Transcript The Kidneys

Animal Survival
Water & Waste
Mr G Davidson
Water & Waste
Getting rid of poisonous wastes and
regulating the amount of water in the body
are two important processes that occur in
animals.
If they are not performed correctly then the
animal may die.
The kidneys deal with both of these
processes.
Water Gain
Our bodies gain weight in three
different ways.
Drinking
In a typical day we drink a variety of
liquids e.g. tea, coffee, milk, etc…. All of
these liquids consist mainly of water.
Water Gain
Water from food.
All the foods we eat contain different amounts
of water.
Water from chemical reactions.
The food we eat is used up by the cells of the
body to supply energy and materials for
growth and repair. The chemical reactions that
release the energy from food also produce
water.
Water Loss
Our bodies lose weight in four
different ways.
Sweat.
Our skin produces sweat in order to cool the
body down. The hotter we are the more sweat
we produce.
Breath.
The air we breathe in may be dry or moist
depending on the weather. The air we breathe
out is always moist.
Water Loss
Urine.
We get rid of excess water and waste
products such as urea and some salts in our
urine. Urine is about.
• 96% water.
• 2% urea.
• 2% minerals.
Faeces.
Our faeces are moist so that they can be
passed out of the body easily.
The Kidneys
The kidneys have 2 main functions.
Maintaining water balance.
Getting rid of poisonous waste substances
from the body.
The Kidneys
The Kidneys
In humans the kidneys are solid, oval
shaped structures found towards the back
of the body below the ribcage.
Blood enters the kidneys through the renal
artery and leaves through the renal vein.
The blood contains useful substances like
glucose and a poisonous waste called
urea.
Testing for Glucose & Urea
Test samples of blood from the renal artery and
renal vein for both glucose and urea.
Test samples of urine for both glucose and urea.
Sample
Renal artery
Renal vein
Urine
Urea present? Glucose present?
The Kidneys
Blood entering the kidneys is filtered.
This removes water containing harmful urea and
useful glucose.
Reabsorption is another process in the kidneys
which takes back glucose and some of the water
into the blood.
This leaves behind the urea and the rest of the
water.
The amount of water reabsorbed depends on
the body’s requirements.
Water Regulation
The kidneys regulate water, but this regulation is
under control from the brain.
The brain produces ANTI-DIURETIC
HORMONE (A.D.H.) which controls the amount
of water reabsorbed by the kidney nephrons.
Different amounts of ADH are produced to suit
the varying water conditions of the body,
ensuring water balance is maintained.
ADH is one of a group of chemicals called
HORMONES.
Role of ADH
Water content of
blood too low
Salt eaten or
much sweating
Brain releases
much ADH
Too much
water drunk
Water content of
blood normal
High volume of
water passes
into blood
High volume of
water reabsorbed
by kidney
Small volume of
concentrated urine
passed to the bladder
Water content of
blood too high
Brain releases
little ADH
Low volume of
water passes
into blood
High volume of dilute
urine passed to the
bladder
Low volume of
water reabsorbed
by kidney
How the Kidneys Work
To explain filtration and reabsorption we
have to look at the detailed structure of the
kidney.
Each kidney is made up of about 1 million
tiny tubes called NEPHRONS which filter
the blood and then reabsorb the useful
substances.
How the Kidneys Work
We know that proteins are broken down to
amino acids in digestion.
These amino acids are used to build new
cells or repair tissues within the body.
Any extra amino acids not needed at the
time are broken down in the liver to a
carbohydrate and a poisonous waste
called urea.
How the Kidneys Work
The urea is then transported by the blood
to the kidney where it is removed.
If, due to kidney damage, the urea is not
removed from the blood its level will build
up and eventually cause death.
How the Kidneys Work
1. Renal artery.
2. Renal vein.
3. Glomerulus.
8
4. Distal convoluted
tubule.
5. Proximal convoluted
tubule.
6. Loop of Henlé.
7. Collecting duct.
8. Bowman’s Capsule
When Kidneys go Wrong
If the kidneys stop working because of
disease or damage, then the person will
die.
This is known as total kidney failure.
Sometimes kidney stones form in the
kidneys. This condition is not usually fatal
but can be very painful, and occasionally
blockages may occur in the kidney.
When Kidneys go Wrong
These stones can usually be removed by
operation and the patient recovers.
If, however, total kidney failure occurs
then this must be treated in one of two
ways or the patient will die.
dialysis on a kidney machine (artificial
kidney)
Kidney transplant
Sugar Diabetes
This is a common disease which in 1987
affected 600,000 people in the U.K.
It is caused by the inability of the body to deal
with glucose in the blood.
This results in too much glucose in the blood
and can be very serious to the patient.
When the blood passes through the kidney,
much of this extra glucose can’t be reabsorbed
and so is found passed out in the urine.