Agenda
 Fetal Circulation
 http://www.indiana.edu/~anat550/cvanim/fetcirc/fetcirc.html
 http://www.youtube.com/watch?v=OV8wtPYGE-I
 Blood Components
 http://www.youtube.com/watch?NR=1&v=CRh_dAzXuoU
 http://www.youtube.com/watch?v=Rpj0emEGShQ&feature=rel
ated
Think About it…
 As a fetus who was dependant on your mother, what
aspects of your circulatory, respiratory and waste
management systems would be different?
 What is unnecessary?
 What areas might cause complications?
Unique Structures:
The fetal circulatory system can’t be the same as the
adult, if you stop to think about it. The fetus, first of
all, can’t breathe air inside the womb, so sending blood
to the lungs won’t do much good. Likewise, the fetus
must get all its nutrients from Mom, as well as let her
take care of its wastes. Obviously, some serious
plumbing problems must be solved.
To solve these problems, the fetus has four
features not present in adults.
 1. OVAL OPENING (foramen
ovale): opening between the two atria,
covered by a flap that acts like a valve.
Some of the blood from the right
atrium is therefore pumped through
this flap and into the left atrium,
bypassing the pulmonary circuit.
 If the oval opening doesn’t close after
birth, it can cause mixing of blood and
“blue babies”. This is very inefficient
because deoxygenated blood gets
mixed with oxygenated blood. Correct
with open heart surgery.
 2. ARTERIAL
DUCT: (ductus
arteriosus) connects
pulmonary artery and
aorta. Much of the
blood being pumped
out of the heart to the
lungs will be directed
away from the lungs
and into the aorta.
Like the oval opening,
the arterial duct’s
function is to bypass
the pulmonary circuit.
 3. UMBILICAL ARTERIES AND VEINS: vessels that
travel to and from PLACENTA (a membrane shared by the
mother and baby across which gases, nutrients, and wastes
are exchanged). The umbilical arteries are grafted to the
iliac arteries.
 4. VENOUS DUCT (ductus venosus): connects umbilical
vein to the venae cava to bring the blood back to the baby’s
heart. It attaches right at the babies liver, but bypasses most
of the liver. This is why chemicals ingested by the mother
can seriously affect the baby!
The Placenta
PATH OF BLOOD THROUGH
FETUS
 1.
Begin with blood collecting in Right Atrium
 2. From there, blood can go into Left Atrium through Oval
opening plus into Right Ventricle through atrioventricle valve.
 3. Right Ventricle to Pulmonary Artery. Most of blood will go
through arterial duct into aorta.
 4. Aorta to tissue. Umbilical arteries lead to placenta, where
exchange of gases and nutrients take place.
 5. Umbilical vein carries O2-rich blood. It enters the venous
duct, passes through liver.
 6. Venous duct joins with inferior venae cava (it mixes here with
deoxygenated blood) and this mixed blood goes back to the back
to heart.
Blood
 Blood is a form of liquid body tissue.
 Blood has many functions within the body.
 It transports oxygen and nutrients to the tissue fluid
surrounding cells and carries away carbon dioxide and
other cellular waste products.
 Blood also helps balance fluid levels, temperature, ion
concentrations, and pH within the body.
 Formed elements in blood (cells) also play important
roles in fighting disease and forming clots following
tissue damage.
Blood is composed of two main parts.
 The liquid component of blood, called plasma, is
mainly water (92%) with many dissolved substances.
 Plasma makes up 55% of the volume of blood.
 The remaining 45% of the blood volume is composed
of formed elements or blood cells of various kinds.
These cells are red blood cells, white blood cells, and
platelets (actually cell fragments).
Plasma

Mainly water which acts as a solvent for the other substances found
dissolved in plasma.

The dissolved substances include;

Plasma proteins - Albumin (maintains blood volume), Immunoglobulins
(fight infection), and fibrinogen (blood clotting).

Salts - sodium ion, potassium ion, chloride ion, calcium ion, etc.

Nutrients - glucose, amino acids, fatty acids, some vitamins.

Gases - oxygen from lungs and carbon dioxide from the tissues.

Waste - urea from the liver.

Hormones - many - examples are thyroxine, insulin, adrenalin, estrogen,
etc.
Blood Cells
(Formed Elements)
All of the following blood cell types are produced in the
red bone marrow. Red bone marrow is located in the
ribs, vertebrae, skull, and the ends of long bones in the
arms and legs.
•
a. RED BLOOD CELLS (ERYTHROCYTES)
Transport oxygen, formed in bone marrow. Over 95%
of formed elements are erythrocytes.
•
b. WHITE BLOOD CELLS (LEUKOCYTES) Fight
infection, formed in bone marrow and lymphoid tissue.
•
c. PLATELETS (THROMBOCYTES) Function in
blood clotting
 The majority of the cells found in blood are red blood cells
or erythrocytes. RBC's are shaped like biconcave disks and
have no nuclei.
 This flattened shape increases the surface area for gas
exchange and aids their transport in capillaries. A single
milliliter of blood will normally contain 4 to 6 billion
RBC's. RBC's are functional in the blood for up to 4
months.
 New RBC's are continually being produced in the red bone
Function
 The function of RBC's is to carry oxygen from the
lungs and deliver it to the body tissues in the
capillaries.
 RBC's contain proteins called hemoglobin. Each
hemoglobin molecule is composed of four polypeptide
chains (an example of quaternary protein structure).
Each of the four polypeptides has a heme group
containing iron. It is this heme group that binds to
oxygen and releases it to the tissues of the body in the
capillaries.
White blood cells
 are larger cells that contain nuclei and vary in colour.
WBC's are spherical in shape.
 Theses WBC's function in the body to fight infection and
develop immunity to future infections. There are many
different kinds of WBC's each with a specific function with
the body. The size and appearance of these WBC's varies
greatly and allows them to be recognized using a
microscope. The life span of a specific type of WBC's also
varies from several days to years depending on the type of
cell and its location. Like RBC's all of the WBC's are
produced in the red bone marrow from stem cells that
differentiate into the many different types of blood cells.
CommonWBC
 Neutrophils - Most common WBC, phagocytic (they engulf and ingest
foreign substances or invaders like bacteria (pathogens) and destroy them.
 Lymphocytes - Mature in lymphatic tissues such as the thymus and spleen.
There are two main types - B lymphocytes and T lymphocytes - both
produce antibodies and provide secondary immunity.
 Antibodies are protein molecules that travel in blood and lymph (tissue
fluid) and attach to specific foreign antigens with a lock and key mechanism
similar to enzymes.
 Antibodies act in many ways to prevent disease. Antibodies are produced to
recognize a specific antigen (foreign substance that is recognized by the
immune system as non-self and needs to be destroyed). Antibodies deal with
foreign antigens by attaching to them and promoting phagocytosis by other
WBC's, or clumping pathogens together, or forming complexes with
pathogens that prevents them from attaching to cells in the respiratory tract
and digestive tract causing disease.
Continued
 Monocytes - largest WBC's, develop into large
macrophages in the body tissues that phagocytize
pathogens during infection.
 Eosinophils - are involved in control of allergic and
inflammatory responses.
 Basophils - release histamine that increases blood flow
to sites of tissue injury.
Platelets (thrombocytes)
Platelets are cell fragments that break away from larger cells in
the red bone marrow. A milliliter of blood contains up to
300 million platelets.
Platelets are involved in blood clotting following tissue injury.
Blood clotting is a complex process involving platelets,
many clotting factors, the proteins fibrinogen and
prothrombin, vitamin K found in green vegetables and
produced by bacteria in the large intestine, and calcium
ions. In the clotting process following injury, platelets act as
a first line of defense by forming a platelet plug that acts to
seal up the leak.
Later, a complex series of events form a protein net around the
platelet plug which traps RBC's. As tissue repair takes place
the plug is dissolved and blood flow resumes.
ANTIBODIES: VERY SPECIFIC PROTEINS that
attach to invading pathogens

Lymphocytes produce antibodies in response to invading pathogens.

Each lymphocyte produces one type of antibody that is specific for one type
of antigen. An antigen is a foreign substance (usually a protein, sometimes a
carbohydrate) that stimulates the release of antibodies to it. e.g. an antigen
could be protein coat of a virus.

Antibodies combine with antigens in such a way that the killer T cells can
destroy them. Each antibody fits its antigen like a lock and key.

An individual is immune to an antigen if he/she has antibodies to that
particular antigens.

The blood in the individual contains lymphocytes that can remain in the
system for years, ready to produce antibodies if that antigen is detected.

Exposure to the antigen, either naturally or by way of a vaccine, can cause
active immunity to develop.
BLOOD TYPES
 What do you already know about blood types
 How does blood transfusions and blood matching
work?
BLOOD TYPING

Human blood is classified according to the antigens present on the surface of
the red blood cells. The most common blood types belong to the ABO
Grouping.

Two antigens that may be present on the red cells are called "A" and "B". An
individual may have one of these antigens present (in which case they will
have type A or type B blood), or both (type AB) or neither (type O).
Therefore, there are four blood types in the ABO Grouping.

Each individual also carries antibodies in his/her plasma to the antigens not
present on that individual's red cells. e.g. Type A blood has antibody b, Type
AB blood has no antibodies.

If the same antigen and antibody are present, agglutination (or clumping) of
red cells will occur (can cause death).

Blood recipients may only receive donated blood for which they have no
antibodies in their plasma.
Blood Transfusions
 Blood that has antibodies on it that is not recognized by the
body will be attacked by your immune system
 O is the Universal Donor because a person with this type of
blood does not have antigens on the surface of the blood
cells - hence will not cause an immune reaction in the
patient.
 AB is the universal Acceptor because this person will not
have an immune reaction to A, B, AB, or O*Just remember,
the antigens on the surface of your cells (or donated cells)
will cause a reaction if your immune system does not
recognize them as being part of you. Hence, if you are Type
A, and transfused with Type B, your body will mobilize a
massive immune response against the "invading" blood.
This will cause coagulation of blood and death.