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
• Kidneys are
important for
homeostasis.
• 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 arterybrings 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/Kidneytransplant/Pages/Introduction.aspx