Cardiovascular system 3 Flashcards
What are the three layers of blood vessels
Tunica Intima - inner most
Tunica Media - Middle layer
Tunica adventitia - outermost
Describe the layers of the Tunica Intima
Endothelium - Simple squamous epithelium lines lumen wall
Sub-endothelium - Sparse pad of loose FCT cushioning endothelium
Internal Elastic Lamina - Condensed sheet of elastic tissue. (well developed in arteries and less developed in veins)
Describe the Tunica Media
Smooth muscle - Support matrix - Mainly elastin and collagen
Thickness of media is proportional to both vessel diameter and BP (If high P thick wall, If low P thin wall)
Describe the Tunica Adventitia
Loose FCT - high collagen content, variable amount of elastin. Tensile protein band stops overdistention
Lymphatics and autonomic nerves (alters tone of muscle)
What is Vasa Vasorum (externa)
supplies nutrients to blood vessels
What is the thickest layer of the blood vessels
Tunica Media
How does blood flow become smooth when the heart is causing pulsating
Elastic tissue passively takes up energy and reuses it to pump when the heart is at rest - causes steady smooth flow. (Thoracic aorta)
What is the role of arterioles
Resistance vessels pf the circulation - determines BP. Flows into capillaries.
(When constricted makes harder for blood to pump)
What is the function of capillaries
Exchange between blood and tissue
What are Venules and what do they do
Smallest vein - Start of the drainage.
Monocusple, Valve leaflets that close to stop backflow
What are the functions of veins
Low pressure, Large volume transporrt system
Unidirectional (One-way flow - from capillaries to heart)
Capacitance vessels - passive uptake - holds blood vol when not needed
Describe the layers of veins
Intima - epithelium (not as elastic as arteries)
Media - Thinner layer - often two distinct ones of smooth muscle
Adventitia - Thickest layer - limits how much can extend/stretch
Are there the same amount of veins to the corresponding artery
No. There are often 2 veins for every corresponding artery as the volume of blood transported needs to be the same
