I/E: The Kidneys

Question 1

What are the main functions of the kidneys?

Answer 1

• Excrete waste products, eg. urea.
• Regulate the water potential of the blood.

Question 2

Ultrafiltration

Answer 2

The process of blood passing through capillaries in the cortex (outer layer) of the kidneys and substances being filtered out and into long tubules surrounding capillaries.

Question 3

Selective reabsorption

Answer 3

The process after ultrafiltration where useful substances, eg. glucose and the right amount of water, are reabsorbed back into the blood.

Question 4

What happen to unwanted substances after selective reabsorption?

Answer 4

Pass to the bladder and are excreted as urine.

Question 5

Nephrons

Answer 5

Long tubules along with bundles of capillaries where the blood is filtered in the kidneys.

Question 6

Describe the process of ultrafiltration:

Answer 6

1. Blood from renal artery enters arterioles in cortex of kidneys.
2. Passes through afferent arteriole into the glomerulus.
3. Passes into the efferent arteriole that has a higher pressure.
4. Forces liquid and small molecules in blood out of the capillary.
5. Pass through capillary wall, basement membrane and epithelium of Bowman’s capsule.
6. Glomerulus filtrate passes from Bowman’s capsule along the rest of the nephron and useful substances are reabsorbed.
7. Filtrate flows through collecting duct and passes out of kidneys along the ureter.

Question 7

Glomerulus

Answer 7

Bundle of capillaries looped inside a hollow ball called a Bowman’s capsule.

Where ultrafiltration takes place.

Question 8

Afferent arteriole

Answer 8

Arteriole that takes blood into each glomerulus.

Question 9

Efferent arteriole

Answer 9

Arteriole that takes blood away from the glomerulus.

Question 10

Glomerular filtrate

Answer 10

Substances that enter Bowman’s capsule.

Question 11

The process of blood passing through capillaries in the cortex (outer layer) of the kidneys and substances being filtered out and into long tubules surrounding capillaries.

Answer 11

Ultrafiltration

Question 12

The process after ultrafiltration where useful substances, eg. glucose and the right amount of water, are reabsorbed back into the blood.

Answer 12

Selective reabsorption

Question 13

Long tubules along with bundles of capillaries where the blood is filtered in the kidneys.

Answer 13

Nephrons

Question 14

Bundle of capillaries looped inside a hollow ball called a Bowman’s capsule.

Where ultrafiltration takes place.

Answer 14

Glomerulus

Question 15

Arteriole that takes blood into each glomerulus.

Answer 15

Afferent arteriole

Question 16

Arteriole that takes blood away from the glomerulus.

Answer 16

Efferent arteriole

Question 17

Substances that enter Bowman’s capsule.

Answer 17

Glomerular filtrate

Question 18

What is the difference between the afferent arteriole and efferent arteriole?

Answer 18

Efferent arteriole is smaller in diameter than the afferent arteriole, so the blood in the glomerulus is under high pressure.

Question 19

What does the high pressure in the glomerulus do?

Answer 19

Forces liquid and small molecules in the blood out of the capillary and into the Bowman’s capsule.

Question 20

The liquid and small molecules forced out of the blood pass through what three layers before entering the Bowman’s capsule?

Answer 20

Capillary wall

Basement membrane

Epithelium of Bowman’s capsule.

Question 21

What type of molecules can’t pass through the layers to enter the Bowman’s capsule?

Answer 21

Larger molecules, eg. proteins and blood cells.

Question 22

Label this diagram of the kidneys:

Answer 22

Question 23

Label this diagram of the nephron:

Answer 23

Question 24

When does selective reabsorption take place?

Answer 24

As glomerular filtrate flows along proximal convuluted tubule (PCT), through the loop of Henle, and along distal convoluted tubule (DCT).

Question 25

Describe an adaption of the PCT for effective reabsorption:

Answer 25

Epithelium of the wall of PCT has microvilli = provides a large surface area.

Question 26

Which processes are used to reabsorb useful solutes along the PCT?

Answer 26

Active transport and facilitated diffusion.

Question 27

How does water enter the blood?

Answer 27

Through osmosis - water potential of blood is lower than that of the filtrate.

Question 28

Where is water reabsorbed?

Answer 28

From the PCT, loop of Henle, DCT and collecting duct.

Question 29

What is urine usually made of?

Answer 29

* Water and dissolved salts * Urea * Other substances, eg. hormones and excess vitamins.

Question 30

What does urine usually **not** contain?

Answer 30

* Protein and blood cells - too big to filter out of blood. * Glucose - actively reabsorbed back into the blood.