DIGESTIVE

• Inner circular layer


  • Thickened as internal sphincter
• Anal canal


  Terminal part of the large intestine, situated between the rectum and anus
• Organs associated with digestive system

  • Pancreas
  • Liver
  • Gallbladder

  
• Pancreas


  • Function is for production of digestive enzymes and hormones
  • Acinar cells secrete digestive proteins
  • Ductal cells transport secretions
  • Islets secrete insulin and other hormones
• Liver


  • Function is for metabolic converter
  • Hepatocytes, portal vascular system and bile drainage are its histological factors
• Gallbladder


  • Stores and concentrates bile and release it into the duodenum to help absorb and digest fats
  • Columnar epithelium with microvilli
• Digestive process pathway


  1. Oral Cavity

  2. Esophagus

  3. Stomach

  4. Small intestine

  5. Large Intestine

  6. Rectum

  
• Ingestion


  The process by which food is taken into the alimentary canal, including chewing, grinding, lubrication by saliva, and swallowing

  
• Digestion


  The process by which ingested material is broken down in the earlier stages of the alimentary canal into a form that can then be absorbed and assimilated into the tissues of the body

  
• Types of digestive processes

  • Mechanical (e.g. chewing, grinding, churning, mixing)
  • Chemical (e.g. action of digestive enzymes, bile, acids, etc.)

  
• Mechanical processes


  • Include the chewing and grinding of food by the teeth and also the churning and mixing of the contents of the stomach
• Chemical processes


  • Begin in the mouth with action of saliva on food, most occur in the stomach and small intestine where partly-digested materials are subjected to gastric juices, pancreatic juice, succus entericus and so on
• Absorption


  Uptake of fluids or other substances by the tissues of the body, occurs in the jejunum and the ileum of the small intestine, facilitated by villi that increase surface area

  
• Assimilation


  The process by which components/chemicals from food are taken into the cells of the body after the food/beverage has been digested and absorbed
• Elimination


  The final stage of digestion, the excretion of metabolic waste products, including from the blood via the kidneys and urinary tract
• The Integumentary System


  Provides vitamin D3 needed for the absorption of calcium and phosphorus, provides lipids for storage by adipocytes in subcutaneous layer
• The Skeletal System


  Axial division and pelvic girdle support and protect parts of digestive tract, teeth important in mechanical processing of food, absorbs calcium and phosphate ions, provides lipids for storage in yellow marrow
• The Nervous System


  ANS regulates movement and secretion, reflexes coordinate passage of materials, control over skeletal muscles regulates ingestion and defecation, hypothalamic centers control hunger, satiation and feeding behaviors, provides substrates essential for neurotransmitter synthesis
• The Endocrine System


  Hormones epinephrine and norepinephrine stimulate constriction of sphincters and depress digestive activity, hormones coordinate activity along tract, provides nutrients and substrates to endocrine cells, endocrine cells of pancreas secrete insulin and glucagon, liver produces angiotensinogen
• The Cardiovascular System


  Distributes the hormones of the digestive tract, carries nutrients, water, and ions from sites of absorption, delivers nutrients and toxins to liver, absorbs fluid to maintain normal blood volume, absorbs vitamin K, liver excretes heme (as bilirubin), synthesizes blood clotting proteins

  
• The Lymphoid System


  Tonsils and other lymphoid nodules along digestive tract defend against infection and toxins absorbed from the tract, lymphatic vessels carry absorbed lipids to venous system, secretions (acids and enzymes) provide nonspecific defense against pathogens

  
• The Respiratory System


  Can assist in defecation by increased thoracic and abdominal pressure through contraction of respiratory muscles, organs may press against the diaphragm to assist in exhalation and limit inhalation
• The Muscular System


  Protects and supports digestive organs in abdominal cavity, controls entrances and exits of digestive tract, liver regulates blood glucose and fatty acid levels, metabolizes lactic acid from active muscles
• The Urinary System


  Excretes toxins absorbed by the digestive epithelium, excretes some bilirubin produced by liver, absorbs water needed to excrete waste products at the kidneys, absorbs ions needed to maintain normal body fluid concentrations
• The Reproductive System


  Provides additional nutrients required to support gamete production and (in pregnant women) embryonic and fetal development
• Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair
• Digestion works by moving food through the gastrointestinal (GI) tract

  
• Digestion begins in the mouth with chewing and ends in the small intestine
• As food passes through the GI tract, it mixes with digestive juices, causing large molecules of food to break down into smaller molecules
• The body then absorbs these smaller molecules through the walls of the small intestine into the bloodstream, which delivers them to the rest of the body
• Waste products of digestion pass through the large intestine and out of the body as a solid matter called stool

  
• Digestive juices contain enzymes that break food down into different nutrients
• The small intestine absorbs most digested food molecules, as well as water and minerals, and passes them on to other parts of the body for storage or further chemical change

  
• Hormone and nerve regulators control the digestive process

  
• system of organs responsible for getting food into and out of the body and for making use of food to keep the body healthy

  Digestive system
• Alimentary canal


  mouth, pharynx, esophagus, stomach, small intestine, and large intestine
• teeth, tongue, gallbladder, salivary glands, liver, and pancreas

  ACCESSORY DIGESTIVE ORGANS
• FUNCTIONS OF THE DIGESTIVE SYSTEM

  Ingestion, mechanical processing, digestion, secretion, absorption, excretion
• mucosa, submucosa, muscularis, serosa

  BASIC HISTOLOGICAL LAYERS
• Lamina Propria • Loose connective tissue rich in blood vessels, lymphatics, lymphocytes, small glands and smooth muscle cells

  mucosa