digestive system - lazarovnikolai.lazarov.pro/files/pharmacy_eng/digestive_system.pdf ·...

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

Prof. Dr. Nikolai Lazarov

Internal organs of human body

2

� 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

SPLANCHNOLOGY


Internal organs

3

� 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

SPLANCHNOLOGY

Prof. Dr. Nikolai Lazarov 4

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)

SPLANCHNOLOGY


General structure of parenchymal organs

� 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

5

Parenchyma vs. Stroma

SPLANCHNOLOGY


Digestive system

6

� Digestion:

� mechanical breakdown of food

� chemical breakdown – enzymes

� traveling down of the bolus (peristalsis)

� absorption of the chyme

� elimination of waste material (defecation)

SPLANCHNOLOGY


Digestive system

7

� Digestive system, systema digestorium, apparatus digestorius:

� alimentary canal – length 9 m

�mouth

� anus

� accessory digestive glands:

� salivary glands

� liver

� pancreas

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

SPLANCHNOLOGY


Oral cavity, cavitas oris

9

� Cavitas (cavum) orisGr. 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

� boundarieso gums and teeth

o hard palate

o part of the soft palate

o diaphragma oris

� contento tongue

o teeth

� fauces – the troat

SPLANCHNOLOGY


Lips, labia oris

10

� 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

SPLANCHNOLOGY


Cheeks, buccae

11

� 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

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

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

SPLANCHNOLOGY


Teeth, dentes

14

� 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

SPLANCHNOLOGY


Human dentition

15

� 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

SPLANCHNOLOGY


Human dentition

16

� 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

SPLANCHNOLOGY


Basic tooth structure

17

� 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

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

SPLANCHNOLOGY


Papillae of the tongue

� Papillae linguales – 4 distinct types:

� papillae filiformes (conicae)

� papillae fungiformes

� papillae vallatae

� papillae foliatae

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!

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 papillaegustatory (von Ebner’s) glands

� mucous glands – in the tongue root posterior lingual (Weber) glands

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

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

SPLANCHNOLOGY


Muscles of the tongue� Proper (instrinsic) lingual muscles – alter its shape:

� m. longitudinalis superior

� m. longitudinalis inferior

� m. transversus linguae

� m. verticalis linguae

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)

SPLANCHNOLOGY


Salivary glands� Large salivary glands, glandulae salivariae majores:

� Parotid gland,

glandula parotidea (parotis)

� Submandibular gland,

glandula submandibularis

� Sublingual gland,

glandula submandibularis

SPLANCHNOLOGY


Fauces, fauces

27

� Isthmus faucium

� Fauces:

� velum palatinum – superiorly

� uvula palatina

� palatoglossal arch

� palatopharyngeal arch

SPLANCHNOLOGY


Waldeyer’s tonsillar ring

28

� Anulus lymphoides Waldeyeri:

� lingual tonsil

� pharyngeal (adenoid) tonsil

� tubal tonsil

� palatine tonsil

� NALT – Nasal-Associated Lymphoid Tissue

von Waldeyer(1836-1921)

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

29

SPLANCHNOLOGY


Macroscopic anatomy

� Three general areas:� epipharynx (nasopharynx) � mesopharynx (oropharynx)� hypopharynx (laryngopharynx)

30

SPLANCHNOLOGY


Pars nasalis pharyngissynonyms: nasopharynx, epipharynx

� Part of the respiratory system:

� fornix pharyngis –

tonsilla pharyngealis (adenoidea)

� tonsilla tubaria

31

SPLANCHNOLOGY


synonyms: oropharynx, mesopharynx

Pars oralis pharyngis

32

SPLANCHNOLOGY


Pars laryngea pharyngissynonyms: laryngopharynx,

hypopharynx

33

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

34

SPLANCHNOLOGY


� Straight muscular tube 25-30 cm long:�begins at the level of

cricoid cartilage – C6

�pass through the mediastinum and penetrates the diaphragm– Th10

�meets the stomach – Th11

Gullet, esophagus

35

SPLANCHNOLOGY


Macroscopic anatomy

36

� Anatomical parts:� cervical part – 5-6 cm� thoracic part – 16-19 cm� abdominal part – 1-4 cm

SPLANCHNOLOGY


Anatomical constrictions

37

� Three anatomical constrictions:� pharyngoesophageal – 15 cm from the incisors

� broncho-aortic– 24 cm from the incisor teeth

� phrenic – 40 cm from the incisor teeth

SPLANCHNOLOGY


1. Aortic – at the site of bifurcation with the aortic arch

2. Cardiac – the lower entrance to the stomach

Physiological constrictions� Two physiological constrictions –

due to the muscle contractions of the esophagus

38

SPLANCHNOLOGY


Microscopic structure

� Lamina epithelialis mucosae:

stratified squamous nonkeratinizingepithelium – 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

39

SPLANCHNOLOGY


Stomach, gaster (ventriculus)

40

� 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

SPLANCHNOLOGY


Microscopic structure� 3 histological regions:

� cardiac�pars cardiaca

� fundic� fundus et

� corpus gastricum

�pyloric�pars pylorica

SPLANCHNOLOGY


� gastric mucosa, tunica mucosa� tela submucosa

� muscle layer, tunica muscularis� serosa, tunica serosa

42

Gastric wall

� Three tissue layers:

SPLANCHNOLOGY


� 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

43

Gastric mucosa

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

SPLANCHNOLOGY


� Tunica serosa:� part of peritoneum

Histological structure� Tela submucosa:

� connective tissue withblood and lymph vessels

45

� Tunica muscularis:� inner oblique layer, fibrae obliquae

� middle circular layer (m. sphincter pyloricus)

� outer longitudinal layer (stratum longitudinale)

SPLANCHNOLOGY


Small intestine, intestinum tenue

46

� 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

SPLANCHNOLOGY


� 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

Duodenum in situ

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 (L2)

� The ileum, ileum:

� vertical arrangement of its loops

� located largely toward the lower right

of the intestinal coils

� ends at the ileocecal junction (L4)

SPLANCHNOLOGY


Intestinal wall

� tunica mucosa – spiral ridges� circular folds, plicae circulares

� tela submucosa� tunica muscularis� tunica serosa

� Three major layers:

SPLANCHNOLOGY


Intestinal mucosa� Mucosa, tunica mucosa:

� intestinal villi – cells

� intestinal glands

� duodenal glands

SPLANCHNOLOGY


Large intestine, intestinum crassum

51

� 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

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

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

SPLANCHNOLOGY


Colon wall

� 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)

� Three major layers:

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

SPLANCHNOLOGY


Microscopic anatomy

SPLANCHNOLOGY


Liver, hepar

57

� 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 tractand its associated organs

� 20-30% – hepatic arteries: arterial blood

� > 500 vital functions – production of bile, major role in metabolism

SPLANCHNOLOGY


Gross anatomy

58

� Two surfaces:� superior diaphragmatic

� inferior visceral – porta hepatis

� posterior – bare area

� Hepatic lobes:� right lobe

� left lobe

� quadratus and caudatus lobes

� Hepatic segments

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

59

SPLANCHNOLOGY


Functional units of liver

60

� “classical” lobule –anatomical model

� portal lobule –

bile secretion

� liver acinus –

blood flow and metabolic

SPLANCHNOLOGY


Gallbladder, vesica biliaris (fellea)

61

� hollow pear-shaped organ:� concentrates bile

� aids in fat digestion

� volume: 40-60 cm3

� three sections:� fundus� body, corpus� neck, collum

� cysticduct,ductus cysticus

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

62

SPLANCHNOLOGY


Pancreas � Gr. πάγκρεαςpan “all”, kreas, “flesh”

63

� 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

SPLANCHNOLOGY


Macroscopic anatomy

64

� 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

SPLANCHNOLOGY


Exocrine pancreas, pars exocrina pancreatis

65

� 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

SPLANCHNOLOGY


Endocrine pancreas, pars endocrina pancreatis

66

� 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

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

67

Voltaire

(1694-1778) 68

“The fate of a nation has often depended on food or bad digestion of a prime minister”

Thank you ...

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