Development Of Respiratory System - Block 3

Respiratory distress syndrome (RDS) is a condition characterized by insufficient surfactant in the lungs. Surfactant is a substance that helps reduce surface tension in the alveoli, preventing them from collapsing during expiration. Therefore, if there is not enough surfactant, the alveoli will indeed collapse during expiration. Hence, the statement "Respiratory distress syndrome (RDS) is when a surfactant is insufficient, alveoli will collapse during expiration" is true.

The correct answer is splanchnic mesoderm. The trachea and lungs develop from the foregut during embryonic development. The splanchnic mesoderm is the layer of mesoderm that surrounds the foregut and gives rise to the cartilaginous, muscular, and connective tissue components of the trachea and lungs. The endodermal layer gives rise to the epithelial lining of the trachea and lungs, while neural crest cells are not involved in the development of these structures. Therefore, the correct answer is splanchnic mesoderm.

The VACTERL association refers to a group of congenital disorders that often occur together. These disorders include vertebral anomalies, anal atresia, cardiac defects, tracheoesophageal fistula, esophageal atresia, renal anomalies, and limb defects. Therefore, the statement that VACTERL association disorders are found together is true.

During the 7th month of development, the premature infant has developed enough capillaries to ensure proper gas exchange. This means that oxygen can be delivered to the body's tissues and carbon dioxide can be removed effectively. As a result, the premature infant is able to survive outside of the womb.

glucocorticoids used to stimulate the type II pneumocytes.

When the lung fluid is absorbed from alveolar sac, surfactant remains deposited as a thin phospholipid coat on alveolar cells membrane. Without surfactant layer, the alveoli would collapse during expiration (atelectasis).

Tracheoesophageal septum divides the foregut into a dorsal portion: the esophagus and a ventral portion: the trachea and lung buds.

Before the bronchial tress reaches it final shape, an additional six divisions form during postnatal life.

Bronchopulmonary segments are indeed the largest subdivision of a lobe. Each segment has its own bronchus, artery, and veins, which allows for independent functioning. This anatomical arrangement also enables surgeons to separate and remove individual segments if necessary. Therefore, the statement is true.

The explanation for the given correct answer is that alveoli, which are tiny air sacs in the lungs responsible for gas exchange, continue to form and develop after birth. It is estimated that only 1/6 of the total adult number of alveoli are present at birth. The remaining alveoli form during the first 10 years of postnatal life through the continuous formation of new primitive alveoli. Therefore, it is true that the majority of alveoli are formed after birth.

During the development of the respiratory system, the respiratory diverticulum, also known as the lung bud, emerges as an outgrowth from the ventral wall of the foregut. This occurs in approximately week 4 of development.

During the week 26 to birth, which is known as the terminal sac period, the type II pneumocytes first appear. These cells are responsible for producing surfactant, a substance that reduces surface tension in the alveoli and prevents them from collapsing. The development of type II pneumocytes is crucial for the proper functioning of the respiratory system and allows for respiration to occur. Therefore, the given answer is correct.

The correct answer is endodermal. The internal lining of the larynx, trachea, bronchi, and lungs is derived from the endoderm, which is one of the primary germ layers formed during embryonic development. The endoderm gives rise to the epithelial lining of various organs in the respiratory and digestive systems, including the respiratory tract. Therefore, the epithelium of the internal lining of the larynx, trachea, bronchi, and lungs is entirely of endodermal origin.

The somatic mesoderm which covers the body wall from the inside becomes the parietal pleura.

During lung development, branching is controlled by interactions between the endoderm of the lung bud and the surrounding splanchnic mesoderm. The splanchnic mesoderm provides signals and cues that guide the branching and differentiation of the lung bud. This interaction is crucial for the proper formation and organization of the lung tissue. Neural crest cells and ectoderm do not play a direct role in this process.

During the canalicular period, which occurs between week 16 to 26 of fetal development, the respiratory bronchioles divide into 3 to 6 alveolar ducts. These alveolar ducts are too thick for efficient gas exchange to occur. This period is characterized by the development of the lung's vascular network and the appearance of type II pneumocytes, which are responsible for producing surfactant. Therefore, the thick alveolar ducts during the canalicular period make them unsuitable for gas exchange.

During the pseudoglandular period, which occurs between week 5 to 16 of fetal development, branching has continued to form terminal bronchioles. However, respiratory bronchioles and alveoli have not yet developed. Without respiratory bronchioles and alveoli, there is no gas exchange, which is essential for sustaining life. Therefore, this period is not compatible with life.

Fetal breathing movements are important for stimulating lung development and conditioning respiratory muscles. These movements help in the maturation of the lungs and the development of the respiratory system. They also aid in strengthening the respiratory muscles, which are essential for proper breathing after birth.

lung buds forms the trachea and two lateral outpocketings: the bronchial buds.

During the 4th week of development, the communication between the thorax and abdomen occurs through the pericardio peritoneal canals. These canals allow for the passage of structures such as blood vessels and nerves between the two regions. The phrenic nerve and common cardinal veins are not specifically involved in this communication pathway during this stage of development. Therefore, the correct answer is pericardio peritoneal canals.

Esophageal atresia with or without tracheoesophageal fistulas (TEF) causes polyhydromnios.

The presense of the bowel in the chest hinders formation of the lungs leading to pulmonary hypoplasia (which decrease the alveolar surface area for gas exchange). The diaphragmatic hernia is repaired surgically.

a small amount of fluid is expelled via trachea and bronchi during delivery

Congenital cysts of the lung can cause dilation of terminal or larger bronchi, resulting in a honeycomb appearance on a radiograph. This condition is present from birth and involves the formation of fluid-filled sacs in the lung tissue. These cysts can lead to respiratory symptoms and may require medical intervention. Ectopic lung lobes, emphysema, and cirrhosis are unrelated conditions and would not cause the honeycomb appearance seen in congenital cysts of the lung.

Before birth, the lungs are full of fluid. The amount of surfactant in the fluid increases particulary during the last 2 weeks before birth. After birth, growth of the lungs are primarily due to an increase in the number of respiratory bronchioles and alveoli.

Type II pneumocytes first appear and begin to secrete surfactant at week 28. Surfactant is a substance that reduces surface tension in the alveoli of the lungs, preventing them from collapsing and aiding in the exchange of gases. The development and secretion of surfactant by type II pneumocytes is crucial for the proper functioning of the respiratory system. Therefore, by week 28, the presence of type II pneumocytes and the secretion of surfactant play a significant role in the maturation of the lungs and the preparation for independent breathing after birth.

Fetal breathing movements begin before BIRTH.