but excess is transported to the liver, where it is converted to urea
o via the kidney, it will leave the body as urine

Question 33

Urine production in the nephron - Step One :

Answer 33

Ultrafiltration

Question 34

Ultrafiltration occurs in the …

Answer 34

glomerulus and the Bowman’s capsule

Question 35

Step One : Ultrafiltration

Answer 35

o blood arrives at a high pressure in the glomerulus
o small molecules are squeezed through pores in the walls of the glomerulus and into the Bowman’s capsule
o large molecules and cells stay in blood (too large to fit through pores)
o result : filtrate contains small molecules

Question 36

Urine production in nephron - Step Two :

Answer 36

Selective Reabsorption

Question 37

Step Two occurs in the …

Answer 37

first coiled tubule

Question 38

The first coiled tubule is also known as the …

Answer 38

proximal convoluted tube

Question 39

Step Two : Selective Reabsorption

Answer 39

o useful molecules such as glucose, amino acids and salts are reabsorbed into the bloodstream by active transport
o some filtrate water moves back into the blood via osmosis
o urea stays in the filtrate
o result : filtrate containing urea

Question 40

Where is blood water level adjusted by the kidneys?

Answer 40

o Some water is filtered into the nephron from blood
o In the PCT some water is reabsorbed into the blood
o In the Loop of Henle more water is reabsorbed into the blood
o In the collecting duct, water levels are finally adjusted and more water is reabsorbed into the blood
o Some water is excreted in urine

Question 41

Water homeostasis : being thirsty

Answer 41

o ADH is secreted
o collecting duct becomes more permeable to water
o more water is reabsorbed into the bloodstream
o less urine is produced

Question 42

Water homeostasis : when hydrated

Answer 42

o less ADH is secreted
o collecting duct is less permeable to water
o less water is reabsorbed into the bloodstream
o more urine is produced