Lecture 7 – Blood Vessels
TYPES OF BLOOD VESSELS
Blood Flow Carries blood away from the heart. Returns blood to the heart.
Blood Pressure - Higher pressure. - Low pressure and often flows
- Needs more muscle and against gravity.
elasticity to withstand pressure - Needs valves to prevent
and smooth out blood flow. backflow, and a way to propel
Amount of Blood - Contain the majority of blood
in Vessel vessels.
- Storage of blood— ~70% of
blood is in the venous system.
Layers - Visible Internal and External - Thinner T. Intima.
Elastic Membranes - IEM is rarely visible, only in
(IEM/EEM). large veins.
- Thicker T. Media than T. - T. Adventitia thickest layer in
- 40-50 layers of SM in largest - 5-15 layers of SM in largest vein
artery (aorta) (vena cava)
- T. Media thinner and contains
Shape - Round - Collapsed, oval
- Small lumen - Flattened, oblong
- Thick walls - Large lumen
- Valves present (covered by
- Thin walls
Contents - Lots of smooth muscle - Dense Irregular CT (e.g.,
- Dense Irregular CT fibroblasts, collagen, etc.)
- Vasa vassorum present in T. - More elaborate vasa vassorum
Adventitia - Nervi vascularis
TYPES OF ARTERIES