Blood Vessels Flashcards
(17 cards)
Arteries
Carries blood away from the heart at high pressure
Arterieoles
Carries blood from the arteries to the capillaries
Capillaries
Site of diffusion between blood and body tissue
Venules
Carries blood from the capillaries into veins
Veins
Returns blood to heart at a low pressure
Artery Adaptation 1
Collagen - Provides strength to prevent the vessel from bursting and to maintain vessel shape
Artery Adaptation 2
Elastic fibres - Contain elastin that lets them stretch and recoil to minimise changes in pressure
Artery Adaptation 3
Thick smooth muscle layer - Contracts/relaxes to constrict/dilate the lumen and control blood flow
Arteriole Adaptations
-Larger lumen
- Their walls have more smooth muscle and less elastin as they do not need to withstand such high pressures
Vasodilation
Smooth muscle relaxes, dilating the blood vessel and increasing blood flow
Vasocontriction
Smooth muscle contracts, constricting the blood vessel and decreasing blood flow
Capillary Adaptation 1
Lumen is very narrow - This allows red blood cells to be close to body cells
Capillary Adaptation 2
Walls are thin - Substances can be exchanged across a short distance by diffusion
Capillary Adaptation 3
Highly branched - This provides a large surface area for diffusion
Vein Adaptation 1
Collagen - Provides strength to prevent the vessel from bursting and maintain vessel shape
Vein Adaptation 2
Little smooth muscle and elastic fibre - Not much is needed due to low blood pressure, and thinner walls allow veins to be easily compressed, aiding the flow of blood
Vein Adaptation 3
Valves - Pocket valves shut to prevent the backflow of blood when veins are squeezed by surrounding skeletal muscle
