MCB 246 EXAM 1 UPDATE 2026
QUESTIONS AND ANSWERS WITH
VERIFIED SOLUTIONS 100%
CORRECT A+
what do veins rely on for 1 way movement
clincial relevance? - CORRECT ANSWES -- function: collect blood from capillaries and
return to the heart
structure:
larger in diameter than arteries. have thinner walls and lower blood pressure
vein classification:
-venules: collect blood from capillaries. diameter is <100 um
-small and medium sized veins (2-9mm)
large veins (> 9mm)
while pressure from the heart drives blood flow in arteries, pressure in veins is often too
low to oppose gravity
rely on skeletal muscle movement and valves in tunica intima to ensure 1 way
movement
clinical relevance:
-resistance to flow (gravity/obesity) causes pooling about valves, veins stretch out
(varicose veins)
-also can trap embolus in valves if opposed by gravity for extended periods of inactivity
(DVT)
what are the percentages of the organs that aid in the distribution of blood? -
CORRECT ANSWES -- heart: 12%
pulmonary circulation: 18%
systemic: 70%
-systemic veins (55% of circulation because they are BLOOD RESERVOIRS)
veins are _____ ____________ due to their ability to stretch 8x's more than arteries.
,because of this, veins can accommodate large changes in blood voluem - CORRECT
ANSWES -- capacitance vessels
capillary function and structure - CORRECT ANSWES -- function: smallest blood
vessels. gas exchanges
-diffuse between blood and interstitial fluid
structure:
-endothelial
-no tunica media or tunica externa
-only tunic interna
-avg. dimension are 8-10 micrometers. 1 mm in length
-3 major types
what are the 3 types of capillaries - CORRECT ANSWES -- continuous: most common
type. continuous lining around the lumen that rests on a complete basement membrane.
gaps between endothelial cells are called intercellular clefts. blood can move in or out of
the blood. size of intercellular clefts prevents the movement of large substances.
continuous are found in muscle, skin, thymus, lungs and cns.
fenestrated: thin areas of fenestrations. these are smal enough to prevent formed
elements from passing through the wall yet large enough to allow the movement of
some smaller plasma proteins. seen with fluid between blood and tissue. found in small
intestine for absorption of nutrients, ciliary process of the eye in the production of
aqueous humor, the choroid plexus of the brain in the production of cerebrospinal fluid,
most of the nedocrine glands to facilitate the absorption of hormones in tohe blood and
the kidneys for filtering the blood
sinusoids: discontinuous. have an incomplete lining with large openings, gaps, and
basement membrane is either discontinuous or absent. these openings allow for
transport of large substance. sinusoids are found in red bone marrow for entrance of
formed elements, the liver, and splee for the remoal of aged rbc from the cardiovascular
circulation, and some endocrine glands for the movement of hrmone molecules into the
blood. reddish color.
capillary bed - CORRECT ANSWES -- is fed by a metarteriole wich is a branch of an
arteriole. the proximal part of the metarteriole is encircled by scatterred smooth muscle
cells, whereas the distal part of the metarteriole has no smooth muscle cells.
thoroughfare channel connects to apostcapillary venule which drains the capillary bed.
single capillary bed is 10-100 capillaries
what are true capillaries - CORRECT ANSWES -- vessels that branch from the
metaarteriole and make up the bulk of the capillary bed. at the origin, a ring called the
precapillary sphincter controls blood flow into the true capillaries. sphincter relaxation
,permits blood to flow into the true capillaries, whereas spincter contraction causes blood
to flow directly from the metarteriole and thoroughfare channel into the postcapillary
venule with blood bypassing the capillary bed. this cycle is called vasomotion.
what are capillary thoroughfare channels - CORRECT ANSWES -- direct capillary
connections. arterioles to venules
controlled by smooth muscle segments covering th eproximal metartioles
-connect to postcapillary venules which drain capillary into venous system
the amount of blood entering capillaries per unit time per gram of tissue is called -
CORRECT ANSWES -- perfusion
true or false: veins can be oxygenated or deoxygenated - CORRECT ANSWES -- true.
depends on the circuit- pulmonary vs systemc
venules are the ______ veins - CORRECT ANSWES -- smallest. smallest are called
postcapillary venules, drain capillaries. largest venules have all three tunics
collect blood from capillaries
pathways of blood vessels - CORRECT ANSWES -- simple: one major artery delivers
blood to the organ or body region and tehen branches into smaller and smaller arteries
to become arterioles. simple pathway includes one artery, a capillary bed, and one vein
associated with an organ or body region. blood transported to and from the spleen is an
example of a simple blood flow pathway. arteries that provide only one pwthway through
which blood can reach an organ are referred to as and arteries.
alternative pathway: differ in the number of arteries, capillary beds, or veins that serve
an organ or body region. 3 of the alternative pathways are designated as anastomoses.
anatsomoses: is the joining together of blood vessels. this is an alternative route for
blood flow.
-arterial anastomosis: includes two or more arteries converging to supply the same body
regions
functional end arteries: other vessels like coronary arteries are so tiny that the function
of the arteries may almost be considered end arteries.
-venous anastomosis: includes tow or more veins draining the same body region. veins
tend to form many more anastomoses than do arteries. veins that drain the upper limb
including the basilic, brachial, and cephalic veins provide an example of a venous
anastomosis
-arteriovenous anastomosis: shunt. transport blood from an artery directly into a vein,
bypassing the capillary bed. present in fingers, toes, palms, ears. vulnerable to frostbite
, different type of blood vessel arrangement is a _______ _________
whats a portal vein
sequence of blood vessels? - CORRECT ANSWES -- portal system
blood flows through 2 capillary beds, with the two capillary beds separated by a portal
vein.
portal vein: delivers blood to another organ first, before the blood is sent back to the
heart. sequence of blood vessels: artery, capillary bed, portal vein, capillary bed., and
vein.
provides a more direct mean of deliving hypothalamic regulatory hormones to the
anterior pituitary.
what is the cross sectional are of a vessel? - CORRECT ANSWES -- is the diameter of
the vessels lumen. the total cross sectional area is estimated as the aggregate lumen
diameter across the total number of give type of vessel if they were all positioned side
by side.
total cross sectional area of arteries is small. same for veins.
cross sectional area is large
capillaries have a large total cross sectional area. small cross sectional area.
cross sectional area is significant bc of it s influence on blood flow velocity
blood flow =
what its relationship to surface area? - CORRECT ANSWES -- volume of blood flowing
through a vessel in given period
inverse relationship bt blood flow and cross sectional area(surface area)
fastest flow=arteries (smallest cross- sectional area)
slowest flow= capillaries (highest cross sectional area)
QUESTIONS AND ANSWERS WITH
VERIFIED SOLUTIONS 100%
CORRECT A+
what do veins rely on for 1 way movement
clincial relevance? - CORRECT ANSWES -- function: collect blood from capillaries and
return to the heart
structure:
larger in diameter than arteries. have thinner walls and lower blood pressure
vein classification:
-venules: collect blood from capillaries. diameter is <100 um
-small and medium sized veins (2-9mm)
large veins (> 9mm)
while pressure from the heart drives blood flow in arteries, pressure in veins is often too
low to oppose gravity
rely on skeletal muscle movement and valves in tunica intima to ensure 1 way
movement
clinical relevance:
-resistance to flow (gravity/obesity) causes pooling about valves, veins stretch out
(varicose veins)
-also can trap embolus in valves if opposed by gravity for extended periods of inactivity
(DVT)
what are the percentages of the organs that aid in the distribution of blood? -
CORRECT ANSWES -- heart: 12%
pulmonary circulation: 18%
systemic: 70%
-systemic veins (55% of circulation because they are BLOOD RESERVOIRS)
veins are _____ ____________ due to their ability to stretch 8x's more than arteries.
,because of this, veins can accommodate large changes in blood voluem - CORRECT
ANSWES -- capacitance vessels
capillary function and structure - CORRECT ANSWES -- function: smallest blood
vessels. gas exchanges
-diffuse between blood and interstitial fluid
structure:
-endothelial
-no tunica media or tunica externa
-only tunic interna
-avg. dimension are 8-10 micrometers. 1 mm in length
-3 major types
what are the 3 types of capillaries - CORRECT ANSWES -- continuous: most common
type. continuous lining around the lumen that rests on a complete basement membrane.
gaps between endothelial cells are called intercellular clefts. blood can move in or out of
the blood. size of intercellular clefts prevents the movement of large substances.
continuous are found in muscle, skin, thymus, lungs and cns.
fenestrated: thin areas of fenestrations. these are smal enough to prevent formed
elements from passing through the wall yet large enough to allow the movement of
some smaller plasma proteins. seen with fluid between blood and tissue. found in small
intestine for absorption of nutrients, ciliary process of the eye in the production of
aqueous humor, the choroid plexus of the brain in the production of cerebrospinal fluid,
most of the nedocrine glands to facilitate the absorption of hormones in tohe blood and
the kidneys for filtering the blood
sinusoids: discontinuous. have an incomplete lining with large openings, gaps, and
basement membrane is either discontinuous or absent. these openings allow for
transport of large substance. sinusoids are found in red bone marrow for entrance of
formed elements, the liver, and splee for the remoal of aged rbc from the cardiovascular
circulation, and some endocrine glands for the movement of hrmone molecules into the
blood. reddish color.
capillary bed - CORRECT ANSWES -- is fed by a metarteriole wich is a branch of an
arteriole. the proximal part of the metarteriole is encircled by scatterred smooth muscle
cells, whereas the distal part of the metarteriole has no smooth muscle cells.
thoroughfare channel connects to apostcapillary venule which drains the capillary bed.
single capillary bed is 10-100 capillaries
what are true capillaries - CORRECT ANSWES -- vessels that branch from the
metaarteriole and make up the bulk of the capillary bed. at the origin, a ring called the
precapillary sphincter controls blood flow into the true capillaries. sphincter relaxation
,permits blood to flow into the true capillaries, whereas spincter contraction causes blood
to flow directly from the metarteriole and thoroughfare channel into the postcapillary
venule with blood bypassing the capillary bed. this cycle is called vasomotion.
what are capillary thoroughfare channels - CORRECT ANSWES -- direct capillary
connections. arterioles to venules
controlled by smooth muscle segments covering th eproximal metartioles
-connect to postcapillary venules which drain capillary into venous system
the amount of blood entering capillaries per unit time per gram of tissue is called -
CORRECT ANSWES -- perfusion
true or false: veins can be oxygenated or deoxygenated - CORRECT ANSWES -- true.
depends on the circuit- pulmonary vs systemc
venules are the ______ veins - CORRECT ANSWES -- smallest. smallest are called
postcapillary venules, drain capillaries. largest venules have all three tunics
collect blood from capillaries
pathways of blood vessels - CORRECT ANSWES -- simple: one major artery delivers
blood to the organ or body region and tehen branches into smaller and smaller arteries
to become arterioles. simple pathway includes one artery, a capillary bed, and one vein
associated with an organ or body region. blood transported to and from the spleen is an
example of a simple blood flow pathway. arteries that provide only one pwthway through
which blood can reach an organ are referred to as and arteries.
alternative pathway: differ in the number of arteries, capillary beds, or veins that serve
an organ or body region. 3 of the alternative pathways are designated as anastomoses.
anatsomoses: is the joining together of blood vessels. this is an alternative route for
blood flow.
-arterial anastomosis: includes two or more arteries converging to supply the same body
regions
functional end arteries: other vessels like coronary arteries are so tiny that the function
of the arteries may almost be considered end arteries.
-venous anastomosis: includes tow or more veins draining the same body region. veins
tend to form many more anastomoses than do arteries. veins that drain the upper limb
including the basilic, brachial, and cephalic veins provide an example of a venous
anastomosis
-arteriovenous anastomosis: shunt. transport blood from an artery directly into a vein,
bypassing the capillary bed. present in fingers, toes, palms, ears. vulnerable to frostbite
, different type of blood vessel arrangement is a _______ _________
whats a portal vein
sequence of blood vessels? - CORRECT ANSWES -- portal system
blood flows through 2 capillary beds, with the two capillary beds separated by a portal
vein.
portal vein: delivers blood to another organ first, before the blood is sent back to the
heart. sequence of blood vessels: artery, capillary bed, portal vein, capillary bed., and
vein.
provides a more direct mean of deliving hypothalamic regulatory hormones to the
anterior pituitary.
what is the cross sectional are of a vessel? - CORRECT ANSWES -- is the diameter of
the vessels lumen. the total cross sectional area is estimated as the aggregate lumen
diameter across the total number of give type of vessel if they were all positioned side
by side.
total cross sectional area of arteries is small. same for veins.
cross sectional area is large
capillaries have a large total cross sectional area. small cross sectional area.
cross sectional area is significant bc of it s influence on blood flow velocity
blood flow =
what its relationship to surface area? - CORRECT ANSWES -- volume of blood flowing
through a vessel in given period
inverse relationship bt blood flow and cross sectional area(surface area)
fastest flow=arteries (smallest cross- sectional area)
slowest flow= capillaries (highest cross sectional area)
