BLOOD VESSELS Flashcards
ARTERIES
Carry blood away from the heart
What are the types of blood vessels in order?
Arteries Arterioles Capillaries Venules Veins
What generates a high pressure when blood is sent away from the heart?
Ventricular systole
Why are arteries lined with endothelium?
To reduce friction of blood
Why do arteries have thick, muscular and elastic walls?
- To stretch under high pressure
- To recoil under low pressure
How are artery walls adapted to be able to withstand and maintain high hydrostatic pressure?
TO WITHSTAND PRESSURE
- Wall is thick
- Thick layer of collagen which provides strength
- Endothelium is folded to ensure no damage to endothelium as it stretches
TO MAINTAIN PRESSURE
- Thick layer of elastic tissue that recoil
- Thick layer of smooth muscle which constricts lumen of artery
Why do arterioles not need to withstand as much pressure as arteries?
They are further away from the heart
Contraction of smooth muscle
Vasoconstriction - lumen increases in size
VEIN
Carry blood towards the heart
Is there a high or a low blood pressure in the veins? Why?
Low blood pressure because veins are further from the heart, blood is travelling mostly against gravity, increased friction
and slowed blood flow due to capillaries.
Is the endothelium thin or thick in the veins? Why?
Thin because blood isn’t under high pressure so a thick wall isn’t required
Relaxation of smooth muscle
Vasodilation - lumen reduces in size
