Blood VesselsGross Anatomy

Blood Vessels

• Vascular system– Closed transportation system for the blood

• Arteries– Leave heart– Carry oxygen (except pulmonary artery!)

• Arterioles– Branches from arteries– Form networks in capillaries

Blood Vessels• Capillary beds– Network connection between arteries and veins– Supply oxygen to tissues

• Venules– Branches of veins – Found in capillary beds

• Veins– Return to heart– Carry carbon dioxide (except pulmonary vein)

Microscopic Anatomy• 3 wall coatings of most vessels– Tunic intima• Internal slick surface

– Tunic media• Middle coat• Smooth muscle• Elastic tissue fibers

– Tunic Externa• Outermost covering• Fibrous connective tissue for support and protection

Structural Differences• Veins– Under low pressure (flow against gravity)– Shallow– Larger valves

• Arteries– Thicker walls, higher pressure– Deep, protected

• Both arteries and veins usually follow a similar path• Skeletal muscle contributes to venous return– “milking” of veins to push up, Valves prevent backflow

Capillaries• ONE layer thick (tunica intima)– Allows for easy gas exchange– Forms a bed or network• Microcirculation

• Two types of vessels in capillary beds– Vascular shunt• Connection point between arteriole and venule

– True capillary• Exchange gases with tissues and vessels• 10 to 100 per capillary bed

Gross Anatomy• Aorta– Largest artery– Size of garden hose– Leaves left ventricle of heart

• Branches into other aortic arteries– Ascending aorta• Arches to left (aortic arch)• Then continues into thorax, through diaphragm, into

abdominal cavity to become abdominal aorta

Aortic Branches

• Ascending aortic– Left and right coronary arteries

• Supply heart with blood

• Aortic Arch– Brachiocephalic trunk

• branches into – R. Carotid/ R. Subclavian

– L. Carotid supplies brain, head, neck– L. Subclavian

• Branches into– Vertebral arteral (brain)– Axillary artery to brachial artery

Aortic Branches• Thoracic Aorta

branches into– Intercostal – Bronchial– Esophageal– Phrenic (diaphragm)

• Supplies thoracic region

Aortic Branches• Abdominal aorta– Celiac trunk• Hepatic, gastric,

splenic arteries

– Superior mesenteric• small/large intestine

– Inferior mesenteric• Lg intestine

– Common iliac• Final branches• Lower body

Major Veins• Veins return deoxygenated blood to the heart

through the venae cavae– Superior (upper body)– Inferior (lower body)

• Named same way as arteries – Location– Organ served

• Great Saphenous– Longest vein in body, legs