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