What are the other changes during puberty?
Girls also undergo a voice change, but it is not as pronounced as in boys. The larynx in the throat is responsible for the voice and the vocal cords are present inside it. In children, the vocal chords are short, so that the voice is rather shrill. During puberty, the larynx grows rapidly in boys and one can clearly see it, the ‘Adam’s apple’, in the centre of the throat.
A stroke is a serious medical condition occurring as a result of an interruption in the supply of oxygen to the brain. The most frequent reason for a stroke is the blockage or bursting of a blood vessel in the brain. In both cases, the blood circulation and, hence, the supply of oxygen to the brain is interrupted. The result is damaged brain tissue. Stroke patients may lose all information that was stored in the damaged area and may have to relearn simple things like walking, swallowing, or writing. Sometimes, the brain can build new connections between the brain cells and repair the damage.
Signal transmission through nerve cells is quite complicated. Like all the other cells, nerve cells also have a cell body with a nucleus. There are fine extended branches known as dendrites and a long ‘tail’ called the axon on the body of the nerve cells. Axons in the brain are smaller than 1 mm, whereas in the spinal cord they can be as long as 1 m. A chemical substance is released through an electrical impulse into the synapses present at the end of the axon. This chemical substance, known as the neurotransmitter, is transferred to the dendrite of another nerve cell and the signals are transmitted.