Flashcards in Vera Vomits Blood Deck (97):
What does the gastroduodenal artery divide into?
Right gastroepiploic and superior pancreaticoduodenal
What is a peptic ulcer?
A chronic lesion in the GI tract usually in stomach or duodenum
Which cells secrete saliva?
What organs is the spleen related to?
The splenic flexture of the colon at its left pole, stomach left kidney and tail of pancreas on visceral surface
Where is pain from the stomach referred to?
Epigastric region via T6-9 dermatomes
Which cells secrete gastrin?
G cells in gastric pits
What are Peyer's patches?
Lymphoid nodules in the ileum that facilitate immune surveillance and response in mucosa
How is gut formed in embryo?
When proximal part of yolk sac gets trapped by infolding of trilaminar disc
How does H. pylori protect itself from the acid of the stomach/ duodenum?
Secreting a urease enzyme that converts urea into ammonia and co2, the ammonia buffers the HCL
What does the common hepatic artery divide into?
Proper hepatic artery and gastro duodenal artery
What are Brunner's glands?
Glands of the duodenum which secrete an alkaline mucus
How does the spleen lie in relation to the stomach?
Laterally to the left and above
How is somastatin release triggered and what does it do?
Released due to negative feedback mechanisms, stimulated due to acid presence in lumen of duodenum. Prevents G cells releasing any more gastrin so prevents more HCL release
What are villi?
Long protrusions into lumen that increase surface area and are richly vascularised as well as containing lymphatic lacteals to take away fat molecules too large to travel freely. This makes them ideal for reabsorption
What are the plexuses of the enteric nervous system and what do they control?
Messiner's plexus - Muscularis mucosae
Auerbach's plexus - Muscularis externa
What is the pylori sphincter formed of?
A thickening of the circular smooth muscle coat
Where does the splenic artery give branches to?
Spleen, upper border of pancreas, short gastric and left gastroepiploic to stomach
Where do left and right gastroepiploic arteries anastomose?
Greater curvature of stomach
What is the parasympathetic innervation of the hindgut and where does it originate?
Pelvic splanchnic nerves from S2-S4 via inferior hypogastric plexus
What do H2 blockers do?
Reduce acid secretion by blocking histamine receptors on parietal cells. Can slow metabolism of drugs like warfarin
Which receptors are on parietal cells and are stimulated to cause HCL secretion?
Where does the coeliac trunk originate?
Level of T12
How do left kidney and left adrenal gland in relation to the stomach?
Laterally to the left
What is the muscularis externa?
A powerful muscular layer containing an inner oblique layer, a thick circular middle layer and a thick longitudinal coat of smooth muscle.
What is the vitelline duct?
The connection between proximal and distal parts of the yolk sac
Where is the most vigorous peristalsis of the GI tract?
The pyloric antrum and pyloric canal
What does parasympathetic stimulation of the salivary glands cause?
Increased blood flow resulting in increased saliva secretion across fenestrated epithelium into glands
What activates pancreatic enzymes?
The acidic environment of the lumen
What does bismuth chelate do?
Enhances mucosal protection of ulcer and coats it, stimulating mucus secretion, prostaglandins and HCO3-
What is intrinsic factor?
A glycoprotein produced by parietal cells which is necessary for vitamin B12 absorption
Where does midgut get it's blood supply from?
Superior mesenteric artery
What are the main branches of the coeliac artery?
Left gastric, common hepatic and splenic arteries
Describe GI smooth muscle in terms of junctions and units
A single visceral muscle with gap junctions that couple cells so acts as a single unit
What does lamina properia contain?
Loose connective tissue
What is the migrating motor complex?
Housekeeping of current motor activity that propagates through GI tract between meals to remove residual undigested material
What is melaena?
Black blood containing stools
Which structures are derived from midgut?
Distal duodenum, jejunum, ileum, caecum and appendix, ascending colon, proximal 2/3 of transverse colon
Which cells reside in the base of gastric pits and what do they secrete?
Chief cells, secrete pepsinogen- the inactive form of pepsin
What does gastric inhibitory peptide do?
Inhibits gastric contractions
Why are combinations of antacids used instead of a single salt?
The Mg containing salts cause diarrhoea and the Ca or Al containing salts cause constipation so the different combinations offset this
What comes from endoderm?
Gut, lungs, liver and heptobiilary system
Where is there an adventitia layer?
In parts of the tract which are embedded in others
What does secretin do?
Stimulates HCO3- secretion and inhibits stomach activity
Where does the hepatic portal vein lie in relation to the stomach?
Behind the pyloric region of the stomach
What is misoprostil?
Drug taken with NSAIDs to reduce negative affect on prostaglandins and mucosa. Cause diahorrea and cramps
What does omezoprole do?
It is a proton pump inhibitor. It blocks H+K+ATPase (only at pH 3 or lower) and prevents HCL secretion
What does the Muscularis externa control?
Peristalsis of gut contents
Where is the stomach located approximately?
In the left upper quadrant of the abdomen, occupying parts of epigastric, umbilical and left hypochondriac regions
What is sucrafate?
Used for stress ulcers and H pylori, ve+ sulphated sucrose binds to HCL forming a viscous adhesive which binds to ve+ groups in ulcer crater. Buffers acid and stimulates mucus, prostaglandins and HCO3- secretion
What are short and long reflexes in the GI system due to?
Long: autonomic nervous activity
Short: enteric nervous activity
What is haematemesis?
Why is omezoprole irreversible?
It forms disulphide bridges with H+/K+ATPase
What acts as a sphincter for the oesophagus?
An area of distinct muscle around the oesophagus as well as the muscular fibres of the diaphragm, particularly the right crus, and the angulation in which the oesophagus enters the cardia creates a functioning flap valve prventing reflux
What is in a gastric pit?
Gastric glands which secrete gastric juice (HCL pepsinogen and mucus)
What does the proper hepatic artery divide into?
Left and right proper hepatic arteries with right usually giving rise to cystic artery
How do left and right vagi become anterior and posterior to the stomach?
The oesophageal plexus involved branches of both right and left vagi, the main parts of these nerves become twisted around the oesophagus as anterior and posterior vagal trunks which pass through the oesophageal sphincter and lie anterior and posterior to the stomach
Where does superior pancreaticoduodenal arterty supply?
Duodenum and pancreas
Which artery runs behind the stomach to the spleen?
The splenic artery
How do body and tail of the pancreas lie in relation to the stomach?
What are the functions of the spleen?
Largest lymph organ, produces white blood cells. Stores red blood cells and platelets. Haemopoiesis in foetus.
What surfaces and borders does the spleen have?
A visceral and diaphragmatic, a notched anterior and smooth posterior border
What does the submucosa contain?
Looser connective tissue containing many blood vessels, lymphatics and nerves
Where is the spleen?
In the upper left hypochondrium behind 9-11th ribs. It's superior anterior border is level with the mid axillary line
How does CCK stimulate gastrin release?
Acts on ECL cells to release histamine as well as acting directly upon parietal cells
What is the allantois?
A diverticulum of the hindgut with close relationship to yolk sac which is non functional in humans but it's vessels make up umbilical artery and vein
Which cells are the pacemakers of the GI tract? What do they do?
The intestinal cells of Cajal create bio electrical slow wave potential that causes smooth muscle contraction. Churn and move chyme
What are rugae?
Large folds of mucus membrane in the stomach
What does Muscularis mucosae control?
Local control of mucosa
What do plica circulares in the ilieum and jejunum do?
Project into lumen to slow passage of food and increase surface area for reabsorption
What comes from ectoderm?
Skin and nervous system
What does motilin do?
Increases gastric and intestinal motility
Which plexus controls the muscularis externa?
Myenteric plexus of Auerbach
Why is the spleen vulnerable to rupture and why might this be dangerous?
If the ribs it lies behind are fractured the spleen may rupture causing a massive haemorrhage as it is so highly vascularised.
Why is the spleen so mobile?
It has two mesenteries
Are enteric nervous system fibres myelinated or unmyelinated?
Why is saliva hypotonic as it is secreted?
It begins as isotonic but salt and water is reabsorbed back into blood stream as it travels down the salivary duct
Where is there an serosa layer?
In parts of the tract which are suspended in the peritoneal cavity
What is the sympathetic innervation of the stomach and where does it originate?
Greater splanchnic nerves (T6-T9) via coeliac plexus
What comes from mesoderm?
Muscles, vasculature, connective tissue including cartilage and bone and kidneys
What is Meckel's diverticulum and when is it important clinically?
The remainder of the vielline duct, usually the proximal part, sometimes remains in adults and inflammation of this will mimic pain caused by an inflamed appendix
What is the enteric nervous system?
The intrinsic nervous system of the GI tract. It works of its own accord with no direct connection to brain function
Which neurotransmitters are exciting and inhibitory in the GI tract?
Acetylcholine is excitatory
Noradrenaline, VIP and ADP are inhibitory
What is the muscularis mucosae?
A thin sheath of smooth muscle whose contractions serve to up the slack of the mucosa and control its local pleating.
Which plexus controls the muscularis mucosae and adjacent submucous glands?
Messiner's (submucosal) plexuses
What are the four layers of ulceration?
Necrotic debris on luminal side, inflammation layer, granulation tissue, fibrous scar
What does the muscularis externa do?
Controls peristalic contractions that propel food down the tract, churn it and expel it as faeces.
Which layers does the mucosa of the GI tract contain?
Gut epithlium, lamina properia and muscularis mucosae
How do NSAIDs cause peptic ulcers?
Aspirin (and other NSAIDs) inhibit COX so prostaglandins aren't made. Prostaglandins, specifically PGE2, contribute to the mucosal defence of the GI tract by stimulating HCO3- and mucus secretion so without them there can be damage
How do left diaphragm and left lobe of the liver relate to the stomach?
Anterior and superior
What is a common complication of a peptic ulcer?
Penetration into the pancreas or liver causing organ failure, or into a major blood vessel causing GI bleeding or into peritoneal can't causing perforation and leakage of GI contents into cavity
Where do lymphatics of the stomach drain to ultimately?
To coeliac (pre aortic) nodes then to thoracic duct via cysterna chyli
Where does the left gastric artery supply?
The lesser curvature of the stomach and gives some oesophageal branches
Which structures are derived from foregut?
Pharynx, oesophagus, lower respiratory tract, stomach, duodenum (proximal to opening of bile duct) liver and pancreas, biliary apparatus
What is the trilaminar disc?
The three layers of the blastocele: ectoderm, mesoderm and endoderm
Where does the fundus of the stomach reach?
To the level of the 5th intercostal space immediately below the diaphragm
What does CCK do?
Stimulates gall bladder contraction to secrete bile, relax proximal stomach, enhance contraction of distal stomach to decrease rate of stomach emptying