Unit 2.2: The cardiovascular system
Composition of blood
· Erythrocytes (Red Blood Cells)
· Leukocytes (White Blood Cells)
· Platelets (Thrombocytes)
Plasma: liquid portion of blood and responsible for the transport
of electrolytes, proteins, gases, nutrients, waste products and
hormones.
Functions of erythrocytes, leukocytes and platelets
Erythrocytes
(red blood cells) they carry oxygen (these cells have an
oxygen-carrying pigment called hemoglobin that give it its
red color)
lungs to body Blood performs a number of
they live for around 120 days and are replaced at 2 specialized functions:
million/second ▪ Transports nutrients, oxygen (O2),
carbon dioxide (CO2), waste
Leukocytes
products and hormones to cells and
(white blood cells) organs around the body.
they combat infection and inflammation by ingesting foreign ▪ Protects us from bleeding to death
microbes (phagocytosis) (clotting) and from disease, by
destroying invasive micro-organisms
Platelets (Not cells!)
and toxic substances.
Involved in clotting and repairing slightly damaged blood ▪ Acts as a regulator of
vessels temperature, the water content in
they contain antibodies produced by inmune systm to fight cells, and body pH.
diseases
It is heavier and more viscous than water and accounts for about 8%
of our total body weight.
Healthy adult males: around 5-6 liters of blood
Healthy adult females: around 4-5 liters of blood
Its color varies, depending upon the amount of oxygen it is carrying,
from dark red (oxygen poor) to scarlet red (oxygen rich)
Unit 2.2: The cardiovascular system 1
, Blood circulation
It's transported around the body through an extensive network of blood vessels
Arteries
Large in diameter with thick muscular walls.
There is high pressure exerted from the O2-rich blood that flows through them away from the heart to
the body
Capillaries
Very thin walls
Extensive network of capillaries throughout the body.
Where exchange between blood and tissues takes place.
Veins
Recieve O2-poor blood from capillaries once the exchange has taken place and deliver blood back to
the heart.
Thinner than arteries because they carry deoxygenated blood (low pressure)
Valves to prevent back-flow
Except when exercising, 80% of our blood is in veins
Blood is pumped around the body through a series of blood vessels; from the heart to large muscular
arteries (send blood away from the heart) to narrower arterioles, to very thin capillaries (gas exchange
takes place here), to larger and flexible venules and then to veins (with valves to prevent backflow) that
send blood back to the heart.
The heart
The heart's primary function is to pump blood around the body (systemic
circulation) and to the lungs (pulmonary circulation)
It's a two-sided (left and right) pump made up of four chambers (two atria and two ventricles)
Chambers
They are made up of walls of specialist muscle fibers (cardiac muscle)
The upper chambers (right and left atria) recieve blood and the lower chambers (right and left ventricles)
pump blood out of the heart
*ventricles are separated by the septum
The atria and ventricle of each side are linked together by valves that prevent backflow of blood (like the
valves in veins)
Unit 2.2: The cardiovascular system 2
Composition of blood
· Erythrocytes (Red Blood Cells)
· Leukocytes (White Blood Cells)
· Platelets (Thrombocytes)
Plasma: liquid portion of blood and responsible for the transport
of electrolytes, proteins, gases, nutrients, waste products and
hormones.
Functions of erythrocytes, leukocytes and platelets
Erythrocytes
(red blood cells) they carry oxygen (these cells have an
oxygen-carrying pigment called hemoglobin that give it its
red color)
lungs to body Blood performs a number of
they live for around 120 days and are replaced at 2 specialized functions:
million/second ▪ Transports nutrients, oxygen (O2),
carbon dioxide (CO2), waste
Leukocytes
products and hormones to cells and
(white blood cells) organs around the body.
they combat infection and inflammation by ingesting foreign ▪ Protects us from bleeding to death
microbes (phagocytosis) (clotting) and from disease, by
destroying invasive micro-organisms
Platelets (Not cells!)
and toxic substances.
Involved in clotting and repairing slightly damaged blood ▪ Acts as a regulator of
vessels temperature, the water content in
they contain antibodies produced by inmune systm to fight cells, and body pH.
diseases
It is heavier and more viscous than water and accounts for about 8%
of our total body weight.
Healthy adult males: around 5-6 liters of blood
Healthy adult females: around 4-5 liters of blood
Its color varies, depending upon the amount of oxygen it is carrying,
from dark red (oxygen poor) to scarlet red (oxygen rich)
Unit 2.2: The cardiovascular system 1
, Blood circulation
It's transported around the body through an extensive network of blood vessels
Arteries
Large in diameter with thick muscular walls.
There is high pressure exerted from the O2-rich blood that flows through them away from the heart to
the body
Capillaries
Very thin walls
Extensive network of capillaries throughout the body.
Where exchange between blood and tissues takes place.
Veins
Recieve O2-poor blood from capillaries once the exchange has taken place and deliver blood back to
the heart.
Thinner than arteries because they carry deoxygenated blood (low pressure)
Valves to prevent back-flow
Except when exercising, 80% of our blood is in veins
Blood is pumped around the body through a series of blood vessels; from the heart to large muscular
arteries (send blood away from the heart) to narrower arterioles, to very thin capillaries (gas exchange
takes place here), to larger and flexible venules and then to veins (with valves to prevent backflow) that
send blood back to the heart.
The heart
The heart's primary function is to pump blood around the body (systemic
circulation) and to the lungs (pulmonary circulation)
It's a two-sided (left and right) pump made up of four chambers (two atria and two ventricles)
Chambers
They are made up of walls of specialist muscle fibers (cardiac muscle)
The upper chambers (right and left atria) recieve blood and the lower chambers (right and left ventricles)
pump blood out of the heart
*ventricles are separated by the septum
The atria and ventricle of each side are linked together by valves that prevent backflow of blood (like the
valves in veins)
Unit 2.2: The cardiovascular system 2
