Arrangement of Blood Vessels Flashcards
which blood vessel has the largest cross sectional area
capillaries
which blood vessel has the smallest cross sectional area
aorta
which blood vessel has the highest flow and which has lowest
highest= aorta
lowest=capillaries
what are the 3 wall layers found in arteries and capillaries
tunica adventita
tunica media
tunica intima
whats found in tunica adventia
collagen fibres
whats found in tunica media
smooth muscle
elastin
whats found in tunica intima
squamous epithelium- endothelium layer
what are the wall layers found in cappillaries
endothelium and basement membrane
what blood vessels does aorta branch into
aorta, elastin arteries, muscular arteries, arterioles
what is the effect of more elastin in tunica media
more distensible - when high bp- elastin arteries
what is the effect of more smooth muscle in tunica media
vasoconstriction
what is the diameter of aorta, elastin arteries, muscular arteries and arterioles
aorta and elastin arteries- 4 mm!
muscular arteries- 0.3-10 mm
arterioles- 10 UM- 0.3 mm
what is the effect of neural/ chemical stimuli on arterioles
change in diameter of arterioles- changes blood flow to capillaries- gas exchange
what is the diameter of capillaries
8-10 UM = smallest diameter of all blood vessels
what are the two types of capillaries and how are they different
continous= tight junction between endothelial cells. have intercellular clefts
fenestrated= pores in endothelial cells so more permeable. found in SI, kidney.
how is blood flow regulated within the capillaries
smooth muscle sphincter
when smooth muscle sphincter contracts= blood flows
what is the meta- arteriole
big blood vessel lying over the capillary bed
what is the diameter of venules
8-100 UM
what is the organisation of venules
largest will have 3 layers
smallest will only have endothelium layer
at any given time, which vessel is 65% of all blood volume
veins- here the bp is also lowest
which vessel is the biggest resistance to flow
arterioles- smooth muscle= vasoconstriction= reduces bp
what controls the blood pressure of the venous return
respiratory pump
skeletal muscle pump
venous valves
what does the respiratory pump do
causes inspiration
- increases abdominal pressure
- also, reduces thoracic pressure, thoracic veins dilate, more blood to R. atrium
what does the skeletal muscle pump do
causes skeletal muscle (legs) to contract, compresses the deep veins between them, propels blood to heart
