digestive system

• digestive system is the process of breaking down food into smaller molecules for absorption
• Each of your cells needs a supply of food to provide chemical energy
• It is an organ that takes in food, digests it, and excretes remaining waste.
• It is made of digestive tract and accessory organs.
• Digestive tract is a long tube with 2 openings at each end. Digestive Tract is the mouth, esophagus, stomach, small and large intestines and anus. Accessory organs include liver, gall bladder, and pancreas.
• Digestive Tract is lined with epithelial tissue.
• Epithelial tissue is made of many cells including goblet cells that secrete mucus.
• Mucus secretion protects digestive tube from digestive enzymes and allows material to pass smoothly along tube.
• Digestive tube has layers of muscle tissue and nerves that attempt to remove toxins rapidly.
• Mouth - breaks down food. Mechanically: tongue and teeth. Chemically: enzymes that break apart molecules of food.
• Saliva - mixture of water and enzymes. produced by cells in epithelial tissue that lines with mouth
• Esophagus - muscular tube that connects the mouth to the stomach
• Esophagus has muscles which are a special type, called smooth muscle, which relaxes and contracts to allow food to pass through which are controlled by nerve tissue.
• Stomach - holds food and churns it.
• Stomach lining contains cells that produce digestive enzymes and acids. Smooth muscle tissue contracts to mix stomach contents.
• Intestines - digestive tract between stomach and anus. Lining of the intestine has cells producing mucus. Many fine blood vessels interlaced through the other tissue. Contracting smooth muscles relaxing without conscious thought.
• Small intestine: 6m and narrow -> where most digestion occurs. Goblet cells release mucus and nutrients diffuse through wall of SI and enter the bloodstream
• Large Intestine: 1.5m (larger in diameter). Lining absorbs water from indigestible food and remaining solid matter is excreted as feces from anus.
• Colitis: epithelial tissue lining colon can become inflamed and stop working properly.
• Causes of colitis: viruses, bacteria, narrowed blood vessels and failure of body's disease fighting mechanism.
• Colitis diagnosed with endoscope and microscope examination of tissue samples taken from colon.
• Accessory organs: liver, pancreas, and gall bladder supply digestive enzymes.
• Liver produces bile (bile breaks down fats)
• Pancreas produces insulin which regulates concentration of glucose.