Digestive system

• Ingestion


  The process of taking food into the body
• Absorption


  The process of nutrients being taken into the bloodstream from the digestive system
• Assimilation


  The process of nutrients being incorporated into the body's cells and tissues
• Excretion


  The process of waste products being eliminated from the body
• The digestive system has three main divisions: mouth region or oral cavity, gastrointestinal tract, and accessory organs

  
• Mouth region or oral cavity

  • Lips have sensory receptors that can detect the texture and temperature of food
  • Palate is the mouth's upper boundary where food is pushed against when chewing

  
• Mechanical and chemical digestion in the mouth

  1. Tongue functions for tasting, mixing, and swallowing food

  2. Papillae on tongue contain taste buds
• Teeth


  • Incisors: cutting
  • Canines: tearing
  • Premolars: tearing, crushing
  • Molars: grinding, crushing
• Pharynx


  • Connects the mouth to the esophagus
  • Nasopharynx: passage of air only
  • Oropharynx: passage of food and air
  • Laryngopharynx: passage of food only

  
• Epiglottis


  • Cartilaginous tissue that prevents the entry of food and water into the respiratory tract
• Esophagus


  • Long muscular tube where food travels from the mouth to the stomach
  • Sphincters prevent the backflow of food
  • smooth and skeletal muscles
• Stomach


  • Hollow and curved organ that functions for the storage and breakdown of food
  • Produces acids, mucus, and enzymes that help in digestion
  • Inner walls have folds (rugae) that allow the stomach to stretch to store large meals
  • Has three sections: the cardia, the fundus, and the pylorus
  • Has two sphincters that prevent the backflow of food: cardiac sphincter and pyloric sphincter

  
• Small intestine


  • Long tube where the final digestion takes place
  • Duodenum: where chyme mixes with enzymes
  • Jejunum: site of nutrient absorption
  • Ileum: site of digestion and further absorption

  
• Large intestine


  • Final organ of the digestive system
  • Site for vitamin and water absorption
  • Converts chyme into feces
• Salivary glands


  • Secrete saliva into the mouth that clean the teeth, lubricate the food, and allow chemical digestion
  • Consist of the parotid gland, submandibular gland, and sublingual gland
• Liver


  • Produces bile which aids in lipid digestion
• Gallbladder


  • Stores and holds the bile until it is needed in the duodenum
• Pancreas


  • Secretes pancreatic juice essential in breaking down proteins, fats, and carbohydrates in food
• The components of the digestive system are the mouth, the gastrointestinal tract, and the accessory organs. Each of these components has its own set of organs that perform specific functions.

  
• The oral cavity is mostly for the physical breakdown of food and the chemical breakdown of specific parts of food.
• The gastrointestinal tract is mostly for the chemical breakdown of food and the absorption of nutrients and water.
• Accessory organs produce different compounds and enzymes that aid in the chemical breakdown of food.
• Food enters the body through the mouth, then proceeds to the gastrointestinal tract. The accessory organs secrete their enzymes into both the mouth and gastrointestinal tract.

  
• Organization of life

  1. atoms
  2. molecules
  3. macromolecules
  4. organelles
  5. cell
  6. tissues
  7. organs
  8. organ system
  9. organism
  10. Population
  11. community
  12. Ecosystem
  13. biosphere
• 3 types of muscles

  1. skeletal
  2. smooth
  3. cardiac
• Skeletal muscle is attached to bones by tendons.
• Cardiac muscle is only found in the heart wall.
• Different sections in the stomach

  1. cardia - connected to the esophagus (where the food enters)
  2. fundus - stores gas from digestion
  3. pylorus - partly digested food from stomach to small intestine
• Smooth muscle is found in the walls of hollow organs such as blood vessels, stomach, intestines, uterus, bladder, etc.
• Dif. cells in the stomach

  1. Paraita cells - HCL
  2. neck cells - mucus
  3. peptic cells - pepsin
• once all the different cells in the stomach mixes, it forms gastric juice
• Other name for upper sphincter:

  • inferior pharyngeal
• Other name for lower sphincter:

  • gastroesophageal sphincter
• 4 macromolecules:

  1. carbohydrates
  2. lipids
  3. protein
  4. Nuclei acid
• Peristalsis - movement of the esophagus to help push down food
• Parts of the small intestines:

  1. duodenum = chyme mixes with enzyme
  2. Jejunum =nutrient absorption
  3. Ileum = digestion and further absorption
• 3 parts of the large intestine

  1. colon
  2. rectum
  3. anus
• 2 kinds of stomach sphincters

  1. cardiac sphincter
  2. pyloric sphincter
• villi - absorbs the nutrients from the small intestine
• capillaries - blood vessels