LE Week 12 Digestive System Notes Student PDF

1. Oral Cavity Ingestion of food Teeth are used in the mechanical breakdown of food which serves to increase surface area for enzyme action.  1. Oral Cavity Carbohydrate digestion begins here by enzymes secreted from the salivary glands using amylase. Oral cavity → Esophagus...

1. Oral Cavity Ingestion of food Teeth are used in the mechanical breakdown of food which serves to increase surface area for enzyme action.  1. Oral Cavity Carbohydrate digestion begins here by enzymes secreted from the salivary glands using amylase. Oral cavity → Esophagus  2. Esophagus Connects mouth to stomach. Peristaltic action of the esophagus moves digested food (bolus) to the stomach. (*no digestion here) peristalsis  3. Stomach (gastro) Mechanical digestion from churning continues to increase the surface area of food.  3. Stomach (gastro) Gastric glands that secrete liquid gastric juice with enzymes & hydrochloric acid (HCl). Mucus lining of the stomach protects it from HCl. Protein digestion begins here.  4. Small Intestine Carbohydrate, protein, & lipid digestion are completed here. Accessory organs like the liver, gall bladder, & pancreas secrete enzymes into the small intestine for chemical digestion. Accessory Organs of the Digestive System.  Liver Bile is produced in the liver to aid in the emulsification of fat in the small intestine. Emulsification- the breakdown large fats into small fats.  Gall Bladder Bile is stored in the gall bladder & secreted into the small intestine.  Pancreas Located near the stomach. For digestive purposes, the pancreas is an exocrine gland that secretes; Proteases- to breakdown proteins into amino acids. Lipases- to breakdown lipids into Fatty acids & glycerol.  Nutrient Absorption The end products of digestion are absorbed by the body in the small intestine by finger-like projections called villi. Microscopic folds that increase the surface area of the small intestine.  End Products of Chemical Digestion Start (ingested) → End (absorbed) Complex → Simple Proteins → amino acids Carbohydrates → glucose Lipids → 3 fatty acids + glycerol Nutrient absorption of simple molecules occurs in the small intestine (diffusion into the blood)  Absorption in the Villi A = Lacteal- absorbs fatty acids & glycerol into the Lymphatic system. (Lymph/Lipid)  Absorption in the Villi B = Capillary network- small blood vessels that absorb glucose & amino acids into the blood of the circulatory system.  5. Large Intestine Water absorption only (no digestion) Habitat for helpful bacteria that digest & produce vitamins. The large intestine passes feces into the rectum for storage before it is egested out of the anus. Large Intestine Large Intestine  7. Anus Opening through which feces passes out of the body (Egestion)