Glossary - Dog Denizens: a poop primer

Anaerobic: Without air, i.e. without oxygen. While we need oxygen to live, it is toxic to many organisms. Hence, these organisms thrive in anaerobic environments, such as the intestines.

Cytokines: Small proteins which are important in cell signalling. Especially important in modulating immune responses.

Electrolyte: A substance which dissolves into ions when introduced to a suitable solvent. Electrolyte balance is important to cells for all sorts of chemical processes. An example of an electrolyte is salt, which dissolves into Na⁺ and Cl^-.

Endospore: A dormant, tough, non-reproductive structure formed by some bacteria to survive periods of environmental stress.

Epithelial cells: Cells which cover those surfaces of the body where it comes into contact with the outside world. The skin is covered in epithelial cells, and so is the lining of the colon. The food that passes through you is essentially the external environment, from which the colon extracts nutrients.

Eukaryotic: Concerning eukaryotes: organisms with a nucleus in their cell(s), which sets them apart from prokaryotes. The latter are organisms without a nucleus in their cell, i.e. bacteria and the less well known Archaea.

Genus: A taxonomic rank in biological classification. The hierarchy of the classification from general to specific is: Domain -> Kingdom -> Phylum -> Class -> Order -> Family -> Genus -> Species.

Gram positive: Bacteria that have a thick outer layer of peptidoglycan are gram positive. They are so-called because of the Gram staining procedure in which these bacteria are coloured purple.

Lyses: Lysis, to lyse: The process whereby a cell's plasma membrane breaks and it dies abruptly, as opposed to the controlled cell death that is apoptosis.

Macrophages: Immune cells that can infiltrate tissues, ingest and destroy pathogens, and activate other components of the immune system by presenting parts of pathogens on their cell membrane.

Mutagenic: Inducing the appearance of mutations in the DNA.

Peptidoglycan: A polymer which consists of sugars and amino acids and forms the cell wall of many bacteria.

Tight junctions: Tight junctions make cells adhere so strongly to each other that leakage between them is nigh impossible. This is achieved by proteins across the cell surface that interact very strongly.

Villi: The finger-like protrusions in the epithelium lining the intestines which increase the surface area for uptake of nutrients immensely.