Circulatory System 2

• carry blood away from heart

• usually O2 rich

• Pulmonary artery – artery leading from heart to lung (deoxygenated)

• connective tissue and muscle

• walls elastic and thick

• precapillary sphincters control blood flow

Arteries

• carry blood to the heart• usually O2 poor • Pulmonary vein – vein leading from lung to

heart (oxygenated)• valves push blood towards heart• smooth surface

Veins

• Valves prevent backflow

• Less pressure than arteries

• Skeletal muscles contract and pump blood back to the heart

Blood Flow in Veins

• smallest blood vessels for gas exchange• High SA• Thin walls• connect arteries/arterioles to veins/venules• Exchanges: carbon dioxide/oxygen and

nutrients/waste

Capillaries

• Arteries to arterioles to capillaries• Capillaries to venules to veins

Arterioles and Venules

• Systemic Circulation– oxygenated blood to tissue

and deoxygenated blood to heart

• Pulmonary Circulation– between lungs and heart– deoxygenated blood goes to

lungs and oxygenated blood goes to heart

Circulation Types

Cardiac Circulation– circulation of blood within

the heart

Circulation Types

• How do nutrients pass from the blood vessels into the individual cells!?!?!?!

• DIFFUSION: molecules move across a membrane from an area of higher concentration to an area of lower concentration

Nutrient Exchange

• In other words …• If the blood in the capillary contains a higher

concentration of oxygen than does the fluid next to it, the oxygen moves spontaneously into the fluid by diffusion

Nutrient Exchange