Cardiovascular System Flashcards
Describe tunica externa
loose fibrous connective tissue, outer layer of vessel
describe the tunica media
layer of smooth muscle, 2 outmost layer
tunica intima
endothelial cells, innermost layer
Which type of artery delivers to specific organs
Muscular arteries
which type of artery is found nearest the heart?
elastic arteries
which type of artery is more active in vasoconstriction
muscular arteries
Describe the structure of arterioles
Single layer of spiralling smooth muscle
How to arterioles react in response to e.g. cold or shock
Can constrict so blood flow bypasses tissues
What are the two types of capillaries?
Fenestrated and continuous
Why type of capillary is least permeable?
Continuous
Where are continuous capillaries found?
Brain, lungs and muscles
What is the difference between fenestrated and continuous capillaries?
Fenestrated are ‘leakier’ - small pores and small gaps between cells - allow for exchange of larger molecules
What are the 3 layers of blood vessels?
- tunica externa/adventitia
- tunica media
-tunica intima
How many layers are veins made of?
three
Do arteries of veins have more smooth muscle/elastin?
Arteries have more
What are venules?
The smallest, post-capillary blood vessels
What percentage of blood is kept as reserve in veins?
65%
Why are there more venous valves in the lower limbs?
to stop blood flowing backwards
Are venules porous?
Yes, very
What are venous sinuses
Group of sinuses that drains venous blood circulating from cranial cavity
What is the venous return
the volume of blood flowing back to heart through veins