Planet Earth and Its Environment A 5000-million year

Maintaining a Balance
Topic 11: Changes in Blood
Biology in Focus, HSC Course
Glenda Childrawi, Margaret Robson and Stephanie Hollis
 Describe the main changes in the chemical composition of
the blood as it moves around the body and identify tissues in
which these changes occur.
The circulatory system in mammals is like a road system within a
city – it is responsible for the transport of substances to and from
various parts. This transport system is involved in moving four
basic groups of chemicals:
1. Gases (carbon dioxide and oxygen)
2. Nutrients
3. Wastes
4. Hormones (chemical signals)
Assisting Metabolism
The chemical functioning of cells (metabolism) relies on the
correct balance of chemical reactants being brought to cells and
the removal of wastes produced.
Assisting Metabolism
Energy is the basis of all
metabolic functioning – for any
cell to function it must produce
the energy it requires by means
of cellular respiration. This
energy production depends on
the correct balance of nutrients
such as glucose and the gas
oxygen arriving at the site.
Assisting Metabolism
Requirements for energy production must be transported from
their source (glucose and food-based nutrients from the digestive
system and oxygen from the lungs) to the sites where they are
needed – the cells of the body that require energy.
Assisting Metabolism
The transport system of vessels
throughout the body is essential,
since the mammalian body is to
large and complex to simply rely
on diffusion for movement of
these substances.
Assisting Metabolism
Once the reactants reach the cells, cellular respiration occurs:
oxygen is combined with glucose to produce energy in the form
of ATP (the chemical energy of cells), and carbon dioxide and
water are released as by-products of this process. The carbon
dioxide is removed as waste.
Assisting Metabolism
Nitrogenous wastes are the end
products of protein breakdown
that occurs during metabolic
functioning. All wastes are
carried from their sites of
production, to organs where
they can be excreted. The blood
vessels are responsible for this
transport of wastes, to ensure
that conditions are right for
enzyme functioning in
Assisting Metabolism
In addition, the transport system is responsible for transporting
hormones – chemical messenger molecules produced by
endocrine glands. These are ductless glands and so they pour
their secretions directly into the bloodstream, which transports
them to their target organs.
Assisting Metabolism
Hormones such as those that
control water and salt balance in
animals are essential to assist
homeostasis, ensuring the
maintenance of an optimal
internal environment for
metabolic functioning.
The Changing Composition of Blood
The difference in the chemical
concentration of blood entering
or leaving an organ, depends on
the function of that organ.
External gaseous exchange
occurs in the lungs.
Deoxygenated blood arrives at
the lungs and it releases carbon
dioxide and picks up oxygen.
Oxygenated blood is returned to
the lungs and then
The Changing Chemical Composition of
Internal gaseous exchange occurs in all organs of the body and is
the result of cellular respiration. Cells release carbon dioxide,
which diffuses into the blood capillaries in the tissues.
The Changing Chemical Composition of
Absorption of nutrients into the
bloodstream takes place in the
digestive tract. These products
of digestion travel in the
bloodstream from the digestive
tract directly to the liver. A
decrease in digestive end
products is evident once blood
has passed through the liver as
this is the centre of food
The Changing Chemical Composition of
Nitrogenous waste products are produced
in the liver and excreted by the kidneys. An
increase in nitrogenous wastes is evident in
blood that has passed through the liver, the
organ where proteins are de-animated to
form these wastes. A decrease in
nitrogenous wastes is evident in blood that
has passed through the kidneys, since they
filter nitrogenous wastes out of the blood
and excrete them.
Complete the Table with students in the following activity:
-11.1.2 Changing Comp of Blood Worksheet