HUMAN TRANSPORT
SYSTEM
Parts of the Circulatory System
Blood
Heart
Blood vessels
BLOOD
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Is a liquid tissue
Your body contains 3 to 5 liters of blood
2 PARTS
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LIQUID – PLASMA- 90% water,also contains
dissolved proteins,salts,sugar,vitamins,food,
and wastes
SOLID - cells
BLOOD
FUNCTIONS OF BLOOD:
Carries materials to the cells (nutrients, oxygen, hormones etc)
Carries wastes away from the cells (carbon dioxide, nitrogenous wastes
etc)
Helps regulate body temperature
Helps to protect against infections
Components of Blood
RED
BLOOD CELLS
• Are disc shaped and biconcave
• Contain hemoglobin (an iron containing
protein) which carries oxygen and gives
blood it’s red color
• Are produced in the bone marrow
• Lack a nucleus
Blood Components
White Blood Cells
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Have a nucleus
Protect the body from disease
Produced in bone marrow, lymph
nodes,spleen
pus= many white blood cells at the site of
an infection
Types of White Blood Cells
PLATELETS
Small cell fragments
 Do not have a nucleus
 Help with the formation of blood clots
(blood clotting is a series of enzyme
controlled reactions)
Heparin- substance produced by the liver
that prevents blood from clotting in the
blood vessels
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BLOOD CELLS
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Can you identify the types of cells?
BLOOD VESSELS
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Arteries:
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Carry blood away from
the heart
Most carry oxygenated
blood
The walls are thick
and elastic
Smallest arteries are
called arterioles
Largest artery is the
aorta
BLOOD VESSELS
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Veins
 Carry blood back to
the heart
 Most carry
deoxygenated blood
 Walls are thin and only
slightly elastic
 Have valves to prevent
the backflow of blood
 Smallest veins are
called venules
 Largest veins are the
inferior and superior
vena cavas
BLOOD VESSELS
Veins
BLOOD VESSELS
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Capillaries
Connect arterioles to
venules
Exchange of materials
between blood and
cells takes place here
(oxygen, nutrients,
wastes)
Are 1 cell layer thick
(RBC’S pass 1 at a
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Next notes on circulation pathways
Lymph
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When blood plasma diffuses through the
walls of the capillaries and surrounds the
cells it is called intracellular fluid or ICF,
which helps move materials between the
blood and cells.
When ICF diffuses into lymph vessels it is
called lymph