Transcript oral cavity structures

DIGESTIVE SYSTEM
drg. ANIS A. MAKKY, MKes
ORAL BIOLOGY DEPARTEMENT
AIRLANGGA UNIVERSITY
SURABAYA, APRIL 16, 2007
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.
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
ALIMENTARY CANAL
* oral cavity
* esophagus
* pharynx
* stomach
* small intestine
* large intestine.
ACCESSORY ORGANS
* teeth
* tongue
* salivary glands
* pancreas
* liver
* gallbladder.
THE DIGESTIVE SYSTEM PERFORMS
6 BASIC ACTIVITIES:
Ingestion
Propulsion
Mechanical Digestion
Chemical Digestion
Absorption
Defecation
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
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 10-12 ducts : floor of the mouth.
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)
SALIVA
contains : enzymatic & nonenzymatic protein
calcium
phosphorus
sodium
other salt
dissolve gasses : N2, O2, CO2
cells (leukocytes : ginggival sulcus)
saliva is 99% water
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
secretion parotid gland : 60-65%
submandibular : 20-30%
sublingual : 2-5%
minor gland : 6-7%
sulcus gingival : 10-100 µl/h
Function of the saliva
1. digestive
2. antibacterial
3. lubrication
4. taste
5. buffering action
6. hygienic action
7. blood coagulation & tissue repair
8. inhibition of dental caries
9. water balance
Control of saliva secretion
1. taste
2. smell
3. mechanical stimulation
4. mechanical irritation
5. mastication of the food
6. chemical irritation
7. distention or irritation of the oesophagus
8. chemical irritation of the stomach
9. pregnancy
PHARYNX
1. oropharynx
2. esophagus :
connects pharynx to stomach
3. peristalsis - rhythmic smooth muscle
contractions propel material inside
LAYER of DIGESTIVE ORGAN
mucosa
submucosa
muscularis
serosa
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
submucosa :
* contains :
** blood vessels, lymphatic vessels
** lymphatic nodules
** nerve fibers :
submucosal plexus
= Meissner plexus
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
Serosa :
most exterior layer
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
SMOOTH MUSCLE POTENTIAL
1. Slow waves : rhytmic, not action potential, resting
freq. 3-12 per minutes
gaster  3/min.
duodenum  12/min.
ileum  8-9/min.
cause  ?
“ sodium-potasium pump”
SMOOTH MUSCLE POTENTIAL
2. Spike potential : true action potential
occurs automatically
firing level : -40 mvolt
RMP : 50-60 mvolt
stimulation : stretch, asetilkolin,
parasympathetic
SMOOTH MUSCLE CONTRACTION
ESOPHAGUS
regulated by :
cardiac or gastroesophageal sphincter
collapsed when : empty
upper 1/3 is skeletal
middle 1/3 a mixture
lower 1/3 smooth
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
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
gastric pits  4 major secretory cells:
a. chief cells
b. parietal cells
c. G-cell
d. mucus cell
a. 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
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
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