Embryology Flashcards
In the initial stages of embryonic development, what is the position of the septum transversum relative to the primordial heart? How does this position change by day 26 of development?
What structure in the embryo contributes to the diaphragm?
Septum transversum (specificlly contributes to the future central tendon of the diaphragm)
Somites within the cervical region associated with C3, C4 and C5
As myoblasts start migrating towards
Which part of the embryo grows at a faster rate? How does this affect the diaphragm?
The dorsal side grows at a faster rate than the ventral side. This causes the diaphragm to move down with respect to the C3, C4, C5 cervical regions.
What is the role pf the pleuroperitoneal membranes?
Slowly fuse with the septum transversum, closing up the pericardio-peritoneal canal (close up the space). Muscular tissue from C3, C4, C5 somites follow the membrane and start to replace it. This is the start of the separation of the thoracic cavity from the abdominal cavity.
The septum transversum becomes the … of the diaphragm.
central tendon
What areas are susceptible to herniation
As the pericardio-peritoneal canal gets closed off by the invading pleuroperitoneal membranes, a separation is created between…
the thoracic and abdominal cavity
What happens when you fail to create a complete distinction between the abdomen and thorax?
hernia….
The intraembryonic coelem will become…
the body cavity
The developing gut tube’s wall is made of…
splanchnopleure, i.e. …
What is the name of the horseshoe-shaped cavity? What does it become?
Intraembryonic coelom - forms future body cavities (pericardial, pleural and peritoneal cavities)
What happens whn the body wall does not “close” properly?
Varying degrees of consequences:
- severe defects (viscera, like the heart or GIT organs, develop outside of the body cavity)
- minor defects (two sides of the sternum do not fuse together, creating a space within the sternum)
Where is the pericardial cavity? Where is the peritoneal cavity?
Pericardial: thorax
Peritoneal: abdomen
Week 5: What is the development of the heart and lungs like?
Substantial development of the heart, little development of the lungs.
Week 6: What is the development of the heart and lungs like?
Distinction is created between the two pleural cavities and the peritoneal cavity (dorsally, ventrally,….)
What allows us to form two rather than one cavity for the lungs?
Initially, lungs start developing dorsally to the heart. However, over time, the pleural spaces become larger causing the lungs to…
wrap around the heart (move ventrally)?
Where are the phrenic nerves?
Directly between the heart (pericardial cavity) and lungs (pleural cavity)
What does the entire respiratory system develop from?
Respiratory diverticulum
Small grooves start to form within the developing gut tube. Name the one related to the respiratory system
Laryngotracheal groove (opening of the respiratory diverticulum, which is like an outpouching)
As the laryngotracheal groove grows larger, …
Where is the trachea growing?
In the laryngeal
Why is the respiratory and digestive system so tightly connected?
Because the respiratory system develops off of the developing digestive tube
What does it mean that the respiratory diverticulum is a blind outpouching?
it is closed
What develops between the future espohagus and respiratory bud?
Tracheoesophageal septum (separation of the trachea and esophagus)
What happens if there is no proper separation between the trachea and esphagus?
Fistula: abnormal opening between the esophagus and trachea
Define atresia
Closure or blind end either of the esophageal or respiratory portion of the tracheoesophageal tube
What is the cause of atresia and fistula?
Mutations in the factors involved in embryonic signalling pathways
As the diverticulum starts to lengthen, it begins to …
bifurcate (split into 2)
As the bronchial buds grow, they will receive signals to branch into ..
secondary bronchial buds, then tertiary bronchial buds, and so forth all the way into alveolar buds.
What can cause the formation of cysts in the lungs?
What causes the absence of lung tissue and tracheobronchial tree on one side of the body? What is this condition called?
Complete unilateral pulmonary agenesis
What is pulmonary sequestration?
A congenital malformation - non-functional lung forms where it shouldn’t
What happens if the intestines start herniating through the ..???? cavity?
Lung may not develop correctly - pulmonary hypoplasia (?)
During the embryonic phase (weeks 4-6)
- respiratory diverticulum forms
- openings at the cuadal and cranial end of … i.e. oropharyngeal membrane and claucal membrane
The oropharyngeal and claucal membranes will give rise to…
During the pseudoglandular phase (weeks 5-17)
- Lungs resemble glands histologically
- Lungs are not viable yet (not enough capillaries and ??)
During the canalicular phase (weeks 16-25)
During the terminal sac phase (week 24-fetal)…
- Capillaries surround the alveoli
- Surfactant production beginning, preventing the alveoli from collapsing
- ## alveoli thin and develop
What do we call the collapse of alveoli due to lack of surfactant?
Atelectasis
Name the 3 factors that affect fetal lung growth
- adequte space in the pleural cavities
- adequate amount of amniotic fluid (why?)
- fetal breathing movements
Explain Potter syndrome
Due to lack of urine production (because kidneys do not develop), there is a substantially lower amount of amniotic fluid circulating in the developing fetus - therefore we won’t have proper lung growth because we won’t have sufficient pressure.
How is urine important of lung development?
What are symptoms of Potter syndrome and their underlying cause
Uterus starts shrinking, causing clubbed feet and flattened facial features
- pulmonary hypoplasia
- fetal growth deficiency
