transport in man Flashcards
layers of arteries and veins
- endothelium
- smooth muscle tissue and elastic fibres
- connective tissue
blood pressure
-force exerted by blood against walls
-contraction of muscular walls of heart generates BP (closer to heart, higher BP)
why is left ventricle thicker than right ventricle?
more muscular: stronger contraction to pump blood at higher pressure to all parts of the body
why is aorta wall thicker than pulmonary artery wall?
withstand greater BP as blood in aorta travels to all parts of the body
blood in pulmonary artery travels at lower pressure as it only needs to reach the lungs
artery properties (3)
- thick muscular walls
- numerous elastic fibres
- smaller lumen size relative to diameter
thick muscular walls
- allows diameter of vessel to be adjusted: bring about vasodilation and vasoconstriction
–> control BP, regulate blood flow
numerous elastic fibres
-elasticity for blood vessels to dilate, stretch and recoil: withstand high BP in vessel, prevent bursting
-stretch and recoil: maintain high BP in vessel
vein properties (3)
- thinner, less muscular and less elastic walls
- semilunar valves present
- veins located btwn large muscles of the body
thinner, less muscular and less elastic walls
BP in veins is lower: less muscular tissue needed to support vessel
semilunar valves present (except in vena cava)
low BP in veins, prevent backflow of blood so blood only flows in one direction
located btwn large muscles
contraction of body muscles: push against walls of the vein, push blood forward to heart against gravity
capillaries properties (3)
- one-cell thick
- small gaps between endothelial cells
- large network
one-cell thick
short distance for quick diffusion
small gaps btwn endothelial cells
-some components of blood leak out from blood plasma, forming tissue fluid
-allow WBCs to squeeze through, too small for large molecules
large network
-increases SA for quick diffusion
-low BP: more time for diffusion to take place
