The primary function of tubular structures is to transport substances within the body. These substances can include blood, urine, air, or digestive enzymes, depending on the specific system. For instance:
Blood vessels transport blood, carrying oxygen and nutrients to tissues and removing waste products. Renal tubules in the kidneys filter blood to form urine, which is then excreted from the body. Bronchi and bronchioles in the respiratory system transport air to and from the alveoli, where gas exchange occurs. Bile ducts transport bile from the liver to the gallbladder and intestine to aid in digestion.
