Cardiovascular Notes

Introduction to Blood Vessels:
● 3 Classes:
○ Arteries - Carry blood away from the heart
■ Elastic Arteries Eg. Aorta & Major Branches (Conducting
vessels)
○ Capillaries - Intimate contact with tissue → facilitate cell
nutrient/waste transfer
■ vascular Shunt
■ True Capillaries
○ Veins - Carry blood back to the heart
■ Post-Capillary Venule (Union of capillaries)
■ Small Veins (Capacitance Vessels - 65% of body’s blood is venous)
■ Large Veins (Capacitance Vessels – 65% of body’s blood is venous)


Blood Vessel Structure:
● 3-Layered Wall:
○ Tunica Intima:
■ Ie. The layer in intimate contact with the blood (luminal)
■ Consists of The Endothelium (Simple Squamous Epithelium)
○ Tunica media:
■ Middle….& Thickest layer (Smooth Muscle & Elastin)
○ Tunica Externa:
■ outermost Layer (Losse collagen fibres)
■ (NB: Also Contains Nerve Fibres, Lymphatics, and Vasa Vasorum (In
larger vessels))

, Fluid Movements Across a Vessel:
● Determined by the balance of 2 forces:
○ 1.Capillary Hydrostatic Pressure:
■ Capillary blood pressure.
○ 2.Colloid Osmotic Pressure:
■ Balance of Blood Osmolarity vs. Tissue Osmolarity
● (:. Net Filtration Pressure = Net Hydrostatic Pressure – Net Osmotic Pressure)