Lecture 3 Grand Tour of the Alimentary Canal Flashcards
Functions of the digestive system
Digestion
Secretion
Absorption
Motility
Function of the mouth
Foodstuffs broken down by chewing; saliva added as lubricant
Function of oesophagus
Conduit between mouth and stomach
Function of stomach
Digestion of proteins; foodstuffs reduced to liquid form; storage and sterilisation
Function of Liver
Bile salts for digestion/absorption of fats in small intestine
Function of gallbladder
Stores and concentrate bile
Function of Small intestine
Final stages of chemical digestion and nutrient absorption
Function of large intestine
Water absorption, bacterial fermentation and formation of faeces
Length of oesophagus to rectum
8meteres
Four distinct layers of alimentary canal
Mucosa
Submucosa
Muscularis externa
Serosa/adventitia
Layers of mucosa
Epithelium
Lamina propria
Muscularis mucosa
What does the submucosa contan
Blood and nerve supply
Submucosa plexus
Function and structure of muscularis externa
Motility
2 concentric layers
Innermost is circular (contracts and narrows)
Outermost os longitudinal (contracts and elongates0
Whats sits between muscle layers of muscularis externa
Myenteric plexus
What is the serosa/adventitia layer
Connective tissue covering
Epithelium in mouth, oesophagus and anal canal
Stratifies squamous
Epithelia in stomach, small & large intestine
Simple columnar
The submucosa contain =s what network neurones
Submucosal (Meissner’s) plexus which is parasympathetic
Submucosal glands are located where
Oesophagus and duodenum
Outside of peritoneum where does the adventitia attach to
oesophagus and rectum
Inside the peritoneum where does the serosa attach to
stomach, small intestine and large intestine
Whats the name of the plexus between the circular muscle and longitudinal muscle in the muscularis externa
Myenteric (Auerbach’s) plexus
What movements do the muscularis externa control
Segmentation and peristalsis
Autonomic control of the alimentary system
Long (parasympathetic) and short ENS reflexes
Parasympathetic nerve and function
Vagus nerve (X) except salivation
Facial (VII) and glossopharyngeal (IX)
Stimulatory: increases secretion and motility
Sympathetic nerve
Splanchnic nerve
Inhibitory except for salivation
Decrease secretion and motility
Venous drainage of stomach
Gastric veins
Venous drainage of pancreas
Splenic vein
Venous drainage of midgut
Superior mesenteric vein
Venous drainage of hind gut
Inferior mesenteric vein
Where do the veins of the GI tract eventually drain into
Hepatic portal vein
Hepatic vein
IVC
