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Introduction to splanchnology
1. General organization of the internal organs
structure of hollow organs
structure of parenchymal organs
2. Methods of investigation in splanchnology
3. Digestive system –
overview and embryonic development
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
Prof. Dr. Nikolai Lazarov
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:
in the lower part of the
abdominal cavity
and in the pelvis
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov
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
4
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 5
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
Prof. Dr. Nikolai Lazarov
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
6
Parenchyma vs. Stroma
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 7
Methods of investigation in splanchnology
HIC MORTUI VIVOS DOCENT
dissection –
macroscopic anatomy
microscopic anatomy –
histological structure
injection-corrosion casting technique
plastination
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 8
Methods of investigation in splanchnology
Imaging anatomy:
conventional radiography
computed tomography (CT)
magnetic resonance imaging
(MRI)
ultrasound technique
(sonography)
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov
Digestive system
9
Digestion:
mechanical breakdown of food
chemical breakdown – enzymes
traveling down of the bolus (peristalsis)
absorption of the chyme
elimination of waste material (defecation)
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov
Digestive system
10
Digestive system,
systema digestorium, apparatus digestorius:
alimentary canal – length 9 m
mouth
anus
accessory digestive
glands:
salivary glands
liver, incl. gallbladder
pancreas
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 11
Alimentary canal
Anterior part:
mouth (oral cavity)
pharynx
esophagus
Middle part – GI tract:
stomach
small intestine
Posterior (terminal) part:
large intestine,
incl. rectum and anus
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov
Embryonic development of the digestive system
12
Embryogenesis:
molecular regulation – homeobox genes
Embryonic origin:
endoderm
epithelium and associated glands
mesenchyme
connective tissue formations
smooth musculature
blood and lymph vessels
lymph follicles
ectoderm
nerve structures
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 13
Primary gut tube: foregut
posterior part of oral cavityo thyroid gland
pharynxo parathyroid glands
o thymus
esophagus
stomach
upper part of duodenumo liver and pancreas
horizontal part of duodenum
midgut small and part of large intestine
proximal ⅔ of the transverse colon
hindgut lateral ⅓ of the transverse colon
descending, sigmoid colon and rectum
Embryonic development of the digestive system
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 14
Embryonic development of the digestive system
Pharyngeal arches – 4th-5th weeks of gestation: mesenchyme –
paraxial and lateral mesoderm
skin ectoderm
endoderm
Derivatives of pharyngeal arches:
SPLANCHNOLOGY
Prof. Dr. Nikolai Lazarov 15
Pharyngeal clefts – derivatives
Pharyngeal pouches – derivatives
Embryonic development of the digestive system
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