Digestive System Oral Cavity Normal functions Pharynx Esophagus Stomach Small intestine Large Intestine Mastication (chew) - Teeth: Grinding - Tongue: mixing movement by the tongue - Mouth: dissolving and lubricating food Enzyme - Salivary amylase: carbohydrate Chemical Mechanical Oral cavity Deglutination (swallow) Propel bolus into NO DIGESTION HERE Pharynx & Esophagus Muscularis Peristalsis - Muscularis: Alternate contraction and relaxation of circular and longitudinal muscle, peristaltic waves - Moves in only one direction Lumen Lumen Serosa Circular muscle Longitudinal muscle 3 Propulsion: Peristaltic wave Protection: Produce mucus Chemical 20XX Mechanical Grinding: vigorous peristalsis + mixing Stomach - Hydrochloric acid: produces by parietal cell Pepsinogen: produced by chief cell - HCL Pepsinogen-------→pepsin - Pepsin (enzyme): protein Retropulsion: pyloric end deliver small amt of chyme into duodenum while forcing most chyme back to stomach 4 Simple columnar epithelium Segmentation - Combines chyme w digestive juices - Push chyme against mucosa – digestion & absorption - Duodenum & ileum mechanical Chemical Digestion Intestinal juice → contains peptidase & maltase peptidase - Polypeptides ------------> amino acids - Maltose ------------> glucose Small Intestine Peristalsis → propulsion - Involves the muscularis layer - Longitudinal & Circular muscles - Smooth muscles → involuntary movement of chyme down the GIT maltase chemical Absorption Circular Folds, Villi, Microvilli → increase S.A to Vol. ratio Villi → glucose & amino acids enter the capillary network into the bloodstream Fatty acids & glycerol absorbed by lacteal → lymphatic system 5 Large Intestine, Rectum & Anus Absorbs mostly water, electrolytes and vitamins No enzymes present Peristalsis occurs to move undigested food to rectum Simple columnar epithelium – no villi Stored in rectum Eliminated via the anus Crypts: glands & goblet cells → secretion and absorption 6 Teeth and Tongue ➢ Teeth provides Mechanical digestion of food (Chewing) ➢ Tongue assists in chewing by moving the food in the mouth, pushing food between teeth. Helping it to form a Bolus Salivary Glands ➢ Responsible for producing Saliva ➢ Saliva contains Salivary Amylase which breaks down starch into maltose (Chemical Digestion) ➢ Moisten food Liver ➢ Production of Bile, which is responsible for Emulsification of dietary fat for efficient digestion of fat ➢ Storage of Glycogen Accessory Organs Gall Bladder ➢ Storage and release of Bile Definition ➢ Organs that are not part of the primary pathway of digestion but still play important roles in the overall function of the Digestive System Pancreas ➢ Production of Pancreatic enzymes ❖ Pancreatic Amylase -> Carbohydrates ❖ Pancreatic Protease -> Proteins ❖ Pancreatic Lipase -> Fats 7 Affected organs Dehydration and GI dysfunction Dehydration • Burned skin = loss of fluid and sodium as it seeps from the blood into the burned tissues • Burn patients are unable to drink water as it lacks sodium • can cause severe hyponatremia by further diluting low sodium levels • 24 hours of IV drip is needed for severe dehydration to take effect. GI dysfunction • Intestinal epithelial barrier disrupted = increased intestinal permeability = cause systemic inflammations • Burn results in increased gastric secretions, reduced intestinal motility, decreased nutrient absorption, bacterial translocation, and GI haemorrhage Effects on digestive organs • The large intestine absorbs the leftover insufficient fluids + reduced intestinal motility • Lack of fluids and slow waste movement = stool hardens, causing constipation • Low water/sodium level leading to electrolyte imbalance + increased gastric secretions by gastric glands • affects the functioning of the gastrointestinal tract and can lead to irritation of the stomach lining, triggering nausea and vomiting. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2933130/#:~:text=Drinkin g%20Na%2B%20free%20fluids%20can,water%20with%20or al%20sa lt%20solutions. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5674226/ https://burnstrauma.biomedcentral.com/articles/10.1186/s41038-019-0162-3#:~:text=The%20severe%20burn%2Dinduced%20disruption,dysfunction%20syndrome%2C%20and%20other%20critical https://www.sciencedirect.com/science/article/abs/pii/S0305417915002314#:~ :text=In%20the%20GI%20system%2C%20burn,4%5D%2C%20%5B5%5D. https://www.reddit.com/r/askscience/comments/q0u5c/why_is_it_not_ advis able_to_give_water_to_burn/ 9 Retroperistalsis → vomiting • Reverse involuntary smooth muscle contraction • Opposite of peristaltic action (food moves backwards in GI tract) • Irritation of stomach → vomiting • Burn → GI dysfunction → increased gastric secretion • Layer of digestive tract affected – submucosa (loose connective tissue, contains nerves) 10 Vomiting (cont.) Stimulus: Irritation of the stomach Sensor: 5HT3 receptors • Enteric nervous system • Motor neurons → peristalsis 1. Abdominal muscles + diaphragm → strong contraction 2. Relaxation and closure of pylorus, relaxation of LES then UES 3. Lower intrathoracic pressure, increased abdominal pressure Control: Emetic center of the brain Effector: sphincter relax and reverse peristalsis occurs Response: Vomiting 11 Esophagus • Affected by acid due to the vomiting • Acid from the vomit will damage the tissues that line the esophagus. ➢Tissue damaged: Stratified squamous epithelium, this cause lesser protection from the outside environment • Mucous membrane may be eroded, lesser protection • Esophagus will get irritated more easily 12 Effect on organs (Large intestine – constipation) • Burns → fluid lost through skin → dehydration • Body loses too much water → water absorbed from undigested material in large intestine, into bloodstream • Burns may affect voluntary movements, e.g., passing out of feces • Toxins/chemicals from fire → slower peristaltic action • Mass movements → slow muscle movement (reduced GL motility) • Stool moves through large intestine slower than usual – more water absorption 13 Thank You!
