GCSE · Biology · Edexcel · Spec 1BI0

Treatments for kidney failure

Your kidneys are filtering your blood right now. Switch them off and a clock starts. Dialysis or a donor kidney: which one wins?

Biology · Weighing two treatments

Is a kidney transplant a better treatment than dialysis?

The claim

A kidney transplant is a better treatment for kidney failure than dialysis.

Place each piece of evidence to load the balance. Mark the strong ones — they count double.

  1. A transplant is a long-term treatment.

    Evidence 1: does it support or challenge the claim?

  2. Dialysis takes several hours and must be completed several times per week.

    Evidence 2: does it support or challenge the claim?

  3. Dialysis can damage the veins.

    Evidence 3: does it support or challenge the claim?

  4. Dialysis may increase the chances of infection.

    Evidence 4: does it support or challenge the claim?

  5. There is a shortage of kidney donors, so patients are often on a waiting list for a very long time.

    Evidence 5: does it support or challenge the claim?

  6. Immunosuppressant drugs are needed to stop the body rejecting the foreign kidney, and are usually taken for the rest of the patient's life.

    Evidence 6: does it support or challenge the claim?

  7. The operation itself carries risks, such as blood loss.

    Evidence 7: does it support or challenge the claim?

  8. Dialysis allows patients to survive until a transplant can occur.

    Evidence 8: does it support or challenge the claim?

Why kidney failure is dangerous

?

Reason it through

Why will a person with kidney failure die if nothing is done?

Link 1 of 4

First link · your turn

Start at the beginning. What can make a person's kidneys fail?

2
Locked — reveal the link above first
3
Locked — reveal the link above first
4
Locked — reveal the link above first

One dialysis session, step by step

Step through it. Which stage is the blood actually cleaned in?

Predict: what moves?

Think about what is already in the dialysis fluid before you choose.

The dialysis fluid has the same concentration of glucose as the patient's blood plasma, and no urea at all. What happens to glucose and urea in the patient's blood?

Biology · Transplant myths

Which idea do you hold?

A patient with kidney failure is being considered for a kidney transplant.

Which of these is closest to what you think right now?
How sure are you?

WHAT YOU'VE LEARNED

A quick recap of today's lesson.

Two treatments, one job: stop waste building up in the blood. Which one costs the patient less?

What you need to know

  • Kidney failure means both kidneys fail to work properly, so the blood isn't filtered effectively.
  • It could be inherited, or caused by a communicable disease or by injury.
  • Waste products stay in the blood, so urea and ions build up. If they aren't reduced, they become toxic and the person dies.
  • Have a goYour mate says: "If the kidneys stop working, the blood stays exactly the same." Which two things build up, and why does it matter?

    Urea and ions build up. They become toxic, and the person will die if they aren't reduced.

    With no effective filtering, waste products aren't removed, so the concentration of urea and ions in the blood increases.

  • There are two treatments: kidney dialysis (an external machine filters the blood) and a kidney transplant (a donor kidney is used).
  • Dialysis temporarily removes blood, filters it in a machine, then returns it. It replaces the kidney's role; it doesn't cure.
  • Have a goPut these in order: blood returned to the body, blood filtered in the machine, blood temporarily removed.

    Removed, then filtered in the machine, then returned.

    The filtering happens outside the body, so the blood has to leave for a while and come back afterwards.

  • Dialysis fluid has the same glucose concentration as blood plasma but no urea, so glucose stays and urea diffuses out.
  • Dialysis takes several hours and must be completed several times per week.
  • A transplant is a long-term treatment, but it needs a good tissue match. Different antigens mean the patient's body rejects the kidney.
  • Have a goA classmate says: "The donor's body rejected the kidney." Whose body is doing the rejecting, and what does it spot?

    The patient's body, which recognises the kidney's different antigens as foreign tissue.

    The donor kidney is the thing being judged. The immune response belongs to the patient who receives it.

  • Relatives tend to match as they share many alleles; a sibling isn't guaranteed, and matching happens before the operation.
  • Donors can be alive or recently deceased, because a person can cope with only one kidney.

The big picture

Kidney failure means both kidneys fail to work properly, so urea and ions build up in the blood until they become toxic. Kidney dialysis filters the blood in an external machine; a kidney transplant uses a donor kidney. Each treatment has real advantages and real costs, so your job is to weigh them and justify a judgement.

Key points

1Kidney failure: both kidneys fail to work properly, so waste products aren't removed. Urea and ions build up, become toxic, and the person dies if they aren't reduced.
2Dialysis filters the blood in an external machine. Urea diffuses into the dialysis fluid through a selectively permeable membrane; glucose stays because the fluid has the same glucose concentration as the plasma.
3Dialysis replaces the kidney's role but does not cure kidney failure, and a session takes several hours, several times per week.
4A transplant uses a donor kidney. It is a long-term treatment, but it needs a good tissue match, and the patient's body rejects a kidney with different antigens.
5Weigh both treatments by their costs: dialysis costs time every week; a transplant costs matching, waiting, drugs usually for life, and operation risks.

Worked example

Problem

Maya needs a kidney transplant and her sister Ana offers to donate. Maya says: "Ana is my sister, so her kidney is bound to be a match and my body won't reject it." Explain what is wrong with Maya's thinking.

⚠ Watch out

Writing "the donor's body rejects the kidney". The rejecting is done by the patient's body. Another trap: calling dialysis a cure. It replaces the kidney's role but doesn't cure kidney failure.

🧠

Memory hook

Dialysis pays in TIME, every week. A transplant pays in MATCHING, WAITING and TABLETS.

✓

Check yourself

Name one cost of dialysis and one cost of a kidney transplant. Then say which cost you think matters more to a patient, and why.

Flashcards

(14)
What is kidney failure?
Both kidneys fail to work properly, so the blood can't be filtered effectively.
What can cause kidney failure?
It could be inherited, or caused by a communicable disease or by injury.
Why is untreated kidney failure fatal?
Waste isn't removed, so urea and ions in the blood increase until they become toxic to the body.
Name the two treatments for kidney failure.
Kidney dialysis (an external machine filters the blood) and a kidney transplant (using a donor kidney).
Does dialysis cure kidney failure?
No. It replaces the role of the kidney with an external machine.
Why does glucose stay in the blood during dialysis?
The dialysis fluid has the same concentration of glucose as the blood plasma, so glucose doesn't move out.
Why does urea leave the blood during dialysis?
The dialysis fluid contains no urea, so urea diffuses from the blood into the fluid through the selectively permeable membrane.
How long and how often is dialysis?
Several hours, and it must be completed several times per week.
Two advantages of dialysis?
It lets patients survive until a transplant can occur, and it lowers the urea in the blood.
Disadvantages of dialysis?
Several hours several days a week; needs specialist equipment; can damage the veins; may increase the chances of infection.
Why does a transplant fail if the antigens differ?
The patient's body recognises the donor kidney as foreign tissue and rejects it.
Why are relatives good sources of donor kidneys?
They tend to have a good tissue match because they share many of the same alleles. A sibling still isn't guaranteed to match.
Who can donate a kidney?
Living donors (a sibling, for instance) or recently deceased donors, because a person can cope with only one kidney.
Disadvantages of a kidney transplant?
A shortage of donors and a long waiting list; immunosuppressant drugs usually for life; risks of the operation, such as blood loss.

Tap any card to flip it, or use Study as deck to go through them one at a time. In the full lesson these run as a spaced-repetition deck — you rate each card Hard, Good or Easy and the tricky ones keep coming back until they stick.

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