Alimentary Flashcards
what does the intraembryonic coelom become?
the peritoneal cavity
what is a mesentery?
a double layer of peritoneum
what develops into the parietal peritoneum?
somatic lateral plate mesoderm
what develops into the gut muscle and visceral peritoneum?
splanchnic lateral plate mesoderm
what is the peritoneum?
a serosal membrane ‘mesothelium’, single squamous epithelium which secretes small amount of fluid
what are the 4 fetal membranes in reptiles, birds and mammals?
allantois, chorion, amnion, yolk sac
how many fetal membranes are there in reptiles, birds and mammals?
4
what does the allantois form in doemstic mammals?
placenta with chorion
what does the chorion develop from?
trophoblast
what do the allantois and chorion form together?
placenta
what contains and protects the yolk sac?
the amnion
what membrane breaks down to form the mouth?
buccopharyngeal membrane
what breaks down to form the anus?
the cloacal plate
what germ layer are the buccopharyngeal membrane and cloacal plate missing?
mesoderm
what are the lungs derived from?
ventral gut
what germ layer forms the lungs?
endoderm
what does the hindgut connect to?
the allantois
what does the midgut connect to?
the yolk sac
what forms the upper mediastinum?
dorsal mesentery in the thorax
what does the ventral mesentery of the hindgut become?
ventral ligament of the bladder
what distorts the ventral mesentery of the foregut?
ventral pancreatic bud and liver biliary tree growing within it
what is the falciform ligament?
the bit between the liver and ventral body wall
how do the 2 pancreatic buds fuse?
ventral bud grows round to join dorsal bud
how does the stomach move to the left hand side?
by rolling around its own axis
how many times does the gut rotate around the root of the mesentery?
3
what does the gut rotate around?
the root of the mesentery
what shape does the gut end up as after rotation?
2 intertwined hooks
what direction does food in the stomach move from?
left to right
what is the greater curvature of the stomach?
the old dorsal edge of the stomach before it rolled
what is the lesser curvature of the stomach?
the old ventral edge of the stomach before it rolled
what does the stomach empty into?
the duodenum
what side does the colon descend on?
left
what does the colon empty into?
the rectum
what is the boundary of the foregut/midgut?
where the duodenum starts to descend
what is the boundary of the midgut/hindgut?
about 3/4 along the transverse colon
what is the lesser omentum?
the ventral mesentery of the stomach
what is the greater omentum?
the dorsal mesentery of the stomach
what does the pancreas drag with it as it burrows through the gut?
the opening of the billowing system of the liver
what does the bile duct run through?
the free edge of the lesser omentum then the dorsal wall of the duodenum
what are mesenteric fusions?
when gut regions end up near each other and their adjacent leaves of mesenteric peritoneum may fuse
what is the ileocaecal fold useful for?
orientation as it attaches the ileum to the caecum
what are the rumen and equine stomachs/RDC/caecums directly attached to?
the dorsal body wall with the mesentery ‘shortened to nothing’
what is the function of the oesophagus?
conveys food, drink and salvia to stomach, conveys vomit, regurgitated food and eructated gas in other direction
what nerves run with the oesophagus?
the vagal nerves
what makes up most of the outer layer of the oesophagus?
loose ‘adventitial’ connective tissue coat
how many layers of muscle does the oesophagus have?
2
what part of the oesophagus is smooth muscle in most species?
the caudal 1/3
what part of the oesophagus is striated muscle in most specie?
the cranial 2/3
in which species is all of the oesophageal muscle striated?
dog and ox
what does the arrangement of the 2 layers of muscle in the oesophagus become as it nears the stomach?
inner circular and outer longitudinal layer
what is the lining of the oesophagus formed from?
keratinised stratified squamous mucosa
which species has the most goblet cells in the oesophageal lining?
dogs
which species has more goblet cells in the oesophageal lining than other species except for dogs?
pigs
what attaches the oesophagus to the larynx?
a 1cm crico-oesophageal tendon
what does the caudal 1/3 of the cat oesophagus have?
distinctive ridges by circular muscle bands
what is the nerve supply to the cranial oesophagus?
somatic fibres of vagus nerve X
what is the nerve supply to the caudal oesophagus?
parasympathetic fibres of vagus
what arteries run alongside the trachea?
the common carotid arteries
what is the peritoneum separated into?
parietal, visceral and mesentery
what does the mesentery of the oesophagus form?
the dorsal part of the mediastinum
what are the pleuropericardial folds?
ventral ingrowths on either side of the pleural+pericardial cavities with common cardinal veins and phrenic nerves
which is dorsal the pleural cavity or the pericardial cavity?
the pleural cavity
which is ventral the pleural cavity or the pericardial cavity?
the pericardial cavity
how does the heart end up in the pericardial cavity?
migrates from cephalic location caudally and squishes into the pericardial cavity
why does the heart have 2 layers of pericardium?
it impinges on the pericardial cavity and displaces the pericardium so there are 2 layers
why do the mediastinum and pleuroparietal folds fuse?
the pleuroparietal folds grow dorsomedially towards the mediastinum
which pericardium forms the shiny ‘epicardium’ stuck to the outside of the heart?
visceral pericardium
what is surgeon’s pericardium a combination of?
mediastinal pleura, connective tissue and parietal pericardium
what is the more superficial layer of pericardium?
parietal pericardium
what causes pleuroperitoneal hernias?
pleuroperitoneal folds don’t form properly so end up with hole which guts wiggle through
what causes a peritoneo-pericardial hernia?
a hole into the pericardial sac which intestines crawl through
what is the stomach tube inserted via in most species?
the mouth
what is the stomach tube inserted via in the horse?
the nose
what is a good way to feed cats in the medium term?
oesophageal tube via nose
what is the benefit of transoesophageal echocardiography?
there is no rib cage in the way
what are the signs of oesophageal disease?
regurgitation, ballooning of neck (especially if abdomen compressed)
what is the difference between regurgitation and retching/vomiting?
retching/vomiting is active contraction of stomach, regurgitation is delayed ejection of undigested food, quite passive
what can oesophageal disease lead to? (5)
inhalation pneumonia, broncho-oesophageal fistula, mediastinitis, pleurisy, pleurisy can develop into pyothorax/pneumothorax
what is inhalation pneumonia caused by?
inhaling ingested food/saliva
what is a fistula?
a rupture
what is mediastinitis?
inflammation of mediastinum
what is pleurisy?
rupture into the pleural cavity
what is megaoesophagus?
a large, floppy, dilated oesophagus
what are the causes of megaoesophagus?
congenital or acquired
what are most foreign bodies in dog oesophagi?
bones in dogs
what may be evidence of functional valves in oesophagi?
usual sites of foreign body obstruction reflect points of external narrowing of oesophagus
what are the sites of external narrowing of the oesophagus?
cricopharyngeus muscle, thoracic inlet, heart base, oesophageal hiatus
what dog breeds does vascular ring anomaly normally occur in?
GSD, Irish setter, greyhound, Boston terrier
what is vascular ring anomaly?
entrapment of oesophagus in ring formed by right aorta, ligamentum arteriosum, or left aorta if present, pulmonary artery, heart
what is the surgical approach for vascular ring anomaly, thoracic foreign bodies and PDA?
via left intercostal space 5
what is the part of the stomach directly after the oesophagus opens into it?
the cardia
what is the output of the stomach?
pyloric canal
what does the old dorsal edge of the stomach become after it rolls?
greater curvature
what does the old ventral edge of the stomach become after it rolls?
lesser curvature
what is the angular incisure?
very sharp kink in lesser curvature present in stomach of some species
what is the left side of stomach like in general?
floppier and less muscular than the right
what is the right side of the stomach like in general?
narrower lumen, thicker muscle, less distensible
which surface of the stomach faces the liver?
parietal
which surface of the stomach faces the intestine, pancreas, right kidney?
the visceral surface
what does the dorsal greater omentum connect?
the greater curvature of the stomach to the epiploon
what is the epiploon?
line on dorsal wall that the dorsal greater omentum connects the stomach to
what does the dorsal greater omentum enclose?
capacious bursa in carnivores, pig and horse
what is the bursa that the dorsal greater omentum encloses accessible via?
the epiploic foramen under free edge of the ventral lesser omentum
what does the ventral lesser omentum connect?
the lesser curvature of the stomach to the liver
what does the ventral lesser omentum convey?
bile duct to duodenum, hepatic artery, portal vein and vagus to liver
how many layers of muscle does the stomach have?
3
what are the layers of muscle in the stomach?
outer longitudinal, middle circular, inner oblique
which layers of stomach muscle are continuous with the oesophagus and duodenum?
outer longitudinal, middle circular
what does the inner oblique muscle of the stomach not cover?
lesser curvature and pylorus
what are the 3 regions of glands in the stomach?
cardiac, proper gastric, pyloric
what glands does the cardiac region of the stomach have?
mucus
what glands does the proper gastric region of the stomach have?
pepsin, HCl, mucus
what is the darker gland region of the stomach?
proper gastric
what glands does the pyloric region of the stomach have?
mucus
what does the stomach have instead of goblet cells?
foveolar cells
what is the foregut artery (coeliac) derived from?
vitelline arteries of the yolk sac
what does the coeliac artery run between?
the 2 layers of mesentery, to under the visceral peritoneum of organs
what does the coeliac artery branch into?
splenic, gastric and common hepatic arteries
what does all gut between the cardia and the distal rectum drain into?
the hepatic portal vein
what is the hepatic portal vein derived from?
vitelline veins
what forms the ventral margin of the epiploic foramen?
the hepatic portal vein
what forms the dorsal margin of the epiploic foramen?
the caudal vena cava
what does the common mesenteric vein form in?
the great mesentery
what veins does the common mesenteric vein receive (in order) to form the hepatic portal vein?
gastrosplenic vein, gastroduodenal vein
what does the hepatic portal vein pass to the porta of the liver via?
the lesser omentum
what does lymphatic drainage of the stomach drain to?
collection of nodes, the coeliac nodes, around the coeliac artery
how does the parasympathetic innervation of the stomach reach the stomach?
vagus enters via oesophageal hiatus, ventral branch follows lesser curvature, dorsal mainly from coeliac plexus and then along artery
what do nerves to the stomach branch in?
submucosal plexi
what are differences between the cat and dog stomach?
cat has narrower lumen, less distensible, extravagant vomiting behaviour
what is the difference between the pig and dog stomach?
pig has diverticulum ventriculi and extensive cardiac gland region, torus pyloricus, shorter greater omentum
what are the diverticulum ventriculi in the pig stomach?
helical ridges of mucosa
what is the torus pyloricus?
an erectile ‘valve’ which may control flow through pyloric canal
what is the difference between the horse and dog stomach?
surprisingly small, sharp angular incisure, blind-ending ‘saccus caecus’, gastrophrenic ligament from proximal greater curvature to crura, extensive keratinised region, dilate proximal duodenal ‘cap’
what is location of the abrupt transition from the keratinised region to the glandular epithelium in the horse stomach called?
margo plicatus
what is the difference between the rabbit and dog stomach?
surprisingly large, holds fermenting caecotrophs
what is the only simple-stomached domestic species in which the stomach can be palpated in healthy individuals?
rabbit
what are caecotrophs?
ingested soft faecal pellets
which are usually better for imaging the stomach, plain radiographs or contrasts?
contrasts
what is gastric dilation/volvulus?
an acute, life-threatening condition where stomach swells without stopping
what are the secondary complications of gastric dilation/volvulus?
post-op sepsis, gastric necrosis, myocardial depression
what are the functions of the liver?
storage, metabolism of C, L, P, vitamins and hormones, detoxification, excretion, immunological function
what is the largest gland in the body?
liver
what is the exocrine function of the pancreas?
digestion of fat, protein and carbohydrate
what is the endocrine function of the pancreas?
produces key hormones for regulation of blood sugar levels- insulin and glycogen
what surface of the liver is visible in the left lateral view?
diaphragmatic (parietal) surface
what are the visceral surface impressions of the dog liver?
stomach, duodenum, R kidney
what are the visceral surface impressions of the pig liver?
stomach, duodenum
what are the visceral surface impressions of the ox liver?
omasum, reticulum, R kidney
what are the visceral surface impressions of the horse liver?
stomach, apex of caecum, diaphragmatic flexure, RDC, R kidney
what species does not have a right kidney impression on the liver?
the pig as the kidneys are further back
what does the coronary ligament of the liver surround?
caudal vena cava to caval hiatus
what is the falciform ligament the remnants of?
the umbilical vein
what does the liver attach to?
duodenum, gallbladder, stomach, spleen, lesser omentum
what cups the cranial pole of the right kidney? (dog)
the caudate process of the liver
what marks the division of the quadrate and right lobes of the liver?
gall bladder
what are the differences between the pig and dog liver?
pig has no papillary process, R kidney doesn’t reach caudate process, less obvious division of quadrate, marked surface lobulation
what is the difference between the horse and dog liver?
horse has no papillary process, has scalloped quadrate lobe, no division of right lobe, no gall bladder
what is the difference between ruminant and dog liver?
ruminant has no division of left lobe, no division of right lobe, clockwise rotation to right, lies almost entirely to right of midline
what are signs of portal hypertension in humans?
portal vein enlargement, portal venous thrombosis, splenomegaly, enlarged superior mesenteric vein and splenic vein, enlarged paraumbilical vein, portosystemic collaterals
how much of the liver blood supply does the hepatic artery provide?
1/5th
how much of the liver oxygen supply does the hepatic artery provide?
3/5ths
where is the ventral lobe of the pancreas found?
in the mesoduodenum
where is the dorsal lobe of the pancreas found?
in the deep leaf of the greater omentum
is the ventral lobe of the pancreas left or right?
right
is the dorsal lobe of the pancreas left or right?
left
do dogs have the main pancreatic duct?
some do, some don’t
which species have the main pancreatic duct?
cat, horse, sheep, most ox, some dogs
which species don’t have the main pancreatic duct?
rabbits, pig, some ox, some dogs
where does the main pancreatic duct come from?
the ventral (right) lobe
which species don’t have the accessory pancreatic duct?
sheep and most cats
what is triaditis in cats?
simultaneous inflammation of the liver, SI and pancreas
why do cats get triaditis?
anatomical adaptations in the feline GI tract increase the risk of bacteria ascending from the duodenum into the liver + pancreas
what percentage of porto-sytemic shunts are congenital?
70%
what breed of dogs get congenital porto-systemic shunts?
small/miniature breeds
what are the symptoms of congenital porto-systemic shunts?
poor growth and response to anaesthesia, post prandial neurological signs
what type of porto-systemic shunt is often possible to treat with surgery?
extra-hepatic
what percentage of porto-systemic shunts in dogs are acquired?
30%
what causes acquired porto-systemic shunts?
microvasculature opens under back-pressure
what is the external landmark for percutaneous liver biopsy in dogs?
caudal to xiphoid process into left lobe
what is the external landmark for percutaneous liver biopsy in ox?
right 10th/11th intercostal space on line between tuber coxae and point of shoulder
what is the external landmark for percutaneous liver biopsy in horse?
right 12th intercostal space- on line between tuber coxae and point of shoulder
what increases the SA of the intestines?
they are tortuous and have mucosal folding
how much longer is the dog intestine than the length of the animal?
3-4x
how much longer is the sheep intestine than the length of the animal?
25x
how much greater is the internal SA of a dog’s SI compared to a featureless tube of same proportions?
around 600x
how much do folds increase SI SA in dogs?
3x
how much do villi and crypts increase SI SA in dogs?
10x
how much do microvilli increase SI SA in dogs?
20x
what is the right-most region of the gut?
the duodenum
what do the glands in the duodenum resemble?
pyloric glands
what is the cranial part of the duodenum, foregut or midgut?
foregut
what is the cranial part of the foregut attached to?
lesser omentum
why do most parasites live in the duodenum?
more nutrients available
what do bile and pancreatic ducts open via in the duodenum?
2 papillae
what are Peyer’s patches?
aggregated lymphoid follicles scattered in small intestine
how many Peyer’s patches are there in the dog SI?
around 22
what are the Peyer’s patches found under?
SI endothelium
what is the ileum defined as?
short stretch with ileocaecal fold and anti-mesenteric artery
what is the difference between the jejunum and ileum?
ileum is firmer and narrower, no abrupt transition
where does the ileum open into the colon?
at ileal papilla (ileocolic sphincter)
what is a common site of impaction in the small intestine?
the ileal papilla/ileocolic sphincter (where ileum opens into colon)
what does the caecum come off?
the colon
what does the caecum open into the colon via?
caecocolic orifice
why is the caecum tortuous in dogs?
due to the ileocaecal fold growing slowly
what are the parts of the caecum?
base, body, apex
does the colon have villi?
no
what is the left-most region of the gut?
descending colon
does the colon have Peyer’s patches?
no
does the colon have lymphoid follicles?
yes
what is the dog rectum defined as?
region of intestine caudal to pelvic brim
where does the rectum run?
down the midline
which way does the distended bladder deviate the rectum?
to the left
which way do the fibres of the rectococcygeus muscle run?
longitudinal smooth muscle fibres pass caudally to attach on Cd5/6
what is the function of the rectococcygeus muscle?
retractor
what does the epithelium transition to in the dog from cranial to caudal anal sphincter?
columnar to cutaneous
what are the characteristics of the ‘internal’ (cranial) anal sphincter?
thickened circular smooth muscle
what are the characteristics of the ‘external’ (caudal) anal sphincter?
striated, ventral to Cd4, fibres blend with genitalia muscles
what supplies the parasympathetic innervation to the midgut?
dorsal vagus
what supplies the parasympathetic innervation to the hindgut?
pelvic plexus (sacral outflow from S1 and 2)
what is the main artery of the midgut?
cranial mesenteric artery
what does the cranial mesenteric artery give off?
jejunals, right colic artery, middle colic artery, ileocolic artery
what does the ileocolic artery branch to?
ileal and antimesenteric artery
what does the hepatic portal vein initially form from?
cranial and caudal mesenteric veins
what do lacteals drain to?
mesenteric nodes which drain to cisterna chyli
where are the mesenteric nodes in dogs?
near to the mesenteric root
what is the difference between the cat and dog intestine?
cat caecum is straight and often palpatable in mid-abdomen
what is the difference between the ferret and dog intestine?
ferret has no caecum
what is the difference between the pig and dog intestine?
pig has some regions elaborated as fermentation chambers, ascending colon lengthens into long hairpin loop which coils into conical helix, caecum drawn to left side, caecum sacculated into haustra, which are ruched up by taenia, mesenteric nodes lie halfway between root and gut
what are haustra?
sacs divided by taenia
what are taenia?
2 thickened strands of longitudinal muscle in to pig caecum that ruche up the haustra
where do the mesenteric nodes lie in pigs?
halfway between the root and gut
what is the only species where the caecum is drawn to the left side?
pig
where is the lesser omentum positioned in the ruminant with respect to duodenum?
dorso-cranially
where is the greater omentum positioned in the ruminant with respect to duodenum?
caudally
what parts of the ruminant duodenum are similar to carnivores?
the descending and ascending parts
where do the mesenteric nodes lie in ruminants?
near to the gut
what % of fermentation takes place in ruminant stomach (rumen)?
75%
what % of fermentation takes place in ruminant caecum + first part of ascending colon?
25%
what is the ileum attached to the caecum by?
ileocaecal fold
what is the caecum like in ruminants?
long featureless tube which sticks far back caudally into pelvic cavity to lie alongside rectum
what is the difference between the opening into the caecum from the colon in ruminants and dogs?
ruminants have no obvious caecocolic sphincter, imperceptible transition
what are the 3 parts to the ascending colon in the ruminant?
ansa proximalis, ansa spiralis, ansa distalis
what is the ansa proximalis?
big dilate S-end of ruminant ascending colon
what does the ansa proximalis empty into?
ansa spiralis
what is the ansa spiralis?
narrow tube in ruminant ascending colon where absorption occurs, spirals into centre then out again
what does the ansa spiralis empty into?
ansa distalis
what is the ansa distalis?
loop in ruminant ascending colon that leads into transverse colon
what species are caecocolic fermenters?
horses and rabbits
what fills the ventral half of the horse abdomen?
caecum and colon
what is the shape of the caecum in the horse?
inverted comma shape
what does the base of the horse caecum attach to?
directly to the right dorsal body wall
what is the body of the horse caecum like?
long, sacculated by 4 taenia
what does the apex of the horse caecum reach?
reaches the xiphisternum
what does the horse ileum appear to open into?
caecal base
what is the caecal base in the horse?
a region of colon ‘stolen’ by the caecum during development
what are the 2 fermenting zones in the horse caecum/colon?
caecum + right and left ventral colon; right descending colon
what are the characteristics of the descending colon?
long, tortuous, sacculated, intermingled with jejunal coils
what is the site of parasite larvae in horses?
cranial mesenteric artery
what does the pelvic flexure act as in the horse?
a valve and site of impaction
where do the mesenteric nodes lie in the horse?
near the root of the mesentery
what is the only domestic mammal with an appendix caeci?
rabbit
what is expanded in the rabbit intestine?
ascending colon, especially caecum
how does double fermentation occur in the rabbit?
by re-ingestion