Blood Vessels Vessel Layers Smooth Muscle Arteries Capillaries

Blood Vessels Vessel Layers Smooth Muscle Arteries Capillaries Marieb: 19

Circulation Arteries Capillaries Veins

The Lumen

Blood Vessel Layers Tunica intima Tunica media Tunica externa

Tunica intima Endothelium Subendothelium

Tunica media Largest layer Smooth Muscle Elastin

Smooth Muscle Non-Straited Involuntary

Smooth Muscle: Multiple Activation Methods Varicosities Gap Junctions Local Factors

Tunica media Vasoconstriction Vasodilation Vasomotor nerve fibers

Tunica externa (Adventitia) Collagen fibers Nerve fibers Vasa vasarum

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