The Alimentary Canal Flashcards
What are the 4 basic functions of the digestive system?
Digestion
Secretion
Absorption
Motility
What is the basic order of organs in the alimentary system? (8)
Mouth > Esophagus > Stomach > Pancreas > Liver > Gallbladder > Small intestine > Large intestine
What is the basic function of the mouth? (2)
Breakdown foodstuff (chewing) Lubricate foodstuff (saliva)
What is the basic function of the Oesophagus?
Transport foodstuff between the mouth and stomach
What is the basic function of the Stomach? (4)
Digestion of proteins
Liquidation of foodstuffs
Storage
Sterilisation
What is the basic function of the Pancreas?
To produce digestive enzymes for carbohydrates, fats and proteins
What is the basic function of the Liver?
To produce bile salts for the digestion/absorption of fats in the small intestine
What is the basic function of the Gallbladder?
To store and concentrate bile
What is the basic function of the small intestine?
Provides final stages of chemical digestion and nutrient absorption
What is the basic function of the large intestine? (3)
Water absorption
Fermentation of bacteria
Formation of faeces
What are the 4 distinctive layers of the alimentary canal?
Mucosa
Submucosa
Muscularis externa
Serosa or adventitia
What are the 3 layers of the mucosa? (from innermost to outermost)
Epithelium
Lamina propria
Muscularis musosae
What type of mucosa epithelium is present in the following areas: Mouth, esophagus, anal canal?
Stratified squamous
What type of mucosa epithelium is present in the following areas: Stomach, small & large intestine?
Simple columnar
What are the 3 functions of the mucosa epithelium?
Separate lumen of canal from the body
Abdsorb products of digestion
Synthesise and secrete digestive enzymes, hormones and mucus
What is the Lamina propria made of?
Loose connective tissue
What is the muscularis mucosae made from?
A thin smooth muscle layer
In which layer of the mucoasa could glands and blood/lymph vessels be found?
Lamina propria
What type of tissue is the submucosa made from?
Thick, irregular connective tissue
What is contained within the submucosa? (3)
Neurones
Blood vessels
Lymphatic vessels
What is the name of the neurone network formed in the submucosa and what type of neurone network is it?
Submucosal plexus - parasympathetic network
What additional feature is contained in the submucosa of only the esophagus and duodenum?
Submucosal glands
What are the 2 cocentric thick layers of smooth muscle in the Muscularis Externa?
Circular muscle - inner layer
Longitudinal muscle - outer later
What is the function of the circular muscle in the Muscularis Externa?
To constrict the lumen
What is the function of the longitudinal muscle in the Muscularis Externa?
Shortens the tube
What is the overall function of the the 2 layers of the Muscularis Externa?
To produce motility (peristalsis, segmentation)
What plexus lies between the circular and longitudinal muscle?
Myenteric Plexus
What do the submucosal and myenteric plexuses make up together?
The enteric nervous system (ENS)
What is the funciton of the ENS (enteric nervous system)?
Independent control of gut function
What type of tissue is the serosa/adventitia made from?
Connective tissue
Which layer (serosa or adventitia) attaches outside the peritoneal cavity and what does it do?
Adventitia - attaches oesophagus and rectum to surrounding structures
Which layer (serosa or adventitia) attaches inside the peritoneal cavity and what does it do?
Serosa - surround the stomach, small intestine and large intestine
What are the (a) Long and (b) Short reflexes of the nervous control of alimentary function?
(a) parasympathetic
(b) Enteric Nervous System
Which nerve innervates the parasympathetic control (except salivation) of alimentary function?
Vagus nerve (X)
What effect does the parasympathetic system have on alimentary function? (2)
It stimulates secretion and motility
Which nerve innervates the sympathetic control of alimentary function?
Splanchnic nerve
What effect does the sympathetic system have on alimentary function? (3)
Inhibits secretion and motility
Stimulates salivation
Which 2 nerves innervate parasympathetic salivation in alimentary function?
Facial (VII)
Glossopharyngeal (IX)
What are the 3 main branches of the D.Aorta for the arterial supply of the GI tract?
Celiac trunk
Superior mesenteric artery
Inferior mesenteric artery
What 4 organs does the celiac trunk supply?
Stomach
Small intestine
Pancreas
Liver
What 4 organs does the Superior mesenteric artery supply?
Small intestine
Caecum
Ascending colon
Transverse colon
What 3 organs does the inferior mesenteric artery supply?
Descending colon
Sigmoid colon
Rectum
Which veins does the stomach drain into?
Gastric veins
Which vein does the pancreas drain into?
Splenic vein
Which vein does the small intestine, caecum, ascending colon and transverse colon drain into?
Superior mesenteric vein
Which vein does the rectum, descending colon and sigmoid colon drain into?
Inferior mesenteric vein
Which vein do all the smaller GI veins drain into before going through the hepatic vein into the IVC?
Hepatic portal vein
