资讯

BBC2 年
The structure of the digestive system
Stomach This is a muscular bag which mixes ... also specialised structures called villi which have a tiny hair-like structure poking into the small intestine to absorb digested food.
BBC3 年
The structure of the digestive system
Stomach This is a muscular bag which mixes ... also specialised structures called villi which have a tiny hair-like structure poking into the small intestine to absorb digested food.