One Y and one X chromosome.
1. Stomach, Breaks down food with acid located in the stomach
2.Mouth, Chews and Grinds food down. Allows the breakdown of enzymes
3.Kidneys, Take out any unhealthy/unneeded substances in the food.
4. Large Intestine, The formation of feces.
Because their TEETH ARE MISALIGNED AND THEY USUALLY POSSESS LONG TONGUE. Respiratory illness is common in people who have down syndrome and their unique airway anatomical factors makes airway management difficult during respiratory distress. For instance, they have narrower upper airway and smaller trachea.
I attached the image related to your concerned question.
In theory, the part of the brain that is responsible for the sleep wake cycle is the hypothalamus; specifically, the ventrolateral preoptic nucleus of the hypothalamus. In the image, the location of the hypothalamus is pointed by the green square.