Development of Lung

Question 1

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as ____

Answer 1

a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of foregut endoderm.

Question 2

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of ____

Answer 2

foregut endoderm.

Question 3

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of foregut endoderm.

→ It is _____ (name of the process?)

Answer 3

a mesoderm dependent process

Question 4

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of foregut endoderm.

→ It is a mesoderm dependent process: Retinoic acid produced by adjacent mesoderm induces expression of TBX4 in some foregut endoderm cells and leads to their ___

Answer 4

differentiation to respiratory diverticulum.

Question 5

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of foregut endoderm.

→ It is a mesoderm dependent process: _____ produced by adjacent mesoderm induces expression of TBX4 in some foregut endoderm cells and leads to their differentiation to respiratory diverticulum.

Answer 5

Retinoic acid

Question 6

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of foregut endoderm.

→ It is a mesoderm dependent process: Retinoic acid produced by adjacent mesoderm induces expression of ____ in some foregut endoderm cells and leads to their differentiation to respiratory diverticulum.

Answer 6

TBX4

Question 7

Appearance of lung buds in 4 weeks old embryo

Initially the lung buds appear as a respiratory (or laryngotracheal) diverticulum, a ventral outgrowth of foregut endoderm.

→ It is a mesoderm dependent process: Retinoic acid produced by adjacent mesoderm induces expression of TBX4 in some ___ and leads to their differentiation to respiratory diverticulum.

Answer 7

foregut endoderm cells

Question 8

Separation of the trachea and esophagus

____ invaginates the surrounding mesenchyme.

Answer 8

The respiratory diverticulum

Question 9

Separation of the trachea and esophagus

The respiratory diverticulum invaginates the surrounding mesenchyme.

→ ___ appear above the respiratory diverticulum.

→ These longitudinal ridges eventually fuse to separate trachea from esophagus.

Answer 9

The respiratory diverticulum

Question 10

Separation of the trachea and esophagus

The respiratory diverticulum invaginates the surrounding mesenchyme.

→ Tracheo-esophageal (or esophago-tracheal) ridges appear above the respiratory diverticulum.

→ These longitudinal ridges eventually fuse to separate ____ from ____

Answer 10

trachea from esophagus.

Question 11

Separation of the trachea and esophagus

First ___ is formed, which is followed by the separation of the trachea and the esophagus.

Answer 11

a tracheo-esophageal septum

Question 12

Development of Larynx

Cartilages and muscle originate from the mesenchyme of ____ and ____

Answer 12

the 4th and 6th Pharyngeal Arches

Question 13

Development of Larynx

All laryngeal muscles are innervated by branches of the 10th Cranial Nerve (Vagus Nerve)

• Superior Laryngeal Nerve comes from ___ (branchial arch?)
• Recurrent Laryngela Nerve ______ (branchial arch?)

Answer 13

• 4th arch
• 6th arch

Question 14

Development of Larynx

Cartilages and muscle originate from the mesenchyme of the 4th and 6th Pharyngeal Arches

→ Mesenchyme of the two arches create the cartilages which are ___- (3)

Answer 14

• Thyroid
• Cricoid
• Arytenoid

Question 15

Development of Larynx

____ proliferates so that the lumen of the organ is temporarily occluded

Answer 15

The laryngeal epithelium

Question 16

Development of Larynx

The laryngeal epithelium proliferates so that the lumen of the organ is temporarily occluded

→ By then it is recanalized to create ____

Answer 16

the Laryngeal Ventricles

(Definition of recanalization

: the process of restoring flow to or reuniting an interrupted channel of a bodily tube(such as a blood vessel or vas deferens))

Question 17

Development of Larynx

The laryngeal epithelium proliferates so that the lumen of the organ is temporarily occluded

→ By then it is recanalized to create a pair of lateral recesses called the Laryngeal Ventricles which are bounded by folds of tissue that become both____ and ____

Answer 17

the False and True Vocal Folds

Question 18

Development of Larynx

Cartilages and muscle originate from the mesenchyme of the 4th and 6th Pharyngeal Arches

→ ____ changes its shape from a sagittal slit to a T-shaped opening

Answer 18

Laryngeal orifice

Question 19

Development of Larynx

All laryngeal muscles are innervated by branches of____

Answer 19

the 10th Cranial Nerve (Vagus Nerve)

Question 20

Development of the trachea

Endodermal lining distal to the larynx differentiates into the ___ and ___

Answer 20

epithelium and glands of the trachea.

Question 21

Development of the trachea

The cartilage, connective tissue and muscles of the trachea derive from ____

Answer 21

the mesoderm.

Question 22

Patterning of the lung

What is branching (dichotomic) morphogenesis?

Answer 22

• The process of repetitive growth and branching

Question 23

Patterning of the lung

Trachea branched into ____

Answer 23

two primary bronchi (left and right)

Question 24

Patterning of the lung

Trachea branched into two primary bronchi (left and right)

→ Left primary bronchus into _____

Answer 24

two secondary bronchi (corresponding to the two lobes of the left lung)

Question 25

**Patterning of the lung** Trachea branched into two primary bronchi (left and right) → Left primary bronchus into two secondary bronchi (corresponding to the two lobes of the left lung) → _____ form on the right

Answer 25

Three secondary buds (corresponding to the 3 lobes of the right lung)

Question 26

**Patterning of the lung** Trachea branched into two primary bronchi (left and right) → Left primary bronchus into two secondary bronchi (corresponding to the two lobes of the left lung) → Three secondary buds form on the right (corresponding to the 3 lobes of the right lung) → ____ form in the right lung

Answer 26

Ten tertiary (segmental) bronchi

Question 27

**Patterning of the lung** Trachea branched into two primary bronchi (left and right) → Left primary bronchus into two secondary bronchi (corresponding to the two lobes of the left lung) → Three secondary buds form on the right (corresponding to the 3 lobes of the right lung) → Ten tertiary (segmental) bronchi form in the right lung → ____ form in the left lung

Answer 27

Eight bronchi

Question 28

**Patterning of the lung** Trachea branched into two primary bronchi (left and right) → Left primary bronchus into two secondary bronchi (corresponding to the two lobes of the left lung) → Three secondary buds form on the right (corresponding to the 3 lobes of the right lung) → Ten tertiary (segmental) bronchi form in the right lung → Eight bronchi form in the left lung → establishing ___ of the adult human lung.

Answer 28

the 18 brochopulmonary segments

Question 29

**Patterning of the lung** By the end of the sixth month, ___ have formed to produce respiratory bronchioli. → Additional divisions occur during postnatal life for a total of 23 branching events.

Answer 29

17 generations of subdivisions

Question 30

**Patterning of the lung** By the end of ____ (month?), 17 generations of subdivisions have formed to produce respiratory bronchioli. → Additional divisions occur during postnatal life for a total of 23 branching events.

Answer 30

the sixth month

Question 31

**Signaling molecules driving lung budding and branching morphogenesis** \_\_\_\_ induce mesenchyme to secrete fibroplast growth factor 10 (FGF10), which acts on FGF receptor 2 to induce epithelial growth.

Answer 31

Tbx4 together with retinoic acid

Question 32

**Growth of lungs into the body cavity** \_\_\_\_ is surrounded by visceral (splanchnopleuric) mesoderm and suspended in body wall by dorsal mesentery

Answer 32

Foregut endoderm

Question 33

**Growth of lungs into the body cavity** Foregut endoderm is surrounded by ____ and suspended in body wall by dorsal mesentery

Answer 33

visceral (splanchnopleuric) mesoderm

Question 34

**Growth of lungs into the body cavity** Foregut endoderm is surrounded by visceral (splanchnopleuric) mesoderm and suspended in body wall by dorsal mesentery → As lungs grow, they expand into \_\_\_\_

Answer 34

the body cavity

Question 35

**Growth of lungs into the body cavity** The epithelial components of the lung are derived from \_\_\_\_

Answer 35

the endoderm

Question 36

**Differentiation of pleural membranes** The lungs buds expand in the pleural cavities surrounded by ____ and \_\_\_\_\_.

Answer 36

the parietal and visceral pleura

Question 37

**Differentiation of pleural membranes** The lungs buds expand in the pleural cavities surrounded by the parietal and visceral pleura. → They “punch” into the visceral mesoderm.

Answer 37

visceral mesoderm

Question 38

**Differentiation of pleural membranes** The lungs buds expand in the pleural cavities surrounded by the parietal and visceral pleura. → They “punch” into the visceral mesoderm. → Consequently, the visceral pleura extends between \_\_\_\_

Answer 38

the lobes of the lung.

Question 39

**Differentiation of pleural membranes** The mesoderm, which covers the outside of the lung, develops into \_\_\_\_

Answer 39

the **visceral pleura**.

Question 40

**Differentiation of pleural membranes** \_\_\_ which covers the outside of the lung, develops into the **visceral pleura**.

Answer 40

The mesoderm

Question 41

**Differentiation of pleural membranes** The somatic mesoderm, covering the body wall from the inside, becomes\_\_\_\_

Answer 41

the **parietal pleura**.

Question 42

**Differentiation of pleural membranes** \_\_\_\_, covering the body wall from the inside, becomes the **parietal pleura**.

Answer 42

The somatic mesoderm

Question 43

**Differentiation of pleural membranes** The mesoderm, which covers the outside of the lung, develops into the **visceral pleura**. The somatic mesoderm, covering the body wall from the inside, becomes the **parietal pleura**. → The space between is \_\_\_

Answer 43

the **pleural cavity**.

Question 44

Maturation of lung is divided into 4 periods which are

Answer 44

- **Pseudoglandular (5 - 17 weeks)** - **Canalicular (16 - 25 weeks)** - **Saccular (24 weeks - birth)** - **Alveolar (late fetal period - childhood)** (These periods overlap each other because the cranial segments of the lungs mature faster than the caudal ones.)

Question 45

**Maturation of the lung -** **Pseudograndular period (5-17 weeks)** Developing lungs somewhat resemble \_\_\_\_ By 17 weeks all major elements of the lung have formed except for those involved in \_\_\_

Answer 45

* an exocrine gland during this period. * gas exchange (alveoli).

Question 46

**Maturation of the lung -** **Pseudograndular period (5-17 weeks)** What is not possible during this period? → Will the fetuses be survived during this period?

Answer 46

Respiration is NOT possible. → Fetuses born during this period are unable to survive.

Question 47

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Lung tissue becomes highly \_\_\_

Answer 47

**vascular (vascularization).**

Question 48

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Lung tissue becomes highly **vascular (vascularization).** → ___ and ____ become larger.

Answer 48

Lumen of bronchi and terminal bronchioles

Question 49

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Lung tissue becomes highly **vascular (vascularization).** → Lumen of bronchi and terminal bronchioles become larger. → By 24 weeks each terminal bronchiole has given rise to\_\_\_

Answer 49

two or more respiratory bronchioles.

Question 50

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Lung tissue becomes highly **vascular (vascularization).** → Lumen of bronchi and terminal bronchioles become larger. → By 24 weeks each terminal bronchiole has given rise to two or more respiratory bronchioles. → The respiratory bronchioles divide into ____ that make up the alveolar ducts. Thus, airspaces are multiplicated by partitioning (**septation**).

Answer 50

3 to 6 tubular passages called canaliculi

Question 51

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Lung tissue becomes highly **vascular (vascularization).** → Lumen of bronchi and terminal bronchioles become larger. → By 24 weeks each terminal bronchiole has given rise to two or more respiratory bronchioles. → The respiratory bronchioles divide into 3 to 6 tubular passages called canaliculi that make up ______ Thus, airspaces are multiplicated by partitioning (**septation**).

Answer 51

the alveolar ducts.

Question 52

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Lung tissue becomes highly **vascular (vascularization).** → Lumen of bronchi and terminal bronchioles become larger. → By 24 weeks each terminal bronchiole has given rise to two or more respiratory bronchioles. → The respiratory bronchioles divide into 3 to 6 tubular passages called canaliculi that make up the alveolar ducts. → Thus, airspaces are multiplicated by \_\_\_\_

Answer 52

partitioning (**septation**).

Question 53

**Maturation of the lung -** **Canalicular period (16-25 weeks)** \_\_\_\_ develop at the end of respiratory bronchioles (**differentiation**)

Answer 53

Some thin-walled terminal sacs (primordial alveoli)

Question 54

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Some thin-walled terminal sacs (primordial alveoli) develop at the end of ____ (**differentiation**)

Answer 54

respiratory bronchioles

Question 55

**Maturation of the lung -** **Canalicular period (16-25 weeks)** Is respiration possible in this period? Will fetuses be survived?

Answer 55

Respiration is possible at the end of this period. Fetus born at the end of this period may survive if given intensive care (but often die because of the immaturity of respiratory as well as other systems)

Question 56

**Maturation of the lung -** **Saccular period (24 weeks-birth)** Many more ___ develop.

Answer 56

terminal sacs

Question 57

**Maturation of the lung -** **Saccular period (24 weeks-birth)** Many more terminal sacs develop. → The epithelial cells of the alveoli and the endothelial cells of the capillaries come in intimate contact and establish \_\_\_\_

Answer 57

the blood-air barrier.

Question 58

**Maturation of the lung -** **Saccular period (24 weeks-birth)** The terminal sacs are lined by \_\_\_- (2 types)

Answer 58

Squamous type I pneumocytes and Rounded secretory, type II pneumocytes, which secrete surfactant (a mixture of phospholipids and special proteins

Question 59

**Maturation of the lung -** **Alveolar period (32 weeks-8 years)** At the beginning of the alveolar period, each respiratory bronchiole terminates in \_\_\_\_\_, separated from one another by loose connective tissue.

Answer 59

a cluster of thin-walled terminal saccules

Question 60

**Maturation of the lung -** **Alveolar period (32 weeks-8 years)** At the beginning of the alveolar period, each respiratory bronchiole terminates in a cluster of thin-walled terminal saccules, separated from one another by loose connective tissue. → These terminal saccules represent \_\_\_\_\_

Answer 60

future alveolar sacs.

Question 61

**Maturation of the lung -** **Alveolar period (32 weeks-8 years)** What is **alveolization?**

Answer 61

terminal sacs

Question 62

**Development of the lung after birth** Growth of lungs after birth is due primarily to\_\_\_\_

Answer 62

increase of respiratory bronchioles and alveoli (not to the growth of the size of alveoli.)

Question 63

**Breathing movements of the fetus** Take ____ into the pulmonary tree

Answer 63

amnionic fluid

Question 64

**The role of surfactant proteins** Surfactant A?

Answer 64

activates macrophages to elicit uterine contractions

Question 65

**The role of surfactant proteins** Surfactant B?

Answer 65

the protein organizes into tubular structures, which are efficient at reducing surface tension

Question 66

**The role of surfactant proteins** Surfactant C?

Answer 66

enhances the functioning of surfactant phospholipids

Question 67

**The role of surfactant proteins** Surfactant D?

Answer 67

important in host defense