Grand tour of alimentary canal Flashcards
What are the 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 Pancreas
Digestive enzymes for digestion of fats, carbs and proteins.
Function of liver
Produce Bile salts for digestion/absorption of fats in small intestine
Function of Gallbladder
Stores and concentrates 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
What are the 4 distinctive layers (tunics) of the Alimentary canal?
Mucosa: epithelium, lamina propria, muscularis mucosae
Submucosa
Muscularis externa
Serosa/adventitia
What type of epithelium mucosa is the mouth, oesophagus and anal canal?
Stratified squamous
What type of epithelium mucosa is the stomach and small & large intestines?
Simple columnar
What does the lamina propria form?
Loose connective tissue (glands, blood/lymph vessels)
What does the Muscularis mucosae form?
Thin smooth muscle layer
What type of tissue supports mucosa?
Thick, irregular connective tissue
What forms the submucosal (Meissner’s) plexus (parasympathetic)?
Neurones
What is serosa/adventitia?
Connective tissue outer layer of alimentary canal
What does Adventitia do outside peritoneal cavity?
It attaches oesophagus and rectum to surrounding structures
What does Serosa do inside peritoneal cavity?
Serosa surrounds stomach, small intestine and large intestine
What is the muscularis externa?
Two concentric thick layers of smooth muscle composed of an inner layer and outer layer
What does the inner and outer layer of the muscularis externa do?
Inner layer = circular muscle (constricts lumen)
Outer layer = longitudinal muscle (shortens tube)
What are the functions of the muscularis externa?
Produce motility and segmental contractions and peristaltic movement in the GI tract
Where is the Myenteric (Auerbach’s) plexus located?
Between the circular (inner) muscle and longitudinal (outer) muscle
What does the Myenteric and Submucosal plexus form?
Enteric nervous system (ENS)
- Independent control of gut function
What directs the autonomic control of alimentary function?
Long (parasympathetic) and short (ENS) reflexes
