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  Each lip is divided into:
1. External aspect----thin Skin with sweat
   glands, hair follicles and sebaceous glands.
2. Vermilion region---pink, very thin skin
   devoid of glands and hair follicles.
3. Mucous or internal aspect-----str.sq.
   epith.non-kerat. With subepith.irregular
   collagenous C.T having minor mucous
   salivary glands.
* The core of the lips is composed of skeletal
   muscle fibers
                 Oral cavity.
Oral mucosa:
*Gingiva, dorsal surface of the anterior two thirds
  of the tongue, and hard palate are covered by
  keratinized or partially (parakeratinized)
  str.sq.epith. with underlying dense irregular
  collagenous C.T.
*The reminder of oral cavity is covered by non-
  keratinized str. Sq. epith. With underlying looser
  collagenous C.T.
 Each  tooth is suspended in bony socket, the
  alveolus by the periodontal (dense irregular
  collagenous C.T.)
 Each tooth is formed of:
     1-Crown—visible part.
     2-Root----in the alveolus.
*The inner part of tooth is the pulp that contain
  soft vascular C.T contains bl. and lymph
  Vessels and nerves
      Mineralized components
 They  are :
 a.Dentin----surrounds the pulp and is covered
 b.Enamel –that cover the crown.
 c.Cementum----that cover the root.

It is composed of:
 Hard  palate (keratinized-st. sq.epith.)
 Soft palate (
 Uvula (
They separate the nasal cavity from the
  oral one.
 IT   has:
1-Dorsal surface---its ant. two thirds is covered
  with ker. St. sq.epith. and separated from post
  one third (covered with non-ker. St. sq.epith) by
  a shallow, V-shaped groove, the sulcus
2-Ventral surface---non-ker. St.sq.epith.
3-Core of skeletal muscle fibers.
*The dorsal surface of posterior one third has
  lingual tonsils.
Lingual tonsil
          Lingual papillae
They are located on the dorsal & lateral aspect of
  the tongue.
There are four types:
1.Filiform papilla : slender structure, covered by sq. epith.DO NOT have taste buds.
2.Fugiform papilla---as mushroom has slender
  stalk connects a broad cap to tongue surface.It
  is covered by non-ker. Str. Epith.It has taste
  buds on dorsal surface of the cap.
Filliform &Fungi form papillae
3.Foliate papillae: are located along
 the posterior aspect of the tongue.
 They have taste buds in neonate only.
 They have furrows in which glands of
 Von Ebner (serous) open.
4.Circumvallate papillae---8 to 12 just
 ant. To sulcus terminalis. They have
 Von Ebner serous glands. They have
 taste buds on their sides only.
Circumvallate papilla
               Taste buds
 Are  intra-epithelial sensory organs for
  perception of taste.
 Each taste bud is formed of;
  1.Dark cells (type I)
  2.Light cells (type II)
  3.Intermediat cells (type III)
  4.Basal cells (type IV)
*Nerve fibers synapse with types I, II, and III (they
  have long microvilli protruding from taste pores)
Taste buds
          Salivary glands

There two types of salivary glands:
 Minor salivary glands (scattered in
 the mucosa of oral cavity-mucous
Major salivary glands ( Parotid, sub
 mandibular and sub lingual)
       Major salivary glands
 There  are three pairs of major salivary
  glands, Parotid, submandibular, and
 They have C.T capsule. provides
  septa that divide the glands into lobes
  and lobules (Stroma).
 Their parenchyma consists of
  secretory portion (tubuloalveolar
  glands) and ducts portion.
        Secretory portions
 Areformed of serous and/or mucous serous
 secretory cells arranged as acini (alveoli-
 serous) or tubules (mucous) that are couched
 by myoepithelial cells.
 Myoepithelial   (basket )cells.
They share the basal lamina of acinar cells
They envelope the cells of secretory acinus and
 intercalated ducts (desmosomes)
They have several long processes.
They are rich in actin and myosin.
They press on the acinus to release the product.
               Serous cells
 Secrete  proteins and polysaccharides.
 Are pyramidal with single round, basally
  located nuclei.
 Are rich in rER, Golgi complex, basal
  mitochondria, and epically situated
  secretory granules.
 They have tight junctions, intercellular
  canaliculi and interdigitated baso-lateral
            Mucous cells
 Are  short pyramidal cells with basal
  flattened nuclei.
 Have few mitochondria, rER, but rich in
  Golgi complex (to form carbohydrates).
 Have less lateral processes and
  intercellular canaliculi than serous cells.
 Apices of cells are rich in secretory
             Duct portions
 Are  highly branched ducts.
 Begin with the smallest intercalated ducts that
  formed of small cuboidal cells having
  myoepithelial cells.
 Intercalated ducts merge to form striated ducts
  which are cuboidal to columnar cells with
  basolateral folds containing mitochondria. They
  join together to form intralobular ducts that unit
  to form interlobular ducts that join to form
  intralobar and interlobar ducts.
 Terminal ducts open into the oral cavity.
         Parotid Gland
 The  largest salivary gland but
  produce 30% of salivary output.
 It secrets pure serous secretion
  that rich in amylase enzyme,
  lactoferrins, lysozymes and
  secretory IgA
Parotid gland
       Submandibular Gland
 It produces 60% of salivary
 It is mixed but the major portion
  (90%) is serous and 10% is
 It has few serous demilunes that
  capped the mucous tubular
  secretory unit.
Submandibular gland
       Sublingual Gland
 It is very small and responsible for 5%
  of salivary secretion.
 Is composed of mucous tubules with
  serous demilunes.
 It produces mixed , but mostly
  mucous saliva.
 Its duct system does not form
  terminal duct, instead several ducts
  open into the floor of oral cavity.
Sub lingual
       Alimentary Canal
 Is the tubular portion of digestive
 About 9 meters and subdivided
  into: esophagus, stomach, small
  intestine (duodenum, jejunum and
  ileum), and large intestine
  (cecum, colon, rectum, anal
  canal, and appendix)
General structure of Alimentary tract
It is formed of 4 concentric layers:
I.Mucosa II.Submucosa III.Muscularis externa
IV.Serosa (adventitia)
                   I- MUCOSA
It is formed of :
2-Lamina propria (Vascular C.T) that contains
   lymph vessels, nodules and glands.
3-Muscularis mucosa:Inner circular and outer
   longitudinal smooth muscle.
 Is  formed of dense irregular elastic
 It has glands ONLY in esophagus
  and duodenum.
 It is rich in blood and lymph vessels.
 It has enteric nervous plexus
  (Meissner”s plexus) that houses
  also post ganglionic parasympathetic
  nerve cell bodies.
 It is responsible for peristaltic activity.
 It is composed of smooth muscle (EXCEPT in
  esophagus, has both smooth & skeletal fibers).
 They are arranged helically.
 Usually organized as inner circular and outer
 Between the two layers they have Auerbach’s
  myenteric plexus.
 that houses also post ganglionic
  parasympathetic nerve cell bodies
 It covers the muscularis externa.
 It is formed of thin layer of vascular
 If it is surrounded by simple
  squamous epith.of the visceral layer
  of peritoneum (mesothelium)---It is
  called serosa.
 If the organ is retropritoneal i.e NO
  epith.—It is called adventitia.
The wall of GIT.
Musculsris externa
Auerbach’s myenteric plexus
Mucosa---stratified sq.epith non-ker,fibroelasic
 lamina propria and longitudinal muscularis
 mucosa (smooth muscle).
L.P has cardiac glands (mucous) near the
 pharynx (upper region) and stomach (lower
Submucosa– has mucous esophageal glands
Muscularis externa of upper third is skeletal
 muscle, middle third is both smooth&skeletal
 and the lowest third is smooth muscle.
 Adventitia until pierces diaphragm---serosa
Mucosa and submucosa of

Gastro-oesophageal junction
esophagus      stomach
Parts of the
Fundic mucosa

        Fundic glands have:
        Short pits—one forth of
        Simple or branched tubular
        Are rich in parietal & chief
Fundic gland
Surface columnar gastric cell
               They secrete thick mucous
Mucus neck cell
Parietal cell   Acidophilic cells, apical
                invaginations that have
                canaliculi lined by microvilli.
                Secrete HCl and gastric
                intrinsic factor (absorption of
                Vit.B12 in the ileum).
Chief cell
             pepsinogen, rennin
             and gastric lipase
DNES cells
Pyloric glands
            Fundic glands
 Their pits are short about one quarter of length
  of mucosa.
 Are simple or branched tubular glands.
 Are numerous and crowded.

          Pyloric glands
* Their pits are deep---about half the length of
* They are branched and convoluted---many
  cross sections.
* The predominant cells are mucous neck cells
  that secrete both mucous and lysozyme.
            Small intestine
 It has 3 regions: duodenum, jejunum and ileum.
 It has:
 * Plicae circulares---transverse folds of mucosa
  and submucosa.
 *Villi—Finger like protrusions of lamina propria that
  is covered with epithelium.They contain Bl.
  &lymphatic vessels (lacteal), smooth muscle
  fibers, loose CT and lymphoid cells.
 * Micrvilli—modifications of the apical region of
  plasmalemma of epithelial cells of villi and surface
Crypts of Lieberkuhn-invaginations of epithelium
  into the L.P between the villi form glands
Cells of the villi and crypts of small
     Cells covering the Villi
 Surface  absorptive cells that has brush
  (microvilli) border and covered wih thick
  glycocalx that has dipeptidase and
  disaccharidase enzymes.They have
  Junction complex.
 Goblet cells—Increase toward the ileum.
 DNES cells.
 M cells (microfold cells)-phagocytose and
  transport Ag present in the intestinal
Absorbtive columnar cells
         Crypts of Lieberkuhn
 They are simple tubular glands that open
  between villi.
 They are composed of surface absorptive cells,
  goblet cells, regenerative cells, DNES cells and
  Paneth cells.
 Paneth cells occupy the bottom of crypts.They
  have acidophilic (eosinophilic) secretory
  granules. They secrete lysozyme (antibacterial
Paneth cell
   Submucosa of the duodenum
 Isformed of dense irregular fibroelasic
 Rich in bl. &lymphatic vessles.
 Contains Meissner’s plexus
 Contains Brunner’s glands that producea
  mucous and bicarbonate-rich fluid as well
  as urogastron that inhibits HCl production.
Wall of the
Gastrodeodenal junction
 Regional differences of small intestine
 Duodenum      is the shortest part (25cm). Its
  villi are broader, taller and more
  numerous. Its submucosa has Brunner’s
 Jejunum-its villi are narrower, shorter. And
  sparser than in duodenum. Goblet cells
  are more.
 Ileum-its villi are shortest, sparest, and
  narrowest. Its lamina propria has lymphoid
  nodules (peyer’s patches) opposite the
  attachment of the mesentery.
              Large intesine
 It is divided into-cecum, colon, rectum, and
  anus –(appendix is blind outpouching of the
 It has NO villi.
 It is rich in crypts that are composed of same
  cells as small intestine but NO Paneth cells.
 Goblet cells increase from cecum to the
 The outer layer of muscularis externa is not
  continuous (3 fascicles-taeniae coli).
 Serosa has fat called appendices epiploicae.
       Vermiform Appendix
 It is long diverticulum of cecum.
 It has shallow crypts of Lieberkuhn.Its
  mucosa is composed of surface
  absorptive cells, goblet cells, DNES
  cells, M-cells, infrequent Paneth cells
  and lymphoid nodules around the
 It is invested by serosa.
Vermiform appendix (Human)
Vermiform appendix (Rabbit)
       Rectum and Anal canal
 Rectum   has fewer but deeper crypts than
 Epithelium of anal mucosa is simple
  cuboidal from rectum to pectinate line,
  then st.sq.non-ker. Epith to the anus, then
  st.sq.ker. Epith. At anus.
 Lamina propria of anal canal has anal
 Submucosa of anal canal has internal and
  external hemorroidal plexuses.
 It has internal and external anal
 Itis both an exocrine (digestive juices) &
  an endocrine (hormones) gland.
 The excretory part is formed of acini &
 Acinar cells are pyramidal cells with basal
  round nuclei that surrounded by basophilic
  cytoplasm (rER, polysomes).
 Apex of acinar cells have zymogen
 Acinar cells secrete many digestive
  enzymes in the duodenum.
      Duct portion of Pancreas
 Ducts  begins within the center of acini with the
  terminus of intercalated duct forming
  centroacinar cells (pale simple cuboidal cells)
  but not form wall of acini.
 Acini have not myoepithelial cells.
 Centroacinar cells &intercalated cells secrete a
  bicarbonate-rich buffer solution.
 Intercalated ducts merge to form intralobular
  ducts that merge to form interlobular ducts, that
  give main pancreatic duct.
       Endocrine portion (Islets of
 Islet is pale, spherical vascularized collection of
 It is surrounded by reticular cells.
 It is formed of 5 types of cells:
  β cells—70% more in center—secrete insulin
  (decreses blood sugar level).
  α cells---20% more in periphery—secrete
  glucagon—increase blood glucose level.
  δ cells---5%--secrete somatostatin—paracrine and
  endocrine (reduce smooth muscle contraction).
  G cells---1%---secrete gastrin---increas HCl.
  PP cells—1%---secrete pancreatic polypeptide—
  inhibit exocrine pancreatic secretion.
Islet of Langerhans
Liver ( its unit is the classic liver
                      It houses:
Portal triad (area)
                      1-branches of hepatic
                      2-tributaries of portal
                      3-interlobular bile
                      4-Lymph vessels.
                      It is isolated from liver
                      parenchyma by limiting
                      plate of modified
Three concepts of liver lobules
                   1-Classic liver lobule---
                   Bl. Flows from periphery
                   toward central vein.
                   2-portal lobule---bile
                   flows to a particular
                   interlobular duct.
                   3-Hepatic (portal)
                   acinus—in which three
                   concentric regions of
                   hepatocytes surrounding
                   a distributing artery in
                   the center.
         Classic liver lobule
It is formed of anastomosing plates of
hepatocytes of tow cells thick.
There are blood sinusoids between plates that
separated from hepatocytes by perisinusoidal
Space of Disse.
Space of Disse contains:

A- Plasma. B-Reticular fibers. C-fat storing cells
(Ito cells). D-nonmyelinated nerve fibers. .E-
Microvilli of hepatocytes. F-Pit cells (natural killer
         Hepatic sinusoids
 They   have gap junctions.
 They have fenestrae.
 They show Kupffer cells, that originate from
  monocytes (phagocytic) and rich in lysosomes
  and have filopodia-like projections.
 They receive blood from inlet arterioles and
  inlet venules.
 Their blood flows into the central vein that give
  sublobular ,then collecting veins to form hepatic

Sinusoidal domain   domain
               Hepatic ducts
 Bile canaliculi that formed by hepatocytes cell
 Bile canaliculi merge with cholangiole (short
  tubules formed of a combination of
  hepatocytes, low cuboidal cells and oval cells).
 Bile from cholangioles enters canals of Hering
  (branches of interlobular ducts).
 Interlobular ducts are lined with simple cuboidal
 Interlobular ducts merge to form hepatic bile
          Gall bladder

 Itis composed of 4 layers.
 1-Simple columnar epithelium.
 2-vascularized loose CT lamina propria
  that contains small mucous glands.
 Smooth muscle arranged as inner oblique
  and outer longtudinal layers.
 Serosal adventitia.
Gall bladder

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