Digestive System

• Human cecum is reduced and has a finger-like extension called appendix which does not directly help with digestion but has a role in immune system.
• The appendix contains a collection of beneficial gut bacteria that is readily available to occupy the intestines after an infection, when even the good bacteria are wiped out by drug treatments.
• The large intestine is about six (6) feet long and frames the small intestine.
• The large intestine reabsorbs water from undigested food and stores waste until it is eliminated.
• The lacteals, in turn, join with larger lymphatic vessels and eventually lead into larger veins that return the blood back to the heart.
• The cecum is the first part of the intestine.
• The learning guide begins with a recap of the four stages of food processing: ingestion, digestion, absorption, and elimination.
• Humans process food following the same stages as other animals.
• The gastrointestinal tract, also called the digestive tract, alimentary canal, or gut, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients.
• The gastric glands contain different types of cells that secrete a variety of enzymes, including hydrochloric acid, which activates the protein-digesting enzyme pepsin.
• The three regions of the small intestine are the duodenum, jejunum, and ileum.
• The digestive system consists of the stomach, small intestine, and large intestine.
• The stomach wall is adapted for the functions of the stomach.
• The large intestine reabsorbs water from undigested food and stores waste until it is eliminated.
• In the epithelium, gastric pits lead to gastric glands that secrete gastric juice.
• Humans have a complete digestive system and an alimentary canal (also called a digestive tract or gastrointestinal tract) that runs from the mouth to the anus.
• The alimentary canal has attached accessory organs that aid in food processing.
• Accessory organs are not part of the alimentary canal, never come in contact with ingested food, and do not have part in mechanically breaking down food.
• Accessory organs play roles in chemically digesting food.
• The alimentary canal begins with the mouth, then the esophagus, the stomach, the small intestine, large intestine, rectum, and anus.
• Accessory organs like the liver, pancreas, and gallbladder, work in synergy with these compartments to primarily aid in chemical digestion.
• These are the mouth, esophagus, stomach, small intestine, and large intestine.
• Peristalsis move the food along our alimentary canal, and strategically located sphincters control their rate of passage.
• Our digestive system mainly breaks down large pieces of food by mechanical or physical ways so that nutrients can be absorbed and energy can be obtained.
• An alimentary canal is more efficient than a gastrointestinal cavity as it has specialized compartments and some of these compartments have sphincters in their junctions.
• Sphincters are circular muscles that control the passage of materials from one compartment to another.
• Swallowing of food bolus has to be carefully coordinated so that it does not end up entering the wrong tube.
• Pepsinogen becomes pepsin (activated form of pepsinogen) only after hydrochloric acid alters the molecule.
• The teeth, which come in different shapes, play a major role in mechanically tearing food into smaller pieces and increasing the surface area for enzymes to act.
• Saliva is composed of mucus, electrolytes, antibacterial compounds, and various enzymes.
• From the descriptive term upper, the upper esophageal sphincter is found at the beginning part of the esophagus.
• The pharynx is the part of the throat behind the mouth and leads into two passageways: the trachea and the esophagus.
• The gastrointestinal tract, also called the digestive tract, alimentary canal, or gut, is the system of organs within multicellular animals that takes in food, digests it to extract energy and nutrients.
• Mucus is primarily responsible for protecting the mouth from abrasion and from drying out.
• Enzymes like amylase breakdown starch and glycogen into smaller polysaccharides or even disaccharides.
• The esophagus has two sphincters: the upper esophageal sphincter and the lower esophageal sphincter.
• Antibacterial enzymes like lysozyme destroy microorganisms.
• The tongue helps form a food bolus, the mass of food that has been chewed and mixed with the saliva, and propel it down to the pharynx.
• The salivary glands have ducts that open to the oral cavity and secrete saliva which moistens the food for easier swallowing.
• The act of swallowing has three phases: the oral phase which is the formation of food bolus and the movement of it toward the back of the mouth with the help of the tongue, the pharyngeal phase which includes the closing of vocal folds and the movement of the larynx upward so that it tips the epiglottis down to cover it, and the esophageal phase which is the movement of food bolus in the esophagus to the stomach through rhythmic smooth muscle contractions called peristalsis.