6.3 Human Diseases and Abnormalities

Introduction

Diseases are caused by either foreign organisms entering the body or the malfunction of the genetic material within the cells. Either method impairs the normal functioning of systems within humans and plants. In society, the term "disease" is often used more broadly to refer to any condition that causes pain, dysfunction, distress, social problems, and/or death to the person afflicted.

In lesson 4, you learned that cancer is caused by a carcinogen that changes the genetic make-up of the cell, thus altering the blueprint of materials produced or the actual function of the cell. This causes the cell to grow abnormally and uncontrollably. Since it grows uncontrollably it usually takes resources from the surrounding healthy cells and tissues. This ultimately affects the organs and eventually the organ systems because once an organ starts to fail it is only a matter of time before the organ system will too. Remember, since all organ systems are interconnected and depend on each other when one system gets compromised, other systems will be too.

In order to examine another example of how interconnected the systems are, lung cancer can be studied. From a previous activity, you learned that cancer affects the cells and tissues of an organ, in this case, the lungs. Eventually, a large amount of tissue within the lung will become cancerous. When that mass becomes large enough the lung will stop functioning properly causing the individual to exchange less oxygen and carbon dioxide. This reduction of gas exchange in the lungs puts obvious stress on the respiratory system, but also the circulatory system as they are connected. The circulatory system is responsible for circulating blood, which carries oxygen, around the body. If it is compromised, then less blood, and as result oxygen, will be circulated around the body, thereby reducing the oxygen supply of all cells in the body, which therefore reduces the efficiency of all cells to function properly. Another interesting point is that cells from tumors can become mobile, using the circulatory system to spread and locate in other organs and systems of the body to cause further damage.

 

  

A chest radiograph showing a cancerous tumor in the left lung. The cancerous tumor is the white circle inside the black square (for easy viewing).

 

Cancer can also be found in plants. Have you ever been walking in the woods and noticed a great big growth coming out of the trunk of a tree? That's cancer, except when it's found in plants it's called a gall. Plants don't have the same type of circulatory systems as humans and animals; therefore, cancers in plants will remain in a fixed location and only cause problems to that small part of the plant. Even if a gall develops, it will not spread to other parts of the plant.

ePortfolio Submission

Now that you have learned about the importance of organ systems, consider the following question, record your voice (1.5-2.0 min), and submit your audio file in your ePortfolio.

1. What can you do in your community to help raise awareness on the importance of organ health?