kidneys

Question 1

what is osmoregulation

Answer 1

osmoregulation is the maintance of constant water levels in the fluids of an organism

Question 2

why is osmoregulation important?

Answer 2

-prevents cells bursting or shrinking when water enters or leaves by osmosis
and
-cellular reaction occur in aqueous solutions : water level affect concentration and the rate of reactions

Question 3

Describe the function of kidneys?

Answer 3

• Remove toxic waste substances from the body.
• Maintain the water levels of body fluid.
• controls the volume and concentration of urine

Question 4

what is the function of the renal artery

Answer 4

The renal artery supplies blood to the function

Question 5

What is the function of the renal vein

Answer 5

Drains blood from the kidneys

Question 6

what is the function of the urethra?

Answer 6

Releases urine from the bladder,out of the body

Question 7

What is a nephron?

Answer 7

functional unit of the kidney where filtration and selective reabsorption takes place.

Question 8

What are the three stages involved in the formation of urine

Answer 8

• Filtration
• Selective reabsorbtion
• osmoregulation

Question 9

Describe filtration in the kidneys

Answer 9

• blood flows through the capillary knots under high pressure
• small molecules such as urea ,glucose, water and salts are filtrated out of the blood and into the bow mans capsule

Question 10

why is there a build up of pressure in the capillary knots?

Answer 10

Arterioles leading into the capillary knots is wider than the arterioles taking blood away from the capillary knots

Question 11

Describe how urea is removed from the blood?

Answer 11

In the glomerulas high hydrostatic pressure is formed this is because of the afferent arterioles have a larger diameter and the efferent arterioles doesn’t. this causes ultrafiltration, so the small molecule like urea are removed from the glomerulas and into the bow mans capsule due to the high pressure and theurea being a small molecule.

Question 12

When a person is dehydrated, the cell volume of an osmoreceptor decreases. Explain why?

Answer 12

This is because the water potential of the blood decreases and water moves from the osmoreceptors into the blood by osmosis

Question 13

Give the location of osmoreceptors in mammals?

Answer 13

The hypothalamus

Question 14

If the glomerular filtrate of a diabetic person contains a high concentration of glucose, he produces a larger volume of urine.Explain why?

Answer 14

Glucose in filtrate lowers water potential and less water gets absorbed by osmosis

Question 15

Describe how ultrafiltration produces glomerular filtrate?

Answer 15

High hydrostatic pressure is in the glomerular, small molecules such as urea,glucose.water,salts pass through the basement membrane. One type of molecule that can not and should not pass through is proteins they are too large to pass through.

Question 16

Some people who have diabetes do not secrete insulin.Explain how a lack of insulin affects reabsorption of glucose in the kidneys of a person who does not secrete insulin?

Answer 16

Due to the person not being able to secrete insulin the glucose levels in the blood are highly concentrated and also there will be a high concentration of glucose in the tubules and the filtrate

Question 17

The urine of a non-diabetic person does not contain glucose.Explain why

Answer 17

This is because the glucose is reabsorbed back into the blood from the kidneys convoluted tubules.

Question 18

A high blood glucose concentration could cause glucose to be present in the blood urine of a diabetic person.Suggest why?

Answer 18

This is because there is a high concentration of glucose in the filtrate and the convoluted tube is to short to reabsorb all of the glucose.

Question 19

A test for glucose in urine uses immobilised enzymes on a plastic test strip. One of these enzymes is glucose oxidase.Explain why the test strip detects glucose and no other substances ?

Answer 19

This is because the enzyme has a specific shape to active site and the active site has a specific tertiary structure.