Histo block I: resp sys- alveoli

Question 1

what are alveolar ducts and their epithelium?

Answer 1

are linear arrangement of alveoli with “knobs” of smooth muscle and simple cuboidal epithelium present between alveoli

Question 2

what are alveolar sacs?

Answer 2

clusters of alveoli at the end of alveolar ducts

Question 3

what are alveolar pores of Kohn?

Answer 3

openings between adjacent alveoli

Question 4

which are the sites of gas exchange ?

Answer 4

Alveolus (Alveoli is plural)

Question 5

alveolus constitutes for how many structural units?

Answer 5

The terminal air spaces, primary structural and functional units (150-250 million per adult /lung).

Question 6

what is the interstitium?

Answer 6

in the alveolus; interalveolar septum abundant continuous capillaries.

Question 7

The alveolar epithelium is composed of:

Answer 7

1. Type I pneumocytes or alveolar cells (40%)
2. Type II pneumocyte or alveolar cell (also called septal cell) (60%)
3. Brush cells

Question 8

describe the Type I pneumocytes or alveolar cells and function

Answer 8

Extremely thin squamous cells with many
occluding junctions. Line most (95%) of
surface area. Gases diffuse through the cell.

Question 9

describe Type II pneumocyte or alveolar cells also called septal cell and function

Answer 9

Are secretory cells.
Cover only 5% of surface area.
Cuboidal cells at septal junctions.
Secrete surfactant from lamellar bodies (decreases surface tension).
Four types of surfactant proteins and phospholipids

Question 10

which are the progenitor cells for type I alveolar cells?

Answer 10

Type II alveolar cells

Question 11

function of brush cells in alveolus

Answer 11

(very few) They may serve as receptors that monitor air quality in the lung.

Question 12

identify

Answer 12

alveolus

Question 13

which is the most important lipidic component of the surfactant?

Answer 13

Dipalmitoylphosphatidylcholine (DPPC)

Question 14

WHich surfactant proteins are present and their function

Answer 14

(SP- A,B,C,D); organize surfactant secreated and immunologic function to attack microorganisms in that region

Question 15

what is the function of surfactant?

Answer 15

decreases the alveolar surface tension and actively participates in the clearance of foreign materials.

Question 16

identify

Answer 16

type II pneumocyte alveolar cell with lamellar bodies

Question 17

identify

Answer 17

SC= septal cells = Type II alveolar = Type II pneumocyte

Question 18

where does the actual site of gas exchange occur?

Answer 18

In the blood-air barrier present in the alveolar septum

Question 19

the blood-air barrier is made of?

Answer 19

Is made of thin layer of surfactant, type I pneumocyte and basal lamina and endothelium of capillaries and basal lamina.

Question 20

what are the regions of the blood-air barrier?

Answer 20

1. thin
2. thick

Question 21

describe the thin region of the blood-air barrier

Answer 21

thin layer of surfactant, type I pneumocyte and basal lamina and endothelium of capillaries and 2 basal lamina fused; passive difussion gases

Question 22

describe the thick region of the blood-air barrier

Answer 22

some connective tissue (CT) between basal lamina, site of fluid transfer. Lymphatic vessels in the CT of the terminal bronchioles drain fluid that accumulates in the thick portion of the septum

Question 23

identify

Answer 23

Electron micrograph of the interalveolar septum

Question 24

Describe the alveolar macrophage and where is it found

Answer 24

Part of the mononuclear phagocytotic system. Can be found in the septum and in the lumen of the alveolus

Question 25

What are the functions of the alveolar macrophage or dust cell?

Answer 25

▪
Phagocytize particles. In congestive heart failure phagocytize RBC, sometimes called congestive heart failure cells. Swept to pharynx and swallowed along with mucous
▪
Alveolar macrophages also phagocytose infectious organisms such as Mycobacterium tuberculosis. These bacilli are not digested by macrophages; conditions that damage alveolar macrophages can cause release of the bacteria and recurrent tuberculosis.
▪
Recent evidence suggests that apoptosis of septal macrophages contributes to the development of emphysema

Question 26

macrophages migrate to where?

Answer 26

back to the alveolar septa where they remain through life

Question 27

presence of lymphocytes indicates?

Answer 27

inflammatory response

Question 28

Septal macrophages are loaded with _______ __________ _________

Answer 28

black cytoplasmic inclusions

Question 29

hemosiderin comes from?

Answer 29

phagocytosed red blood cells

Question 30

innervation to the airways and blood vessels (smooth muscle_ are:

Answer 30

1. sympathetic
2. parasypathetic

Question 31

how is the blood supply of the respiratory system?

Answer 31

 Pulmonary arteries (gas exchange)
 Bronchial arteries (nutrients to parenchyma of lung)

Question 32

what is the pleura?

Answer 32

visceral and parietal mesothelium and connective tissue

Question 33

describe lymphatics of the respiratory system

Answer 33

Dual systems parallel blood vessels
Extensive in pleura and lungs
(particularly at time of birth)

Question 34

explain cystic fibrosis

Answer 34

Cystic fibrosis (CF, mucoviscidosis) It is an autosomal recessive disorder caused by a mutation in a gene called thecystic fibrosis transmembrane conductance regulator (CFTR)located on chromosome 7.
*
The product of this gene, theCl−channel protein, is involved in final alteration of mucus.
*
All mutations of CFTR gene result in abnormal epithelial transport of Cl−that affects the viscosity of the secretion of the exocrine glands.
*
Individuals with cystic fibrosis have frequent respiratory tract infections.
*
Gene therapy treatment: recently a type of virus called a lentivirus, has been used to deliver a healthy copy of a gene called CFTR

Question 35

what is Chronic obstructive pulmonary disease (COPD)?

Answer 35

pulmonary condition characterized by chronic obstruction of airflow

Question 36

What are the subtypes of COPD and causes

Answer 36

Subtypes of COPD include: chronic bronchitis, chronic obstructive asthma, and emphysema. The destruction of the alveolar wall may be associated with excess lysis of elastin and other structural proteins in the interalveolar septa.

Question 37

explain emphysema

Answer 37

Elastase and other proteases are derived from lung neutrophils, macrophages, and monocytes. A specific genetic disease, α1-antitrypsin deficiency, causes a particularly severe form of emphysema. Its severity can be reduced by supplying the enzyme inhibitor exogenously

Question 38

explain pneumonia

Answer 38

Pneumonia is a generic term that describes inflammation of the lung. It is often caused by viruses and bacteria. Some drugs (immunosuppressive agents) and autoimmune diseases increase the risk of certain types of pneumonia
*
In the earliest stage of bacterial pneumonia, protein-rich fluid containing numerous microorganisms fills the lung alveoli. Marked enlargement of the capillaries surrounding the alveoli is followed by a massive migration of neutrophils and erythrocytes into the alveolar air space.
*
In the later stage, macrophages phagocytose the fragmented neutrophils and other cellular and tissue debris; the alveolar exudate is then removed, the alveolar spaces gradually become refilled with air, and the lungs return to their normal function.

Question 39

identify

Answer 39

Emphysema is a condition of the lung characterized by permanent enlargement of the air spaces distal to the terminal bronchiole. The changes in the lung parenchyma are accompanied by thickening of the wall of the pulmonary vessels (arrows) and the presence of numerous cells within the air spaces. It is characterized by exhalation being twice as long as inhalation

Question 40

identify

Answer 40

Pneumonia image of the lung of an individual in the early stages of acute pneumonia (inflammation of the lung). The air spaces are filled with exudate containing white blood cells (mainly neutrophils), red blood cells, and fibrin.

Question 41

when does surfactant synthesis occur in fetuses?

Answer 41

The surfactant produced by type II alveolar cells reduces the surface tension. Surfactant synthesis in the fetus occurs after the 35th week of gestation and is modulated by a variety of hormones, including cortisol, insulin, prolactin, and thyroxine. Without adequate secretion of surfactant, the alveoli would collapse on each successive exhalation.

Question 42

Which is the most critical agent for air space stability?

Answer 42

a specific phospholipid called dipalmitoylphosphatidylcholine (DPPC), which accounts for almost all surface tension–reducing properties of surfactant.

Question 43

what happens to preterm infants?

Answer 43

there is not enough surfactant production and neonatal respiratory distress syndrome (RDS) can occur. It is also know as Hyaline Membrane Disease. Administration of exogenous surfactant at birth to preterm infants reduces the incidence of RDS.

Question 44

what can decrease neonatal mortality?

Answer 44

antenatal administration of corticosteroids (glucocorticoids) to women with threatened preterm delivery

Question 45

identify

Answer 45

Respiratory Distress Syndrome = Hyaline Membrane Disease