Digestive System Embryology Flashcards
What is the vitelline duct
Narrow connective between the midgut and yolk sac
What is the stomodeum
The blind end of the foregut as a ectodermal depression which later forms oral cavity
What is the provtodeum
Ectodermal depression with blind end of the hind gut which later forms the anus
What is the oropharyngeal membrane
The ecto-endodermal membrane which separates stomodeum from the foregut
What is the anal membrane
The ecto-endodermal membrane between hind gut and proctodeum
What is the primitive gut tube and what is it composed of
Derived from endoderm and extends from oropharygeal membrane to the cloacal membrane and is composed of the foregut midgut and hind gut
Later development the membranes regress and becomes continuous
What 2 major abdominal organs come from distal region of the foregut
Liver and pancreas
What is the stomach and what happens to the stomach in embryological development
Fusiform dilation of the caudal part of the foregut and attached to dorsal abdominal wall by dorsal mesogastrium and ventral wall by ventral mesogastrium
As dorsal region grows at a greater rate than ventral it results in a dorsal greater curvature
What are the 2 rotations of the stomach in embryological development
First is moves through an angle of 90 degrees to the left about a cranial caudal axis so the former left side is ventral and former right side is dorsal
Second?
What happens in the liver development
Liver develops from the hepatic diverticulum, an endodermal outpouching of the foregut, and grows into the ventral mesogastrium
What is the lesser omentum
Connecting the stomach (lesser curvature) and the liver
What is the falciform ligament
Connecting the liver to the ventral body wall
Describe (simple) the spleen embryological development
The spleen develops within the dorsal mesogastrium, which is the mesentery attached to the greater curvature side of the stomach
What is the proper oral cavity
Space within the dental arcades
What separates the vestibule oral cavity and the proper oral cavity
Dental arcades
How does the vestibule communicate with proper oral cavity
Interdental spaces
What is the labial vestibule
Space between incisors and lips
What is the buccal vestibule
Spaces between molar teeth and cheeks
What are the salivary glands
Paired organs that secrete saliva via their ducts into oral cavity and keeps mucosa of the mouth moist and mixed with food to lubricated passage of the food during swallowing
What are the groups of salivary glands
Minor and major salivary glands
Where are minor salivary glands
In the mucosa of the lips, cheeks, tongue, palate and the sublingual oral floor.
What do minor salivary glands produce
Mucosa, thick protective, secretion
Where are the major salivary glands
Located at a distance from the oral cavity and drain through ducts
What does the major salivary glands release
Watery, serous fluid, some of them a serous-mucous secretion with amylase which initiates carbohydrate digestion
What does saliva contain
Water, mucin, amylase and salts, especially sodium bicarbonate
Name the major salivary glands
Parotid
Mandibular
Sublingual
Zygomatic
What is the parotid salivary gland
Paired organ, mixed, serous-mucous, tubuloacinous gland
parotid duct opens into the oral vestibule at the top of a small pailla opposite 4th cheek tooth
Where is the parotid salivary gland
Junction of the head and neck, ventral to the auricular cartilage in the retromandibular fossa
What is the mandibular salivary gland
It drains by a single large duct, which passes ventral to the mucosa of the floor of the oral cavity
Where is the mandibular salivary gland
Close to the angle of the jaw and is partially covered by the parotid salivary gland, slightly bigger than the parotid gland in most dogs and cats
What is the sublingual salivary gland
Shares a common opening with the mandibular salivary duct on top of the sublingual caruncle protruding from the prefenular part of the floor of the oral cavity
Where is the sublingual salivary gland
Composed of monostomatic and polystomatic portions, largest and most caudal component of the monostomatic portion is found within the capsular shared by the mandibular salivary gland
What is the pharynx
Common cavity through which both air and ingested material pass, connects oral cavity with oesophagus and nasa cavity with the larynx
What are the 3 parts of the oesophagus
cervical, thoracic and abdominal
What way does the oesophagus run
Dorsal to the trachea then it runs ventral to the ascending aorta and passes over the dorsal border of the liver to join the stomach at the cardia
Inlet of stomach called
cardia
Outlet of stomach called
Pylorus
Name of what controls openings to the stomach
Sphincters
What are the two parts of the pylorus
Pyloric antrum
pyloric canal towards the duodenum
Name the portions of the stomach
Cardia
fundus
body
pyloric portions
Describe the 2 omentums
Greater and lesser omentum attached to the stomach at the greater and lesser curvatures respectively
What artery supplies the stomach
Celiac artery
3 branches of the celiac artery
Splenic, hepatic, and left gastric arteries
each provides blood flow to a portion of the stomach
What does the hepatic artery from the celiac artery supply and then branch off to
Liver and gallbladder then continues as the right gastric artery to supply pylorus and pyloric antrum
Then it anastomoses with left gastric artery along lesser curvature of stomach
What does the splenic artery suppy and then branch off to
Gives off tributaries to the left limb of the pancreas and spleen before becoming the left gastroepiploic artery to supply greater curvature of stomach
Then it anastomoses with the right gastroepiploic artery
Where do the left and right gastric arteries run along
Lesser curvature of stomach
Where do the left and right gastroepiploic run along
Greater curvature of stomach
Define the division of the intestines
Commences at pylorus and continues to the anus
Small- pylorus to the caecum
Large- Caesum to the anus
What is the duodenum
Proximal part of the small intestine extending from the pyloric part of the stomach to the jejunum
What is the jejunum
Longest part of small intestine betwen the dudodenum and ileum on left side of body
What is the ileum
Short terminal part of the small intestine on right side of the body
Difference of jejunum and ileum
Distinction is defined by the proximal extent of the ileocecal fold
Also ileum on right and jejunum on left side
What is the caecum
Blind tube, which is demarcated from the colon by the entrance of the ileum
connects ileum by ileal orifice
connects colon by caecocolic orifice
3 parts of colon
ascending colon
transverse colon
descending colon
3 parts of the pancreas
body
right lobe
left lobe
What nerve innervations is in muscous membranes of pharynx, soft palate and muscle except the tensor muscle of soft palte
Plexus formed mainly by the vagus nerve and to a lesser extent by the glossopharyngeal nerve
What nerve innervations is in tensor muscle of soft palate
mandibular nerve
What nerve innervations is in the stomach
parasympathetic fibres of the vagus nerve and sympathetic fibres of the celiac plexus
Which embryonic structure gives rise to the pancreas and liver
Foregut
Which structures separates the oral cavity proper from the vestibule in the oral cavity
Dental arcades
What is the main reason rabbits do not need to fast before anaesthesia
Structure of stomach
What is the primary role of antiperistalsis in the large intestine of birds
Moves urine from the cloaca into the large intestine for water reabsorption
From which artery does the blood supply to the stomach originate
Celiac artery
How does differential growth of tube contribute to formation of stomach’s curvatures
More rapid growth of dorsal portion the stomach expands leading to greater and lesser curvature
2 stomach rotations
90 degrees about its long axis
Anti-clockwise around a dorsoventral axis
What is connected to the dorsal mesogastrium
greater omentum
what is connected to the ventral mesogastrium
lesser omentum
Organs of foregut
oesophagus, stomach, cranial duodenum, liver and pancreas
Organs of midgut
small intestines, cecum, ascending colon, part of transverse colon
Organs of hindgut
transverse and descending colon, cloaca, rectum and most anal canal
Blood supply for organs of foregut, midgut and hindgut
celiac, cranial mesenteric, caudal mesenteric arteries respectively
Rabbits feeding cycle name
crepuscular
what is crepuscular
feeding at dusk and early morning
What type of digestive system/ diet for a rabbit
Rabbits are non-ruminant herbivore with a large hind gut
Rabbit stomach shape and position
J shaped, thin walled and lies on left side
pH of adult rabbit stomach
1-2 makes the stomach and small intestine almost sterile
Percentage of GI volume of small intestine in rabbit
12%
How do the bile duct and pancreatic duct enter the duodenum in rabbit
widely separated points, bile at beginning and pancreatic at end
longest section of small bowl in rabbit
jejunum
What is the terminal ileum like in the rabbit
enlarges into aspherical thick dilation called sacculus rotundus which is unique to the rabbit
what is the sacculus rotundus
in the rabbit the terminal ileum enlarges into aspherical thick dilation
what animals has the largest cecum
rabbit, relative to size
capacity of cecum in rabbit compared to stomach
10 times
percentage of intestinal content in rabbit cecum
40%
length of proximal colon in rabbit
approx 50 cm
length of distal colon in rabbit
approx 90cm
3 parts of proximal colon in rabbit
3 longitudinal muscular bands called taenia creating 3 haustra
a single taenia/haustra
the fusus coli
difference of proximal and distal colon in rabbit
distal colon has no sacculations
What stomachs do birds have
glandular/proventriculus
muscular/gizzard
What does the glandular stomach do
receives food from esophagus and secretes mucus, HCL and pepsinogen, similar to mammalian stomach
What does the gizzard do
disk shapes, very muscular and in many birds contains small stones that facilitate grinding of foodstuffs
what do birds large intestines have
short villi extend into the lumen of the colon unlike mammals
What is the cloaca
expanded, tubular structure that serves as the common opening of the digestive, reproductive and urinary systems which opens to the outside of the bird as the vent
What is antiperistalsis in the cloaca
prominent pattern of motility in avian colon and suggested to assist not only filling of ceca but to flush urine from the cloaca into the large gut for absorption of water
How many cecum in birds
typically a pair of ceca that can be dispensable in some species or important sites of fermentation in other species
