2. Veins
• veins are blood vessels that carry
blood toward the heart.
• Most veins carry deoxygenated blood from
the tissues back to the heart
• Exceptions is the pulmonary vein which carry
oxygenated blood to the heart.
• In contrast to veins, arteries carry blood away
from the heart.
3. • Veins are less muscular than arteries and are
often closer to the skin.
• There are valves in most veins to
prevent backflow
4. Structure of vein
• The thick outermost layer of a vein is made
of connective tissue called tunica adventitia
or tunica externa.
• There is a middle layer bands of smooth
muscle called tunica media
• The interior is lined with endothelial
cells called tunica intima
5. Venous system
• The largest veins in the human body are
the venae cava
• The superior venae cava carries blood from
the arms and head to the right atrium of
the heart
• The inferioir venae cava carries blood from
the legs and abdomen to the heart.
6. • The pulmonary veins carry relatively
oxygenated blood from the lungs to the heart.
• The superior and inferior venae cavae carry
relatively deoxygenated blood from the upper
and lower systemic circulations, respectively.
7.
8. capillaries
• Capillaries are the smallest of a body's blood
vessels that make up the micro circulation
• These micro vessels, measuring around 5 to
10 (µm) in diameter
• It connect arterioles and venules and they
help to enable the exchange of water oxygen
and carbon dioxide
9. • Blood flows from the heart through arteries
which branch and narrow into arterioles
• Then branch further into capillaries , the
capillaries then join and widen to
become venules which in turn widen and
converge to become veins which then return
blood back to the heart through the great
veins
