The heart and great vessels are located in the between the lungs and above the diaphragm from the center to the left of the thorax.

mediastinum

Explanation:

The mediastinum is a division of the thoracic cavity. The heart, thymus gland, portions of the esophagus and trachea, and other structures are located in the mediastinum

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.

it's anything that aren't producers and consumers.

explanation:

you've got to be clear on what "this" is