Cardiovascular System: Circulation Pathways and Lymphatics Comparative Anatomy Tony Serino, Ph.D. Biology Department Misericordia Univ.

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

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

Vessel Anatomy

Capillary Anatomy Three types: tight, fenestrated and sinusoids

Capillary Bed (blood flowing)

Capillary Bed (blood shunted)

Atherosclerotic plaque

Venous Side

Skeletal Muscle Pump

Lymphatic Circulation Drains tissue fluid (interstitial fluid) Prevents edema Filters the lymph Returns clean lymph to circulation at junction of subclavian and jugular veins

Lymphatic System

Lymphatic Capillaries

Accumulation of Lymph

Lymphatic Vessels

Lymph Drainage

Thoracic Duct

Lymph Node –filters lymph

Lymph Node Cortex Germinal Center Medulla

Thymus

Tonsils Pharyngeal Tonsil (adenoids)

Spleen

Internal Spleen