Blood VesselsThe tubes that transport the blood

The Basics Arterial system takes

blood away from theheart

Venous system takesblood back toward theheart

Arteries (aa) and arterioles (a-ole) Thick middle muscular wall layer Blood pressure (bp) is typically measured

here Largest are aorta and pulmonary arteries

Arteries (aa) and aterioles (a-ole)

Veins (vv) and venules (v-ule) Carry blood toward the heart “Capacitance” vessels Thin, inconstant middle muscular wall layer Under little or no blood pressure Some vv contain pocket valves that are

formed by folds from the inner wall layer

Veins (vv) and venules (v-ule)

Capillaries connection between a-oles and v-ules Functions for the exchange of:

Oxygen and carbon dioxide Nutrients Waste materials

Usually expand to form extensive capillary beds Essentially contact almost all cells of the body other

than e.t.

Capillaries

Blood Circuit Simple Route

Heart arteries arterioles capillaries venulesveinsheart

Wall Structure All blood vessels havethree layers except forcapillaries which onlyhave one.

Tunica Externa (= adventitia) Outermost layer

Loose c.t. with elastinand collagen fibers

Tunica Media Middle layer

Smooth muscle and c.twith elastin fibers

Tunica Intima Innermost layer

Endothelium(= epithelium)

Simple squamous e.t. +basal lamina + c.t.