Digestive system

• What are the functions of the digestive system?

  ingestion of food and liquid , mastication , motility , secretion , hormone release , elimination and immune defense
• What are the components of the oral cavity?

  Mouth , tongue , teeth , salivary glands and tonsils
• What are the functions of the oral cavity?

  Mastication , taste , immune system
• What are the characteristics of the masticatory mucosa?

  Localized in the gingica and hard palate , keratinized or parakeratinized stratified squamouns epithelium , thick papillary layer (loose CT)
• What are the characteristics of the lining mucosa?


  Localized in lips , cheeks , floor of the mouth , inferior surfaces of the tongue and soft palate. Non keratinized epithelium , short papillae , covers striated muscle
• What are the characteristics of the lips?

  Mucocutaneous transition , striated muscle helps ingestion and communication
• What are the layers of the lips ?

  Internal mucous surface (lining mucosa , non keratinized epithelium , minor salivary glands) , Vermilion zone (thin keratinized stratified squamous epithelium , no salivary or sweat glands , CT with many capillaries and sensory innervation). Outer surface (Epidermal and dermal layers sweat glands sebaceous glands and hair follicles)
• What are the characteristics of the tongue?

  Mass of striated muscle covered by mucosa , muscle fibers are oriented in all directions: high mobility. Lower surface (lining mucosa) , dorsal surface
• What are the characteristics of the lingual glands?

  saliva production (serous and mucous glands)
• What are the characteristics of the llingual tonsil?

  Aggregates of lymphoid nodules , localized in the lamina propria of the root (MALT)
• What is the specialized mucosa of the tongue?

  Lingual papillae and their associated buds
• What is filiform papillae?

  Smallest and most numerous , conical shape , highly keratinized stratified squamous epithelium , mechanical role , no taste buds
• What is fungiform papillae?

  Mushroom shape , less numerous , stratified squamous epithelium lightly keratinized , interspersed among filiform papillae , taste buds dorsal papillae surface
• What is foliate papillae?

  Parallel low ridges separated by deep mucosal clefts , lateral edge of the tongue , many taste buds in the lateral walls , small serous glands , more abundant in children and young individuals
• What is circumvallate papillae?

  Largest papillae , taste buds on the sides , surrounded by a moat like invagination , serous salivary glands empty their secretion in the base of the moat. Continuous flow of fluid that washing away food from taste buds
• What are some characteristics of taste buds?

  Present on: Fungiform , foliate and circumvallate papillae. Oval , pale staining bodies with epithelium , taste ingested material , taste pore: small opening onto epithelial surface
• What are the three types of cells?

  Neuroepithelial , supporting , basal cells
• What are the characteristics of the neuroepithelial cells?

  Most numerous cells in the tase buds , from the basal membrane to the taste pore , microvilli in the apical surface , tight function in the apical surface , synapse at the base with an afferent sensory axon
• What are the characteristics of the supporting cells?

  Less numerous , extends from the basal lamina to the taste pore , microvilli in the apical area , tight junctions , they do not synapse with nerves
• What are the basal cells?


  Small cells , localized near the basal lamina , stem cells
• What is taste?


  Chemical sensation , tastants interact with taste receptors in the apical surface of neuroepitheliaal cells
• How does taste work?

  Taste receptor in the apical membrane of neuroepithelial cells (opening and closing of ion channels) bind ti membrane G protein receptors . Intracellular signalling activation,release of NT
• How are tastes tasted?

  Salty taste: Na+ or K+ ions

  
  

  Sour taste: H+ ions from acid compounds

  
  

  Bitter: alkaloids and certain toxins

  
  

  Sweet taste: sugar and related compounds

  
  

  Umami: Amino acids
• What are the characteristics of the gastrointestinal tract?

  from esophagus to anal canal , tube with basic structural organization
• What is the structure of the esophagus?

  Mucosa , submucosa , muscularis externa , adventitia
• What are the components of the mucosa?

  nonkeratinized stratified squamous epithelium , lamina propria (lymphatic tissues , esophageal cardiac glands) , muscularis mucosae
• What are the components of the submucosa?


  Dense irregular CT , glands , meissner's plexus (ganglion cells) , large blood and lymphatic vessels , diffuse lymphatic tissue
• What are the components of the muscularis externa?


  Inner circular and outer longitudinal , upper one third striated muscle , middle part is mixture , auerbach's plexus
• What are the characteristics of the sphincters in esophagus?


  smooth muscle layer from sphincters
• What is the function of the stomach?

  Mix and mechanical disggregation , partial digestion , hormone secretion , absorption
• What are the anatomical regions of the stomach?

  cardia, fundus, body, pylorus
• What are the histological regions of the stomach?

  cardia, fundus, pylorus
• What type of epithelium is located in the gastroesophageal junctions?

  simple columnar epithelium
• What are the stomach's mucosa?

  gastric pits , simple columnar epithelium , mucous cells , mucinogen granules , mucus layers , cardiac glands ,gastric glands
• What is the mucus layer made up of?

  Water , mucins , bicarbonate ions to neutralize the acid microenvironment
• What are the characteristics of the cardiac glands?

  Tubular mucous secreting , apical cytoplasm with mucin granules
• What are the characteristics of the gastric glands?

  simple branched tubular glands , isthmus (stem cells between pit and glands) and several glands open into a single pit
• What are the functions of the gastric glands?

  Production of gastric glands , made up of : water , electrolytes , HCL , mucus , pepsin , intrinsic factors , hormones .
• What are the 5 types of cells in gastric glands?

  Mucous neck cellos , parietal cells or oxyntic cells , chief cells , enteroendocrine cells , stem cells
• What are the characteristics of the mucous neck cells?

  Localized in the neck region , parietal cells are interspersed between them , shorter than surface mucous cell , less mucinogen in the apical area