Figure 2: The complex web of gut microbiota contributions to host physiology. Different gut microflora components can affect many aspects of normal host development, while the microbiota as a whole often exhibits functional redundancy. Members of the microbiota are shown in gray, with their components or products of their metabolism. Their effects on the host at the cellular or organ level are shown in white. Black ellipses represent the affected host phenotypes. Only some examples of microbial members/components contributing to any given phenotype are shown. AMP: antimicrobial peptides; DC: dendritic cells; Gm−: gram negative; HPA: hypothalamus-pituitary adrenal; Iap: intestinal alkaline phosphatase; PG: peptidoglycan; PSA: polysaccharide A. Extracted from: Phys Rev 2010 Sekirov et al.