Unit 4 GP Organ systems and Evolution

Organ Systems

For the human body to go about its daily routine , it needs energy . We need energy to run , to play , to read , to study , to watch TV , even in sleeping we burn off energy . This energy comes from the various foodstuffs which we eat , as well as from the air we breathe and the water we drink . From these raw materials , the body has to convert these things into a form which the human body can use . Finally , the useable energy should be distributed all along the human body . All these

tasks are accomplished by the various organ systems in the body . Together these systems cooperate to make sure that the nutrients we take in is properly utilized by the billions of cells in the human body

Blood performs a very special duty in the body as it forms the transportation system of the body . Each cell in the body needs food water and air to function . Blood is responsible for getting these things from the responsible organ system and bringing it to the different cells . The responsibility for keeping the blood flowing across the human body falls on the circulatory system . The circulatory system is composed of the heart , arteries , veins and capillaries . The heart is arguably the most important part as it acts like a pump which keeps the blood flowing . The heart has two entrances and two exits . There is one entrance and exit for blood which goes and comes back from the lungs and another pair for blood which goes and comes back from the rest of the body . Blood actually goes around in a figure eight , going from the circulatory system to the respiratory system to get its load of oxygen then returning to the heart where it will be sent out all over the body so that the cells can use the oxygen and food carried in the blood stream

Arteries are blood vessels which carry blood away from the heart while veins are blood vessels which carry blood back to the heart . Capillaries are the tiniest of blood vessels . Blood does not simply travel through ' the capillaries , the important nutrients carried by blood actually leaks through the capillaries into the surrounding cells . We can then make the following analogy that the arteries and veins are the railroad tracks of the body while the capillaries are the actual stops where the cargo and passengers are unloaded

As mentioned , the heart is the most important organ in the whole circulatory system . We all know that a heart which has stopped beating is synonymous with death , underscoring the heart 's importance not only in the circulatory system but also to the human body . Its purpose is simple , to keep blood flowing . It is composed of cardiac muscle - a special form of involuntary muscle specially suited for the continuous operating condition of the heart . The heart containts four chambers , two atriums (which act as receiving chambers for blood coming into the heart ) and two ventricles...