Sometimes, you just feel drained, tired and hungry. However, you must be able to tell when those feelings are just that, or something more serious that may affect your health. Understanding the basic symptoms and signs of fatigue and those of excessive hunger help you to listen to what your body is telling you.

Lumps in the throat that you can feel with your fingers from the outside of your neck can mean anything from a swollen lymph node to a thyroid cyst or a tumor.

The human immunodeficiency virus -- HIV -- causes acquired immunodeficiency syndrome, or AIDS. You can be infected with HIV for many years and show few if any symptoms before the development of AIDS. However, people who are HIV-infected can transmit the virus to other people.

Mono, which is more formally referred to as mononucleosis, is an infectious disease caused by exposure to the Epstein-Barr virus, or EBV.

The human immunodeficiency virus--HIV--is a disease that causes progressive degradation of the immune system. As a result, patients with HIV are at a high risk of developing recurrent infections that can include gastrointestinal complications.

If you are constantly sick or tired, your lymphatic system may have stopped working properly.

Events caused by sleep apnea and atrial fibrillation, two disorders that share many of the same risk factors and symptoms, can wake you up to a pounding heart. Unless you have an emotional condition, such as anxiety, your increased pulse rate may have these physical causes.

Your stomach secretes a variety of fluids that aid in digestion, including stomach acid. Stomach acid is composed primarily of hydrochloric acid, making the stomach a very acidic environment with a pH of 1 to 2.

The human immunodeficiency virus (HIV) is an infectious, contagious virus that can be passed from an infected mother to her newborn infant during childbirth. Over two million children under the age of 15 throughout the world are infected by HIV.

HIV is a blood-borne illness that is most commonly spread via high-risk sexual activities and use of illegal drugs. It can also be transmitted from a mother to child during the childbirth, and via blood products.

HIV is an acronym for human immunodeficiency virus, the virus that causes AIDS, or acquired immune deficiency syndrome. The Centers for Disease Control and Prevention (CDC) report that the virus attacks the immune system, eventually leaving the body prone to multiple different types of infections.

Overtraining can affect anyone who exercises regularly, not just endurance athletes. Increasing the frequency, duration and intensity of your workout program too quickly can lead to this syndrome, which manifests in a myriad of ways.