1. Physiological functions of the mouth ,pharynx & oesophagus
Digestive Physiology
By: M.H.Dashti
Lecture 3
Physiological functions of the mouth ,pharynx & oesophagus

2. Digestion in the Mouth Mechanical digestion (mastication or chewing)
Food breaks into pieces
mixes with saliva so it forms a bolus
Chemical digestion
α amylase (ptyalin)
begins starch digestion at pH of 6.5 or 7.0 found in mouth
when bolus & enzyme hit the pH 2.5 gastric juices hydrolysis ceases
lingual lipase
secreted by glands in tongue
begins breakdown of triglycerides into fatty acids and glycerol

3. Motility of the mouth Food intake (voluntary , CN VII )
Mastication : (involuntary but highly affected voluntarily )
successive stretch & inverse stretch reflexes
buccal swallowing (voluntary)

4. Mastication reflex 2 Successive Golgi-tendon apparatus Stretch &
Inverse stretch
Reflexes fallow
One another
Masticator
Muscle
Extrafusal
fibers
Muscle spindle
Intrafusal fibers
GTA
Golgi-tendon apparatus + _
I.S.R
S.R
Mandibular
branch
Of CN V
Trigeminal
nuclei
Sensory receptors
Are muscle spindle
& Golgi-Tendon
Apparatus respectively
Sensory & motor
Neurons and integrating center
Is of Mandibular branch
Of Trigeminal nerve

5. Food Propulsion Swallowing (Deglutition) Buccal phase Pharyngeal phase
Food enters pharynx
Pharyngeal phase
Food passes through pharynx & enters
esophagus
esophageal phase
Food passes through esophagus & enters the stomach
Coordination of numerous actions by CN V, vii ,IX ,X, XI & XII

6. Deglutition: Buccal phase
voluntary, tongue pushes food to back of oral cavity against the soft palate
Once food contacts touch receptors in the pharynx & Pharyngeal Tonsils next phase starts

7. Deglutition: Pharyngeal phase
Involuntary phase
1-Tongue lift against hard palate to close the mouth
2-soft palate & uvula are lifted to close off nasopharynx
3-breathing stops & airways are closed because:
a-vocal cords close
b-epiglottis is bent over airway as larynx is lifted
4-Upper esophageal sphincter relaxes
Epiglottis
closes
Upper esophageal
Sphincter relaxes
5-Pharyngeal folds pulled away to form swallowing groove on the pharyngeal roof
6-A peristaltic wave passes the bolus to the esophagus

8. Deglutition: Esophageal phase
Upper esophageal sphincter closes again
Peristalsis pushes food
down by contraction of circular fibers behind bolus
longitudinal fibers in front of bolus shorten the distance of travel
Travel time is 4-8 seconds for solids and 1 sec for liquids
Lower sphincter relaxes as food approaches
Secondary peristaltic

9. Pressure changes in pharynx ,esophagus & esophageal sphincters during swallowing

10. Control of lower esophageal sphincter
LES is controlled by :
Parasympathetic preganglionic fibers via ENS stimulatory & inhibitory neurons
sympathetic which inhibit ENS neurons and directly stimulate LES
L.E.S. MUSCLE
NANC neuron
VIP,ATP,NO -
Vagal
nucleus +
Cholinergic
Vagal neurons
ENS
Neuron
Post ganglionic
Sympathetic
Neurons

11. Gastroesophageal sphincter Diseases-1:Achalasea
Lower sphincter fails to open
distension of esophagus feels like chest pain or heart attack-
Treatment
Air balloon
Surgical
Myotomy
sympathectomy

12. Gastro esophageal sphincter Diseases- 2 : (GERD)
Lower esophageal sphincter fails to close
stomach acids , bile & enzymes enter esophagus & erode esophagus
Presentation: post- prandial heart burn, regurgitation at 1 hour
Control the symptoms by avoiding
a large meal and lay down in front of TV
smoking and alcohol , coffee, chocolate, tomatoes, fatty foods, onions & mint
Bending to tie the shoes
Control the symptoms by
taking Tagamet HB 60 minutes before eating
neutralize existing stomach acids with Digel