1. Blood Vessels
Peter, Sam and Alex

3. Arteries – Structure Outer layer of connective tissue
Layer of elastic tissue
Smooth muscle
Another elastic tissue layer
Bottom layer is endothelium
Arterioles: Smaller branches of arteries, thinner, lead to capillaries

4. Arteries - Function
Carry oxygen-rich blood to the body and head and deoxygenated blood to lungs
Muscles contract when heart relaxes and expand when it pumps to regulate flow and pressure
Wide diameter allows fast, easy blood flow
Thick and elastic to withstand blood pressure
Muscle in arterioles contract and expand to control flow speed and volume

5. Capillaries – Structure
10-40 billion in body
.001 cm from every cell at farthest
3-7 micrometers wide (red blood cells 8)
1 epithelial cell thick

6. Capillaries – Function
Provide oxygen and nutrients to organs while removing wastes like carbon dioxide
Thinness allows easy diffusion of oxygen (out), carbon dioxide (in) and other nutrients/wastes
Pressure inside capillary can lead to bulk flow of water and solutes out
Small diameter (red blood cells pressing against wall) and slowed blood flow make diffusion easier
High number and closeness to cells allows almost every cell access

7. Veins – Structure Outer layer of connective tissue
Smooth muscle with elastic fibers
Endothelium is innermost layer
Valves
Venules: small veins, thin, allow some
diffusion, help control capillary pressure

8. Veins – Function
Return deoxygenated blood to to heart (which pumps it to the lungs)
Heart cannot pump blood in veins so skeletal muscles alongside contract to move it
Valves allow flow of blood only towards heart
Valves closed by blood backflow, can hold/store blood

10. Questions?

11. Sources
Bianco, Carl.  "How Your Heart Works." 1 April October <
“The Human Heart” The Franklin Institute The Franklin Institute. 28 October 2008 <
“Circulatory System” Microsoft Encarta Online Encyclopedia Encarta Encyclopedia. 27 October 2008 <
Starr, Cecie and Ralph Taggart, Biology: The Unity and Diversity of Life. Pacific Grove: Brooks/Cole, 2000.