Digestive System
1. General organization of the internal organs 2. Digestive system – overview 3. Anterior digestive tract 4. Gastrointestinal tract 5. Rectoanal region 6. Hepatobiliary system 7. Peritoneum SPLANCHNOLOGY Internal organs of human body
Internal organs – viscera (splanchna): organs of the digestive, respiratory and urogenital systems located primarily in the thoracic and abdominal cavities functions – organs of vegetative state (vegetative organs) metabolism reproduction structural and functional differentiation hollow organs (tube or pouch) or parenchymal organs
Prof. Dr. Nikolai Lazarov 2 SPLANCHNOLOGY Internal organs Digestive system: from cranial to caudal end of the body, mostly in the abdominal cavity Respiratory system: mainly in the thoracic cavity Urogenital system: lower part of the abdominal cavity and in the pelvis
Prof. Dr. Nikolai Lazarov 3 SPLANCHNOLOGY Tissue structure of the internal organs
Main tissues:
epithelial tissue – functionally distinct tissue
smooth muscle tissue
connective tissue:
loose connective tissue
dense connective tissue
reticular tissue
cartilage tissue nervous tissue:
nerve cells (neurons)
autonomic nerves
sensory receptors
Prof. Dr. Nikolai Lazarov 4 SPLANCHNOLOGY General structure of hollow organs mucosa, tunica mucosa: lamina epithelialis – covering epithelium lamina propria – loose connective tissue blood and lymph vessels lymph follicles (MALT, GALT, BALT) elastic fibers, nerves and nerve structures mucosal glands – in stomach and gut lamina muscularis mucosae – smooth muscle (membrana elastica) tela submucosa blood vessels submucosal plexus (plexus of Meissner) glands – in esophagus and duodenum tunica muscularis inner circular layer myenteric plexus (plexus of Auerbach) outer longitudinal layer tunica serosa (adventitia) Prof. Dr. Nikolai Lazarov 5 SPLANCHNOLOGY General structure of parenchymal organs Parenchyma vs. Stroma Solid organs, organa solida: epithelial tissue – parenchyma connective tissue – stroma blood and lymph vessels nerve structures Structure principle: structural units lobules, segments, lobes fibrous capsule adventitia or serosa Main functions: secretion and excretion gas exchange formation of sex cells Representatives: liver, pancreas kidney, spleen ovary, glands Prof. Dr. Nikolai Lazarov 6 SPLANCHNOLOGY Digestive system Digestion: mechanical breakdown of food chemical breakdown – enzymes traveling down of the bolus (peristalsis) absorption of the chyme elimination of waste material (defecation)
Prof. Dr. Nikolai Lazarov 7 SPLANCHNOLOGY Digestive system
Digestive system, systema digestorium, apparatus digestorius: alimentary canal – length 9 m mouth anus accessory digestive glands: salivary glands liver pancreas
Prof. Dr. Nikolai Lazarov 8 SPLANCHNOLOGY Alimentary canal Anterior part:
mouth and oral cavity
throat, pharynx
gullet (esophagus) Middle part – GI tract:
stomach
small intestine Posterior (terminal) part:
large intestine, incl. rectum and anus
Prof. Dr. Nikolai Lazarov 9 SPLANCHNOLOGY Oral cavity, cavitas oris
Cavitas (cavum) oris Gr. stoma, stomatos: in the facial region of the head rima oris isthmus faucium Parts of the oral cavity: oral vestibule, vestibulum oris oral cavity proper, cavitas oris propria boundaries o gums and teeth o hard palate o part of the soft palate o diaphragma oris content o tongue o teeth fauces – the troat
Prof. Dr. Nikolai Lazarov 10 SPLANCHNOLOGY Lips, labia oris Macroscopic anatomy: oral fissure angle of mouth labial frenulum Upper lip, labium superius Lower lip, labium inferius Structure – orbicularis oris muscle: cutaneous portion – hairy skin marginal (red) portion mucosa– stratified squamous epithelium
Prof. Dr. Nikolai Lazarov 11 SPLANCHNOLOGY Cheeks, buccae
Structure – two membranous walls: enclose the mouth laterally similar to lips structure skin muscle layer – buccinator muscle subcutaneous fat tissue, – buccal fat pad (Bichat) buccal mucosa
Prof. Dr. Nikolai Lazarov 12 SPLANCHNOLOGY Palate Palate, palatum: separates the oral cavity from the nasal cavity palatum durum palatum molle Hard (bone) palate, palatum durum (osseum) – anterior ⅔: processus palatinus maxillae lamina horizontalis ossis palatini transverse palatal ridges Soft palate, palatum molle – posterior ⅓ velum palatini with uvula pharyngopalatine arch skeletal muscle glandular tissue, no bone
Prof. Dr. Nikolai Lazarov 13 SPLANCHNOLOGY Gums, gingivae
Gums, gingivae: pars fixa pars libera s. marginalis Macroscopic anatomy: gingival margin gingival sulcus papilla gingivalis (interdentalis) vestibular oral Microscopic anatomy: lamina epithelialis stratified squamous nonkeratinized epithelium lamina propria – papillae abundant blood supply rich innervation Prof. Dr. Nikolai Lazarov 14 SPLANCHNOLOGY Teeth, dentes Teeth, dentes (Gr. odus, odontos ): mechanical breakdown (chew) of food help in phonation derivatives of oral mucosa Characteristics of human dentition: close contact between teeth heterodont – teeth differ morphologically diphyodont – two successions of teeth in a process of evolution – reduction in number
Prof. Dr. Nikolai Lazarov 15 SPLANCHNOLOGY Human dentition
Permanent teeth, dentes permanentes: 32 teeth into two symmetrical halves upper dental arch , arcus dentalis superior lower dental arch , arcus dentalis inferior anatomical and functional groups: incisors, dentes incisivi canine (dogteeth), dentes canini premolars, dentes premolares molars, dentes molares
Prof. Dr. Nikolai Lazarov 16 SPLANCHNOLOGY Human dentition
Deciduous (milk) teeth, dentes decidui: the first set of teeth in the growth development of humans 20 teeth into two symmetrical halves distinguishing features (traits): similar morphology but smaller in size slightly blue tone of enamel shorter roots wider root canals and cavity anatomical and functional groups: incisors, dentes incisivi 2 canine teeth, dentes canini – 1 molars, dentes molares – 2
Prof. Dr. Nikolai Lazarov 17 SPLANCHNOLOGY Basic tooth structure Principal parts of a tooth: tooth crown, corona dentis – surfaces margo incisialis (incisivus) – incisors facies occlusalis (masticatoria) – premolars and molars o tuberculum dentale (cuspis dentalis) facies vestibularis (labialis, buccalis) facies lingualis facies contactus (mesialis et distalis) anatomical vs. clinical crown tooth neck, cervix dentis root, radix dentis – in dental alveolus apex radicis dentis cavity – cavitas dentis (pulparis) cavitas coronae canalis radicis dentis tooth pulp, pulpa dentis pulpa coronalis pulpa radicularis Prof. Dr. Nikolai Lazarov 18 SPLANCHNOLOGY Tongue, lingua (Gr. glossa) Parts of the tongue: body, corpus linguae apex linguae root of tongue, radix linguae divided by the sulcus terminalis Surface anatomy of the tongue: upper surface, dorsum linguae pars presulcalis (anterior, oralis) pars postsulcalis (posterior, pharyngealis) sulcus terminalis foramen cecum sulcus medianus linguae lower, facies inferior linguae plica fimbriata frenulum linguae caruncula sublingualis plica sublingualis margin of the tongue, margo linguae
Prof. Dr. Nikolai Lazarov 19 SPLANCHNOLOGY Papillae of the tongue
Papillae linguales – 4 distinct types: papillae filiformes (conicae) papillae fungiformes papillae vallatae papillae foliatae
Prof. Dr. Nikolai Lazarov 20 SPLANCHNOLOGY Taste perception taste buds, caliculi (gemmae) gustatorii – 2000 9000: vallate papillae – most numerous, plentiful in the posterior ⅓ of tongue fungiform and foliate papillae soft palate, epiglottis and pharynx reduction in number (up to ⅓) with age our sense of taste can and do change over time!
Prof. Dr. Nikolai Lazarov 21 SPLANCHNOLOGY Glands of the tongue
Glandulae linguales – minor salivary glands: mixed (seromucous) glands – near the tip anterior lingual (Nuhn’s) glands serous glands – in the vallate papillae gustatory (von Ebner’s) glands mucous glands – in the tongue root posterior lingual (Weber) glands
Prof. Dr. Nikolai Lazarov 22 SPLANCHNOLOGY Lingual tonsil Tonsilla lingualis: small, rounded mass of lymphoid tissue in the posterior ⅓ of the tongue tonsillar papillae, tonsillar crypts Weber’s salivary glands covered with stratified squamous epithelium
Prof. Dr. Nikolai Lazarov 23 SPLANCHNOLOGY Muscles of the tongue Skeletal (extrinsic) lingual muscles – move the tongue: m. genioglossus – most well developed m. hyoglossus m. styloglossus m. palatoglossus m. chondroglossus – inconstant
Prof. Dr. Nikolai Lazarov 24 SPLANCHNOLOGY Muscles of the tongue Proper (instrinsic) lingual muscles – alter its shape: m. longitudinalis superior m. longitudinalis inferior m. transversus linguae m. verticalis linguae
Prof. Dr. Nikolai Lazarov 25 SPLANCHNOLOGY Salivary glands
Small salivary glands, glandulae salivariae minores: mixed glands: labial buccal molar anterior lingual glands (Nuhn) serous glands: von Ebner ’s glands in the tongue mucous glands: palatine glands posterior lingual glands (Weber)
Prof. Dr. Nikolai Lazarov 26 SPLANCHNOLOGY Salivary glands Large salivary glands, glandulae salivariae majores: Parotid gland, glandula parotidea (parotis) Submandibular gland, glandula submandibularis Sublingual gland, glandula submandibularis
Prof. Dr. Nikolai Lazarov 27 SPLANCHNOLOGY Fauces, fauces Isthmus faucium Fauces: velum palatinum – superiorly uvula palatina palatoglossal arch palatopharyngeal arch
Prof. Dr. Nikolai Lazarov 28 SPLANCHNOLOGY Waldeyer’s tonsillar ring NALT – Nasal Associated Lymphoid Tissue Anulus lymphoides Waldeyeri: lingual tonsil pharyngeal (adenoid) tonsil tubal tonsil palatine tonsil von Waldeyer (1836-1921)
Prof. Dr. Nikolai Lazarov 29 SPLANCHNOLOGY Throat, pharynx
food and air conduction crossroad part of the digestive and respiratory systems important in vocalization cone shaped muscular membranous sac: length– 12 15 cm diameter – upper portion: 3.5 cm lower portion: 1.5 cm
Prof. Dr. Nikolai Lazarov 30 SPLANCHNOLOGY Macroscopic anatomy
Three general areas: epipharynx (nasopharynx) mesopharynx (oropharynx) hypopharynx (laryngopharynx) Prof. Dr. Nikolai Lazarov 31 SPLANCHNOLOGY Pars nasalis pharyngis synonyms: nasopharynx, epipharynx Part of the respiratory system: fornix pharyngis – tonsilla pharyngealis (adenoidea) tonsilla tubaria
Prof. Dr. Nikolai Lazarov 32 SPLANCHNOLOGY Pars oralis pharyngis synonyms: oropharynx, mesopharynx
Prof. Dr. Nikolai Lazarov 33 SPLANCHNOLOGY Pars laryngea pharyngis synonyms: laryngopharynx, hypopharynx
Prof. Dr. Nikolai Lazarov 34 SPLANCHNOLOGY Muscles of the pharynx Skeletal muscles tunica muscularis pharyngis: deep layer of longitudinally oriented muscles superficial layer of circular skeletal muscle
Two functional groups: mm. levatores pharyngis mm. constrictores pharyngis Prof. Dr. Nikolai Lazarov 35 SPLANCHNOLOGY Gullet, esophagus Straight muscular tube 25-30 cm long: begins at the level of
cricoid cartilage – C6 pass through the mediastinum and penetrates the diaphragm
– Th 10 meets the stomach
– Th 11
Prof. Dr. Nikolai Lazarov 36 SPLANCHNOLOGY Macroscopic anatomy Anatomical parts: cervical part – 5 6 cm thoracic part – 16 19 cm abdominal part – 1 4 cm
Prof. Dr. Nikolai Lazarov 37 SPLANCHNOLOGY Anatomical constrictions Three anatomical constrictions: pharyngoesophageal – 15 cm from the incisors broncho aortic – 24 cm from the incisor teeth phrenic – 40 cm from the incisor teeth
Prof. Dr. Nikolai Lazarov 38 SPLANCHNOLOGY Physiological constrictions Two physiological constrictions – due to the muscle contractions of the esophagus
1. Aortic – at the site of bifurcation with the aortic arch
2. Cardiac – the lower entrance to the stomach
Prof. Dr. Nikolai Lazarov 39 SPLANCHNOLOGY Microscopic structure
Lamina epithelialis mucosae: stratified squamous nonkeratinizing epithelium – 20 24 layers Lamina propria mucosae: cardiac glands Lamina muscularis mucosae: longitudinal smooth muscles Tela submucosa : esophageal glands plexus submucosus (Meissneri) Tunica muscularis – transition internal circular layer external longitudinal layer plexus myentericus (Auerbachi) Tunica adventitia: loose connective tissue serosa below the diaphragm
Prof. Dr. Nikolai Lazarov 40 SPLANCHNOLOGY Stomach, gaster (ventriculus)
the dilated portion of the alimentary canal, pouch like, J shaped organ: stores food – 1 1.7 l in the upper left part of the abdomen, below the diaphragm 4 anatomical regions: cardiac region, cardia fundic region, fundus body, corpus pyloric region, pylorus Two walls: anterior posterior lesser and greater curvature
Prof. Dr. Nikolai Lazarov 41 SPLANCHNOLOGY Microscopic structure 3 histological regions: cardiac pars cardiaca fundic fundus et corpus gastricum pyloric pars pylorica
Prof. Dr. Nikolai Lazarov 42 SPLANCHNOLOGY Gastric wall Three tissue layers:
gastric mucosa, tunica mucosa tela submucosa muscle layer, tunica muscularis serosa, tunica serosa
Prof. Dr. Nikolai Lazarov 43 SPLANCHNOLOGY Gastric mucosa
lamina epithelialis – simple columnar glandular epithelium: surface mucous cells (4 7 days) и pit cells lamina propria mucosae – gastric glands lamina muscularis mucosae – gastric rugae
Prof. Dr. Nikolai Lazarov 44 SPLANCHNOLOGY Gastric glands
gastric glands proper – 35 million glandulae gastricae propriae pepsinogen and hydrochloric acid gastric intrinsic factor cardiac – glandulae cardiacae pyloric – glandulae pyloricae, 3.5 million
Prof. Dr. Nikolai Lazarov 45 SPLANCHNOLOGY Gastric glands glandulae gastricae propriae – parts: isthmus, cervix, pars principalis (corpus, fundus) cells: epitheliocyti nondifferentiati glandulae pyloricae : stem cells exocrinocyti principales: pepsinogen and gastric lipase exocrinocyti parietales: HCl, intrinsic factor mucocyti cervicales – PAS positive endocrinocyti gastrointestinales: gastrin , SOM, VIP, SER, histamine, ghrelin, bombesin
Prof. Dr. Nikolai Lazarov 46 SPLANCHNOLOGY Histological structure Tela submucosa: connective tissue with blood and lymph vessels
Tunica muscularis: inner oblique layer, fibrae obliquae middle circular layer (m. sphincter pyloricus) outer longitudinal layer (stratum longitudinale) Tunica serosa: part of peritoneum Prof. Dr. Nikolai Lazarov 47 SPLANCHNOLOGY Small intestine, intestinum tenue
Small intestine – convoluted tube: longest part of the digestive tract from pylorus to the ileocecal valve length – 6 8 m diameter – 4 3 cm capacity – 4 l functional peculiarities Three portions: the duodenum, duodenum – first 25 30 cm
the jejunum, jejunum – 2/5
the ileum, ileum – 3/5
Prof. Dr. Nikolai Lazarov 48 SPLANCHNOLOGY Duodenum in situ Location and anatomical parts: shortest, widest and most fixed intestinal part C shaped curve around pancreatic head superior part – 5 cm descending – 7.5 cm horizontal – 10 cm ascending – 2.5 cm
Prof. Dr. Nikolai Lazarov 49 SPLANCHNOLOGY Mesenteric small intestine
Mesenteric small intestine: intraperitoneal position projected in: regio mesogastrica regio hypogastrica The jejunum, jejunum: horizontal arrangement of its loops located largely toward the upper left of the intestinal coils
begin from duodendojejunal flexure (L 2) The ileum, ileum: vertical arrangement of its loops located largely toward the lower right of the intestinal coils
ends at the ileocecal junction (L 4) Prof. Dr. Nikolai Lazarov 50 SPLANCHNOLOGY Intestinal wall Three major layers: tunica mucosa – spiral ridges circular folds, plicae circulares tela submucosa tunica muscularis tunica serosa
Prof. Dr. Nikolai Lazarov 51 SPLANCHNOLOGY Intestinal mucosa Mucosa, tunica mucosa: intestinal villi – cells intestinal glands duodenal glands
Prof. Dr. Nikolai Lazarov 52 SPLANCHNOLOGY Large intestine, intestinum crassum
Large intestine: end part of the digestive tract length 1.5 2 m, diameter 6.5 cm capacity 2 3 l functions: formation and evacuation of bolus water absorption degradation of food matter – cellulose, waste material, mucus Parts: cecum (caecum) colon rectum
Prof. Dr. Nikolai Lazarov 53 SPLANCHNOLOGY Cecum and appendix Cecum: blind pouch in lower right abdominal quadrant inferior to ileocecal valve intraperitoneal position Appendix vermiformis: blind tube 7 8 cm long intraperitoneal mesoappendix
Prof. Dr. Nikolai Lazarov 54 SPLANCHNOLOGY Colon
Four sections: ascending, colon ascendens transverse, colon transversum descending, colon descendens sigmoid, colon sigmoideum Anatomy: longitudinal ribbon like muscular strips, taeniae coli taenia libera taenia omentalis taenia mesocolica pouches, haustrae coli club like fatty pouches of peritoneum, epiploic appendages semilunar folds, plicae semilunares coli
Prof. Dr. Nikolai Lazarov 55 SPLANCHNOLOGY Colon wall Three major layers: mucosa, tunica mucosa intestinal glands, no intestinal villi tela submucosa submucosal plexus (Meissner) muscle layer, tunica muscularis internal circular layer external longitudinal layer – in teniae myenteric plexus (Auerbach) serosa, tunica serosa (adventitia)
Prof. Dr. Nikolai Lazarov 56 SPLANCHNOLOGY Rectum, Gr. proctos Anatomy of recto anal region: 3 transverse folds, rectal valves length 12 15 cm, S shaped rectal ampulla anal canal – final 3 cm longitudinal ridges, anal columns anal sinuses anal verge, anus internal and external anal sphincter
Prof. Dr. Nikolai Lazarov 57 SPLANCHNOLOGY Microscopic anatomy
Prof. Dr. Nikolai Lazarov 58 SPLANCHNOLOGY Liver, hepar Largest internal organ and largest gland in the human body: volume – ~1500 cm3 weight – 1.5 2.4 kg unequal size and shape soft, reddish brown, triangular organ Location: beneath the diaphragm right hypochondriac and epigastric regions Dual blood supply: 70 80% – hepatic portal vein: venous blood from the spleen, entire gastrointestinal tract and its associated organs 20 30% – hepatic arteries: arterial blood > 500 vital functions – production of bile, major role in metabolism Prof. Dr. Nikolai Lazarov 59 SPLANCHNOLOGY Gross anatomy Two surfaces: superior diaphragmatic inferior visceral – porta hepatis posterior – bare area Hepatic lobes: right lobe left lobe quadratus and caudatus lobes Hepatic segments
Prof. Dr. Nikolai Lazarov 60 SPLANCHNOLOGY Microscopic anatomy
serosa, tunica serosa fibrous capsule of Glisson , tunica fibrosa hepatic lobules, lobuli hepatis: total number – ~1 000 000 shape – hexagonal size – 0.7 x 2 mm content: • parenchyma, hepatocytes • central vein • sinusoids
Prof. Dr. Nikolai Lazarov 61 SPLANCHNOLOGY Functional units of liver “classical” lobule – anatomical model portal lobule – bile secretion liver acinus – blood flow and metabolic
Prof. Dr. Nikolai Lazarov 62 SPLANCHNOLOGY Gallbladder, vesica biliaris (fellea)
hollow pear shaped organ: concentrates bile aids in fat digestion volume: 40 60 cm3 three sections: fundus body, corpus neck, collum cystic duct, ductus cysticus
Prof. Dr. Nikolai Lazarov 63 SPLANCHNOLOGY Biliary tree bile canaliculi bile ducts (canals of Hering ) interlobular bile ducts left and right hepatic ducts common hepatic duct cystic duct common bile duct
Prof. Dr. Nikolai Lazarov 64 SPLANCHNOLOGY
Gr. πάγκρεας Pancreas pan “all” , kreas, “flesh” A large glandular organ: weight – 80 g (30 180 g) size – 15 cm long, 2.5 thick exocrine and endocrine gland location – retroperitoneal: hidden behind the stomach
Prof. Dr. Nikolai Lazarov 65 SPLANCHNOLOGY Macroscopic anatomy
5 anatomical parts: head, caput pancreatis uncinate process neck, collum pancreatis body, corpus pancreatis tail, cauda pancreatis Pancreatic structure: exocrine part – pancreatic acini endocrine part – pancreatic islets
Prof. Dr. Nikolai Lazarov 66 SPLANCHNOLOGY Exocrine pancreas, pars exocrina pancreatis Exocrine tissue – pancreatic juice: secretory acini – serous acinar cells duct system: intercalated ducts intralobular ducts interlobular ducts main pancreatic duct (of Wirsung) accessory pancreatic duct (of Santorini) pancreatic lobules, connective tissue septa thin pancreatic capsule, capsula pancreatis
Prof. Dr. Nikolai Lazarov 67 SPLANCHNOLOGY Endocrine pancreas, pars endocrina pancreatis Islets of Langerhans, insulae pancreaticae: > 1 million (1 2% of the volume) weight ~ 1 g diameter 100 300 µm most numerous in the tail Cell types: A cells – 15 20%, glucagon B cells – 60 80%, insulin D cells – 5 10%, somatostatin PP cells – 2 5%, pancreatic polypeptide
D1 cells – 0.5 1%, VIP EC cells G cells – gastrin, Y cells – ghrelin
Prof. Dr. Nikolai Lazarov 68 SPLANCHNOLOGY Peritoneum
Serous membrane: visceral peritoneum parietal peritoneum meso- and ligaments Peritoneal cavity peritoneal fluid Microscopic anatomy: mesothelium subserous connective tissue Peritoneal positions of organs: intraperitoneal mesoperitoneal retroperitoneal, extraperitoneal
Prof. Dr. Nikolai Lazarov 69 “The fate of a nation has often depended on food or bad digestion of a prime minister”
Voltaire (1694 ---1778) Thank you ... 70