Sierra College Department of Biological Sciences

Discover the Biological Sciences

The introductory information for this site has been contributed as a joint assignment by students in Bio. Sci. 10.

Anatomy - Circulatory System

By: Kenda Shaughnessy

Circulatory System

Biological science comes in many forms. When studying human anatomy, the circulatory system is always the first at view because the circulatory system is the working connection of three main functions of a human’s body. Without these three functions life would not exist for humans. The circulatory system is divided into three major parts; the heart, the blood and the blood vessels. They are responsible for transporting material throughout the entire body. Circulatory system transports nutrients, water, and oxygen to the billions of cell in your body but also carries away wastes like carbon dioxide. In studying the circulatory system it is necessary to study the heart, blood and blood vessels.

The heart is an organ that beats three billion times during an average lifetime and is the strongest muscle in your body. It is the hearts job to pump your blood and keep the blood moving throughout your body. Your heart is divided into two sides the right side and the left side. The right side of your heart pumps stale blood into your lungs where the red blood cells in your blood pick up oxygen to carry it to the rest of your cells and organ throughout your body helping them to function with the help of the left side of your heart. The left side of the heart pumps the oxygen saturated blood to the rest of the body by the contraction and squeezing of the heart muscle. The blood is circulated through the heart more than 1,000 times per day.

Your blood is an absolute necessity and an amazing substance that constantly circulates through your body. Blood is pumped and controlled by the heart and your blood travels in thousand of miles of blood vessels. Your blood contains blood cells, platelets, and plasma. There are three types of blood cells that function differently but work as a team, the red bloods cells, white blood cells and platelets. Red blood cells are responsible for carrying oxygen and disposing carbon dioxide in the lungs. As stale red blood cells gather oxygen in the lung from breathing in (respiratory system) carbon dioxide is disposes of by breathing out. White blood cells fight off germs that attack our bodies. When there is an infection your body will produce more white blood cells to fight off the infection. Platelets are blood cells that control bleeding. When we cut ourselves, bruise, or break blood vessels platelets clogs the holes. As platelets stick to damaged vessels they will attract other platelets and from a scab to stop the bleeding. Blood cells can’t get around by themselves the need the help of plasma which is the liquid part of the blood and consists of over 50% of your blood. Your blood is produced in different parts of your body. Your blood cells are produced by bone marrow and plasma is produced in the liver so again without bone marrow or your liver functions life could be at a stand still.

Blood vessels also consist of three different parts; the arteries, capillaries and veins. The blood vessels are just that, vessels to carry blood around to every part of your body. Arteries carry oxygen rich blood away from the heart, the capillaries are the connection of the arteries to the veins and also pass nutrients, oxygen and wastes through the capillary walls, and veins carry blood back to the heart. Although the circulatory system involves the heart, blood and blood vessels it needs the help of the respiratory system, bones and liver and without a complete system diseases or death can occur.

Not all living organisms have a circulatory system. The organisms that do have a circulator system either have an open or a closed system. What makes this interesting is that there is only one component that causes an organism to have either an open or close circulatory system. Your vertebrates or lack of are the deciphering component. If you have a vertebrate you have a closed circulatory system. Invertebrates have an open circulatory system. A closed circulatory system means that the blood never leaves the system and an open system means there is no distinction between blood and interstitial fluid. The combined fluid in an open circulatory system is called hemolymph. The muscular movements of the animals that contain an open system during locomotion facilitate flow of their fluids. What an open and closed system has in common is the transportation of nutrients, gases, and wastes to every part of our living systems.



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