Gastrointestinal Tract (GL Tract)

DIGESTIVE SYSTEM: Class notes: Gastrointestinal tract(GL tract) Alimentart cana---- Path the food takes (long tube) 1.​ Mouth(mechanical/physical digestion) -​ When the food leaves it collects the bolus.(round mass of chewed food) 2.​ Pharynx(throat) 3.​ Esophagus -​ peristalsis((wave-like muscular contractions that are pushing the bolus down the esophagus) 4.​ Stomach(Physical+mechanical digestion) -​ Churning of the stomach muscles cuase physical and chemical digestion. -​ Enzymes help with the chemical digestion -​ When food enters, it goes through the cardiac sphincter. -​ When food leaves, it goes through the pyloric sphincter -​ chyme=when food leaves 5.​ Small intestine -​ Duodenom(chemical digestion Continue break down of food and absorb nutrients) -​ jejunem(chemical digestion and absorption-carbo,protiens, fats, digested good) -​ Ileum(Absorption-from digested food like vitamin B12 and bile salts) 6.​ Large intestine -​ Excess H2O is absorbed -​ Feces are made 7.​ Anus -​ Waste is removed via anus. Accessory Digestion -​ Involved in digestion, but food does pass through the tract itself -​ Like the Pancreas , Liver, gall bladder, and Salivary glands 1.​ Pancreas -​ Stores and releases many different digestive enzymes. -​ Example of enzymes: -​ Lipase(fats/lipids) -​ Trypsin(protein) -​ Mathase(sugars) -​ Peptidase(protein) -Also, an endocrine gland that controls blood sugar. -The horomones are insulin and glucigon -Insulin lowers blood pressure and glucose increases it. 2.​ Liver -​ Produces byle(emusifying agent) -​ Bile breaks up fat into globules -​ Then the lipase can break down fat even further. -​ Detoxify our body from harmful substances(Alcohol and drugs) 3.​ Gal Bladder -​ The stomach stores and releases bile into the duodenum when food enters the small intestines. Chemical digestion: -The use of enzymes to chemically break down food. Physical digestion: -Actual force caused by the teeth, tongue, and muscles through the GL tract that physically breaks down the food. Macro Molecules: Carbohydrates, Proteins, lipids(fats) CarbohydratesFood: Bread, rice, paste, cereal Polymer: Polysaccharide starch, cellulose, chitin, glycogen. Monomer: Monosaccharide- glucose Enzyme : Amylase (]; breaks down complex carbohydrates,) Lipase (; breaks down fats), Protease (; breaks down proteins) Chemical digestion: Starts in the mouth, ends in the small intestine (jejunum) ProteinFood: meat, tofu, beans, eggs, fish, nuts Polymer: polypeptide Monomer: amino acids Enzymes: trypsin,pepsin, and erepsin Chemical digestion: starts in stomach and ends in small intestines. Lipids(fats)Food: animal fat, butter, plant fat, olive oil, cheese, milk Polymer:not a polymer- 1 glycerol(3c),3 fatty acids Monomer: non Enzyme: Lipases Chemical digestion starts and ends in the small intestines Notes that lipids not actually a polymer its a triglyceride, c-c-c Layers of the stomach: -​ Rugae folds -​ Inside is the mucosa which secretes lots of mucus Stomach: -​ Food spends 4-6 hours in the stomach -​ Produces gastric juices(HCL acid Ph=1, mucus, and enzymes, HCl Kills bacteria) 4 layers of the stomach: -​ Mucosa-(secretes gastric juices)(folds rugae) -​ Submucosa-nerves, blood vessels, connective tissue -​ Muculoris- Mechanical digestion -​ Serosa -secretes serous fluid to lubricate internal structures. This lubricating fluid aids in reducing friction during movement. Small Intestines: -​ Small in diameter but very long -​ Lined with finger-like projections called vili(Vilos) -​ Increases surface area -​ lactated, capillaries Ulcer: -hole in the lining of the stomach Heliobacter pylori -Burning sensation -Causes ulcers - treated with antibiotics and bland food. ​ ​ ●​ Digestion:​ ○​ Mechanical: Physical breakdown of food through chewing and churning.​ ○​ Chemical: Breakdown of food into simpler molecules by enzymes and acids.​​ ●​ Absorption: The process by which nutrients from digested food are taken into the bloodstream or lymphatic system.​​ ●​ Egestion: The elimination of undigested food and waste products from the body.​​ Oral Cavity and Pharynx ●​ Salivary Glands: Glands in the mouth that secrete saliva, which contains enzymes like amylase to begin carbohydrate digestion.​​ ●​ Bolus: A soft mass of chewed food mixed with saliva, ready to be swallowed.​​ ●​ Epiglottis: A flap of tissue that covers the trachea during swallowing to prevent food from entering the airway.​​ ●​ Pharynx: The throat region that directs food from the mouth to the esophagus.​​ Esophagus and Stomach ●​ Esophagus: A muscular tube that conveys food from the pharynx to the stomach.​​ ●​ Peristalsis: Wave-like muscular contractions that move food through the digestive tract.​​ ●​ Lower Esophageal Sphincter: A ring of muscle that prevents stomach contents from flowing back into the esophagus.​​ ●​ Pyloric Sphincter: Regulates the passage of partially digested food (chyme) from the stomach to the small intestine.​​ ●​ Stomach: A muscular organ that further breaks down food with gastric juices, turning it into chyme.​ ●​ Ulcer (Helicobacter pylori): Sores in the stomach lining caused by an infection with H. pylori bacteria.​​ ●​ Gastric Juices: A mixture of hydrochloric acid and enzymes that digest proteins.​​ ●​ Mucosa: The innermost layer of the stomach lining that secretes mucus to protect against acid.​​ ●​ Muscularis: Muscle layers responsible for churning and mixing food in the stomach.​​ ●​ Hydrochloric Acid: An acid in gastric juice that helps digest food and kills harmful microorganisms.​​ ●​ Chyme: Partially digested food mixed with gastric juices, moving from the stomach to the small intestine.​​