SB7i The Kidneys

Question 1

Name all the components/organs that are apart of the urinary system.

Answer 1

Renal artery
Kidney
Renal vein
Ureter
Bladder
Urethra

Question 2

Explain the process in which urea is removed from the body.

Answer 2

The kidneys receive blood from the renal artery at high pressure. The blood is oxygenated and contains urea.

The blood gets filtered, urea is removed from it and gets excreted in urine.

Urine drains all the time from the kidneys down the ureters into the
bladder.

When the bladder is full, stretch receptors transmit nerve impulses to the brain which in turn transmits nerve impulses to the sphincter muscle at the base of the urethra to relax, to empty the bladder.

Deoxygenated blood at low pressure without urea leaves the kidneys through the renal vein.

Question 3

Name all the parts of the nephron (structure).

Answer 3

Bowman’s capsule
first convoluted tube
loop of Henle
second convoluted tubule
collecting duct

Question 4

What are the three sections the nephron is split up too?

Answer 4

 Ultrafiltration
 Selective reabsorption
 Reabsorption

Question 5

What happens during Ultrafiltration?

Answer 5

The capsule has tiny holes that let small molecules like water, urea, and glucose through into the nephron. Big molecules like proteins and blood cells stay in the blood. This is called ultrafiltration.

Question 6

What happens during Selective reabsorption?

Answer 6

The fluid flows along inside the nephron. Some substances are reabsorbed back through the walls of the nephron into the blood. Only useful substance that the body needs return to the blood – such as glucose and some mineral ions. This is selective reabsorption

Question 7

How is selective reabsorption carried out? where?

Answer 7

These substances are pumped through proteins in the cell membranes of the first convoluted tubule of the nephron by active transport.

Question 8

What is a network of capillaries called?

Answer 8

glomerulus

Question 9

What happens during Reabsorption? where?

Answer 9

Water is also reabsorbed depending on how much the body needs, Water reabsorption happens in the loop of Henle and in the collecting duct.

Question 10

How are nephrons adapted for their use?

Answer 10

 Large surface area of contact between the nephron and capillaries.

 The cells membrane of the cells lining the first convoluted tubule has tiny folds called microvilli – these increase the surface area-to-volume
ratio of the cells.

 Cells that have protein pumps in the cells contain many mitochondria to
produce energy.

Question 11

What hormone controls water reabsorption and which gland releases it?

Answer 11

Antidiuretic hormone (ADH) and is released by the pituitary gland

Question 12

What happens when the brain senses there is not enough water in the blood?

Answer 12

The pituitary gland secretes more ADH which the causes kidneys to reabsorb more water.

Question 13

What does it mean if a small amount of ADH is produced? Will it result in a large volume of concentrated urine?

Answer 13

the brain senses their is too much water in the blood

Question 14

What factors cause kidney failure?

Answer 14

Kidney failure can occur due to:
 Infection
 Diabetes
 High blood pressure
 Accident

Question 15

How can Kidney failure be treated?

Answer 15

Kidney failure can also be treated by giving a patient a kidney transplant.
This involves replacing the damaged kidney with a healthy kidney from a
donor.

Question 16

What are the risks of kidney transplants?

Answer 16

One of the risks of kidney transplants is rejection.

Question 17

How is rejection during kidney transplants prevented?

Answer 17

 A donor kidney of a similar ‘tissue type’ as the patient, is used. This
means that the antigens on the new organ will be as similar as possible
to those of the patient.

 Before and after a transplant operation, a patient takes
immunosuppressant drugs. These drugs inhibit the activity of the
immune system.

Question 18

What are some problems related to transplants?

Answer 18

Immunosuppressant drugs lower a patients resistance to infection and can make infections hard to treat.

The patient will also be more susceptible to being infected by pathogens

Question 19

Explain why urine contains water but not glucose. You should refer to
the way that a nephron works in your answer.

Answer 19

Both water and glucose are filtered into the nephron in the glomerulus. In
the convoluted tubule all the glucose is reabsorbed into the blood, but
only some of the water is reabsorbed as it passes through collecting duct,
so the urine will contain some water but usually no glucose.

Question 19

What happens during kidney dialysis?

Answer 19

1. A tube is connected to a vein in the patient’s arm.
2. The patient’s blood flows along the tube, into the machine.
3. Inside the machine, the blood is pumped through semi-permeable tubes surrounded by dialysis fluid. Dialysis fluid contains in the same concentrations as the blood plasma of a healthy person.

Question 20

What are the disadvantages of kidney dialysis?

Answer 20

 It is difficult to control the diffusion of substances in a dialysis machine as well as in a kidney so people on dialysis often have to carefully control their fluid intake and diet.

 Dialysis can involve a patient going to hospital up to three times a week and being connected up to the dialyser for bout four hours at a time.

Question 21

Explain what ‘negative feedback’ means

Answer 21

When a change in something causes the opposite change to happen and
so keep the level of something fairly steady. For instance, an increase above
the normal value is corrected by a decrease down to the normal value.

Question 22

Most people with kidney failure would prefer a kidney transplant to
dialysis. Discuss the reasons for this, and explain why many people are
unable to have a kidney transplant.

Answer 22

Kidney transplant gives better control of the levels of chemicals in the
blood, which is better for you. It also means that you don’t have to have
dialysis treatment for several hours two or three times a week. However,
many people can’t have a kidney transplant because there are not enough
kidneys available for transplant, and there must be a good match of
antigens between the donor and the recipient.