Functional anatomy of alimentary (digestive) system

Alimentary system is a collection of organs which provide mechanical and chemical digestion of food, absorption of nutrients into blood and lymph and excretion of feces

Alimentary system organs Oral cavity Pharynx Oesophagus Liver Stomach Pancreas Small intestine Large intestine

Parts of small intestine Duodenum Jejunum Ileum

Parts of large intestine Transverse colon Descending colon Ascending colon Sigmoid colon Caecum Rectum

mouth anus

fauces I II III IV V VI

Lingual papillae

Taste sensation of tongue

Parotid gland Sublingual gland Submandibular gland

Parodontium includes: periodontal fibres, jawbone, gum and dental root

Permanent teeth 2.1.2.3 Deciduous teeth 2.1.0.2

Upper right quadrant Upper left quadrant Lower right quadrant Lower left quadrant

Total length of digestive tract is about 10 m Pharynx (12-15 cm) Oesophagus (25-30 cm) Small intestine (6 – 7 m) Large intestine (1,5 – 2 m)

VI cervical vertebra X-XI thoracic vertebra I lumbar vertebra

Epigastrium Mesogastrium Hypogastrium

The digestive organs Hollow Parenchymatous Pharynx; Oesophagus; Stomach; Small intestine; 5.Large intestine 6. Gallbladder Salivary glands; Liver; Pancreas

Other organs Hollow Parenchymatous Urinary bladder; Uterus; Ureter; Deferent duct; 5.Uterine tube Spleen; Lungs; Testes; Prostate Endocrine glands

Structure of hollow organs Serous layer Muscular layer Mucous layer

Structure of hollow organs Mucous layer Muscular layer Serous (or adventitial) layer

Structure of mucosa Lymphatic follicle Epithelium Lamina propria muscularis Submucous layer Glands

Oral mucosa

Gastric mucosa Gastric pits Simple columnar epithelium

Intestinal mucosa Villus Simple columnar epithelium

Mucosa of colon Crypt Simple columnar epithelium

Muscular layer in oesophagus Circular layer Longitudinal layer

Muscular layer in stomach

Muscular layer in small intestine

Muscular layer in large intestine Haustra Taenia

Cardiac (lower oesophageal) sphincter

ileocaecal valve ileocaecal orifice

Visceral peritoneum Parietal peritoneum Retroperitoneal space Greater omentum Mesentery Peritoneal cavity

Relatively to the peritoneum the organs can be divided into: Intraperitoneal Mesoperitoneal Extraperitoneal

Intraperitoneal organs Stomach Spleen Jejunum Ileum 5. Caecum with appendix 6. Transverse colon 7. Sigmoid colon 8. Upper rectum

Mesoperitoneal organs Liver Gallbladder Ascending colon Descending colon 5. Uterus 6. Full urinary bladder 8. Middle rectum

Extraperitoneal organs Pancreas Duodenum Lower rectum 4. Empty urinary bladder 5. Kidneys 6. Suprarenal glands

Structure of hollow organs Serous (or adventitial) layer Muscular layer Mucous layer

Structure of parenchymatous organs - consist of glandular tissue - have no lumen inside The smallest parts of the parenchymatous organs, bounded by connective-tissue frame and surrounded by their own blood stream, are called structural and functional units.

In the liver the structural and functional unit is hepatic lobule

In the pancreas the structural and functional unit is pancreatic acinus

Liver segmentation

I Caudate lobe II Superolateral segment of left lobe III Inferolateral segment of left lobe IV Medial segment of right lobe V Anteroinferior segment of right lobe VI Posteroinferior segment of right lobe VII Posterosuperior segment of right lobe VII Anterosuperior segment of right lobe

Development of digestive system: stage of 20 days

Development of digestive system: stage of 20 days neural tube chorda celom mesoderm ectoderm entoderm

Derivatives of ectoderm enamel 2. salivary glands ectoderm

Derivatives of ectoderm epithelium 2. glands (liver, pancreas) entoderm (primitive gut)

Derivatives of mesoderm splanchnopleura splanchnopleura 1. mucosa 2. submucous layer 3. muscular layer 4. serous layer (visceral peritoneum)

Derivatives of mesoderm somatopleura somatopleura parietal peritoneum

Development of digestive system: stage of 30 days pharynx oesophagus stomodeum stomach yolk stalk allantois liver midgut proctodeum hindgut cloaca

Development of digestive system: stage of 35 days cerebral and neural tubes chorda trachea oesophagus heart stomach liver allantois yolk stalk midgut cloaca coelom (peritoneal cavity) hindgut rectum

Division of the primitive gut into the parts Foregut descending limb Midgut umbilical (yolk) loop Hindgut ascending limb

Division of the primitive gut into the parts Oesophagus, stomach, descending part of duodenum Foregut Small intestine (from descending limb); Caecum,ascending colon, transverse colon (from descending limb) Midgut Descending colon, sigmoid colon rectum Hindgut

Development of mesenteries stomach liver spleen ventral mesentery pancreas dorsal mesentery Falciform ligament Hepatogastric ligament Hepatoduodenal ligament Greater omentum Mesentery of small intestine Sigmoid mesocolon

The twist of gut tube: stage of 5 weeks

I branchial arch the walls of the oral cavity (including maxilla and mandible) lips - masticatory muscles

II branchial arch hyoid bone - mimic muscles