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lips Each lip is divided into:

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1 lips Each lip is divided into:
External aspect----thin Skin with sweat glands, hair follicles and sebaceous glands. Vermilion region---pink, very thin skin devoid of glands and hair follicles. 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

2 Lip

3 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.

4 Teeth 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. 3-Cervix---inbetween. *The inner part of tooth is the pulp that contain soft vascular C.T contains bl. and lymph Vessels and nerves

5 Mineralized components
They are : a.Dentin----surrounds the pulp and is covered with; b.Enamel –that cover the crown. c.Cementum----that cover the root.

6 Teeth

7 Palate Hard palate (keratinized-st. sq.epith.)
It is composed of: Hard palate (keratinized-st. sq.epith.) Soft palate (non-ker.st.sq.epit.) Uvula (non-ker.st.sq.epith) They separate the nasal cavity from the oral one.

8 Tongue 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 terminalis. 2-Ventral surface---non-ker. St.sq.epith. 3-Core of skeletal muscle fibers. *The dorsal surface of posterior one third has lingual tonsils.

9 Tongue

10 Lingual tonsil

11 Lingual papillae They are located on the dorsal & lateral aspect of the tongue. There are four types: 1.Filiform papilla : slender structure, covered by ker.st. 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.

12 Filliform &Fungi form papillae

13 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.

14 Circumvallate papilla

15 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)

16 Taste buds

17 Salivary glands There two types of salivary glands:
Minor salivary glands (scattered in the mucosa of oral cavity-mucous secreting). Major salivary glands ( Parotid, sub mandibular and sub lingual)

18 Major salivary glands There are three pairs of major salivary glands, Parotid, submandibular, and sublingual. 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.

19 Secretory portions Myoepithelial (basket )cells.
Are formed 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 (hemidesmosomes). 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.

20 Salivary secretory unit

21 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 processes.

22 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 granules.

23 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.

24 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

25 Parotid gland

26 Submandibular Gland It produces 60% of salivary output.
It is mixed but the major portion (90%) is serous and 10% is mucous. It has few serous demilunes that capped the mucous tubular secretory unit.

27 Submandibular gland

28 Sublingual Gland It is very small and responsible for 5% of salivary secretion. It 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.

29 Sub lingual gland

30 Alimentary Canal Is the tubular portion of digestive system.
About 9 meters and subdivided into: esophagus, stomach, small intestine (duodenum, jejunum and ileum), and large intestine (cecum, colon, rectum, anal canal, and appendix)

31 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 : 1-Epithelium. 2-Lamina propria (Vascular C.T) that contains lymph vessels, nodules and glands. 3-Muscularis mucosa: longitudinal smooth muscle.

32 The wall of GIT. (esophagus)

33 II-SUBMUCOSA Is formed of dense irregular elastic C.T.
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.

34 III-MUSCULRIS EXTERNA
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 longitudinal. Between the two layers they have Auerbach’s myenteric plexus. that houses also post ganglionic parasympathetic nerve cell bodies

35 Musculsris externa Auerbach’s myenteric plexus

36 IV-SEROSA OR ADVENTITIA
It covers the muscularis externa. It is formed of thin layer of vascular C.T. 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.

37 Esophagus 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 region). Submucosa– has mucous esophageal glands proper. 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

38 Mucosa and submucosa of esophagus

39 Gastro-oesophageal junction
esophagus stomach

40 Parts of the stomach

41 Fundic mucosa Fundic glands have: Short pits—one forth of mucosa.
Simple or branched tubular glands. Are rich in parietal & chief cells.

42 Fundic gland

43 Surface columnar gastric cell
They secrete thick mucous

44 Mucus neck cell

45 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).

46 Chief cell *Basophilic cytoplasm.
*Secrete pepsinogen, rennin and gastric lipase

47 DNES cells

48 Pyloric glands

49 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 mucosa. * They are branched and convoluted---many cross sections. * The predominant cells are mucous neck cells that secrete both mucous and lysozyme.

50 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 epithelium. Crypts of Lieberkuhn-invaginations of epithelium into the L.P between the villi form glands

51 Cells of the villi and crypts of small intestine

52 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 lumen.

53 Absorbtive columnar cells

54 M-cell

55 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 agent)

56 Paneth cell

57 Submucosa of the duodenum
Is formed of dense irregular fibroelasic CT. Rich in bl. &lymphatic vessles. Contains Meissner’s plexus (parasympathetic). Contains Brunner’s glands that producea mucous and bicarbonate-rich fluid as well as urogastron that inhibits HCl production.

58 Duodenum

59 Wall of the duodenum

60 Duodenum

61 Gastrodeodenal junction

62 Regional differences of small intestine
Duodenum is the shortest part (25cm). Its villi are broader, taller and more numerous. Its submucosa has Brunner’s glands. 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.

63 Large intesine It is divided into-cecum, colon, rectum, and anus –(appendix is blind outpouching of the cecum). 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 sigmoid. The outer layer of muscularis externa is not continuous (3 fascicles-taeniae coli). Serosa has fat called appendices epiploicae.

64 Colon

65

66 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 wall. It is invested by serosa.

67 Vermiform appendix (Human)

68 Vermiform appendix (Rabbit)

69

70 Rectum and Anal canal Rectum has fewer but deeper crypts than colon.
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 glands. Submucosa of anal canal has internal and external hemorroidal plexuses. It has internal and external anal sphincters.

71 Pancreas It is both an exocrine (digestive juices) & an endocrine (hormones) gland. The excretory part is formed of acini & ducts. Acinar cells are pyramidal cells with basal round nuclei that surrounded by basophilic cytoplasm (rER, polysomes). Apex of acinar cells have zymogen granules-acidophilic. Acinar cells secrete many digestive enzymes in the duodenum.

72 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.

73 Pancreas

74 Pancreas

75 Endocrine portion (Islets of Langerhans)
Islet is pale, spherical vascularized collection of cells. 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.

76 Islet of Langerhans

77 Liver ( its unit is the classic liver lobule)

78

79 Portal triad (area) It houses: 1-branches of hepatic artery.
2-tributaries of portal vein. 3-interlobular bile ducts. 4-Lymph vessels. It is isolated from liver parenchyma by limiting plate of modified hepatocytes

80 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.

81 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 cells).

82 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 veins.

83

84 Hepatocytes Lateral domain Sinusoidal domain

85 Hepatic ducts Bile canaliculi that formed by hepatocytes cell membranes. 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 epithelium. Interlobular ducts merge to form hepatic bile ducts.

86 Gall bladder It is 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.

87 Gall bladder


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