Blood vessels Flashcards
How many miles of blood vessels do we have
60,000
How long does it take a drop of blood to circulate your body
60 seconds
How many endothelial cells in circulatory system
1 trillion
What is angiogenesis
process where body regulates rebuilding and breaking down of new blood vessels
What does to many and too little blood vessels cause
> cancer by feeding diseased tissue
< tissue loss
3 tissue layers of vessels
Tunica Externa
Tunica Media
Tunica Intima
What is Tunica Externa
Outer coat - mainly consist of collagen fibres
What is Tunica Media
Middle coat - mainly consists of Muscle and elastic tissue
What is Tunica Intima
Inner coat - Consisting mainly of endothelial cells, some collagen fibres
What are the differences between the various blood vessels
Related to their function within the circulatory system
What do arteries do
Transport blood away from the heart
How is blood pumped and how does this affect the arteries
Pumped at high pressure - arteries structured to withstand and maintain high pressure
How are lumen arteries structured
Relatively narrow to maintain high pressure
Structure of Tunica intima
Formed by an endothelium, mainly consists of endothelial cells
Structure of tunica media
Smooth, Elastic muscle that forms the thickest layer of artery wall - Enables vessels to flex + withstand high BP
Structure of tunica externa
Connective tissue, consists mainly of tough collagen fibres, provide strength and durability
Where are arteolies
Branch off from arteries
Structure of arterioles
Similar in structure to arteries with less elastic tissue and more smooth muscle
How does structure of arterioles help
Enables them to constrict and reduce blood flow through the capillaries
Where are capillaries
Branch off from arterioles
What size are capillaries
Smallest blood vessels
What do capillaries form
Capillary beds - bring blood as close to cells as possible to enable efficient exchange of substances
What is lumen
Very narrow ~7um in diameter, just enough for individual RBCs to pass through one at a time -> Slows down blood flow to allow substances to diffuse in and out
What is endothelium
Very thin, only one cell thick to allow efficient diffusion
What is basement membrane
Anchors capillaries in position within tissues
What are venules
Drains blood from capillary beds and feed it back into veins
Structure of venules
Contain smooth muscle, can constrict to control blood flow through capillaries
What do veins do
Transport blood back to the heart; at lower BP than arteries impacting structure
Structure of veins
Lumen
Tunica intima
Tunica Media
Tunica Externa
Valves - contain valves to prevent backflow of blood away from the heart & prevents blood pooling in bottom of body due to gravity
Blood flow in veins during contraction
As skeletal muscles contract, blood beyond the site of contraction is forced towards the heart opening the valves
Blood flow in veins during relaxation
blood pushes back against the valves causing them to close and prevent blood being forced away from the heart again
What causes varicose veins
if a vein wall becomes weakened, valves may no longer close properly
What are varicose veins like
Enlarged, bumpy, and varicose
Where does variocse veins happen
Superficial veins (Skin surface underneath muscle)
How to get rid of varicose veins
Can be surgically removed without affecting blood flow, as most blood is returned to the heart by deep veins
