the digestive system hey- chew on this! we’ve made it to the
TRANSCRIPT
The Digestive System
Hey- chew on this! We’ve made it to the..
• Gastrointestinal System• Function-physical and
chemical breakdown of food
• Includes alimentary canal and accessory organs
• Accessory organs: Salivary glands, tongue, teeth, liver, gallbladder, and pancreas
Alimentary canal
• Mouth- physical and chemical breakdown.
• Mastication-the act of chewing
• Saliva contains enzyme amylase to break down carbohydrates
• Pharynx- contains opening to trachea as well. Epiglottis covers opening of trachea.
• Esophagus-muscular tube dorsal to trachea
• Relies on a rhythmic wave-like motion called peristalsis
Esophagus- transverse view
• Sphincter-a circular muscle that constricts a passage or closes a natural orifice (opening)
• Cardiac sphincter• Pyloric sphincter• Food sits in stomach
for 1-4 hours. Gastric juices contain hydrochloric acid- activates pepsin, kills bacteria.
• Small intestine: not so small! 20ft x 1’’
• Duodenum- 1st 10 inches. Bile and pancreatic juice enter here
• Jejunum- next 8 ft.• Ileum- final 12 ft.
When food leaves small intestine, digestion is complete
• Small intestine has lots of enzymes: peptidases
• maltase, sucrase, lactase, amylase.
• Lipase • Bile
Digested food is absorbed into the bloodstream.
• Large intestine- 5 ft x 2’’. Separated from small intestine by ileocecal valve
• Final absorption of water, storage of indigestible material, absorption of vitamins B and K by bacteria.
• Colon connects to rectum- anal canal opens to the anus (final opening). Fecal material is expelled.
But Wait! What about the accessory organs: Liver, gall bladder and pancreas • Liver- largest gland in
your body• Secretes bile-
emulsifies fat, makes them water soluble.
• Stores glucose in the form of glycogen
• Makes clotting proteins
• Detoxifies blood
• Gall bladder- stores and concentrates bile
• Pancreas- produces insulin, pancreatic juices amylase and lipase. Insulin regulates the uptake of glucose by the cells
Diseases• Appendicitis• Cholecystitis- gall bladder• Cirrhosis- destruction of liver cells• Diarrhea• Diverticulitis• Gasteroenteritis• Hernia• Pancreatitis• Liver transplant• Ulcer• Colitis• Bariatric surgery