The lymph vessel flows from the tissue to the lymph nodes, flow to the largest lymphatic vessel in the thorax called thoracic duct, then drain to the subclavian vein.
The lymphatic vessel is a thin tubular organ made of the endothelial cell. It has a valve like the vein to prevent backflow of lymph. Lymphatic vessel delivers the lymph through the body and has a role in the immune system. 
        
                    
             
        
        
        
Answer:
The most important abiotic factors include water, sunlight, oxygen, soil and temperature. Water (H2O) is a very important abiotic factor – it is often said that “water is life.” All living organisms need water.
 
        
             
        
        
        
Answer:
Igneous rocks form when molten rock (magma or lava) cools and solidifies. Sedimentary rocks originate when particles settle out of water or air, or by precipitation of minerals from water. Crystallization, erosion, sedimentation, and metamorphism transform one rock type into another or change sediments into rock. The rock cycle describes the transformations of one type of rock to another. The process by which a rock changes form or mineral content as a result of environmental changes such as heat and pressure. a rock that was altered by metamorphism.
 
        
             
        
        
        
Other reasons are 
Not finishing the antibiotics. 
Or
Taking antibiotics too often