Paul Andersen explains how hugs between tissues can help maintain homeostasis. Countercurrent heat exchange allows heat to stay within the core of the body. Close contacts between the capillaries and alveoli allow our body to maintain the correct concentration of oxygen. Capillaries also hug the tubules in the nephron to maintain osmolarity and filter the blood. Hugs in the gills of a fish allow them to maintain an adequate amount of oxygen in an oxygen-poor environment.