Unit 5 - Biology Flashcards
(194 cards)
Why do veins close?
Veins close to prevent back flow of blood
Do arteries have vales?
No
Do veins have a folded endothelium?
No, veins are flat
Which types of vessels have a smooth endothelium?
Arteries and veins
What is the role of arteries?
Arteries transport blood away from the heart at a high pressure
What is the role of veins?
Veins transport blood from the body’s tissues back to the heart
Why do arteries need to have thick elastic layer?
Arteries are under high pressure so the elastic layer is there to help maintain this high pressure
What are elastic fibres made of?
They are composed of elastin
What do elastic fibres do?
They can stretch and recoil to give flexibility
What does smooth muscle do?
Contracts and relaxes, which changes the size of the lumen
What does collagen do?
Gives structural support to maintain shape and volume of the blood vessel
Which type of blood vessel has the highest pressure?
Artery
Which type of blood vessel has valves?
Veins
What are the smaller branches of veins that feed into the capillaries?
Venules
Which arteries do not carry oxygenated blood?
Pulmonary artery and the umbilical artery
What does the pulmonary artery do?
It carries deoxygenated blood FROM the heart to the lungs
What does the umbilical artery do?
Carries deoxygenated blood from the foetus to the placenta
Why do arteries need a folded endothelium?
Folded endothelium allows the lumen to expand under high blood pressure
Why does the endothelium of arteries and veins need to be smooth?
Reduces the friction for the red blood cells that are travelling through them
Where does the gas exchange happen for CO2 and Oxygen?
Capillaries
Where does the body have the most veins?
In the legs
Explain how veins carry blood against gravity even though they have no pulse of their own
The valves in veins squeeze the blood in a one way direction because the valves are opening and closing
Why do veins need to have thin walls?
To reduce the blood pressure
What do capillaries do?
Link arteries to veins and they let oxygen out of blood as well as letting carbon dioxide into blood