Grand Tour of The Alimentary Canal Flashcards
What does the GI tract consist of?
Hollow organs in a long, twisting tube from the mouth to the anus
What organs are the accessory organs of the GI tract?
Salivary Glands
Liver
Pancreas
Gallbladder
What are the main functions of the digestive system?
Digestion
Absorption
Secretion
Motility
Explain Digestion
Breaking down of food we eat into simple substances that out bodies can absorb
What is digestive absorption?
Passage of end products of digestion from gastrointestinal tract into the blood and lymphatic vessels
Explain secretion
Process of which substances are produced and discharged from the cell, gland, or organ for a particular function in the organism or for excretion
Explain motility
Is the ability of an organism to move independently, using metabolic energy
What are the 3 types of salivary glands?
Paroted
Sublingual
Submandibular
Describe the function of the mouth
Foodstuffs are broken down by chewing and saliva is added as lubricant
Describe the function of the oesophagus
Conduit between mouth and stomach
Describe the function of stomach
Digestion of proteins
Foodstuffs reduced to semi-liquid form
Storage
Sterilisation
Describe the function of the pancreas
Digestive enzymes for digestion of fats, carbohydrates and proteins
Describe the function of the liver
Bile salts for digestion/absorption of fats in small intestine
Describe the function of the gallbladder
Stores and concentrates bile
Describe the function of the small intestine
Final stages of chemical digestion and nutrient absorption
Describe the function of the large intestine
Water absorption
Bacterial fermentation
Formation of faeces
Describe the general structure of the alimentary canal
Continuous hollow tube with varying diameter
Usually about 8 metres long
Tube has same structural organisation throughout length
What are the 4 distinctive layers of the alimentary canal?
Mucosa
Submucosa
Muscularis externa
Serosa/ adventitia
What are the sub layers of the mucosa?
Epithelium
Lamina Propria
Muscularis Muscosae
What is the peritoneum?
Is the serous membrane forming the lining of the abdominal cavity
Where are the myenteric plexus and submucosal plexus found?
Myenteric - between circular and longitudinal layer of the muscularis
Submucosal - between circular and submucosa
What type of epithelium is in the GI tract?
Stratified squamous - mouth, oesophagus and anal canal
Simple columnar - stomach, small and large intestine
What are the function of the epithelium in the GI tract?
Barrier separating lumen
Synthesis and secretion of digestive enzymes, hormones and mucus
Absorbs products
Describe the lamina propria
Loose CT - glands, blood and lymph vessels
Describe the muscularis mucosae
Thin smooth muscle layer
What is the submucosa?
Thick irregular CT which supports mucosa - contains neurons, blood vessels and lymph vessels
Glands in oesophagus and duodenum
What is the serosa/ adventitia ?
Connective tissue outer layer of the alimentary canal
Outside peritoneal cavity - adventitia
Inside - serosa
Describe the muscularis externa
Two thick layers of smooth muscle - inner is circular and outer is longitudinal
Produces motility for peristalsis and segmentation
Explain the enteric nervous system
Submucosal and myenteric plexuses which supply independent control of the gut function
Describe the nervous control of the alimentary function
Autonomic - long parasympathetic and short ENS reflexes
Parasympathetic
Sympathetic
Explain parasympathetic nerve control of alimentary function
Vagus nerve (X)
Salvation is facial and glossopharyngeal
Stimulatory function so increases secretion and motility
Explain sympathetic nerve control of the alimentary function
Splanchnic nerve
Inhibitory so decreases secretion and motility
What organs does the celiac trunk supply?
Stomach
Small intestine
Pancreas
Liver
What organs does the superior mesenteric artery supply?
Small intestine
Caecum
Ascending colon
Transverse colon
What organs does the inferior mesenteric artery supply?
Descending colon
Sigmoid colon
Rectum
What vein controls is the venous drainage of stomach?
Gastric veins
What vein controls venous drainage of pancreas?
Splenic veins
What does the superior mesenteric vein drain?
Small intestine
Caecum
Ascending colon
Transverse colon
What does the inferior mesenteric vein drain?
Descending colon
Sigmoid colon
Rectum
Describe the venous drainage from the GI tract
Gastric, Splenic, superior mesenteric and inferior mesenteric veins all drain to hepatic portal vein
Then hepatic vein joining circulation at liver then inferior vena cava
