Download Red blood cells

Blood
 By the end of the lesson you should be
able to:
 State the composition of Blood
 State the function of red blood cells and
plasma
 Explain the function of haemoglobin in
the transport of oxygen
 State the function of macrophages and
lymphocytes
Blood
 the average human has 5 litres of
blood
 it is a transporting fluid
 it carries vital substances to all parts
of the body
Total volume of blood is ~5.5 liters
About 55% is plasma; rest is cells (RBC, WBC,
platelets)
Most are red cells (RBCs)
Cells are specialized to carry oxygen
full of hemoglobin; no organelles
4-6 million RBCs per cc for males; 4-5 million
for females
What factors affect RBC count and activity?
Roles of blood
oxygen transport
nutrient transport
waste transport
transport of other essential molecules
(antibodies, hormones, etc.)
regulation (temperature, metabolism, etc.)
fighting infection
Human blood smear
X 500
skool blood plasma
plasma (55%)
red blood cells
(5-6-million /ml)
white blood cells
(5000/ml)
platelets
x 1000
Plasma
liquid part of blood
plasma transports: Clotting factors
 soluble food molecules
(sugars, vitamins, minerals,
etc.)
 waste products
 hormones
 enzymes
 antibodies
 and other proteins
 Plasma also contains blood clotting
factors, sugars, lipids, vitamins,
minerals, hormones, enzymes,
antibodies, and other proteins
All blood cells are formed in the bone marrow
Red blood cells (RBC) (erythrocytes)
White blood cells (WBC) (leukocytes)
Phagocytes
lymphocytes
Platelets
Red blood cells
(RBCs)
(erythrocyte)
 transport oxygen
 specialised to do
this
Also carry some CO2
Insufficient red cell production and/or
oxygen delivery- anemia
Causes:
iron deficiency (most common)
vitamin B12, folic acid (pernicious anemia)
hemolytic anemia
sickle cell anemia
blood loss
bone marrow disease
infections
White blood cells (WBC)
(leukocytes)
 the bodies “defence”
 part of the immune
system
 much larger than RBCs
 far fewer
 have a nucleus
 4000-13000 per mm3
 2 types
phagocytes and
lymphocytes
Platelets
(blood clotting)
if you get cut: platelets release
coagulating chemicals
 And produce
tiny fibrin threads
 these form a web-like
mesh that traps blood
cells.
 these harden forming
a clot, or "scab.“
Platelets
 Thirteen different blood clotting factors, in addition to
platelets, need to interact for clotting to occur. They do so
in a cascading manner, one factor triggering another.
Hemophiliacs lack the ability to produce either blood factor
8 or 9.
 Recent research has shown that platelets also help fight
infections by releasing proteins that kill invading bacteria
and some other microorganisms. In addition, platelets
stimulate the immune system
Red blood cells specialisations
1) biconcave shape
increases the
surface area so
more oxygen can be
carried
2) no nucleus
 extra space inside
3) contain haemoglobin
 the oxygen carrying
molecule
 250million molecules
/ cell
Haemoglobin
 gives red blood
cells their colour
 can carry up to 4
molecules of O2
 associates and
dissociates with
O2
 contains iron
Function of Haemoglobin
When there is a high concentration of oxygen e.g
in the alveoli haemoglobin combines with oxygen to
form oxyhaemoglobin. When the blood reaches the
tissue which have a low concentration of oxygen
the haemoglobin dissociates with the oxygen and
the oxygen is released into body tissues
Monocytes
Phagocytes
 Monocytes and macrophages
 Provide a non-specific response to
infection
 http://www.microbelibrary.org/images/tte
rry/anim/phago053.html
Lymphocyte
Lymphocytes
Provide a specific immune response to
infectious diseases.
There are 2 types: - T-cells
- B-cells
They produce antibodies.
Blood
Can you?
 State the composition of Blood
 State the function of red blood cells and
plasma
 Explain the function of haemoglobin in
the transport of oxygen
 State the function of macrophages and
lymphocytes
Hemostasis (clotting; stoppage of blood loss)
Platelets- plug formation; can repair small
wounds
Clotting factors (coagulation)
A cascade
Red blood cell antigens and blood typing
Antigen: a molecule that is recognized as foreign
by the immune system
Lots of these: several different types of antigens
found on red blood cells (RBCs)
ABO system especially important
Four blood types: A, B, AB, O
A and B are dominant, O is recessive
Human ABO Blood Types
Image courtesy of Wikipedia.
People with type A blood can tolerate type A
blood from other individuals
But type A people make antibodies to type B
antigens
People with type AB can tolerate all blood types:
universal recipient (of CELLS)
People with type O blood can donate to all but
have antibodies to both A and B antigens:
universal donor (of CELLS)
Rh antigen is also important
People either have the antigen or do not
Rh-negative people will develop antibodies to
the Rh antigen if they are exposed to the
Rh-positive blood
If a Rh-negative woman becomes pregnant
with a Rh-positive fetus she may make
antibodies to the fetus’ RBCs
This can be prevented with RhoGAM
Implications for:
blood transfusions
Blood type antigen
A
B
AB
O
A
B
A, B
neither
antibody
anti-B
anti-A
neither
anti-A and B
Transfusions are preferred between people of
the same blood type
If blood is properly processed and administered:
A can receive from A and O
B from B and O
AB from AB, A, B and O
O only from type O- but can donate to everyone
else
Rh-positive can receive from negative and positive
Rh-negative only from negative
Blood types are inherited
In some parts of the world some blood types are
more common than others
In U.S.:
~45% are O, ~40% are A, 12% are B, and
about 3% are AB
about 85% are Rh-positive