Download Planet Earth and Its Environment A 5000

Maintaining a Balance
Topic 8: Chemical Substances and How They are Transported
Biology in Focus, HSC Course
DOT POINT
 identify the form(s) in which each of the following is carried
in mammalian blood:
 carbon dioxide
 oxygen
 water
 salts
 lipids
 nitrogenous waste
 other products of digestion
Introduction
To maintain homeostasis, chemicals being transported in the
blood must also be maintained at a particular concentration and
carried in a specific form that will not affect the balance in the
internal environment of the body.
vascularbodybuildingmuscle.blogspot.com
Introduction
If the normal balance of substances in
the blood is altered, conditions such
as ‘low blood sugar levels’ or ‘high
blood pressure’ will arise. This brings
on unpleasant and sometimes
dangerous side effects. Its an
indication that metabolic functioning
has been compromised. Homeostasis
relies on maintaining a balance of
chemicals within the blood.
cosmosmagazine.com
Hand Out DOT Point 2.1
Fill in the chart as we go through the rest of today’s
presentation.
Blood Gases
All living cells in the body require oxygen and produce carbon
dioxide. Oxygen is required for the process of cellular respiration
and carbon dioxide is produced as a waste product. These gases
are carries in particular forms within the plasma or red blood
cells of blood, so that the pH and fluid concentrations remain
stable.
bwlibys.blogspot.com
Oxygen Transport
When oxygen diffuses (high concentration to low concentration)
across the respiratory surface of the lung into the blood, most of
it (98.5%) combines reversibly with haemoglobin inside red
blood cells. The remaining 1.5% may travel dissolved in the
plasma.
hyperphysics.phy-astr.gsu.edu
Oxygen Transport
Red blood cells are ideally adapted to carrying oxygen. They
don’t have a nucleus which results in plenty of space for
haemoglobin. Haemoglobin has an affinity for (its chemically
attracted to) oxygen. Each red blood cell contains approximately
250 million molecules of haemoglobin, resulting in a very high
oxygen carrying capacity.
beltina.org
Oxygen Transport
The slightly flattened biconcave shape of red blood cells gives
them a larger surface area to volume ratio for easy diffusion of
oxygen across the surface.
exchange3d.com
Oxygen Transport
When blood in the lungs comes into contact with oxygen that has
entered the body by diffusion, haemoglobin in the red blood cells
binds with this oxygen, forming a compound called
oxyhaemoglobin. This compound gives a bright red colour to
blood.
gassama.myweb.uga.edu
Oxygen Transport
Most arteries carry bright red oxygenated blood, whereas most
venous blood is a dark red colour. Veins beneath the skin may
appear blue, but this is a combination of the dark red
deoxygenated blood within the white-yellow vessel wall.
gurneyjourney.blogspot.com
Carbon Dioxide Transport
When carbon dioxide enters the blood, most (70%) of it is
transported in the form of hydrogen carbonate ions. This is
formed in the red blood cells but is carried in the plasma. The
remaining carbon dioxide is carried either dissolved in the plasma
(7%) or is carried combined with haemoglobin (23%).
rsc.org
Carbon Dioxide Transport
Since carbon dioxide mixed with water forms carbonic acid, it is
not ideal for all of the carbon dioxide to dissolve in the plasma,
since this would affect the pH of blood. Instead, a large portion of
the carbon dioxide enters the red blood cells. Once there one of
two things happen.
middleschoolchemistry.com
Carbon Dioxide Transport
1. Most of the carbon dioxide mixes with water in the cytoplasm
within the blood cells and forms carbonic acid. This is rapidly
converted to hydrogen carbonate ions (bicarbonate ions). These
ions then move out of the red blood cells into the blood plasma
and 70% of carbon dioxide is transported in this form. This can
be summarised as:
Carbon dioxide + water → carbonic acid → hydrogen
carbonate + buffered hydrogen ions
CO₂ + H₂O → HCO → H₂CO₃⁻ + H⁺
extraordinarylight.blogspot.com
Carbon Dioxide Transport
2. Some carbon dioxide binds to
haemoglobin, forming
carbaminohaemoglobin.
Haemoglobin does not bind to
carbon dioxide in the same way
that it binds to oxygen. Oxygen
binds to the iron atom of
haemoglobin, whereas carbon
dioxide binds to the amino group
of the protein part-the globin
molecule, forming
carbaminohaemoglobin.
bioc208.blogspot.com
Carbon Dioxide Transport
As with oxygen, this is a
reversible reaction and many
carbon dioxide molecules can
combine with a single
haemoglobin molecule. Only
23% of carbon dioxide is
carried in this form.
chemistry.wustl.edu
Water and Salt
Water is the medium of transport of all substances in the body. It
forms the basis of the cytoplasm in all cells, the interstitial fluid
(tissue fluids) surrounding the cells and blood and lymph.
learner.org
Water and Salt
About 90% of blood
plasma is water. The other
10% is made up mostly of
various kinds of protein
molecules as well as other
substances including
hormones, vitamins, end
products of digestion and
salts.
paduiblog.com
Water and Salt
Salts are carried in blood as ions (charged particles) dissolved in
the plasma. For example, the salt sodium chloride (NaCl) is
carried as positively charged sodium ions (Na⁺) and negatively
charged chloride ions (Cl⁻) in solution of the watery medium of
the plasma.
chem4kids.com
Water and Salt
Substances (such as salts) that
become ions in solution are
often referred to as electrolytes,
because their capacity to
conduct electricity. The balance
of the electrolytes in our bodies
is essential for normal function
of our cells and our organs.
Common electrolytes include
sodium, potassium, chloride
and bicarbonate.
health.howstuffworks.com
Lipids and Other Products of Digestion
The aim of digestion is to break large molecules down to a size
small enough for absorption through the intestine wall and into
the bloodstream, so that they can be transported to cells in the
body where they are required.
kvhs.nbed.nb.ca
Lipids and Other Products of Digestion
The digestion of large organic molecules to their smaller end
products is summarised below:
Carbohydrates
→
glucose (simple sugars)
Proteins
→
amino acids
Lipids (fats and oils) →
fatty acids and glycerol
Nucleic Acids
→
nucleotides
extraordinarylight.blogspot.com
Lipids and Other Products of Digestion
Glucose and amino acids are
water soluble and so they are
transported in the bloodstream
dissolved in the plasma, along
with other soluble substances
such as nitrogen bases, vitamins
and glycerol, absorbed from the
digestive tract.
middleschoolchemistry.com
Lipids and Other Products of Digestion
Lipids pose a problem in terms of transport, since they are
insoluble in water and therefore cannot be carried dissolved in
plasma. They need to be packaged into small droplets (micelles),
which pass into the lymphatic system and then into the
bloodstream.
chm.bris.ac.uk
Nitrogen Wastes
Nitrogenous wastes are harmful substances produced in the body
as a result of the breakdown of proteins. These substances need
to be transported in a diluted form, from cells where they are
produced to the excretory organs where they can be eliminated
from the body. Such wastes in the form of ammonia, urea, uric
acid and creatinine are all carried dissolved in blood plasma.
baxter.com
Activity/Homework
-NIL!! Enjoy!