Upper gastrointestinal Tract Flashcards
What is digestion?
Digestion is the process of breaking down macromolecules to allow absorption
What is absorption?
Absorption is the process of moving nutrients & water across a membrane
What is the basic plan of the gut wall?
- Mucosa
- epithelium
- Lamina propri (loose connective tissue)
- Musculsris mucosae - submucosa (connective tissue contain nerve plexus)
- Muscularis: smooth muscle containing nerve plexus
- Seroda/Adventitia: connective tissue +/- epithelium
Describe the teeth
TEETH - 32 in total •8 incisors •4 canines •8 premolars •12 molars
What are the muscles in the oral cavity?
•Masseter muscle – largest jaw muscle
- responsible for biting
•Several muscles control position of mandible
What are the salivary glands?
•Food mixed with saliva (aqueous secretion & digestive enzymes)
•Lingual lipase (fat digestion)
Salivary amylase (carbohydrate digestion
What does the tongue do?
- Intrinsic muscles
- fine motor control & moving food
- Extrinsic muscles
- gross movement of tongue (in, out, up & down)
- Assists mechanical digestion
What is the epithelium of the oesophagus like?
- Non-keratinising
- ‘Wear & Tear’ lining (extremes of temp. & texture)
- Lubrication – Mucus secreting glands (& saliva)
What is the muscle like in oesophagus?
- Tonically active
- Swallowing centre
- Peristalsis
- Circular muscle
What is the Gastro-oesphgeal junction?
- Reflux – prevented by diaphragm
- Epithelial transition
- Gastric folds - rugae
What is stage 0 in swallowing?
- Stage 0: Oral phase
- Chewing & saliva prepare bolus
- Both oesophageal sphincters constricted
What is stage 1 in swallowing?
- Stage 1: Pharyngeal phase
- Pharyngeal musculature guides food bolus towards oesophagus
- Both oesophageal sphincters open
What is stage 2 in swallowing?
- Stage 2: Upper oesophageal phase
- Upper sphincter closes
- Superior circular muscle rings contract & inferior rings dilate
- Sequential contractions of longitudinal muscle
What is stage 3 in swallowing?
- Stage 3: Lower oesophageal phase
* Lower sphincter closes as food passes through
What are functions of stomach?
- Breaks food into smaller particles (acid & pepsin)
- Holds food, releasing it in controlled steady rate into duodenum
- Kills parasites & certain bacteria