The Heart
The heart, an organ the size of your fist, is responsible for the survival and functioning of the entire body. The human heart has 4 chambers, namely the left ventricle, the left atrium, the right ventricle and the right atrium. The familiar “lub-dub” sounds are made when valves between these chambers open and close to allow blood to flow from one chamber to another. In a normal medical examination, doctors, with their stethoscopes, listen for sounds at 4 of these valves:
- Mitral (between the left ventricle and left atrium)
- Tricuspid (between the right ventricle and right atrium)
- Aortic (between the left ventricle and the aortic arch)
- Pulmonic (between the right ventricle and the pulmonary artery)
Heart sound abnormalities come in various forms, such as heart murmurs, muffled rhythms and extra heart sounds. Some of these can be picked up by trained ears to detect possible cardiac problems or disease early on in their development.
The Lungs
Sounds heard in the lungs are made by the movement of air during breathing. Before reaching the air sacs where oxygen and carbon dioxide are exchanged between inhaled air and our blood, the air passes through the upper and lower airways, including the nasal cavity, pharynx, larynx, trachea, bronchi and bronchioles, in that order. These airways are progressively smaller as they enter the lungs. Any obstructions to these airways can cause abnormal whistling or crackling sounds that can be picked up by trained ears and flagged for medical attention.
The human lungs are divided into 5 lobes: right superior, middle, inferior lobes, and left superior and inferior lobes. This division aids in specifying the location of wheezes and crackles while characterising potential respiratory diseases. Spanning a considerable volume of the chest cavity, the lungs can also be considered as left and right anterior, lateral and posterior aspects.