~ 7%
Blood makes up around 7% of the weight of the
human body.
Twice
If you could stretch out all of a human's blood
vessels, they would be long enough to go around
the world twice.
7 days
Half your body’s red blood cells are replaced every
seven days.
120 days
The average life span of a single red blood cell in the
circulatory system.
20 – 60 s
The time it takes a drop of blood to travel away
from the heart and back again.
100 000
The number of times the heart beats each day.
Functions of the Cardiovascular System:

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delivers vital nutrients (e.g., oxygen) to all
body cells
eliminates waste products and carbon
dioxide
transports chemical messengers (e.g.,
hormones) from one part of the body to
another
helps to maintain a constant body
temperature
Open Circulatory System – Hemolymph (mix of blood
and tissue fluid) is pumped directly into the body cavity.
-
Closed Circulatory System – Blood is separate
from the rest of the body in a network of
tubes.
Single-circuit circulatory system – Only one track the
blood can travel
Two-circuit circulatory system - Circulation to the lungs
is separated from circulation to the rest of the body.
Two-Circuit Circulatory System:
Circulation to the lungs is separated from
circulation to the rest of the body.

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pulmonary circuit:
the part of the circulatory system that
delivers blood to the lungs
systemic circuit:
the part of the circulatory system that
delivers blood around the body
Human body contains 4L to 5L of
blood depending on the size of the
individual
 Blood is a connective tissue – a tissue that
consists of cells suspended in an intercellular
matrix
 Using a centrifuge, blood can be separated into
its two components – plasma (less dense, rises
to top) and cellular components (more dense,
sinks to bottom)
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Protein-rich liquid; over 90% is water
Oxygen, proteins, nutrients (glucose,
minerals and vitamins), carbon dioxide and
other waste products from cellular respiration
are dissolved or suspended in plasma

Blood proteins in plasma include; albumins,
globulins, fibrogens
 Albumins: helps regulate the amount of water
within the body
 Globulins: transports lipids, cholesterol, some fatsoluble vitamins, some minerals
▪ Immunglobins (or antibodies) help fight infectious
diseases
 Fibrogens: play a critical role in blood clotting;
plasma with fibrogen removed is called serum

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Plasma also carries a number of dissolved ions:
Na+, K+, Ca2+, Cl- , HCO3-. Na+ and Cl- are most
common ions. When the concentration of Na+ in
the plasma is high, it creates an osmotic
pressure gradient and causes water to enter the
blood stream. As more water enters the blood,
the total volume of blood increases and the
blood pressure rises. This explains why high salt
diets lead to hypertension (high blood pressure)

Red Blood Cells - For Transport
 (erythrocytes) carry oxygen from the lungs to the body
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cells and carry carbon dioxide from the body cells back to
the lungs to be expelled
Formed from stem cells in marrow of vertebrae, ribs,
breastbone, skull and bones of the arms and legs
Erythrocytes die after about 120 days ; then removed by
the liver and spleen
Between 2million and 3 million erythrocytes are
produced each second
When erythrocytes are developing in the marrow, they
have a nucleus, but as they mature and are released into
the blood stream, their nucleus breaks down and
disappears.
- (Leukocytes) are formed in
bone marrow and always have a nuclei
first line of defense against harmful
bacteria, viruses and other
disease causing agents

▪ Granular – have grains in their cytoplasm and
attach foreign material and microorganisms
▪ Agranular – specialized for engulfing bacteria and
microorganisms through phagocytosis. This
involves engulfing the bacteria within the cell
membrane and release enzymes to destroy the
target and the leucocyte itself
 Remnants of leuckocytes and whatever it engulfed
are left behind in a whitish substance called pus
 For protection; involved in clotting or coagulation
 Small cell fragments produced from stem cells in
bone marrow
 When blood vessel is broken, chemicals in
platelets cause the platelets to stick to collagen
fibres in the blood vessel wall. As more and more
platelets stick to the fibres, a clot is created to seal
the hole in the blood vessel
 The permanent clot stops the leakage of blood
and allows time for the injury to heal and then the
blood clot is absorbed by the body.

Recall that the four blood types are: A, B, AB, O.
The Rhesus Factor:
 The Rhesus factor is another inherited factor
discovered by studying the blood of rhesus monkeys.
The rhesus factor is an antigen on erythrocytes that
produce an antibody reaction. This is not as severe as
the antibody reaction to blood type markers. The
rhesus factor is present in approximately 85% of the
population deeming them Rh-positive. The remaining
15% do not have this factor and are considered Rhnegative. Rh-negative people can donate their blood
to Rh-positive people, but they cannot receive Rhpositive blood.