Blood Vessels Arteries Capillaries Marieb 19 Arterial System

Blood Vessels Arteries Capillaries Marieb: 19

Arterial System Elastic (Conducting) 1 cm-2. 5 cm Muscular (Distributing) 0. 3 mm-1 cm Arterioles 10 um- 0. 3 mm Diameters for lumens

Elastic (Conducting) Arteries Fire Hose Very elastic Conduct blood with little resistance

Compliance/Distensibility Pressure waves Decreases pressure in smaller vessels

Muscular (Distributing) Arteries Carry blood to organs Smallest named arteries Less elastin, more smooth muscle

Arterioles Largest 3 layers Smallest 2 layers Change diameter

Capillaries Smallest vessel Tunica intima

Three Types of Capillaries Continuous Fenestrated Sinusoidal

Continuous Capillaries Endothelial cells Tight junctions Blood Brain Barrier

Fenestrated Capillaries Pores More material in and out of blood SI Kidney Endocrine glands

Sinusoidal Capillaries Very large fenestrated pores Big intercellular clefts Liver Bone marrow

Capillary Beds

Capillary Beds: Closed Terminal Arterioles Metarterioles + Thoroughfare channel Vascular Shunt Postcapillary venule

Capillary Beds: Open Precapillary sphincters True capillaries

Venous System Venules Veins Superior Vena Cava Inferior Vena Cava

Venous Blood Pressure No pulse Very low pressure Blood is pushed back up to the heart

Systemic Venous System Large Lumen Thin walls Less smooth muscle Less elastin Holds ~65% of blood

Venous Valves

Varicose Veins Pressure destroys valves Veins collapse and become deformed

The Muscular Pump Muscle contraction drives blood to heart

The Respiratory Pump