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Large Intestine - Anatomy & Physiology (view source)
Revision as of 14:51, 22 July 2008
, 14:51, 22 July 2008→Function
'''Storage and Defecation'''
'''Storage and Defecation'''
*Remaining water, waste and undigested food is stored as faeces prior to defecation. Defecation is the periodical expulsion of faeces into the environment.
*Remaining water, waste and undigested food is stored as faeces prior to defecation. Defecation is the periodical expulsion of faeces into the environment.
'''Defence Against Pathogens'''
''Secretions''
*Mucus - inhibits contact and protects the mucosal surface
*Digestive enzymes - nonspecifically target bacteria and viruses
*Bile - kills some bacteria and viruses
''Epithelium''
*"Tight junctions" between epithelial cells prevent entry of macromolecules and pathogens into the intestinal tract.
*Epithelial cells have a very high turnover rate thus preventing pathogens with a longer life cycle from successfully colonising.
''Commensal flora''
*Commensal flora competitively inhibit attachment of pathogens to enterocytes in addition to competing for nutrition and substrates. Many also produce inhibitory growth substances that are toxic to other bacteria (McGavin and Zachary, 2007).
''Movement''
*Continuous peristalsis discourages persistence of toxins and aids in their elimination from the gut.
''Cell-mediated and humoural defences''
*The lamina propria contains macrophages, B and T lymphocytes, plasma cells, and [[Mast cells - Anatomy & Physiology|mast cells]].
*Lymphoid aggregates known as [[Peyer's Patches - Anatomy & Physiology|Peyer's patches]] within the small intestine aid in immunity.
*Secretory IgA and IgM provide humoural immunity and help prevent attachment of pathogens to the intestinal epithelium.
*Lysozyme from Paneth cells inhibits bacterial growth (McGavin & Zachary, 2007).
==Vasculature==
==Vasculature==