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Slide 1

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Excretion ­ the removal of
metabolic waste from the body.…read more

Slide 2

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What needs to be excreted?
Almost any cell product formed in excess needs to be
excreted. The two main products the need to be
excreted are:
·Carbon Dioxide, ·Urea which is
which is produced by produced from excess
every living cell as a amino acids in the
result of respiration. liver.…read more

Slide 3

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Carbon Dioxide ­ Effects of too much
There are 3 main effects of too much carbon
dioxide in the body;
· The majority of CO is carried in the blood as
hydrogencarbonate ions. The formation of these
ions also forms hydrogen ions in the red blood cells.
These then combine with haemoglobin and compete
for space with oxygen. If there is too much carbon
dioxide in the blood, it can reduce oxygen transport.…read more

Slide 4

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The CO can also directly combine with
haemoglobin to form
carbaminohaemoglobin. This has a lower
affinity for oxygen then normal haemoglobin.
· CO2 dissolves in the blood plasma which
lowers the pH of the blood by disassociating
protons (CO2 + H2O H2CO3 H++ HCO3- )
This causes Respiratory acidosis if pH drops
below 7.35.…read more

Slide 5

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Nitrogenous Compounds - Urea
Deamination is where the potentially toxic amino (NH)
group is removed and used to form less toxic and
more soluble compound, urea. The urea is then
transported to the kidney for excretion.
Amino acid + Oxygen Ammonia + Keto acid
Ammonia + CO2 Urea + H2O
The body cannot store proteins
or amino acids, but as they
contain so much energy, it would
be wasteful to simply excrete
them!…read more

Slide 6

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The liver
The liver has two blood supplies, one from the heart
and one from the digestive system.
Hepatic Artery: supplies oxygenated blood from the
heart that is essential for aerobic respiration.
Hepatic Portal Vein: supplies blood from the
digestive system, rich in the products of digestion.
Concentrations of certain compounds are
uncontrolled, and the blood may contain toxic
compounds which need to be removed.…read more

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