Grand Tour of Alimentary Canal Flashcards
4 Functions of the digestive system
Digestion
Secretion
Absorption
Motility
Names of the 3 pairs of Salivary Glands
- Parotid salivary gland
- Sublingual salivary gland
- Submandibular salivary gland
Role of mouth in digestive system
Breakdown food by chewing
Add saliva as lubricant
Does food move passively down oesophagus?
Nah, peristalsis is a wavelike contraction of muscle in the oesophagus that can actively move food against gravity
Role of stomach in digestive system
Digestion of proteins Reduce foodstuffs to liquid Sterilization Storage (convenience) Production of intrinsic factor
Role of liver in digestive system
Produce bile salts for lipid digestion
Absorb fats from blood
Role of gallbladder in digestive system
Store and concentrate bile
Role of small intestine in digestive system
Chemical digestion and nutrient absorption
Role of large intestine in digestive system
Water absorption
Bacterial fermentation and formation of faeces
How does the stomach prevent dumping syndrome?
Dumping syndrome is movement of nutrients into small intestine too quickly (can be painful). Stomach can store food and allow for controlled release into intestine
Approximate distance from oesophagus to rectum?
8m
The alimentary canal has the same general structural organization throughout, what are the 4 distinct layers of the tube?
Mucosa
Submucosa
Muscularis externa
Serosa/adventitia
3 layers of the mucosa?
Epithelium Lamina propria (loose CT - mostly unspecialized, some immune cells/lymph nodules) Muscularis mucosae (thin SM - support)
How does the mucosal epithelium differ along the digestive tract?
Mouth, oesophagus and anal canal - stratified squamous
Stomach, small and large intestine - simple columnar
Functions of mucosal epithelium in the digestive tract?
Barrier separating lumen of alimentary canal from body
Synthesis and secretion of - digestive enzymes, hormones and mucus
Absorb products of digestion
Function & structure of submucosa?
Thick, irregular CT to support mucosa
Contains nerves, blood and lymph vessels, main supply for serosa and muscularis externa
Submucosal glands in the oesophagus and duodenum
Arrangement of neurones in submucosa?
Form an extensive network, the submucosal (Meissner’s) plexus (parasympathetic)
Structure & function of serosa/adventitia?
Protective CT layer around the canal
Difference between serosa and adventitia?
serosa is inside the peritoneal cavity, adventitia is outside of it and connects to surrounding structures
Describe layers of the muscularis externa
Inner layer - circular fibre orientation, constrict the lumen
Outer - longitudinal fibres, shortens the cana
Work to produce motility - peristalsis & segmentation
Nervous system that allows for independent gut function and its constituents
Enteric Nervous System (ENS) - part of ANS
Myenteric plexus between layers of muscularis externa + submucosal (Meissner’s) plexus
Nerves and action of parasympathetic system on alimentary function
Mostly via vagus nerve
(except salivation - facial (VII) and glossopharyngeal (IX)
Stimulatory action - increase secretion and motility
Nerves and action of sympathetic system on alimentary function
Via splanchnic nerves
Inhibitory action - except for salivation
Parts of GI tract supplied by celiac trunk
Stomach
Small intestine
Pancreas
Liver
Parts of GI tract supplied by superior mesenteric artery
Small intestine
Caecum
Ascending colon
Transverse colon
Parts of GI tract supplied by inferior mesenteric artery
Descending colon
Sigmoid colon
Rectum
Venous drainage of stomach and pancreas?
Stomach - gastric veins
Pancreas - splenic vein
Describe venous drainage of the rest of the GI tract (not stomach & pancreas)
Superior mesenteric vein drains what it’s corresponding artery supplies, same goes for inferior mes v.
Inferior mesenteric then drains to splenic, splenic and superior mes. drain to hepatic portal vein
Hepatic portal - hepatic - IVC
