Download Circulatory System

A presentation by Ms. Vriksha
~for educational purposes only~
System
Circulatory System (cont’d)
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The word circulation means “going around”
Circulatory system – organ system
Moves food and oxygen to each cell
It then takes away cell wastes
Like all systems, each part of the circulatory
system has structures to help get the job done
Blood vessels
• Like roads for blood cells
• Three kinds of blood vessels:
1. Arteries
2. Capillaries
3. Vein
Arteries
Arteries (cont’d)
• Have thick, muscular walls
• These walls stretch as the heart pushes
blood into them
• Branch many times into smaller and smaller
tubes.
Capillary
• Smallest arteries branch to become capillaries
• Smallest kind of blood vessel
• Side by side, 10 capillaries would be barely as
thick as one hair
• Capillary walls are only one cell thick
• Gases can pass through these thin walls
• Oxygen and glucose move them the blood
cells in capillaries to your body’s cells
Capillaries (cont’d)
• Gases can pass through these thin walls
• Oxygen and glucose move from the blood cells
in capillaries to your body’s cells
• Carbon dioxide and other wastes move from
cells to the blood in the capillaries
Veins
• Blood cells that transport blood toward the
heart
• Tiny veins join together to form larger veins
• Unlike arteries and capillaries, veins have
valves
Veins (cont’d)
• Valves are flaps that act like doors to keep
blood flowing in only in one direction
• Valves open to let blood flow to the heart
• Valves close if the blood starts flowing away
form the heart
Arteries vs Veins
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Arteries
Carry blood away from
the heart always.
Have thick muscular walls
Have a pulse
Deep under the skin
Have no valves
Arteries branch at their
ends, into tiny arterioles
those then join capillaries
Veins
1. Carry blood to the heart.
2. Have thin walls
3. Do not have a pulse
4. Near surface of the skin
5. Have valves to stop backflow of blood.
6. Veins branch at their
beginnings into tiny venules
which join capillaries.
Blood vessels (cont’d)
• Huge numbers of blood vessels form a
network throughout your body
• If all blood vessels were laid end-to-end, they
would stretch around Earth more than twice