Circulatory System

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The circulatory system functions in the delivery of oxygen, nutrient molecules, and hormones and the removal of carbon dioxide, ammonia and other metabolic wastes.
Explain the relationship between the structure and function of arteries, capillaries, and veins.

Arteries have an outer layer of collagen and elastic fibers to avoid leaks.

Veins are made of thin layers with circular elastic and muscle fibers.

Capillaries are the reason the distance for diffusion is small and that diffusion can occur rapidly.

Explain the route of blood through the heart.

The blood travels through the tricuspid valve and builds up in the right ventricle. The right ventricle then pumps the blood up through the pulmonic valve. The blood moves through the pulmonary artery to the lungs where the exchange for oxygen takes place. Oxygenated blood flows from the lungs into the pulmonary veins. The pulmonary veins then dump the blood into the left atrium. Blood funnels through the mitral valve. Then finally the blood is pushed through the aortic valve into the aorta where the blood is then moved throughout the body.


Describe the composition of blood, including plasma, erythrocytes, leukocytes and platelets.

Plasma - the blood cells are suspended.

Red blood cells (erythrocytes) - carry oxygen from the lungs to the rest of the body.

White blood cells (leukocytes) - fight infections and aid in the immune process.

Platelets (thrombocytes) - help blood clotting.


Disorders in the circulatory system.

Aneurysms are common with 200K to 3M US cases per year. Symptoms include pain in the abdomen, arm, leg, or back or headaches and bleeding. Treatments can include endovascular coiling, Vascular grafting, Clipping, Embolization, or endovascular aneurysm repair.


One of the most common diseases of the circulatory system is arteriosclerosis, in which the fatty deposits in the arteries causes the walls to stiffen and thicken the walls. Common symptoms include: pain in the leg, chest, arm, shortness of breath, or fatigue. In a recent study of 262 hearts 52% had some arteriosclerosis, it was also present in 85% of people aged 50 and over, and 17% of the teens had arteriosclerosis. Taking drugs for high cholesterol and high blood pressure will slow and perhaps even stop the progression of atherosclerosis altogether.