BIOL-L 112 1nd Edition Lecture 4 Outline of Last Lecture I. NutritionII. Essential NutrientsA. Essential Amino AcidsB. Essential Fatty AcidsC. Essential VitaminsD. Essential MineralsIII. MalnutritionA. UndernutritionB. Essential Nutrients DeficienciesIV. Introduction to the Four Stages of Food ProcessingOutline of Current Lecture I. The Oral Cavity’s Role in the Human Digestive SystemII. The Stomach’s Role in the Human Digestive SystemIII. The Small Intestine’s Role in the Human Digestive SystemA. Enzymes in the PancreasCurrent LectureI. The oral cavity in the mouth is where chemical and mechanical digestion of food begins. Chewing food signals a nervous reflex with signals the salivary glands to release saliva. This saliva contains mucus (a mixture of water, salts, cells, and mucins), buffers (help to neutralize acids and protect teeth), and antibacterial agents, called lysozymes. Located inthe oral cavity, the tongue processes ingested material for swallowing. It helps shape a bolus, or a ball of chewed food. When the bolus reaches the throat, a swallowing reflex is triggered and the epiglottis moves down to prevent food from entering the trachea. The bolus then enters the esophagus. Peristalsis then moves the bolus towards the stomach. II. Within the stomach, four major cells are in the lining that makes up the gastric glands. First, mucus cells recreate mucus that lubricates and protects the stomach cells. Chief cells secrete the protein pepsinogen. Pepsin is an enzyme that functions to digest peptide bonds and attacks proteins, which break into polypeptides. Lastly, parietal cells secrete HCl which functions to kill bacteria, denature proteins to lose their tertiary These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.structure, and activate pepsinogen to pepsin. In the stomach, ulcers can occur from bacteria but may be treated with antibiotics.III. Most of the chemical digestion processes take place within the small intestine. The chyme (a molecule of food substance) is mixed with digestive juices from the pancreas, liver, and gallbladder in the duodenum (the first 25 cm of the small intestine). The duodenum also secretes its own digestive enzymes in addition to the others. The liver serves to produce bile, and the gallbladder functions to concentrate and store this bile. A. The enzymes from the pancreas serve to digest molecules of proteins, carbohydrates, lipids, and nucleic acids by enzymatic hydrolysis. The pH levels go from 2-7 really quickly because of the powerful buffer (bicarbonate ion) that is present in the pancreas