Download Digestive System

Digestive System
Azami PHD
Digestive System Anatomy
• Digestive tract
– Alimentary tract or
canal
– GI tract
• Accessory organs
– Primarily glands
• Regions
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Mouth or oral cavity
Pharynx
Esophagus
Stomach
Small intestine
Large intestine
Anus
Oral Cavity
• Mouth or oral cavity
– Vestibule: Space
between lips or
cheeks and alveolar
processes
– Oral cavity proper
• Lips (labia) and
cheeks
• Palate: Oral cavity
roof
– Hard and soft
• Palatine tonsils
• Tongue: Involved in
speech, taste,
mastication,
swallowing
Salivary Glands
• Produce saliva
– Prevents bacterial
infection
– Lubrication
– Contains salivary
amylase
• Breaks down Starch
• Three pairs
– Parotid: Largest
– Submandibular
– Sublingual: Smallest
Teeth
• Two sets
– Primary, deciduous,
milk: Childhood
– Permanent or
secondary: Adult (32)
• Types
– Incisors, canine,
premolar and molars
Tooth structure:
Pharynx and Esophagus
• Pharynx
– Nasopharynx
– Oropharynx: Transmits
food
– Laryngopharynx:
Transmits food
• Esophagus
– Transports food from
pharynx to stomach
– Passes through
esophageal hiatus
(opening) of diaphragm
and ends at stomach
(Swallowing)
• Three phases
– Voluntary
– Pharyngeal
• Reflex
– Esophageal
• Reflex
Digestive Tract Histology
Digestive System Regulation
• Nervous regulation
– Involves enteric nervous
system
• Types of neurons:
sensory, motor,
interneurons
– Coordinates peristalsis
and regulates local
reflexes
• Chemical regulation
– Production of hormones
– Production of paracrine
chemicals
Digestive Tract Anatomy
serous membranes
Peritoneum
• Peritoneum
– Visceral: Covers organs
– Parietal: Covers interior
Retroperitoneal
surface of body wall
– Retroperitoneal:
Behind peritoneum as
kidneys, pancreas,
duodenum
• Mesenteries
– Routes which vessels
and nerves pass from
body wall to organs
Mesenteries
• Mesenteries
– Routes which vessels
and nerves pass from
body wall to organs
Mesenteries
Mesenteries
Lesser omentum from ventral mesentery
Lesser omentum from ventral mesentery
greater omentum from dorsal mesentery
greater omentum from dorsal mesentery
greater omentum
Greater sac
Lesser sac
Stomach Anatomy
• Openings
– Gastroesophageal
: To esophagus
– Pyloric: To
duodenum
• Regions
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Cardiac
Fundus
Body
Pyloric
Stomach Histology:
• Layers
– Serosa or visceral
peritoneum:
Outermost
– Muscularis: Three
layers
• Outer longitudinal
• Middle circular
• Inner oblique
– Submucosa
– Mucosa
Stomach Histology
• Rugae: Folds in
stomach when empty
• Gastric pits: Openings
for gastric glands
– Contain cells
Small Intestine anatomy and
Histology
• Site of greatest amount of
digestion and absorption
• Divisions
– Duodenum
– Jejunum
– Ileum: Peyer’s patches or
lymph nodules
• Modifications
– Circular folds or plicae
circulares, villi, microvilli
• Cells of mucosa
– Absorptive, goblet, granular,
endocrine
Small Intestine Secretions
• Mucus
– Protects against digestive enzymes and stomach acids
• Digestive enzymes
– Disaccharidases: Break down disaccharides to
monosaccharides
– Peptidases: Hydrolyze peptide bonds
– Nucleases: Break down nucleic acids
• Duodenal glands
– Stimulated by vagus nerve, secretin
secretin increases water and bicarbonate secretion
from duodenal (Brunner's) glands
Duodenum