The GI Tract Flashcards
Which 2 oral cavity muscles are innervated by the hypoglossal nerve
Geniohyoid
Thryohyoid
Which muscle of the oral cavity is innervated by the facial nerve
Digastric posterior belly
Which 6 muscles of the oral cavity are innervated by the meningeal trigeminal nerve
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid
Digastric anterior belly
Mylohyoid
Which 3 muscles of the oral cavity are innervated by the C1-C3
Omohyoid
Sternohyoid
Sternothyroid
What is the parotid gland parasympathetically innervated by
Auriculotemporal branch of glossopharyngeal nerve
What is the parotid gland sympathetically innervated by
Sympathetic plexus of the external carotid artery
What are the submandibular and sublingual glands parasympathetically innervated by
Facial nerve and chorda tympani via the lingual branch of CN V3
What are the submandibular and sublingual glands sympathetically innervated by
Carotid sympathetic plexus running in the walls of submental and or sublingual arteries
What are the 3 parts which the pharynx can be categorised into
Nasopharynx
Oropharynx
Laryngopharynx
What is the nasopharynx
Continuous with the nasal cavity, humidifies and warms inspired air, contains adenoid tonsils
What is the oropharynx
Between soft palate and superior border of epiglottis
Contains posterior 1/3 of tongue and palatine and lingual tonsils and superior constrictor muscles
What is the laryngopharynx
Between superior border of epiglottis and inferior border of cricoid cartilage
Contains the middle and inferior constrictor muscles
What are the 3 pairs of longitudinal muscles in the pharynx
Salpingopharyngeus
Palatopharyngeus
Stylopharyngeus
What are the 3 constrictor muscles of the pharynx
Superior constrictor
Middle constrictor
Inferior constrictor
What do the 3 pairs of longitudinal muscles of the pharynx do
Shorten and widen the pharynx and elevate the larynx during swallowing
What is the motor innervation for all the pharynx muscles expect the stylopharyngeus
Vagus nerve
What is the motor innervation for the stylopharyngeus
Glossopharyngeal nerve
What is peristalsis
The wavelike contractions of circular and longitudinal muscle in the oesophagus to move the food
How does the oesophagus enter the abdomen
Through the oesophageal hiatus
In the first third of the oesophagus what are the muscle layers
Striated skeletal muscle and under voluntary control
In the final third of the oesophagus what are the muscle layers
Smooth muscle and involuntary
What is the origin of the upper part of the oesophagus
Nucleus ambiguus
What is the origin of the lower part of the oesophagus
Dorsal motor nucleus
What nerves supply the muscles in the oesophagus
Via the vagal trunks and oesophageal plexus
What is the pharyngo oesophageal junction contracted by
The sling of the cricopharyngeus muscle which creates an anatomical sphincter to reduce casual entry of air
What prevents the reflux of acidic stomach contents into the oesophagus
The physiological sphincter at the gastro oesophageal junction
What is the epithelium of the oesophageal mucosa
Non keratinised stratified squamous
What are the 4 divisions of the stomach
Cardia
Fundus
Body
Pylorus
What is the cardia
Surrounds superior opening of stomach
What is the fundus
Rounded portion superior and left of cardia often gas filled in stomach
What is the pylorus
Connecting stomach to duodenum divided into antrum, canal and sphincter
What are the 3 sections that the pylorus is split into
Antrum
Canal
Sphincter
How much ingested food does the stomach accumulate
2-3L
What arteries supply the lateral stomach
Left and right gastro one tall arteries and short gastric arteries which follow the greater curvature
What is the third inner muscle of the stomach
Oblique muscle layer
What does the oblique muscle layer in the stomach do
Churns converting food to semi liquid chyme
What are the 4 cells within the glands of the stomach
Foveolar cells
Parietal (oxyntic) cells
Chief (zymogenic) cells
Scattered enteroendocrine cells
What do foveolar cells do
At the entrance secrete protective mucus to prevent acid damage
What do parietal (oxyntic) cells do
Secrete hydrochloric acid and gastric intrinsic factor
What do chief (zymogenic) cells do
Secrete pepsinogen and gastric lipase
What do scattered enteroendocrine cells do
Usually located at the base of the gastric glands and secrete a number of hormones
What is the pH level in the mouth
5-7
What is the pH level in the stomach
1-3
What is the pH level in the colon
5-7
What is the pH level in the small intestine
6-7.5
What are the 4 section of the duodenum
1st superior
2nd descending
3rd inferior
4th ascending
How is the superior part of the duodenum connected to the liver
By hepatoduodenal ligament containing the portal triad
What does the descending part of the duodenum do
Openings at which pancreatic and bile secretions enter
How does the ascending part of the duodenum join the jejunum
At the duodenojejunal flexure
What is brunners glands
Tubular submucosal glands found above the hepatopancreatic sphincter
Produce mucus rich, alkaline secretion which coats and protects the duodenum from acidic chyme
What is happens in Crohn’s disease
Inflammatory bowel disease results in blunting of the villi and is also associated with inflammation and ulceration
Where are villi and micro villi found in the GI tract
Duodenum
What does the liver secrete
400-800 ml of bile per day
What does bile do
Neutralise the acidic chyme as it leaves the stomach
Emulsify lipids into micelles allowing pancreatic lipase to digest lipids within the small intestine
How does bile enter the duodenum
Gall bladder contracts and the hepatopancreatic sphincter relaxes
What 2 ducts does the pancreas have
Main pancreatic duct
Accessory duct
What 7 enzyme precursors does the pancreas acinar cells secrete
Trypsinogen
Chymotrypsinogen
Elastase
Carboxypeptidase
Lipase
Nuclease
Amylase
What do the cells lining the ducts in the pancreas secrete
Sodium hydrogen carbonate to neutralise acidic gastric contents
Where is the jejumun found
Upper left quadrant
Where is the ileum found
Lower right quadrant
What is the intestinal wall of the jejumun
Thick
What is the intestinal wall of the ileum
Thin
What is the vasa recta of the jejunum
Longer
what is the vasa recta of the ileum
Shorter
What are the arcades of the jejunum
Fewer
what are the arcades of the ileum
More
What is the colour of the jejunum
Reddish
What is the colour of the ileum
Pinkish
What veins drain the jejunum and ileum
Superior mesenteric vein, which joins with the splenic vein to form the hepatic portal vein draining to the liver
What are plicae circulares
The mucosa of the small intestine is ridged into circular folds known as this
Where do peyers patches lie
Within the lamina propria and submucosa
What are peyers patches
About 100 aggregations of lymphocytes in the distal jejunum and ileum that can deploy in a rapid immune response against any absorbed pathogens
What are interstitial cells of caial
Pacemakers for peristaltic action of the gut and sit in the myenteric and submucosal plexuses
What does the vagal nerve help do in the GI tract
Control oesophageal propulsion, gastric acid secretion and emptying, gallbladder contraction, pancreatic exocrine secretions
What does the large intestine retrieve
H20
Na+
Vitamins
What does the large intestine secrete
Large amounts of mucus and some hormones
What is the epithelium of the large intestine
Columnar absorptive cells with striated border many goblet cells, endocrine cells and basal stem cells
Where does the foregut run
From the abdominal oesophagus to just below the major duodenal papilla
Where does the midgut run
2/3rds along the transverse colon
Where does the hindgut run
To the upper part of the anal canal
What is the peritoneum
A thin secretory membrane lining the potential cavity of the abdomen and pelvis
Simple squamous mesothelium
What is parietal peritoneum
Where the membrane is in direct contact with the cavity walls
What is visceral peritoneum
When the membrane is directly covering an organ
What is intraperitoneal
When an organ is entirely enclosed in visceral peritoneum and the double layered sheet of peritoneum suspending the organ is a mesentery
What is retroperitoneal
An organ pressed against the abdominal wall by peritoneal membrane
Which organs are retroperitoneal in the GI tract
Duodenum
Pancreas
Ascending and descending colon
Rectum
