Development of the Respiratory System Flashcards
Describe the development of the neural crest
Part of the ectoderm will develop into the neural groove and the tips of the walls of this groove are called neural crest cells.
What do the parietal (somatic) and visceral (splanchnic) mesoderm form?
Parietal = body walls, Visceral = Surround the organs
Describe what occurs in lateral plate mesoderm folding
The parietal layer of the lateral plate mesoderm merges with the ectoderm. The primitive yolk sac will become pinched and will form the digestive tract or gut tube and the visceral layer will envelope the future gut tract. Finally the parietal layer and ectoderm merge and fuse in the ventral midline.
What does the connection between the gut tube and secondary yolk sac form?
Vitelline duct
At the end of lateral folding, what is present?
- A cavity which will become the thoracic, abdominal and pelvic cavity.
- A body wall made out of the surface ectoderm and parietal lateral plate mesoderm below it.
- Gut tube, suspended by visceral layer of lateral plate mesoderm
What occurs while the lateral folding takes place?
Cranio-caudal folding which it where head and tail meet with the two lateral folds at the umbilicus.
Describe the start of the development of the lung buds at week 4
In the cervical region of the gut tube, the respiratory diverticulum starts to appear. It begins to expand ventrally towards the chest. Meanwhile tracheo-oesophageal ridges (folds) grow towards each other and split the respiratory diverticulum from the gut tube. The diverticulum bifurcates into two branches. Later these expand. Terminal ends of these are called lung buds.
What are pharyngeal arches?
Growth of mesenchyme tissue in the cranial region resulting in formation of arches which are separated by pharyngeal clefts
How many pharyngeal arches are there?
5, numbered; 1,2,3,4,6.
When do the pharyngeal arches begin to develop?
4-5th week of development
Where does the laryngeal orifice arise?
In-between the laryngeal and epiglottic swellings
What is maintained despite the tracheo-esophageal septum separates gut tube and resp tract.
The laryngeal opening. This is because both nose and mouth share a common pathway
What does the upper, middle and lower end of the respiratory diverticulum become?
Upper - Larynx,
Middle - Trachea,
Lower - Tertiary bronchi, bronchioles and alveoli.
What is the respiratory diverticulum developed from?
Endoderm and is then surrounded by the visceral layer of lateral plate mesoderm
Describe what occurs when the bronchial tree begins to develop?
It pushes the viseral layer of lateral plate mesoderm which becomes the visceral pleura