Download Arteries - Cobb Learning

BLOOD VESSELS
ARTERIES
• Arteries carry blood away from the heart.
• Arteries branch into smaller blood vessels
called arterioles.
• Arteries have thick, smooth muscle walls
and are very elastic.
• What is the largest artery in the body?
• What is the only artery in the body that
carries deoxygenated blood?
VEINS
• Veins carry blood to the heart.
• Veins have much thinner walls and less elasticity than
the arteries.
• Veins have valves to prevent the backflow of blood.
• Veins are the confluence of smaller blood vessels called
venules.
• What are the largest veins in the body?
• What are the only veins in the body that carry
oxygenated blood?
Capillaries
• Capillaries connect arterioles and venules.
• Capillary walls are only one-cell thick.
This enables nutrients and oxygen in the
blood to easily pass out of the capillary and
into the cells of the body where they are
needed. It also enables wastes and carbon
dioxide to pass out of the body cells and
into the blood in the capillaries.
So, the pathway of blood from the heart is
aorta arteries arterioles capillaries
venules veins vena cavae right atrium
All exchanges of gases (oxygen
and carbon dioxide), nutrients,
and wastes take place at the level
of the capillaries.
Histology of the Blood Vessels
Artery-Vein Pair
Artery is on left, vein on right
Longitudinal Section of a Capillary – Note that it is
only as wide as the diameter of a red blood cell.
Do you remember that we said that arteries had a lot
of elasticity? Here you can clearly see the internal
elastic membrane of an artery.
Here you can see the internal elastic
membrane at higher magnification using a
different histological stain.
Low magnification of an artery. The artery is
the thick, round structure in the center.
Another artery; another stain
Small artery-vein pair. Artery is
on left, vein on right.
Do you know what a lumen is?
Vein – You can see the valve here.
Realize you are looking at at a 2dimensional representation of a 3dimensional object.
Longitudinal section of a vein. Note that
this cannot be a capillary since its
diameter is more than 1-cell wide.