Two openings (one for food entrance, one for exit of waste materials)
Digestive system openings
Mouth: entrance of food, anterior opening of digestive system
Anus: exit of waste products, posterior opening
Digestive processes
Ingestion: Taking of food
Mastication: Chewing of food
Digestion: Breaking down of food
Absorption: Food into the bloodstream
Circulation: Food distribution
Assimilation: Incorporation of food into the body tissues and cells
Defecation / Egestion: Dumping of waste products
Types of digestion
Mechanical / Physical: Physical breaking of food from a big piece to small pieces
Chemical / Enzymatic: Converting the food into simple substance that can be absorbed and utilized by the body
Digestive system parts
Accessory parts
Digestive glands
Digestive tract
Accessory parts
Oral cavity (mouth)
Palate
Uvula
Tongue
Lips
Pharynx
Teeth
Oral cavity (mouth)
Entrance of food
Palate
Hard palate: anterior end of buccal cavity
Soft palate: posterior end of buccal cavity
Ceiling of the oral cavity
Uvula
Guards the nasal entrance
Prevents the entry of food in the nasal cavity
Tongue
Holds and directs the food
Maneuvers food to the opening of the esophagus
Floor of mouth where tongue is located, important in holding food while inside the buccal cavity
Attached to the floor of the mouth called FRENULUM
Lips
Upper lip
Lower lip
Aid procurement of food
Pharynx
Cone shaped passageway leading from oral and nasal cavities to esophagus and larynx
Helps in breathing and digesting food
Nasopharynx: leads to nasal cavity
Oropharynx: esophagus
Laryngopharynx: leads to larynx
Teeth
Physical or mechanical digestion
Cut food into pieces, shred food
Primary teeth: erupt in early stages, first is central incisor, will shed, replace by permanent teeth
Permanent teeth: Replaces primary teeth, does not shed
Crown: exposed part
Root: embedded
Neck: between crown and root
Enamel: covering of crown
Dentin: inside of enamel, major interior
Pulp cavity: middle of dentin, contains blood vessels and nerves, lymphatic vessels
Cementum: cements root of the tooth, covers and attaches root
Digestive glands
Salivary glands
Liver & glands
Pancreas
Gastric gland
Intestinal gland
Salivary glands
Moisten and soften the food
Helps in chewing & swallowing
Aids in digestion - AMYLASE (polysaccharide digestion)
Contains antibodies that kill germs
Parotid gland: Anterior to the ear
Submandibular gland: Inner to mandible
Sublingual gland: Below the tongue
Liver & glands
Liver produces bile
Bile: fat emulsification
Gallbladder: Stores bile
Pancreas
Secretion of pancreatic juice, aids in process of digestion because it contains TRYPSIN, CHYMOTRYPSIN, CARBOXYPEPTIDASE: digestion of protein
PANCREATIC AMYLASE: digestion of carbohydrates
LIPASE: digestion of fats
Duodenum
First segment of small intestine that connects to stomach and liver
Responsible for breaking down food with enzymes and bile, and absorbing nutrients into the bloodstream
Gastric gland
Produces gastric juice
HYDROCHLORIC ACID: protection, kills bacteria, activate pepsinogen (necessary for digestion of protein)
PEPSIN: protein digestion
MUCIN: protects gastric wall, lubricate wall of stomach
Intestinal gland
Production of intestinal juice (small intestine)
PROTEASE: protein breakdown
LIPASE: fat breakdown
AMYLASE: carbohydrates breakdown
Digestive tract parts
Stomach
Esophagus (oesophagus)
Small intestine
Large intestine
Stomach
Partial digestion
Temporary storage of food
Rugae: redundant folds of gastric mucosa that are most prominent when the stomach is collapsed
Esophagus (oesophagus)
Tube connects stomach from oral cavity
Passage of food from oral cavity to the stomach
Gastroesophageal sphincter: protect entrance of stomach
Pyloric sphincter: protect exit of stomach
Small intestine
Final digestion and absorption of food
20 ft long
Duodenum: 1st and shortest region, secretes secretin (protect duodenum from acid damage) (hormone that regulates water homeostasis and gastric acid secretion)
Jejunum: 2nd region
Ileum: last and coiled region
Large intestine
Reabsorption of water and mineral ions (Na and Cl)
Formation and temporary storage of feces
Cecum: Pouch at the junction of the small and large intestines, receives undigested food
Ascending colon: attached to small intestine, appendix (researched that it is related with immune system) is located
Transverse colon: a section that runs across the abdomen
Descending colon: connects the transverse colon to the sigmoid colon and primarily stores stool that will eventually empty into the rectum
Sigmoid colon: connected to the rectum
Rectum: Temporary storage of feces
Anus: Posterior opening
Process of digestion
1. Oral cavity - accessory parts: Mechanical digestion (chewing and swallowing), Chemical digestion of carbohydrates
2. Stomach: Mechanical digestion (peristaltic mixing and propulsion), Chemical digestion of proteins, Absorption (nutrients to bloodstream) of lipid-soluble substances, such as aspirin
3. Small intestine: Mechanical digestion (mixing and propulsion, primarily by segmentation), Chemical digestion of carbohydrates, lipids, proteins, and nucleic acids
4. Large intestine: Mechanical digestion (segmental mixing, mass movement for propulsion), No chemical digestion except by bacteria, Absorption of ions, water, minerals, vitamins, and small organic molecules produced by bacteria
Digestive system clinical considerations
Bacterial diseases
Viral diseases
Bacterial diseases
Dental caries (tooth decay)
Periodontal diseases
Trench mouth
Dental caries (tooth decay)
Caused by Streptococcus mutans (consumes glucose)
Glucan: dental plaque formation
Lactic acid: tooth enamel breakdown
Periodontal diseases
Bleeding and sensitive gums
Bad breath
Tooth discoloration
Tooth loosening
Caused by: Porphyromonas gingivalis, releases enzymes that causes weakening of gingival tissues (gums and surrounding tissues)
Gingivitis: Inflammation of gums
Periodontitis: Inflammation of the tissue around the roots of the teeth
Trench mouth
Also called Vincent's disease or Acute Necrotising Ulcerative Gingivitis (ANUG)