Lecture 2c 16 January 2015 Ingestion Digestion Absorption Metabolism Transport Excretion Common digestive tract problems

Overview of lecture 2c 1) ingestion 2) digestion 3) absorption 4) transport 5) metabolism 6) excretion 7) regulation of IDATME 8) common digestive tract disorders -dysregulation of IDATME

INGESTION a)Mouth-open, chew and swallow b)Tube feeding c) IV and catheter

DIGESTION a) Sequencing of events b) Digestion -process by which food is broken down into absorbable units -anatomy -function of each of anatomical parts-figure 3-1 Rolfes et al -mechanics -muscular action of digestion -peristalsis -stomach action -segmentation -sphincters -secretions of digestion

Fig. 3-1, p. 71

digestive glands/secretions (enzymes) -saliva -gastric – water, HCl and pepsin-proteins -pancreatic juice/intestinal enzymes carbohydrases lipases proteases summary of digestive secretions-pg 74-76

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Absorption 1) define-passage of nutrients from gi tract into blood or lymph A) simple diffusion-water small lipids/fat soluble vitamins B) facilitated diffusion-fructose/water soluble vitamins C) active transport-glucose/amino acids do not confuse active transport with the transport discussed below 2) anatomy-goblet cells/crypts/villi and microvilli

Fig. 3-10, p. 79

Transport defined getting nutrients, via blood or lymphatic systems, to where needed (W) when needed (W) in the form needed (F) and in the correct quantities needed (Q) WWFQ

anatomy of transport two routes -blood and lymph

Anatomy BLOOD ROUTE Heart to artery to capillaries (intestine) to vein to capillaries (liver)–in liver get detoxification and preparation of nutrients for body use-vein to heart from liver for distribution to the rest of the body. water soluble nutrients and smaller products of fat digestion go this route

Lymph route Lymph (tissue spaces to blood) intestine to heart directly for distribution to rest of body -larger fat digestion products and fat soluble vitamins (ADEK) use this route

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Metabolism Building up - requires energy Tearing down- gives energy Tearing down-provides building blocks to build up -also leads to excretion

Excretion-in whole or as a metabolite -urine-protein (urea), minerals, water, carbohydrate, vitamins -feces-carbohydrates, lipid, vitamins, protein, water, minerals -sweat-minerals,water -saliva?-minerals?, carbohydrates?, lipids?, protein?, water?, vitamins? -breathing-O 2 and CO 2

Regulation of IDATME-pgs Rolfes et al. - all hinges on homeostasis homeostasis-maintenance of constant internal conditions homeostasis can be disrupted by physical immaturity, aging, illness, nutrition -stomach pH homeostasis – pH 1.5-hormonal regulation-important for digestion

Regulation of IDATME Digestion regulation Pyloric sphincter hold food ready for duodenum duodenum has pH sensors -too acid-close pyloric sphincter and bicarbonate added to chyme making chyme neutral and then pyloric sphincter opens again why? -pH important for enzyme function

Regulation of IDATME Digestion regulation continued hormonal regulation of 3 types of enzymes- type and amount of enzymes from pancreas bile-fat emulsion-amount under hormonal regulation fat slows peristalsis-hormonal digestion regulation leads to absorption regulation leads to transport regulation

Regulation of IDATME Ingestion regulates digestion Digestion regulates absorption Absorption regulates transport Transport regulates metabolism (WWFQ) Metabolism regulates excretion

Common digestive problems choking- epiglottis-tough meats, hot dogs, nuts, grapes carrots, hard candies, popcorn and peanut butter vomiting-cause-gastric irritation -effects are : dehydration : nutrient loss (salts) : teeth damage if excessive (bulimia) : aspiration -solution-replace salts/fluids by oral or IV diarrhea-cause-infection, drugs, sorbitol, olestra, colitis -effects-if not reversed get dehydration and nutrient loss -solutions-oral or IV replacement of fluid and nutrients with low fat small meals and a gradual increase in fibre

Common digestive problems constipation-cause-failure to respond to defecation signal -lack of activity (intestinal muscle tone) -medications -tumours -solution-eat fibre(eg prunes)- attracts water -drink more water -eat fat- bile produced-attracts water belching -cause-swallowing air, gallbladder disease or peptic ulcer -solution-medical treatment of cause gas-cause-carbohydrate rich diet with partial digestion of fibre in gut and rest goes to bacteria that make gas -solution-change diet

Common digestive problems heartburn and acid indigestion cause-acid reflux-anatomical defect -eat or drink too much -chew too little -smoking -solution- if not an anatomical defect- eliminate other causes ulcers-gastric or peptic (duodenal)-cell erosion -cause-not stress or spicy foods -H. pylori story -AIDS drugs -solution-avoid pertinent infections

disorders causing excessive gastric acid secretion treat via- antibiotics - withdrawl of offending foods -withdrawal of caffeine or alcohol on a case by case basis

Next lecture Carbohydrates-structure and classification -IDATME of carbohydrate