I told you at the first of the year that we were going to review body systems in the order that I do a physical exam. In honor of Valentine ™s Day, we ™ll be looking at the heart early. The heart is truly just a big pump. It has four chambers with one-way valves between them. Blood enters the right side of the heart and then passes to the lungs so that carbon dioxide can be removed and oxygen can be added. It then passes to the left side of the heart. Electrical stimulation from a little group of cells at the base of the heart travels along very specific pathways and tells the heart muscle to contract. When the muscle contracts in a coordinated fashion, and when the valves open and close synchronously with this contraction, blood can be pushed from the heart all the way to the tip of the tail! This blood carries oxygen and nutrients to every cell in the body. Arteries are the vessels that conduct the blood away from the heart. They have stiff walls and a higher blood pressure. Veins are the vessels that conduct blood back to the heart and they tend to be softer and of lower pressure. Special vessels called capillaries exist between arteries and veins.
When the electrical, valvular, muscle and vessel parts of the cardiovascular system all work properly, it is amazing what the body can accomplish. When one of these factors becomes inefficient, everything can fall to pieces. have a great Valentine ™s Day and we ™ll talk about heart disease next week.
by Bonnie Markoff, DVM, ABVP