HE 20 Respiratory II

Question 1

What are type 1 pneumocytes?

Answer 1

Squamous cells in the alveoli
Very thin
Line majority of the alveolar lumen
Joined to each other by tight junctions
Non-mitotic

Question 2

What makes up the interalveolar septum (blood-air-barrier)?

Answer 2

Type I alveolar cells
Type I capillary endothelium
Fused basal lamina between the two
These are the layers that O2 must pass through to get to the blood.

Question 3

What is ARDS and it causes?

Answer 3

Adult Respiratory Distress Syndrome
Inhaled toxic fumes or hot vapors damage alveoli or bacteria in the blood from sepsis damages the endothelial cell.
Either way, the septum is damaged and fluid can leak out of the vessels into the alveolar lumen. A hyaline membrane also builds up over the damaged area.
Causes acute respiratory failure.

Question 4

What are septal cells?

Answer 4

Type II alveolar cells
Cuboidal
Stem cells of the alveoli
Secrete surfactant
Located at the junctions of alveoli
Help with anti-bacterial-viral-fungal
Involved in inflammatory response

Question 5

What are dust cells?

Answer 5

In the alveolus
Originate from monocytes
Phagocytosis: irritants, particulate, microorganisms, surfactant
Antigen presentation

Question 6

What ensures patency in the alveoli?

Answer 6

Structural from elastic fibers

Chemical from surfactant

Question 7

What epithelial cells are present in the respiratory branches of the lungs and not in the other parts?

Answer 7

Squamous epithelium.

The simple squamous cells are the type 1 alveolar cells that line the alveoli and allow for gas exchange to occur.

Question 8

What is the last branch to have all cuboidal epithelial cells?

Answer 8

Terminal bronchiole because it is the smallest branch that does not participate in gas exchange.

Question 9

What are the three types of cells that serve as stem cells in the respiratory tract?

Answer 9

Basal Cells down to the bronchi
Clara cells in bronchioles (including resp. bronchioles)
Type II alveolar cells in the respiratory structures including resp. bronchioles

Question 10

What is the last structure to have cuboidal cells?

Answer 10

respiratory bronchioles

Question 11

What is the only structural difference between alveolar duct and sac?

Answer 11

The duct has slips of smooth muscle and the alveolar sacs do not have smooth muscle.

Question 12

Epidermis comes from which germ layer?

Answer 12

Surface ectoderm

Question 13

The CNS and PNS come from what embryonic germ layers?

Answer 13

CNS from neural tube

PNS from neural crest

Question 14

What germ layers for the epithelium of the GI tract and respiratory systems?

Answer 14

Endoderm

Question 15

What does intermediate mesoderm become?

Answer 15

Urinary and reproductive systems

Question 16

What germ layer gives rise to the dermis?

Answer 16

Dermatome which comes from mesoderm

Question 17

What germ layer produces the axial skeleton?

Answer 17

Sclerotome from paraxial mesoderm (somites)

Question 18

Where does skeletal muscle come from?

Answer 18

Myotome

Question 19

What germ layer forms the bones, cartilage and general CT of the body wall and limbs?

Answer 19

parietal mesoderm from the lateral plate

Question 20

What does visceral mesoderm become?

Answer 20

cardiac, smooth muscle, general CT (organs), circulatory system

Question 21

What is the most common complication during the formation of the lungs (respiratory diverticulum) from the gut tube early in embryonic development?

Answer 21

Superior portion of esophagus separates from trachea but the inferior portion does not. This creates esophageal atresia (a blind esophagus superiorly) and tracheoesophageal fistula where the inferior portion of the esophagus is attached to the trachea.

Question 22

What are the symptoms or signs in a baby of esophageal atresia with tracheoesophageal fistula?

Answer 22

Polyhydramnios prenatally because baby can’t swallow
Can’t drink milk postnatally
Stomach juices in the lungs

Question 23

By what gestational age have the secondary and tertiary bronchi formed?

Answer 23

By week 8

Question 24

By week 16, what respiratory structures have formed and what is the name of this period?

Answer 24

Trachea down to the terminal bronchioles. No respiratory portions have formed quite yet. Called the pseudoglandular period.

Question 25

What is the period from 16 weeks to 26-28 weeks development and what is it called?

Answer 25

Canalicular period
Development down to respiratory bronchioles, but still no gas exchange possible at this point. Surfactant is secreted by clara cells.
Capillaries not associated with the structures

Question 26

When does surfactant begin to be secreted?

Answer 26

Week 20

Question 27

What is the name of the last period of lung development in a fetus, when is it, and what happens?

Answer 27

Terminal sac period
26-28 weeks until birth
Terminal sacs or primitive alveoli form with simple squamous epithelium.
Capillaries now associated with the primitive alveoli.
Blood-air barrier established

Question 28

What is the lung development period after birth called, how long does it last, and what happens during this time?

Answer 28

Alveolar period
Birth to 8-10 years
At birth, the alveoli are primitive and dense. During this time they greatly multiply and mature into the open and lacy appearing adult alveoli.

Question 29

What are the two pleura in the lungs and how are they innervated?

Answer 29

Visceral which lines the lungs, comes from visceral mesoderm and is innervated by autonomic nerves.
Parietal pleura lines the body wall, came from parietal mesoderm? and is innervated by somatic nerves