Tour of Alimentary Canal Flashcards
Which two tracts make up the digestive system?
Alimentary tract
GI tract
Which accessory organs make up the digestive system?
Salivary glands
Pancreas
Liver
Gallbladder
Where does the GI tract start and end?
Start- mouth
End- anus
Describe the pathway through the body of the GI tract.
Mouth, oesophagus, stomach, small intestine, large intestine, anus.
What are the four main functions of the digestive system?
Digestion
Secretion
Absorption
Motility
What is meant by digestion?
Breaking down of food into substances which our bodies can absorb.
What is meant by digestive absorption?
The passage of the end products of digestion from the GI tract into the blood and lymphatics.
Which processes can absorption be carried out by?
Active transport or diffusion
What is meant by secretion?
Process by which substances are produced and removed by a cell, gland or organ, either to have a function or to be excreted
Define motility.
The ability of an organism to move independently
Which type of energy does motility require?
Metabolic energy
Describe what happens in the mouth in digestive system.
Food broken down by chewing and saliva added as lubricant
How does the food travel between the mouth and the stomach?
The oesophagus
Describe what happens in the stomach in the digestive system.
Digestion of proteins
Storage
Sterilisation
What role does the pancreas have in digestion?
Produces digestive enzymes for the digestion of fats, carbs and proteins
What role does the liver have in digestion?
Produces bile salts for the digestion/absorption of fats in the small intestine.
What is the role of the gallbladder?
Stores and concentrates bile.
What happens in the small intestine during digestion?
Final stages of nutrient absorption and chemical digestion.
What happens in the large intestine during digestion?
Water absorption
Bacterial fermentation
Formation of faeces
Briefly describe the structure of the alimentary canal.
Continuous hollow tube, varying in diameter.
How long in the alimentary canal approx?
8 meters
Name the four distinct layers (tunics) of the alimentary canal.
Mucosa
Submucosa
Muscularis externa
Adventitia/serosa
Name the three types of mucosa found in the alimentary canal.
Epithelium
Lamina propria
Muscularis muscosae
What forms the lining of the abdominal cavity?
Peritoneum, a type of serous membrane
When is the connective tissue layer known as adventitia?
When it is found outside the peritoneal cavity
When is the connective tissue layer known as serosa?
When it is found inside the peritoneal cavity
Name the two layers of the muscularis externa.
Circular muscle layer
Longitudal muscle layer
Where in the digestive system would you find stratified squamous epithelium?
Mouth, oesophagus, anal canal.
->these parts of the system tend to have bulkier products in them so more than one layer of epithelium is required to protect from friction :)
Where in the digestive system would you find simple columnar epithelium?
Stomach
Small intestine
Large intestine
-> the columnar epithelium has cilia which helps with movement through the intestines :)
What type of tissue makes up the lamina propria?
Loose connective tissue
Which other features does the lamina propria contain?
Glands
Blood/lymph vessels
Which type of muscle makes up the Muscularis mucosae layer?
Smooth muscle
Which layer of the alimentary canal has a nerve and blood supply?
Submucosa
Name the nerve plexus which is found between the circular and longitudal layers of the muscularis.
Myenteric plexus
Name the nerve plexus found between the submucusal layer and the circular muscularis.
Submucosal plexus
What is the main function of the epithelium in the mucosa?
Acts as a barrier which separates the lumen of the alimentary canal from the body.
Mucosa also has a role in the synthesis and secretion of what?
Digestive enzymes
Hormones
Mucus
Why do the intestines and stomach have simple columnar epithelium?
Helps with absorption of food
Has thick layers to protect from digestive juices.
What type of tissue makes up the submucosa?
Irregular CT
Where in the body would you find submucosal glands?
Oesophagus
Duodenum
Are the nerves in the submucosal plexus sympathetic or parasympathetic?
Parasympathetic
What does the circular layer of the muscularis do to the lumen of the alimentary canal?
Constricts it
What does the longitudal layer of the muscularis do to the lumen of the alimentary canal?
Shortens it
What does the constriction and shortening of the lumen of the alimentary canal allow for?
Motility
Describe the difference between segmentation and peristalsis.
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Which plexuses make up the enteric nervous system?
Myenteric plexus
Submucosal plexus
Which nerve provides most of the parasympathetic innervation to the alimentary tract?
Vagus nerve
Which never provides most of the sympathetic innervation to the alimentary tract?
Splanctic nerve
Which two nerves provide parasympathetic innervation for the process of salivation?
Facial nerve
Glossopharyngeal nerve
What effect does parasympathetic innervation have on the alimentary function?
Increases secretion and motility
Does the parasympathetic innervation have a inhibitory or stimulating effect on the alimentary system?
Stimulating
Does the sympathetic innervation have a inhibitory or stimulating effect on the alimentary system?
Inhibitory- except for salivation
What effect does sympathetic innervation have on the alimentary function?
Decreases motility and secretion
After eating, which type of innervation will be working harder?
Parasympathetic
->this is why you have to wait between eating and exercising, you are too relaxed and if running, you need to sympathetic NS to be working more effectively :)
What supplies the blood to the GIT?
Descending abdominal aorta
Name the three branches coming off the descending abdominal aorta
Superior mesenteric artery
Inferior mesenteric artery
Celiac trunk
Where will the celiac trunk supply blood to?
Stomach
Small intestine
Pancreas
Liver
Where will the superior mesenteric artery supply blood to?
Small intestine
Caecum
Ascending colon
Transverse colon
Where will the inferior mesenteric artery supply blood to?
Descending colon
Sigmoid colon
Rectum
What is the venous draining for the stomach via?
Gastric veins
What is the venous draining for the pancreas via?
Splenic vein
What is the venous draining for the descending colon, sigmoid colon
and rectum via?
Inferior mesenteric vein
What is the venous draining for the small intestine
caecum, ascending colon, transverse colon via?
Superior mesenteric vein
What do the gastric veins, splenic veins, inferior mesenteric veins and the superior mesenteric veins all form together?
Hepatic portal vein
What does the hepatic portal vein do?
Carries all the blood from the GIT to the liver
After the blood has left the liver, which veins takes it and where?
Hepatic vein takes it to inferior vena cava
