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

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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

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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

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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

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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

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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

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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

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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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