Chapter 15 – The Lung: Congenital Anomalies

Question 1

The lungs are ingeniously constructed to carry out their cardinal function:

Answer 1

the exchange of
gases between inspired air and blood

Question 2

Developmentally, the respiratory system is an outgrowth
from the ______________

Answer 2

ventral wall of the foregut.

The midline trachea develops two lateral outpocketings, the
lung buds.

Question 3

Which lung deveop with 3 branches?

Answer 3

The right lung bud eventually divides into three branches—the lobar bronchi—and
the left into two lobar bronchi,

thRee= RIGHT

Question 4

How many branches does the left lung has?

Answer 4

TWO

lefT

Question 5

Why are aspirated foreign materials, such as vomitus, blood, and foreign bodies, tend to
enter the right lung more than the left.

Answer 5

The right main stem bronchus is more vertical and more directly in line with the trachea.
Consequently, aspirated foreign materials, such as vomitus, blood, and foreign bodies, tend to
enter the right lung more than the left.

Question 6

The lobar right and left bronchi branch _______,
giving rise to progressively smaller airways.

Answer 6

dichotomously

Question 7

Describe the arterial supply of the lungs.

Answer 7

Accompanying the branching airways is the double
arterial supply to the lungs, that is, the pulmonary and bronchial arteries.

Question 8

What is the order of branching towards the lungs?

Answer 8

• bronchi
• bronchioles
• terminal bronchioles
• acinus
  
  • respiratory bronchioles
  • alveolar ducts and
  • alveolar sacs

Question 9

Differentiatebronchi forms bronchioles

Answer 9

which are distinguished from bronchi
by the lack of cartilage and submucosal glands within their walls.

Question 10

Further branching of
bronchioles leads to the____________

Answer 10

terminal bronchioles, which are less than 2 mm in diameter

Question 11

What is an acinus?

Answer 11

The part of
the lung distal to the terminal bronchioleis called the acinus; it isroughly spherical, with a
diameter of about 7 mm.

Question 12

An acinus is composed of :

Answer 12

• respiratory bronchioles (which give off several alveoli from their sides),
• alveolar ducts,
• and alveolar sacs

Question 13

What are alveolar sacs?

Answer 13

alveolar sacs, the blind ends of the
respiratory passages, whose walls are formed entirely of alveoli, which are the site of gas
exchange.

Question 14

Whta is a pulmonary lobule?

Answer 14

A cluster of three to five terminal bronchioles, each with its appended acinus, is
referred to as the pulmonary lobule.

This lobular architecture assumes importance in
distinguishing the major forms of emphysema

Question 15

What is the lining epithelium of the respiratory tree?

Answer 15

Except for the vocal cords, which are covered by stratified squamous epithelium, the entire
respiratory tree, including the larynx, trachea, and bronchioles, is lined by pseudostratified, tall,
columnar, ciliated epithelial cells.

Question 16

What can you find the the bronchial mucosa?

Answer 16

The bronchial mucosa also contains a population of
neuroendocrine cells that have neurosecretory-type granules and can release a variety of
factors, including serotonin, calcitonin, and gastrin-releasing peptide (bombesin).

Numerous
mucus-secreting goblet cells and submucosal glands are dispersed throughout the walls of the
trachea and bronchi (but not the bronchioles).

Question 17

Numerous
mucus-secreting goblet cells and submucosal glands are dispersed throughout the walls of the
trachea and bronchi and the bronchioles?

T or F

Answer 17

FALSE

Numerous
mucus-secreting goblet cells and submucosal glands are dispersed throughout the walls of the
trachea and bronchi (but not the bronchioles).

Question 18

The microscopic structure of the alveolar walls (or alveolar septa) consists, from blood to air, of
the following

Answer 18

• Capillary endothelium
• Basement membrane and surrounding interstitial tissue
• Alveolar epithelium
• Alveolar macrophages

Question 19

What separates the endothelial cells from the alveolar lining epithelial cells?

Answer 19

Basement membrane and surrounding interstitial tissue separating the endothelial cells
from the alveolar lining epithelial cells

Question 20

Describe thee difference between the thin portions of the alveolar septum from the thick portion of the alveolar septum.

Answer 20

. In thin portions of the alveolar septum, the
basement membranes of epithelium and endothelium are fused, whereas in thicker
portions they are separated by an interstitial space (pulmonary interstitium) containing
fine elastic fibers, small bundles of collagen, a few fibroblast-like interstitial cells, smooth
muscle cells, mast cells, and rarely lymphocytes and monocytes.

Question 21

What are the contents of the pulmonary interstitium?

Answer 21

(pulmonary interstitium) containing

• *fine elastic fibers, small bundles of collagen**, a few fibroblast-like interstitial cells, smooth
• *muscle cells, mast cells, and rarely lymphocytes and monocytes.**

Question 22

Describe the alveolar epithelium.

Answer 22

Alveolar epithelium, a continuous layer of two cell types: flattened, platelike type I
pneumocytes covering 95% of the alveolar surface and rounded type II pneumocytes.

Type II cells synthesize surfactant, contained in osmiophilic lamellar bodies seen with
electron microscopy, and are involved in the repair of alveolar epithelium through their
ability to give rise to type I cells.

Question 23

What are the two types of cells of the alveolar epithelium?

Answer 23

Alveolar epithelium, a continuous layer of two cell types:

Type I and Type II

Question 24

What is the type I pneumocyte?

Answer 24

flattened, platelike type I
pneumocytes covering 95% of the alveolar surface

Question 25

Describe the type II pneumocytes.

Answer 25

**rounded type II pneumocytes.** ## Footnote Type II cells **synthesize surfactant**, **contained in osmiophilic lamellar bodies** seen with electron microscopy, and are i**nvolved in the repair of alveolar epithelium** through their ability to give rise to type I cells.

Question 26

Describe the alveolar macrpphages?

Answer 26

Alveolar macrophages, loosely attached to the epithelial cells or lying free within the alveolar spaces, are derived from blood monocytes and belong to the mononuclear phagocyte system. Often, they are filled with carbon particles and other phagocytosed materials.

Question 27

What are pores of Kohn?

Answer 27

The alveolar walls are perforated by numerous pores of Kohn, **which permit the passage of** **bacteria** and **exudate between adjacent alveoli** (see Fig. 15-34B ). Adjacent to the alveolar cell membrane is the pulmonary surfactant layer.

Question 28

Answer 28

FIGURE 15-1 Microscopic structure of the alveolar wall. Note that the basement membrane (yellow) is thin on one side and widened where it is continuous with the interstitial space. Portions of interstitial cells are shown.

Question 29

Answer 29

FIGURE 15-34 Stages of bacterial pneumonia. **A, Acute pneumonia**. The congested septal capillaries and extensive neutrophil exudation into alveoli corresponds to early red hepatization. Fibrin nets have not yet formed. **B, Early organization** of intra-alveolar exudate, seen in areas to be streaming through the pores of Kohn (arrow). C, **Advanced organizing** **pneumonia** featuring transformation of exudates to fibromyxoid masses richly infiltrated by macrophages and fibroblasts

Question 30

Whta are the stages of bacterial pneumonia?

Answer 30

A, **Acute pneumonia**. The congested septal capillaries and extensive neutrophil exudation into alveoli corresponds to early red hepatization. **Fibrin nets have not yet formed.** B, **Early organization** of intra-alveolar exudate, seen in areas to be streaming through the pores of Kohn (arrow). C, **Advanced organizing pneumonia** featuring transformation of exudates to fibromyxoid masses richly infiltrated by macrophages and fibroblasts

Question 31

Congenital Anomalies Developmental defects of the lung include the following:

Answer 31

* Agenesis or hypoplasia of both lungs, one lung, or single lobes * • Tracheal and bronchial anomalies (atresia, stenosis, tracheoesophageal fistula) * • Vascular anomalies * • Congenital lobar overinflation (emphysema) * • Foregut cysts * • Congenital pulmonary airway malformation * • Pulmonary sequestrations

Question 32

more common anomalies are

Answer 32

* Pulmonary hypoplasia * Foregut cysts * Pulmonary sequestration

Question 33

What is pulmonary hypoplasia?

Answer 33

Pulmonary hypoplasia is the **defective development of both lungs**(**one may be more affected than the other**) resulting in**decreased weight, volume, and acini disproportional to the body weight and gestational age.** It is caused by a variety of abnormalities that compress the lung(s) or impede normal lung expansion in utero such as **congenital diaphragmatic hernia and oligohydramnions.**

Question 34

What is a foregut cyt?

Answer 34

Foregut cysts arise from an **abnormal detachment of primitive foregut** and **are most often located in the hilum or middle mediastinum.** **Depending on the wall structure, these cysts are classified as *bronchogenic (most common)****,****esophageal, or enteric***. A bronchogenic cyst is **rarely connected to the tracheobronchial tree.** Microscopically, the cyst is lined b**y ciliated pseudostratified columnar epithelium with squamous metaplasia occurring in areas of inflammation**. The wall contains bronchial **glands, cartilage, and smooth muscle**. Surgical resection is curative.

Question 35

What is pulmonary sequestration?

Answer 35

Pulmonary sequestration refers to the **presence of a discrete mass of lung tissu**e _***without normal connection to the airway system.***_

Question 36

blood supply of the sequestered areas arises from the pulmonary arteries. T or F

Answer 36

FALSE Blood supply to the sequestered area arises **not from the pulmonary arteries*****but from the aorta or its branches***

Question 37

What are the two types of sequestration?

Answer 37

* Extralobar sequestrations * Intralobar sequestrations

Question 38

What are extralobar sequestrations?

Answer 38

Extralobar sequestrations are **external to the lung** and **may be located anywhere in the thorax or mediastinum.** They **most** * *commonly come to attention in infants as abnormal mass lesions, and may be associated with** * *other congenital anomalies.**

Question 39

What are intralobar sequestrations?

Answer 39

Intralobar sequestrations **occur within the lung substance usually in** **older children** and **are often associated with recurrent localized infection or bronchiectasis.**