Lecture 23- Mouth And Stomach Flashcards
Where does ingestion occur?
Only at the mouth
Mouth
Stratified squamous epithelial mucosa-lined cavity
Lips and cheeks have core of skeletal muscle covered by skin that helps keep food between teeth when we chew
Hard palate
Bony,aids in manipulation of food
Soft palate
Rises during swallowing to close nasopharynx
Tongue
Made of skeletal muscle and used to reposition foods when chewing mix food with saliva, initiate swallowing and aid in speech production
Papillae on tonguehouse taste buds
What cells compose salivary glands?
Serous cells- produce watery secretion
Mucous cells- produce mucous
Saliva
Mostly water but contains electrolytes, enzymes salivary glands and lingual lipase, muffins, lysozyme and antibodies along with a. Small amount of metabolic waste
Teeth
Tear and grind food to break it into small pieces
Mastication
Chewing, the mechanical breakdown of food
Primary dentition
Baby teeth, 20 teeth hat are lost to make room for permanent dentition
Permanent dentition
Consists of 32 teeth including wisdom teeth and third molars
Types of teeth
Incisors- used for cutting
Canines- tear or pierce
Premolars and molars- used for grinding
Adult dental formula
I 2/2 C1/1 P2/2 M3/3
Three Regions of tooth
Enamel covered crown
Gingiva (gums)
Root embedded in mandible
Cementum
Calcified connective tissue that anchors root to periodontal ligaments holding tooth in bony socket of jaw
Dentin
Bone like material, underlies enamel and surrounds pulp cavity which contains blood and nerve supply
Cardiac orfice
Where laryngopahrynx and stomach join together
Gastroesophaeal sphincter
Located in between esophagus and stomach, prevent contents from stomach to move upward
Deglutition
Swallowing
Tw o major phases of deglutition
Buffalo phase- voluntary, occurs in mouth where blues of food is forced into oropharnx by tongue
Pharyngeal-esophageal phase- involuntary, occurs when food is squeezed through pharynx into esophagus, controlled by swallowing centre of medulla and pons
Functions of stomach
- Mechanical breakdown of food
- Holding area for food
- Delivers chyme to small intestiene
- Denatures protein with HCL
- Pepsin carries out enzymatic digestion of proteins
- Lipid soluble alcohol and aspirin absorbed into blood through stomach endothelium
- Only stomach function essential to life is secretion of intrinsic factor for B12 absorption
Stomach
Temporarily stores food and begins protein digestion
Empt stomach has volume of 50mL and a capacity of 4L, when empty walls fall into folds called RUGAE
Major regions of stomach
Cardia
Fundus
Body
Pylorus
Histology of stomach
Surface epithelium of stomach mucosa is simple columnar epithelium with goblet cells which produce protective two-layer coat of alkaline mucous
Gastric glands of stomach
Produce gastric juice
May be composed of combination of mucous, HCLm intrinsic factor, pepsinogen and variety of hormones
Surface mucous cells and mucous neck cells
Secrete mucous, which helps protect epithelium from HCL of stomach
Parietal cells
Secrete HCL to denature proteins
Activate pepsin
Break down plant cell walls
Kill many microbes
Secret intrinsic factor
Chief cells
Secrete pepsinogen that is activated to pepsin which hydrolysis denatured proteins
Produce lipase enzymes that hydrolysis small portion of lipids
Enteroendocrine cells
Secrete chemical messenger and hormones, interacting with enteric nervous system, in the same way the endocrine system interacts with nervous system
