The Digestive System

• GI Tract: series of hollow organs, pathway of food from the mouth to the anus
• Mouth: oval-shaped cavity inside the skull where food enters the body
• Teeth: chews (mastication) and breaks down food into small pieces
• Incisor: middle, flat, for cutting
• Canine: for tearing
• Premolar & Molar: for grinding, wide dimension
• Salivary Glands: secretes saliva into the mouth through the salivary ducts
• Parotid Gland: near cheeks
• Sublingual gland: below tongue
• Submandibular gland: below mandible
• Tongue: taste (gustation), mixes food and saliva
• Pharynx: connects mouth and esophagus and larynx, passageway of both food and air
• Glottis: opening in larynx
• Epiglottis: above/lid of glottis
• Esophagus/Gullet: passageway of food/liquid from the mouth to the stomach
• Peristalsis: muscular contraction that happens in the gut wall, wave-like contractions
• Circular muscle: inner side, when it contracts, the lumen constricts, area of contraction
• Longitudinal Muscle: outer side, when it contracts, the lumen widens, area of relaxation
• Stomach: muscular bag, J-shaped, thick and developed walls to churn food, contains gastric glands that produce gastric juices/acid
• Rugae - folds in the innermost layer of the stomach wall, will stretch to allow storage of more food
• Pyloric Sphincter: between the stomach and small intestine (duodenum), acts as a gate to prevent food from going into the small intestine
• Small Intestine: six meters in length, absorption of nutrients and water from food takes place
• Small Intestine Parts

  • Duodenum
  • Jejunum
  • Ileum
• Large Intestine: final absorption of water from food
• The intestines are attached to the wall using mesenteries
• Large Intestine Parts

  • Cecum
  • Colon
  • ascending
  • transverse
  • descending
  • sigmoid
  • Rectum (anus)
• Accessory organs secrete chemical substances that help with digestion
• Pancreas: flesh, secretes pancreatic juice (enzymes) in the small intestine, secretes hormones (insulin & glucagon)
• The pancreatic duct is connected to the bile duct
• Gall Bladder: greenish-yellow bag, stores bile temporarily
• Liver: dark red, has 5 lobes, largest organ inside the body, detoxifies blood, able to regenerate, produces and secretes bile
• Bile: alkaline fluid that neutralizes the acidic food