BIOM20002 Lecture Notes - Lecture 42: Cecum, Jejunum, Duodenum
Document Summary
Digestion of food: enzymatic breakdown of different macronutrients into absorbable components. Fermentation of indigestible food: by the gut microbiome. Caecum and ascending colon for fermentation by microbiota. Solvents and catalysts water, bile, digestive enzymes various sources. Control systems cns, ens, hormones, muscle, microbiome. Thin layer of longitudinal smooth muscle lines whole gut. Control must coordinate different parts of digestive system. Locally: major control system is enteric nervous system (ens) - largest network of neurons outside brain (including spinal cord) in any animal. Pns and sns modulate ens but do not control it. Longer distance central reflex pathways (run via brain stem, spinal cord): Ens is controlled by cns functions which operate through vagus nerve (parasympathetic pathway that runs into colon from distal spinal cord) and sympathetic ns - all modulate/coordinate activity of local parts of ens. Sensory neurons send processes into gut and brain, activate reflexes that operate through vagus and sympathetic pathway - modulated by cephalic pathway.
