Why is an egg cell bigger than a sperm cell

Egg cells are considerably larger than sperm cells because they carry the cytoplasm and organelles necessary for cell division and growth to begin, while sperm cells are basically a cell nucleus and a tail. 

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.