Pulmonary System and Lung Development

Question 1

Zones of the airway?

Generations that make up the zones?

Answer 1

conducting zone (16 generations)

transitional/respiratory zone (7 )

23 generations total

Question 2

lung stages of development

Answer 2

EPCSA

embryonic

pseudoglandular

canalicular

Saccular

Alveolar

Question 3

Days:
embryonic

pseudoglandular

canalicular

Saccular

Alveolar

Answer 3

embryonic
- 26 days - 6 weeks

pseudoglandular
- 6 weeks - 16 weeks

canalicular
- 16 weeks - 28 weeks

Saccular
- 28 weeks - 36 weeks

Alveolar
- 36 weeks - 6 yrs old

Question 4

Embryonic stage of development

• how does it form?
• how many rounds of branching?
• what structures are formed?

Answer 4

foregut endoderm extends into surrounding mesenchyme and mesoderm
- branching pattern determined by mesoderm

3 rounds of branching

proximal struc of tracheobronchial tree - bronchiole

Question 5

Pseudoglandular stage of development

• how many rounds of branching?
• what structures are formed?

Answer 5

14 rounds of branching from terminal bronchioles

formation of conducting airways completed at end of pseudo stage (cartilage, sm, mucous glands)

Question 6

Canalicular stage of development

- what structures are formed?

Answer 6

terminal bronchioles (comp at end of pseudo) divides into 2+ resp bronchioles

Surfactant begins

Question 7

Saccular stage of development

• what structures are formed?
• hallmark?

Answer 7

respiratory bronchioles (comp at end of canalicular stg) subdivides into terminal sacs (which continue developing into childhood)

epithelial cell diferentiation is hallmark (type I and II pneumocytes) - cont into alveolar stg

Question 8

What stage of development is fetal breathing detected?

Answer 8

canalicular stage 16-28 weeks

Question 9

What is the earliest stage that a fetus survive?

Answer 9

Canalicular poss but w resp distress syndrome

Question 10

inspiratory muscles:

Answer 10

1. Diaphragm
   
   2. External intercostals
      a. Pulling ribs forward and outward
   3. SCM + Scalenes
      a. Their function is to elevate the rib cage.

Question 11

expiratory muscles

Answer 11

During normal breathing, expiration is passive, as no muscle movement is necessary for it to occur.

1. M in abdominal wall
	a. Push diaphragm upwards
2. Internal intercostals
	a. Pulls ribs in and downward (↓ing thoracic vol)

Question 12

How would the diaphragm be during obstructive diseases?

Answer 12

Ob diseases: cant exhale all air out, breath at higher lung volumes, diaphragm is more contracted (shorter)

Question 13

Compliance

Answer 13

how easily an applied pressure induces a volume change

C, provides a measure of the elastic properties of the lung • Compliance is inversely proportional to the elasticity of the lung.

Question 14

Do restrictive diseases have an increase or decrease in compliance? What would this do to inspiration?

Answer 14

decrease
- restrictive diseases like pulm fibrosis are more diff to inflate bc lungs are more rigid

decreases inspiration

Question 15

Does emphysema have an increase or decrease in compliance? What would this do to EXpiration?

Answer 15

Emphysema = obstructive
increase in compliance,
decreases expiration

Question 16

what does the p-v curve look like for emphysema? pulm fibrosis?

Answer 16

emphysema: up and to LEFT

Pulm fibrosis (restrictive): down and to RIGHT

Question 17

3 things that decrease chest wall compliance?

Answer 17

old age
obesity
scar tissue

Question 18

surface tension leads to decreased or increased lung compliance?

Answer 18

decreased since it tends to make alveoli smaller and water can accumulate in the lung.

Question 19

In respiratory distress syndrome, and pulm edema, are there more or less surfactant? What does this do to surface tension?

Answer 19

Less –> suffer form effects of increased surface tension