HBIO 301 FINAL EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
3 Major types of blood vessels
1. Arteries
1a. Arterioles
2. Capillaries
3a. Venules
3b. Veins
Arteries
carry blood away from the heart
Arterioles
The smallest branches of arteries
Capillaries
smallest blood vessels, site of exchange between blood & interstitial fluid
Venules
collect blood from capillaries
Veins
return blood to heart
The largest blood vessels
2.5 cm diameter
pulmonary trunk & aorta - originating from right and left ventricles respectively
,Smallest blood vessels
capillaries
4 μm diameter
- form an extensive network of 10 billion covering 60,000 - 100,00 miles
- most cells are no further than 100 mm away from a capillary bed for exchange of
gases, nutrients & wastes
Blood vessel wall structure (layers)
1. Tunica Intima (innermost)
2. Tunica Media
3. Tunica Externa (outermost)
Tunica Intima
- innermost layer
- endothelial lining and underlying connective tissue with elastic membrane (called
internal elastic membrane in arteries)
Tunica Media
- middle layer
- concentric sheets of smooth muscle in loose connective tissue with external elastic
membrane (arteries only)
- contains smooth muscle responsible for dilation/constriction
Tunica Externa
- outermost layer
- connective tissue sheath
- anchors vessel to adjacent tissues
,- contains collagen & elastic fibers
- contains smooth muscle in veins only
In the tunica media of elastic arteries
there are some 40 to 70 layers of elastic sheets perforated like swiss cheese with thin
layers of smooth muscle, collagen, and elastic fibers.
- perforations allow routes for nerves & vasa vasorum
Internal & External elastic membranes
elastic arteries & muscular arteries have the internal & external elastic lamina that
separate the tunica media from the other two layers (intima & external)
- elastic membrane are more easy to microscopically distinguish in muscular
arteries than elastic arteries
Histological structures of blood vessels
Elasticity function in arteries
Elasticity allows arteries to absorb pressure waves from heartbeat
Contractility in arteries
- change in vessel diameter via sympathetic division of ANS
- vasoconstriction & vasodilation
- both affect afterload on heart, peripheral blood pressure, and capillary blood
flow
Afterload on heart
the amount of pressure that the heart needs to exert to eject the blood during ventricular
contraction
Vasoconstriction of arteries
, The contraction of arterial smooth muscle by the ANS, shrink lumen (hollow space
inside artery)
Vasodilation of arteries
the relaxation of arterial smooth muscle, enlarging the lumen
Elastic arteries
- also called conducting arteries
1 - 2.5 cm
- large vessels (pulmonary trunk & aorta)
- tunica media has many elastic fibers & few muscle cells (elastic fibers help
to even out the pulse (surge of blood) pumped out during systole and reduce the
difference between high and low blood pressures in blood flow)
Muscular arteries
- also called distribution arteries
0.3 - 1 cm
- medium sized (most arteries)
- tunica media has many muscle cells
Arterioles structure
10 μm - 0.3 mm
- no longer a pulse (surge), rather even flow
- have little to no tunica externa
- thin or incomplete tunica media
Aneurysm
COMPLETE SOLUTIONS GRADED A++ LATEST UPDATE
3 Major types of blood vessels
1. Arteries
1a. Arterioles
2. Capillaries
3a. Venules
3b. Veins
Arteries
carry blood away from the heart
Arterioles
The smallest branches of arteries
Capillaries
smallest blood vessels, site of exchange between blood & interstitial fluid
Venules
collect blood from capillaries
Veins
return blood to heart
The largest blood vessels
2.5 cm diameter
pulmonary trunk & aorta - originating from right and left ventricles respectively
,Smallest blood vessels
capillaries
4 μm diameter
- form an extensive network of 10 billion covering 60,000 - 100,00 miles
- most cells are no further than 100 mm away from a capillary bed for exchange of
gases, nutrients & wastes
Blood vessel wall structure (layers)
1. Tunica Intima (innermost)
2. Tunica Media
3. Tunica Externa (outermost)
Tunica Intima
- innermost layer
- endothelial lining and underlying connective tissue with elastic membrane (called
internal elastic membrane in arteries)
Tunica Media
- middle layer
- concentric sheets of smooth muscle in loose connective tissue with external elastic
membrane (arteries only)
- contains smooth muscle responsible for dilation/constriction
Tunica Externa
- outermost layer
- connective tissue sheath
- anchors vessel to adjacent tissues
,- contains collagen & elastic fibers
- contains smooth muscle in veins only
In the tunica media of elastic arteries
there are some 40 to 70 layers of elastic sheets perforated like swiss cheese with thin
layers of smooth muscle, collagen, and elastic fibers.
- perforations allow routes for nerves & vasa vasorum
Internal & External elastic membranes
elastic arteries & muscular arteries have the internal & external elastic lamina that
separate the tunica media from the other two layers (intima & external)
- elastic membrane are more easy to microscopically distinguish in muscular
arteries than elastic arteries
Histological structures of blood vessels
Elasticity function in arteries
Elasticity allows arteries to absorb pressure waves from heartbeat
Contractility in arteries
- change in vessel diameter via sympathetic division of ANS
- vasoconstriction & vasodilation
- both affect afterload on heart, peripheral blood pressure, and capillary blood
flow
Afterload on heart
the amount of pressure that the heart needs to exert to eject the blood during ventricular
contraction
Vasoconstriction of arteries
, The contraction of arterial smooth muscle by the ANS, shrink lumen (hollow space
inside artery)
Vasodilation of arteries
the relaxation of arterial smooth muscle, enlarging the lumen
Elastic arteries
- also called conducting arteries
1 - 2.5 cm
- large vessels (pulmonary trunk & aorta)
- tunica media has many elastic fibers & few muscle cells (elastic fibers help
to even out the pulse (surge of blood) pumped out during systole and reduce the
difference between high and low blood pressures in blood flow)
Muscular arteries
- also called distribution arteries
0.3 - 1 cm
- medium sized (most arteries)
- tunica media has many muscle cells
Arterioles structure
10 μm - 0.3 mm
- no longer a pulse (surge), rather even flow
- have little to no tunica externa
- thin or incomplete tunica media
Aneurysm
