Blood Vessel - Anatomy: Elastic Arteries Muscular Arteries Arterioles Capillaries Vessel Types: Heart 1) Arteries (away) 2) Capillaries 3) Veins (toward) Venules Veins

Structure and function - arterial system. 1/3 Conducting The aorta & major branches Thickest Largest Elastic tubes Arteriosclerosis Atherosclerosis (thickening) = turbulent flow Balloon or burst (aneurysm)

Arterial System 2/3 Distributing 3/3 Arterioles Delivery to organs More active constriction Less distensible Renal/urine - NFP 3/3 Arterioles Flow determined by arteriole diameter Constricted = bypassed Dilated = local flow

Capillary Flow Control Precapillary sphincter Cuff of smooth muscle fibers Open = flow Closed = shunt

Venous System. ↑ diameter walls gradually ↔ Vein Valve: Venules→Veins Larger lumens than corresponding arteries Reservoirs 65% body’s blood supply VALVES for backflow Most abundant in limbs - gravity

Blood Vessels: Arteries Arteries Arterioles Capillaries Heart Venules Carry blood away from heart Thick-walled: Smooth muscle / elastic fibers Withstand high pressure Venules Veins

Blood Vessels: Arteries Arterioles Arterioles Capillaries Heart Control distribution of blood flow Smooth muscle expands / contracts Under hormone / NS control Venules Veins

Blood Vessels: Arteries Arterioles Capillaries Capillaries Heart Nutrients / waste exchanged with cells: Vessel wall one-cell thick Blood flow very slow Materials exit / enter via diffusion Venules Veins

Blood Vessels: Arteries Arterioles Veins Capillaries Heart Venules Carry blood towards the heart Thin-walled; large diameter 65% blood volume in veins Venules Veins

Blood Vessels: Arteries Arterioles Veins Capillaries Heart Venules Carry blood towards the heart Thin-walled; large diameter 65% blood volume in veins Low pressure system Blood return to heart assisted by: 1) Valves 2) Skeletal muscle pumps Venules Veins

Blood Vessels Major arteries. Major veins Aorta Brachiocephalic Ascending, arch, thoracic, abdominal Brachiocephalic Ext. & Int. carotid Pulmonary Axillary, brachial, radial, ulnar Femoral, post. tibial Major veins Superior VC Ext. & int. jugular Brachiocephalics Internal & external iliac Femoral..

Heart - Flow Through Heart: Myocardial Infarction:: Prolonged blockage of coronary vessels

Circuits of the Circulatory System:

Major branches - coronary

Coronary Vessels

Sequence of Excitation Heart Physiology: Sequence of Excitation Step 1: Depolarization wave initiated by sinoatrial node (SA Node) Step 2: Impulse to atrioventricular node (AV Node) where briefly delayed

Sequence of Excitation Heart Physiology: Sequence of Excitation Step 3: Impulse to atrioventricular bundle and into bundle branches Step 4: Impulse spreads throughout ventricles along Purkinje fibers

Intrinsic Conduction System:

Control of heart rate: