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4.3.2 Varicose Veins
Transcript of 4.3.2 Varicose Veins
How do varicose veins form and why we do not ever see varicose arteries?
How and why arteries and veins differ in structure?
Arteries receive blood from the heart, the blood they receive is under a lot of pressure. Arteries are elastic and thick. Arteries have thicker walls than veins. The walls of the arteries contains smooth muscle fibers that contract and relax under the rules of the nervous system.
How blood is helped in its return back to the heart
The blood in veins is at a lower pressure than it is in the arteries. The lower pressure makes for challenges getting that blood back to the heart. As there is less force (pressure) in the veins, blood would pool in the lower parts of the body if there were not mechanisms to prevent that.
How varicose veins form
Varicose veins can be caused by weak or damaged valves in the veins. The heart pumps blood filled with oxygen and nutrients to the whole body through the arteries.
If the valves become weak, blood can leak back into the veins and collect there. When backed-up blood makes the veins bigger, they can become varicose.
Why don't varicose arteries ever form?
Varicose arteries don't form because they do not have valves that can malfunction and result in backflow. No backflow means the arteries do not stretch like a vein would and become enlarged like a varicose vein.
Even if arteries were to be enlarged, they wouldn't be easily visible because they are deep under the surface of the skin.
Arteries are also many times thicker and stronger than veins and would be much harder to stretch.
The veins only receive the blood after it has traveled quite far from the heart. The blood pressure in the veins is thus much less; the blood is certainly much less likely to burst through walls of the veins than arteries. The walls of the veins consist of three layers of tissues that are thinner and less elastic than the layers of the arteries.
At the same time, downward movement of the diaphragm causes pressure in the abdomen to rise, pushing blood back to heart. The entire process of sending blood to the heart is called the venous pump.
Other body systems
Skeletal muscle contracts during exercise. Pressure in the chest allows for expansion of the upper chambers of the heart, each time the heart beats. This all allows for blood to return to the heart