Circulatory system

The circulatory system is made up of two components, pulmonary circulation and systemic circulation. Pulmonary circulation is responsible for getting deoxygenated blood to the lungs for oxygenation. Systemic circulation is responsible for getting the oxygenated blood to the body. The heart is made up of four chambers. The right side of the heart collects deoxygenated blood and pumps it to the lungs; the left side collects oxygenated blood and pumps it to the rest of the body. Blood vessels are named based on the direction of blood flow through them. Arteries carry blood away from the heart; veins carry blood toward the heart. Oxygen levels play no role in their name.

The arterial system is tree-like in structure with larger vessels branching into medium vessels, which branch into smaller vessels. This branching occurs in a regular pattern. Arteries also show interconnectivity through anastomoses. Anastomoses are communicating vessels that provide for collateral circulation. Sometimes there may be brief moments when a small artery might be twisted, preventing blood flow through it. Anastomoses allow an alternative route for blood so there is never an interruption of blood flow to a target organ. Anastomoses will proliferate if a blockage builds over time, creating more and more routes of possible blood flow. Some arteries do not have an extensive anastomoses system and they are called end arteries.

Venous circulation is like a river tributary system. Smaller veins feed into medium veins which in turn feed into larger veins. Veins are idiosyncratic and their patterns will vary. Certain large channels are consistent and they can be identified by name. Naming small channels is not as easy. Veins have cup like flaps called valves that provide a mechanism to allow a net flow of blood toward the heart.

Category: Anatomy Notes