A low hemoglobin count can also be due to blood loss, which can occur because of: 1  Bleeding from a wound. 2  Bleeding in your digestive tract, such as from ulcers, cancers or hemorrhoids. 3  Bleeding in your urinary tract.  Frequent blood 1  donation. Heavy menstrual bleeding.
The brain is the control centre for your body and it sits in your skull at the top of your spinal cord. The brain has three main parts. 1  The cerebellum (say se-re-bell-um). The brain stem, that controls a lot of the 'automatic' actions of your body such as breathing and heart beat, and links the brain to the spinal cord and the rest of the body.
Longitudinal Waves and Tuning Forks. Sound waves are produced by vibrating objects. Whether it be the sound of a person's voice, the sound of a piano, the sound of a trombone or the sound of a physics book slamming to the floor, the source of the sound is always a vibrating object. A tuning fork serves as a useful illustration of how a vibrating object can produce sound. The fork consists of a handle and two tines. When the tuning fork is hit with a rubber hammer, the tines begin to vibrate. The back and forth vibration of the tines produce disturbances of surrounding air molecules.