Anatomy of the Gastrointestinal Tract (GIT)
The Gastrointestinal Tract (GIT) is a continuous tube that runs from the mouth to the anus, responsible for digestion, absorption, and excretion.
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🧠Main Sections of the GIT:
1. Mouth (Oral Cavity)
Functions: Ingestion, chewing (mastication), and mixing with saliva.
Structures: Tongue, teeth, salivary glands.
2. Pharynx
A muscular tube connecting the mouth to the esophagus.
Function: Swallowing (deglutition).
3. Esophagus
A muscular tube (~25 cm) that connects the pharynx to the stomach.
Function: Transports food using peristalsis.
4. Stomach
Regions: Cardia, fundus, body, pylorus.
Function: Secretes acid and enzymes; starts protein digestion.
5. Small Intestine
Divided into:
Duodenum: Receives bile and pancreatic juice.
Jejunum: Main site of nutrient absorption.
Ileum: Absorbs vitamin B12, bile salts.
6. Large Intestine
Parts: Cecum, colon (ascending, transverse, descending, sigmoid), rectum, anus.
Function: Absorbs water and electrolytes, forms feces.
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🧫 Accessory Organs (not part of GIT but essential):
Liver: Produces bile to help digest fats.
Gallbladder: Stores and releases bile.
Pancreas: Produces digestive enzymes and bicarbonate.
📊 Wall Layers of the GIT (from inner to outer):
1. Mucosa – Secretes mucus and enzymes; absorbs nutrients.
2. Submucosa – Contains blood vessels and nerves.
3. Muscularis externa – Responsible for peristalsis (2 muscle layers).
4. Serosa (or Adventitia) – Outer protective layer.
🧠Nerve Supply:
Enteric Nervous System (ENS): Controls local GIT activity.
Autonomic Nervous System (ANS)
Parasympathetic (vagus nerve): Stimulates digestion.
Sympathetic: Inhibits digestion.
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