BBC3 年
The structure of the digestive system
The digestive system breaks down food into tiny particles ... In the small intestine there are also specialised structures called villi which have a tiny hair-like structure poking into the ...
BBC2 年
The structure of the digestive system
The digestive system breaks down food into tiny particles ... In the small intestine there are also specialised structures called villi which have a tiny hair-like structure poking into the ...