Veins Biology 20 Human Systems Project By: Alex Lokhorst

Components of Veins Adventitia is the outer layer of the veins composed of connective tissue and fibers. This helps prevent to much stretching of the veins. Lumen is the empty space where the blood vessels flows. Smooth muscle is the muscle that helps the valves close and move the blood towards the heart. Venous Valve help prevent backflow of blood in the veins.

The Function of Veins  To transfer blood to the heart and carbon dioxide.  Venules – are smaller types of veins which help take deoxygenated blood from the extracellular fluid and carbon dioxide waste from the cells outside of the veins back to the heart.  The Veins also transfer red blood cells and white blood cells which help when the body is attacked.  In the blood there is carboxyhemoglobin which helps with the transfer of carbon dioxide to the heart then to the lungs then released out the oral and nasal cavity.

Capillary Fluid Exchange  There is two types of pressures in the capillary fluid exchange.  Osmotic pressure which is from high to low pressure.  Fluid pressure or blood pressure from the heart pumping it.  This fluid exchange happens when there is low pressure in the extracellular fluid outside the capillaries and a high in the blood.  The blood then moves from the capillaries into the extracellular fluid then the blood gets deoxygenated by the cells and carbon dioxide is released into the extracellular fluid.  Then the pressure increases in the extracellular fluid which then moves the blood and carbon dioxide into the capillaries then into the venules then veins.  This capillary fluid exchange happens constantly making a equilibrium.

Facts about Veins  The veins are part of the circulatory system which then connects to all other systems in some ways.  A vein can range in size from 1 millimeter to centimeters in diameter.  There is only one type of veins called pulmonary veins which carry oxygenated blood from the lungs to the heart.  The color of veins in your arm are blue because they are deoxygenated but once you are cut the blood is exposed to oxygen in the air and turns red instantly.  The veins contain 65% of all the blood in the body.  The veins are much weaker than arteries because they have so low pressure that is why they test your blood pressure in the arteries not veins.

Venous Valves  Since the low pressure in the veins valves are needed to prevent backflow of blood.  The skeletal muscles help the venous valves closes when the contract.  This is because the skeletal muscles bulge when they contract, there by decreasing the diameter.  The force of the skeletal muscles increase the pressure making the blood go through the next venous valve and continue to the heart.

Dysfunctions of the Veins or Problems  Superficial venous thrombosis or phlebitis:  Is when there is a blood clot in the veins due to a build up of blood. This superficial venous thrombosis or phlebitis is usually found close to the skin. This clot usually doesn’t travel to the lungs unless it moves to the deep venous system first. This causes lots of pain for the surrounding area. Cures: Many types of medications such as aspirin but mostly depends on the types of conditions that person is in. Varicose Veins :  Surface veins that gradually become larger and begin to bulge because of the increase of blood in the veins. This is the result from a unhealthy lifestyle and standing too long making prolong compression on the veins making a weakening of the cell walls. Preventions: The preventions of varicose veins is to be active and don’t be a couch potato and move around frequently to help prevent stress on the veins.

Biography    spx spx  Nelson Biology 20 Alberta Textbook 