PPT is about the roles of the blood from AS Biology

1. The roles of the blood
Chapter 1B

2. Learning objectives
 Understand the role of haemoglobin in
the transport of oxygen and carbon
dioxide.
 Understand the oxygen dissociation
curve of haemoglobin, the Bohr effect
and the significance of the oxygen
affinity of fetal haemoglobin compared
with adult haemoglobin.
 Understand the blood clotting process.

3. Cardiovascular system
 Contains:
 1. Blood vessels
 2. Heart
 3. Blood

6. Erythrocytes (RBC)
 1 mm3=5 million (in women-4-5, in men
5-6)
 Made in bone marrow
 No nucleus in mature RBC’s
 Live nearly 120 days
 Biconcave shape
 1 RBC=250-300 million
haemoglobin molecule

7. Leukocytes(WBC)
 Much larger than RBC
 1mm3=4000-11000
 Made in bone
marrow, some mature
in thymus gland.
 Have a nucleus
 Have different types

8. Platelets
 Fragments of megakaryocytes
 1 mm3= 150000-400000
 Involved in clotting

9. Transport of oxygen

10.  When oxygen binds to haemoglobin,
oxyhaemoglobin is formed.
 Oxygen + Haemoglobin Oxyhaemoglobin
 4O2 + Hb Hb• 4O 2

11.  The first oxygen molecule binds with
haemoglobin harder, but makes a
change in the HB structure, which
makes other oxygen molecules to bind
easier.

13. Transport of carbon dioxide
 Waste CO2 diffuses from the respiring cells
of the body tissues into the blood along a
concentration gradient.

14.  About 5 % is carried in the plasma
 10-20 % combines with HB, and makes
carbaminohaemoglobin
 75-85 % is carried
as hydrogen
carbonate ion.

17. The Bohr effect
 Changes in the oxygen dissociation
curve as a result of carbon dioxide
levels are known as the Bohr effect,
or Bohr shift
 When the partial pressure of carbon
dioxide in the blood is high,
haemoglobin’s affinity for oxygen is
reduced

19. Foetal haemoglobin
 The haemoglobin of a developing foetus has
a higher affinity for oxygen than adult
haemoglobin
 This is vital as it allows a foetus to obtain
oxygen from its mother's blood at the
placenta
◦ Foetal haemoglobin can bind to oxygen at low
pO2
◦ At this low pO2 the mother's haemoglobin
is dissociating with oxygen

22. Adaptations in elephant seal for
diving
 More blood volume
 More RBC
 More myoglobin

23. Clotting
 This process stops blood loss, and
entrance of pathogens.
 A break in the mucous membranes or
skin membranes causes the release of
molecules that trigger a chemical
cascade which results in blood
clotting

24.  Platelets work with serotonin and
thromboplastin.
 Serotonin- causes smooth muscles to
contract, by making vasoconstriction
 Thromboplastin- an enzyme that
starts the chain of reactions.
 Vitamin K is needed for production of
some clotting factors.

25. Thrombosis
 Thrombosis occurs when blood
clots block veins or arteries.
Symptoms include pain and swelling
in one leg, chest pain, or numbness
on one side of the body.
Complications of thrombosis can be
life-threatening, such as a stroke or
heart attack.