Cardiovascular System PA 544 Clinical Anatomy Tony Serino, Ph.D.

General Circulatory System Cardiovascular Consists of a closed system of vessels which transport blood Two circuits: Systemic and Pulmonary Arteries move blood away from the heart Veins move blood toward the heart

General Circulatory System Lymphvascular –moves lymph Consist of blind end tubes which collect interstitial fluid (now called lymph) and returns it to circulation The lymph is cleaned before returned to the blood vessels

Blood Vessels Arteries –conduct blood away from heart Elastic arteries, Muscular arteries, arterioles Veins –conduct blood toward heart Venules, small and large veins Capillaries –thinnest blood vessel; used in exchange, is the functional unit of circulatory system (Microcirculation) AV shunts, metarterioles, pre-capillary sphincters, and capillary bed

Blood Vessels Types

Vessel Anatomy

Capillary Anatomy Three types: tight, fenestrated and sinusoids

Capillary Types Tight Capillary Fenestrated Capillary Sinusoidal Capillary

Capillary Bed

Arteries and Veins Arteries are known as resistance vessels, especially the arterioles Arteries withstand the greatest BP Veins are capacitance vessels, they are able to change the diameter to hold more or less blood

BP through Vascular Tree Small changes in arteriolar diameter produce big changes in resistance; termed total peripheral resistance (TPR)

TPR (total peripheral resistance) TPR is the opposition to blood flow through the vessel (caused by friction) Arteries with their smaller lumen resist blood flow Arteriolar diameter contribute the most to TPR Arteriolar compliance (the ability of the vessel to distend) controls the TPR Sympathetic innervation controls arteriolar radius The viscosity of the blood also affects resistance

Blood Flow Velocity in Vascular Tree

Blood Flow Changes During Exercise

Atherosclerotic plaque

Pressure Points

Skeletal Muscle Pump