Blood Vessels Flashcards
What is the movement of blood?
arteries→arterioles→capillaries→venules→veins
What is the function of arteries?
to carry high pressure blood away from the heart to the tissue and should maintain and withstand high pressure
How does the structure of arteries relate to their function?
Outer layer- fibrous, tough(to resist pressure), made of collagen, flexible
Middle layer - smooth muscle to contract/relax to maintain pressure and elastic fibres to allow stretch and recoil of vessel to absorb pressure change (stretch with high blood pressure, recoil when blood pressure lowers) smooth blood flow and push blood along
Inner layer - endothelium=smooth+flat to reduce friction for blood flow
Narrow lumen - maintain high pressure
What are arterioles?
narrower arteries whith lower pressure but proportionally more muscle to allow contraction to restrict blood flow or relax to allow full blood flow (control movement of blood flow) - less elastic tissue than arteries
What is the function of capillaries?
connect arteries with veins and allow exchange of substances between blood and tissues
How does the structure of capillaries relate to its function?
- form a network through tissues (capillary beds)
- made of squamous epithelium → very thin an flat + one cell thick = short diffusion distance
- narrow lumen = reduces flow rate giving more time for diffusion
- small diameter to give large SA:Vol/ short diffusion distance
- fenestrations (small gaps/pores) allow seepage of plasma/water to form tissue fluid and allow large muscles through
What are venules?
narrower veins
What is the function of veins?
return low pressure blood from tissues to the heart
How does the structure of veins relate to their function?
Outer layer - fibrous, tough, made of collagen
Middle layer - less smooth muscle and few elastic fibres = don’t need to withstand high pressure and fluctuations
Inner layer - endothelium, smooth and flat cells
Wider lumen - eases flow of blood back to the heart at low pressure and has semi lunar valves to prevent backflow
Skeletal muscle - embedded to aid return of blood and relaxation of heart when drawing blood back in
How does thickness of walls differ in blood vessels?
A = thick
C = one cell thick
V = thin
How does diameter differ in blood vessels?
A = narrow
C = very narrow
V = wide
How does components of wall differ in blood vessels?
A = highly elastic, inner layer of endothelium, outer layer of collagen
C = outer layer of endothelium, fenestrations
V = less elastic + muscle, inner layer of endothelium
How does blood pressure differ in blood vessels?
A = higher and fluctuations
C = low
V = lower
Which blood vessels have valves?
Veins only = semi- lunar
How does cause of flow differ in blood vessels?
A = blood pressure and recoil of elastic fibres
C = blood pressure
V = blood pressure and squeezing action of skeletal muscle and relaxation of atria
