For instance, a problem in the spleen may lead to the destruction of white blood cells and platelets within a human body beyond the required level, thereby causing weakness and leading towards a weak immune system. The proper functioning of an immune system is highly critical to other systems found within a human body, such as the immune system, nervous system, and circulatory system. To explain things more clearly, let’s take the example of the circulatory system. The function of a circulatory system is to enable proper blood flow within the human body and its interaction with the immune system enables the transference of white blood cells along the circulatory system. If the immune system fails to function properly, by, for instance, producing less or more blood cells than may be required, then its circulation along the blood vessels can be very dangerous for a healthy human body (Parham, 2005). There are many instances when things can go wrong with an immune system and cause it to work improperly. We all know of allergies. What most of us don’t know is allergies develop as a result of our immune system’s incapability to the handling of alien substances such as pollen grains, dust, or even pet hair for that matter which a human body may come across. These problems definitely interfere with human lives as, for instance when people are allergic, they often can’t concentrate or do their work properly as they are often found sneezing, vomiting, having red eyes, itchy palms etc.