CIRCULATORY- EXCRETORY

-       - The nephron is a tiny filtering structure in the kidneys. Each of the kidneys contain more than a million tiny filtering nephrons that help clean the blood.

-       - The nephrons help remove excess water, waste and other substances from the blood. By the Glomerulus with is a tiny blood vessel that filters the blood.

-       - The Nephron returns substances like sodium, potassium or phosphorus when one of the substances run low in the body

CIRCULATORY- DIGESTIVE

-       - Villi play a very important role in digestion but it is also  essential for the absorption of digested nutrients. The cells of the villi and another part of the small intestine, that transports food from the digestive tract into the bloodstream, where the body can use them.

-       - The villi aid in absorption by increasing the surface area of the intestine and contain specialized cells which transport different types of nutrients into the blood.

-    CIRCULATORY - NERVOUS

-        - The heart rate is controlled by the nervous system. The sympathetic nerves are the ones that increase the heart rate while exercise and the parasympathetic nerves slow the heart rate when the body is calmed.

-       - The sympathetic nerves, carry nerve impulses from the brain to the heart. And the hear responds by increasing both the rate of contractions and the strength of the contraction.

-      -  The normal heart rate for an average adult is 60 to 100  beats per minute. This number can increase to a maximum heart rate during exercise that varies with age.

CIRCULATORY- ENDOCRINE 

- Hormones travel through the circulatory system.

- Organs that secrete hormones usually have big blood streams around, so that they could secrete those hormones on the blood and then the blood transports them to their target. The heart is myogenic (auto regulated), but sometimes hormones can affect it, like adrenalin.

- When you suffer from the thyroid (located on the upper part of the trachea. Image), you might be either tall or small because of growth hormones do not get to their target or get there in large amounts. This is only one example of the thyroid problem. As this gland is one the biggest in the endocrine system, it affects many other things.

CIRCULATORY - RESPIRATORY

- Alveolus is the principal structure in the gas exchange between the circulatory system and respiratory system (O2 and CO2).

- The alveoli are in charge of collecting all the oxygen that are present in the lungs and put it into the capillaries so that the oxygenated blood is distribute around all the body. The CO2 is taken by the alveoli and give it to the lungs so that it is expelled. To perform this function, the alveoli have to be wet and have pores to led the air in and out (image).

- If the alveoli do not work properly, then the gas exchange could not happen, leading to a non-oxygenated blood.