I agree because an ecosystem and a host are basically the same thing.
The inferior vena cava brings deoxygenated blood back into the heart from the lower body. For comparison, the part that directs deoxygenated blood from the upper body is the superior vena cava.
When food is digested, the food is broken down into Glucose, which can get into the bloodstream through the small intestines. It travels around the body in the bloods plasma and is then diffused into the body's cells through the capillaries. Once the Glucose is in the body cells, it can be used for respiration.
The breathing system is used in respiration because we need it to respire aerobically, so that our body gets all the vital oxygen it needs. When we breathe, oxygen is stored in the alveoli in the lungs. From there, it can be diffused into the bloodstream, to be used for respiration.
The products of aerobic respiration is Carbon Dioxide and Water. The Water leaves the body as sweat or waste such as urine. The Carbon Dioxide is carried through the blood to our lungs where we can breathe it out. Where as in anaerobic respiration, the product is Lactic Acid. This ends up being broken by oxygen after exercise (oxygen debt) and is also turned into Carbon Dioxide and Water.
<span>The circulatory body system, otherwise known as the cardiovascular or vascular system, is composed of four major parts: the heart, arteries, and veins. The vital responsibilities of the said system is to circulate blood throughout the body, transport nutrients, and carry away waste for elimination. Circulation starts when the heart pumps out blood through the main artery aorta, into the lung capillaries for oxygenation, and throughout the body via the arteries. Besides oxygen, nutrients and metabolic products are distributed as blood circulates, waste is processed and soon after eliminated by the kidneys as blood circulates there, and un-oxygenated blood returns to the heart through the superior and inferior vena cava (veins), the whole cycle therefore carrying on.</span>
