Flashcards in Lecture 3 Deck (78)
What are the foregut structures?
- (Lower respiratory tract - tracheobronchial diverticulum)
- (Proximal oesophagus)
- Distal oesophagus
- Biliary apparatus
- Proximal 1/2 Duodenum
What artery is the foregut supplied by?
Coeliac axis at T12
Is the spleen a part of the gut tube? Why?
No, it is a lymphoid mass
What are the midgut structures?
Distal 1/2 duodenum
Proximal 2/3 transverse colon
What artery is the midgut supplied by?
Superior mesenteric artery at L1
What are the hindgut structures?
- Distal 1/3 transverse colon
- Descending colon
- Sigmoid colon
- Proximal 2/3 anal canal
What artery is the hindgut supplied by?
Inferior mesenteric artery at L3
What does the epiblast become?
What does the hypoblast become?
What does the mesoderm create?
3rd layer between ectoderm and endoderm
What does the ectoderm go on to form?
Skin and outer body wall
What does the endoderm eventually form?
Gut tube and anything mucosal
What does the mesoderm eventually form?
Forms muscles, blood vessels, nerves
What does the oropharyngeal membrane ultimately form?
Describe the process of transverse folding in the development of the gut
- Ectoderm and mesoderm fold laterally and ventrally
- Closes off endoderm, forming a separated gut-tube structure
- Endoderm formed epithelial lining of tube
- Mesoderm gives rise to supporting structures and smooth muscle
- Outer mesenchymal layer gives rise to outer tissue layer
- Space between mesodermal layers gives rise to body cavity
What is mesenchyme?
Undifferentiated stem cells
Describe the process of longtudinal folding in the development of the gut
- Starts to draw opening of gut tube to yolk sac closed
- Divides into anterior intestinal portion (foregut) and posterior intestinal portion (hindgut)
- Midgut remains open to yolk sac
- Further folding - communication with yolk sac gets smaller
- Fore/mid/hindgut regions become more refined
What is at the extremities of the gut tube?
Cranial end: oropharyngeal membrane (ectoderm of the stomodeum)
Caudal end: anal membrane (ectoderm of the anal pit)
What eventually happens to the oropharyngeal and anal membrane?
What is the composition of the oropharyngeal and anal membrane?
Both transitional regions between endoderm and ectoderm. Between mucosal tissue and skin. Inside of mouth is endoderm origin and outside dry skin is ectoderm.
Where is the oesophagus found?
Immediately caudal to pharynx
What does the oesophagus partition from?
Partitions from the trachea, forming the respiratory diverticulum
What are the positions of the trachea and oesophagus respective to each other?
Trachea is ventral
Oesophagus is dorsal
Is the oesophagus initially short or long?
Initially short but rapidly elongates
What happens if the oesophagus doesn't elongate?
It can displace the stomach cranially
What is an atresia?
A blockage of a tube
What is a fistula?
Connection between tubes
What do atresia and fistula occur as a result of?
When does atresia present?
Soon after birth because infant will suckle milk and vomit it up. This is because milk will gather in the sack and have nowhere to go.