blood vessels Flashcards
innermost layer
Tunica intima
is the only part of a vessel that
is in contact with blood
Tunica intima
its smoothness prevents
abnormal blood clotting
Tunica intima
is made of simple squamous
epithelium called endothelium
w/c is continuous w/ the
endocardium of the heart
Tunica intima
middle layer
Tunica media
is made of smooth muscle &
elastic connective tissue
Tunica media
controls the diameter of the
vessel’s lumen
Tunica media
involved in the maintenance
of normal blood pressure
Tunica media
tunica media controls the diameter of the vessels ___?
lumen
_____ of smooth muscle
→ ____ lumen diameter →
vasodilation & BP ____
relaxation and high and low
___ of smooth muscle→ low lumen diameter → ____
contraction and vasoconstriction & BP high
also called tunica adventitia
Tunica externa
outer layer
Tunica externa
is made of fibrous connective
tissue
Tunica externa
is important to prevent the
rupture or bursting of the
larger arteries that carry
blood under high pressure
Tunica externa
TYPES of Blood Vessels
- Arteries
- Capillaries
- Veins
PATHWAY of Blood in Blood Vessels
heart, large artery, small artery, arteriole, capillary, venule, veins
carry blood from the heart to
the capillaries
Arteries
have higher pressures since
they directly arise from the
heart
Arteries
to withstand pressure, they
have thicker tunica media &
externa compared to veins
Arteries
the
pressure generated by the
pumping action of the heart w/c
helps propel blood rapidly to the
capillaries & facilitate exchange
bet. tissues;
hydrostatic pressure
this pressure
decreases as blood gets farther
away from the heart
hydrostatic pressure
start as larger arteries &
branch off into smaller ones
Arteries
as they branch out, they
usually ____ or connect
w/ one another to provide
____ for the flow of
blood called ____, if one vessel
becomes obstructed
anastomose, alternate routes, collateral
circulation
the largest artery
aorta
the artery which has
the highest
hydrostatic pressure
aorta
where all the large,
medium & small
arteries of the
systemic circulation
arise from
aorta
smallest, almost
microscopic, arteries
that branch off the
small arteries into
capillaries
arterioles
its smooth muscles
control the amount of
blood reaching the
capillaries
arterioles
the smallest of blood
vessels
Capillaries
are thin-walled,
microscopic vessels
(5-10 μm wide) which
connect the arterioles
& venules (smallest
veins)
Capillaries
they surround
almost every cell
in the body
Capillaries
are more
numerous in the
muscles, liver,
kidneys, &
nervous system
Capillaries
are fewer in the
tendons &
ligaments
Capillaries
are absent in the
covering & lining
epithelia, cornea
& cartilage.
Capillaries
only made up of
endothelium
Capillaries
their thin walls
permit exchange
of substances
between blood &
interstitial fluid
Capillaries
the rate of
blood flow in
capillaries is
slow to permit
sufficient time
for the
exchange of
substances
Capillaries
refers to the movement of substances
between blood & interstitial fluid w/c
occurs mostly via diffusion &
filtration
capillary exchange
this process is opposite
in the case of gas exchange in the
pulmonary capillaries]
diffusion
occurs in the arterial end
of a capillary; the high hydrostatic
pressure pushes plasma & dissolved
nutrients
filtration
follows filtration; occurs
in the venous end of a capillary; since
there is low hydrostatic pressure in this
area, the high colloid osmotic pressure
exerted by albumin in the blood pulls
back most of the pushed fluid from the
tissues into the capillaries
reabsorption
carry blood from capillaries
back to the heart
have thinner tunica media &
externa compared to arteries
Veins
their tunica intima contains
valves w/c prevent backflow
of blood (valves most
numerous in leg veins)
Veins
their tunica intima contains
valves w/c prevent backflow
of blood (valves most
numerous in leg veins)
Veins
contain the largest portion
(64%) of blood volume at rest;
thus, they serve as blood
reservoirs
when the need for blood
arises (e.g. hemorrhage,
exercise), their tunica media
constrict to venous return to
the heart
Veins
they also anastomose to
ensure that blood will be able
to return to the heart in order
to be pumped again
Veins
have lower hydrostatic
pressures compared to
arteries
Veins
small, almost
microscopic, veins
that carry blood
away from the
capillaries toward
the heart
venules
collective term for
the superior &
inferior vena cava
venae cavae
the largest of all the
veins w/c return
blood back to the
heart
venae cavae
form larger veins as
they approach the
heart
venules
