如果可以的话,帮我简单的解释一下他们的结构,功能,和消化系统消化系统唾腺(salivary glands)食道(esophagus)十二指肠(duodenum)空肠(jejunum)回肠(Ileum)大肠large intestine胃(stomach)胰腺(pancreas)肝,(liver)胆gallbladder直肠和肛门(rectum and anus) 呼吸系统nasal cavity(鼻腔)pharynx(咽)larynx(喉)trachea(气管)bronchi(支气管)alveoli(肺泡)