Gastro-intestinal System Flashcards
What does the gastro-intestinal system do?
Digests food and absorbs nutrients. Extorted waste. Supported by accessory organs that contribute to digestion.
What order does food pass through the gastro-intestinal (digestive system)?
1) oral cavity
2) pharynx
3) oesophagus
4) stomach
5)small intestine
6) large intestine
7) rectum
8) anus
How long is the gastrointestinal system and what is its structure?
8m long , muscular tube - passes through thoracic and abdominopelvic cavities
The Gi tract is a long muscular tube from the mouth the anus. It contains 4 layers, what are these 4 layers from deep-superficial?
Deepest:
Mucosa
Submucosa
Muscularis externa (muscular layer )
Adventitita (serosa (serous later)
What is mucosa?
Moist inner lining of GI system and , some organs and body cavities. Surface epithelium has underlying connective tissue and small amount of smooth muscle.
Some regions = folded with projections that extend into lumen ; this increases absorption surface.
Within Lamina Propria (connective tissue in middle of mucosa) = Mucosa-Associated Lymphoid Tissue (MALT)
What is submucosa?
Loose, connective tissue.
Contains= glands, blood vessels, lymphatic vessels and nerves.
Nourishes surrounding tissues and carry’s away absorbed material.
Muscularis Propria (muscular layer)
Circular fibres on inner coat cause contraction
Longitudinal fibres run length way causing shortening
Adventitia (serous layer)
Superficial layer
Visceral peritoneum on the outside, connective tissue beneath
Protects underlying tissues and secretes serous fluid
What are mesentery folds
Fan shaped Folds of the peritoneum that binds
SMALL INTESTINE -> POSTERIOR ABDOMINAL WALL
What are mesocolon
Fold in peritoneum that binds LARGE INTESTINE -> POSTERIOR WALL
Carries blood and lymphatic vessels to the intestines.
What is the peritoneum
Largest serous membrane of the body.
Parietal peritoneum line wall of abdominopelvic cavity
Visceral peritoneum covers organs in the cavity and is serosa .
How does the nervous system control GI tract ?
Enteric nervous system - contains around 100 million neurons.
Motor neurons control motility and secretion by epithelial cells
Sensory neurons contain chemoreceptors and stretch receptors
How does the autonomic nervous system control the nervous system?
Parasympathetic stimulation via the vagus nerve INCREASES GI secretion and motility.
Sympathetic stimulation DECREASES GI secretion and motility.
What are the 3 stages of swallowing?
1) Voluntary - bonus passed to oropharnyx
2) pharyngeal - involuntary passage through pharynx to oesophagus
3) oesophageal - involuntary passage through oesophagus to stomach ; peristalsis pushes bolus forward.
What is deglutition
The act of swallowing
Stomach
Higher portion = fundus
Cardia
Body
Lower portion = pylorus
It is a muscular bag with a capacity of 1.5L , serves as a mixing chamber and holding reservoir.
