1. ORAL BIOLOGY DEPARTEMENT
DIGESTIVE SYSTEM
drg. ANIS A. MAKKY, MKes
ORAL BIOLOGY DEPARTEMENT
AIRLANGGA UNIVERSITY
SURABAYA, APRIL 16, 2007

2. FUNCTION
1. ingest food
2. break food down physically and chemically into absorbable nutrient molecule
3. absorb those molecules into the bloodstream
4. eliminate any indigestible remains.

3. IN THE DIGESTIVE SYSTEM
2 MAJOR GROUPS OF ORGANS
IN THE DIGESTIVE SYSTEM
ALIMENTARY CANAL :
organs thrue which food actually passes
ACCESSORY ORGANS :
they assist in digestion, but no food actually
passes through them

4. ALIMENTARY CANAL
* oral cavity
* esophagus
* pharynx
* stomach
* small intestine
* large intestine.
ACCESSORY ORGANS
* teeth
* tongue
* salivary glands
* pancreas
* liver
* gallbladder.

6. THE DIGESTIVE SYSTEM PERFORMS
6 BASIC ACTIVITIES:
Ingestion
Propulsion
Mechanical Digestion
Chemical Digestion
Absorption
Defecation

10. ORAL CAVITY STRUCTURES
1. deciduous teeth (20)     2. permanent teeth (32)     3. tongue        a. skeletal muscles        b. moves food mass “bolus”        c. appropriate use of “lingual” terminology

11. ORAL CAVITY STRUCTURES
    4. major salivary glands (3 pair)        a. parotid masseter
- mumps     
b. submandibular
- medial aspect of the mandibular body
- duct : lingual frenulum        c. sublingual anterior submandibular gland & under the tongue
- its ducts : floor of the mouth.
   

12. ORAL CAVITY STRUCTURES
    5. minor salivary glands
* lingual glands (on the tongue)
* buccal & labial glands (in the cheek & lip)
* palatine glands (in the palate)
* glossopalatine glands (on the glossopalatine
fold)    

14. SALIVA contains : enzymatic & nonenzymatic protein calcium phosphorus
sodium
other salt
dissolve gasses : N2, O2, CO2
cells (leukocytes : ginggival sulcus)
saliva is 99% water

15. pH : depends on the rate of secretion
faster : more alkaline (meal)
sleep : low
resting : 5, 81 (parotid gland)
6,39 (submandibular gland)
average : 6,7
secretion : follow diurnal rhytms
total volume : 600 – 700 ml up to 1500 ml

16. secretion parotid gland : 60-65%
submandibular : 20-30%
sublingual : 2-5%
minor gland : 6-7%
sulcus gingival : µl/h

17. Function of the saliva digestive antibacterial lubrication taste
buffering action
hygienic action
blood coagulation & tissue repair
inhibition of dental caries
water balance

18. Control of saliva secretion
taste
smell
mechanical stimulation
mechanical irritation
mastication of the food
chemical irritation
distention or irritation of the oesophagus
chemical irritation of the stomach
pregnancy

20. PHARYNX
    1. oropharynx     2. esophagus :
connects pharynx to stomach     3. peristalsis - rhythmic smooth muscle
contractions propel material inside

21. LAYER of DIGESTIVE ORGAN
mucosa
submucosa
muscularis
serosa

23. MUCOSA functions : protecting against pathogens; absorbing nutrients;
and secreting mucus, enzymes, hormones
the mucosa consists of 3 sublayers:
* epithelium : hormone, enzyme, goblet cell
* lamina propria : blood vessels, lymph vessels,
and lymph nodules
* muscularis mucosae :
local movements of the mucosa

25. submucosa :
* contains :
** blood vessels, lymphatic vessels
** lymphatic nodules
** nerve fibers :
submucosal plexus
= Meissner plexus

26. muscularis externa :
* 2 layers of smooth muscle :
circular & longitudinal
* between 2 layers :
myenteric plexus = Auerbach plexus
* functions : segmentation & peristalsis
* in several places :
the circular layer thickens to form sphincters

27. Serosa :
most exterior layer

28. MUSCLE of GIT : most smooth m.
2 types : 1. multi unit smooth m.
2. visceral smooth m.
Smooth m. consist of :
actin
dense bodies : actin + actin
myosin

31. SMOOTH MUSCLE POTENTIAL
Slow waves : rhytmic, not action potential, resting
freq per minutes
gaster  3/min.
duodenum  12/min.
ileum  8-9/min.
cause  ?
“ sodium-potasium pump”

32. SMOOTH MUSCLE POTENTIAL
2. Spike potential : true action potential
occurs automatically
firing level : -40 mvolt
RMP : mvolt
stimulation : stretch, asetilkolin,
parasympathetic

34. SMOOTH MUSCLE CONTRACTION

36. ESOPHAGUS regulated by : cardiac or gastroesophageal sphincter
collapsed when : empty
upper 1/3 is skeletal
middle 1/3 a mixture
lower 1/3 smooth

37. STOMACH its functions include : * storage of food
* chemical and mechanical digestion
bolus  chyme (paste)
it is found nearly hidden by the liver
when it is empty : its J-shaped
and collapsed : folds  known as rugae

38.  general anatomic regions     a. cardia     b. fundus     c. body     d. pyloric region
it is important in the process of physical digest
gastric pits
pyloric sphincter regulates
entry into the duodenum

40. gastric pits  4 major secretory cells: a. chief cells b
 gastric pits  4 major secretory cells:        a. chief cells        b. parietal cells        c. G-cell        d. mucus cell                 

41. chief cells : pepsinogen. activation : by low pH to form pepsin
chief cells : pepsinogen * activation : by low pH to form pepsin * pepsin is a protease for protein digestion
b. parietal cells i. HCl    * secretion enhanced by histamine via H2 recep.    * tagamet blocks H2 histamine receptors to
inhibit HCl secretion ii. intrinsic factor     binds to and allows B12 absorption in intestines     

42. c. G-cell : gastrin hormone     * activates gastric juice secretion &
gastric smooth muscle “churning”     * activates gastroileal reflex which moves
chyme from ileum to colon d. mucus cell :     protective role of mucus against acids
and digestive enzymes     

44. What prevents the proteolytic enzymes and HCl secreted by the stomach from damaging itself?
There are 3 basic reasons :
a thick coat of alkaline mucus coats the
stomach walls
mucosal epithelial cells are joined by tight
junctions and are impermeable to HCl
damaged epithelial cells are quickly shed and
replaced