Kidney

Learning Objectives

1. To understand why the kidneys are so important.

2. To know how your kidneys work.

3. To know how sugar and dissolved ions are moved back into the blood. (Higher)

• Kidneys are important for homeostasis.

Kidneys

• Can you remember why??

Getting rid of urea!!

• If you eat too much protein it is broken down into amino acids.

• These amino acids are broken down by the liver and make urea.

Getting rid of urea!!

• Urea is poisonous so it must be removed!

• It passes into the blood and the kidneys will filter it out.

• When it mixes with water it makes urine.

• The urine then passes to the bladder until you want to empty it!

Kidneys

• If the concentration of fluids change in your body, it can cause water to move in or out by osmosis.

• This could destroy your cells.

Kidneys • Water levels can change by; - Breathing out water.

- Eating and drinking.

- If you sweat or not.

So how do your kidneys balance these changes?

When are you most likely to produce these urine samples?

A and B

Kidneys

• The renal artery brings blood containing urea and other substances.

• The renal vein carries blood away from the kidneys after urea and other substances have been removed from the blood.

The structure of the kidney. Blood flows in through the renal artery, is filtered and leaves the kidney in the renal vein. The waste urine, containing water, salts, and urea, passes down the ureter to the bladder.

Videos about how the kidneys work • http://www.nhs.uk/livewell/kidneyhealth/pa ges/kidneyhealthhome.aspx

• http://www.bbc.co.uk/scotland/learning/bite size/standard/biology/animal_survival/wate r_and_waste_rev3.shtml

Kidneys • If you eat a lot of processed foods they are high in salt.

• The kidneys will remove excess mineral ions that can be lost in urine.

How do your Kidneys work?

• Your kidneys filter your blood and then reabsorb everything you need.

• Glucose, amino acids, mineral salts and urea all move out of the blood into the kidneys by diffusion.

How do your Kidneys work?

• Blood cells can not pass through the membrane as they are too big.

• Then,

all

of the sugar is reabsorbed back into the blood by active transport.

• The amount of water and mineral ions reabsorbed varies depending on what your body needs.

• This is called

selective reabsorption.

How do your Kidneys work?

Higher Tier

• Both sugar and mineral ions move back into the blood by active transport.

• This is to make sure no sugar is left in the urine and the correct amount of mineral ions are reabsorbed.

How do your Kidneys work • The amount of water reabsorbed depends on what your body needs by a feedback mechanism.

• Urea is lost in your urine. • However, some of it moves from the kidneys back into the blood by diffusion.

How do your Kidneys work • Kidneys have a rich blood supply so they constantly produce urine. • It moves down the bladder until you wish to empty it.

Dialysis- an artificial kidney

Learning Objectives

1. To understand why kidneys fail.

2. To know what dialysis is.

3. To know how dialysis works.

Dialysis- an artificial kidney

• Kidneys can be damaged in a number of ways; 1. By infections 2. Genetic problems 3. Accidents

• Nick Cannon had mild kidney failure • For centuries if someone had kidney failure it would lead to death.

• We can survive on one kidney very well, but total kidney failure would be fatal if not treated.

• But now there two methods to treat this, kidney dialysis or a kidney transplant.

• Liam has one kidney

Dialysis- an artificial kidney

• If the kidneys have been damaged, toxins such as urea could build up.

• And salt and water balance can be lost.

1.

With dialysis the blood leaves their body and flow between a partially permeable membrane.

2. On the other side of the membrane is dialysis fluid.

Dialysis- an artificial kidney 3. The dialysis fluid contains the same concentration of glucose and mineral ions as normal blood plasma so there is no net movement of glucose out of the blood.

4. It contains normal plasma levels of mineral ions so excess ions are lost from the blood.

Dialysis- an artificial kidney

5. The dialysis fluid contains no urea, so all of the urea moves from the blood in to the dialysis fluid.

http://www.kidneypatientguide.org.uk/site/HDanim.php

A dialysis machine works by,

Videos about peoples experience with dialysis • http://www.nhs.uk/conditions/Dialysis/Pag es/Introduction.aspx

• http://www.nhs.uk/conditions/Dialysis/Pag es/Introduction.aspx

Disadvantages of Dialysis • Have to follow a carefully controlled diet (amount of water) • Have to have long sessions connected to a dialysis machine.

• Many years of dialysis means it can become difficult to control the balance of substances.

Advantage of Dialysis

• It is about life rather than death.

•

Kidney machines

can keep patients alive until a transplant becomes available but they have several disadvantages: • they are expensive • the patient must have his or her blood connected to the machine for several hours every week • patients must follow a very rigid diet to avoid complications • they only work for a limited time for a patient

Kidney Transplants

Learning Objectives

1. To understand why kidney transplants are sometimes rejected.

2. To be able to explain, which one is better, dialysis or a kidney transplant.

• It is about life rather than death.

Kidney Transplants

• If kidneys fail they can be replaced by a healthy kidney from a donor.

Problems with Kidney Transplants • Because the kidney comes from a different person, they will have different antigens on the surface.

• This means there is a possibility the kidney could be rejected by the immune system.

Reducing the risk of rejection

1.

2.

The tissue type is similar between the donor and the recipient and same blood group.

Also the recipient will be given immunosuppresant drugs for the rest of their lives.

Immunosuppresant drugs the down sides People who take these drugs means they can not deal with infectious diseases very well.

Dialysis vs Transplants

• Advantages • Once a person has had a transplant they can eat what they like.

• They do not have to spend long periods of time having dialysis.

• Disadvantages • There is a risk of rejection.

• Have to take immunosuppresant drugs for the rest of their lives.

• Regular check up to ensure kidney is not being rejected.

• Finding a donor as there is a lack of donors avaliable.

Videos about Kidney Transplants • http://www.nhs.uk/conditions/Kidney transplant/Pages/Introduction.aspx