Lung: Week 1a

Question 1

What is the percent oxygen in dry air at sea level?

Answer 1

20.93%

Question 2

What is the partial pressure of O2 at sea level? What is the equation?

Answer 2

0.2093 x 760mmHg = 159mmHg

Question 3

What is the partial pressure of O2 inside the lung? Why is it different than in the air?

Answer 3

In the lung, water vapor pressure = 47mmHg

760mmHg - 47mmHg = 713mmHg

0.2093 x 713mmHg = 149mmHg

Question 4

What does Fick’s law state?

Answer 4

The amount of gas that moves across a sheet of tissue is proportional to the area of the sheet and inversely proportional to the thickness.

Question 5

How does inspired air move to the terminal bronchioles? How does it move in the respiratory zone?

Answer 5

It moves to terminal bronchioles by bulk flow. It then moves by diffusion in the respiratory zone.

Question 6

Why does the velocity of gas flow diminish greatly in the respiratory zone?

Answer 6

The total cross-sectional area increases tremendously.

Question 7

What are the two major zones of the respirator system?

Answer 7

The conducting zone and the respiratory zone.

Question 8

What is the volume of the anatomic dead space?

Answer 8

~150ml

Question 9

What is the volume of the alveolar region?

Answer 9

~2.5-3L

Question 10

How thick are the alveoli? How many alveoli are there, and what is the total surface area?

Answer 10

Alveoli are about 0.2-0.3 microns thick. There are about 500 million of them, and they have a total surface area of 50-100m^2

Question 11

What is the role of surfactant?

Answer 11

it lowers surface tension and prevents the alveoli from collapsing.

Question 12

Alveoli have no cilia, so how do they clear debris?

Answer 12

Particles that are deposited in the alveoli are engulfed by macrophages and removed by blood or lymphatic system.

Question 13

What is the tidal volume?

Answer 13

normal breathing

Question 14

what is vital capacity?

Answer 14

max inhale to max exhale

Question 15

What is residual volume?

Answer 15

What’s left after max exhale, the bit you can never get rid of.

Question 16

What is functional residual capacity?

Answer 16

amount left in lung after normal exhale.

Question 17

How can we measure functional residual capacity (FRC)?

Answer 17

use a known concentration of Helium, breath it in, and find new concentration.

Question 18

How can we measure TLC in older people?

Answer 18

plethysmograph

Question 19

What can a spirometer measure?

Answer 19

TV and VC

Question 20

What is the equation to measure total ventilation? What are the approximate values?

Answer 20

RR x TV

15 breaths/minute x 500ml = 7500ml/min

Question 21

What is the physiologic dead space? What is Anatomic Dead Space?

Answer 21

Physiologic: volume of gas that does not eliminate CO2.

Anatomic: volume of conducting airways, ~150ml

Question 22

How are the physiologic and anatomic dead spaces related in healthy people? How can they change with lung disease?

Answer 22

In healthy people, PDS = ADS

In lung disease, PDS > ADS

Question 23

How many tertiary bronchial divisions and lobes are there in the R lung? The L lung?

Answer 23

R lung: 3 lobes, 10 tertiary divisions

L lung: 2 lobes, 8 tertiary divisions

Question 24

When is the pseudoglandular period? What happens then?

Answer 24

5-16 weeks. branching has continued to form terminal bronchioles. no respiratory bronchioles or alveoli are present.

Question 25

When is the canalicular period? What happens then?

Answer 25

16-26 weeks. each terminal bronchiole divides into two or more respiratory bronchioles, which in turn divide into 3-6 alveolar ducts.

Question 26

When is the terminal sac period? What happens then?

Answer 26

26 weeks to birth. terminal sac with primitive alveoli form, and capillaries establish close contact.

Question 27

When is the alveolar period? What happens then?

Answer 27

8months to childhood. terminal sacs form, and capillaries establish close contact.

Question 28

How many of the adult number of alveoli are present at birth?

Answer 28

1/6

Question 29

What is the respiratory tract an outgrowth of?

Answer 29

ventral wall of foregut

Question 30

What does the endoderm give rise to? Mesoderm?

Answer 30

Endoderm: epithelium or larynx, trachea, bronchi and alveoli

Mesoderm: cartilaginous, muscular and connective tissue components.

Question 31

What gene is affected by cystic fibrosus?

Answer 31

CFTR (cystic fibrosis transmembrane regulator)

Question 32

What are the types of CFTR mutations that can lead to CF?

Answer 32

a. no synthesis
b. block in processing (deltaF508 is the most commone, >70%)
c. block in regulation
d. altered conductance
e. reduced synthesis

Question 33

How do infections spread in CF?

Answer 33

mucus layer gets very thick and bacteria hide in there. Cytokines are released, IL-8 goes up and attracts neutrophils. When neutrophils die, they release lots of bad stuff.

Question 34

What is Kartagener syndrome?

Answer 34

An immotile cilia syndrome. It’s a genetic disease, and a form of primary ciliary dyskinesia.

Question 35

How is malnutrition associated with lung disease?

Answer 35

low birth weight is associated with impaired lung function in adults, COPD and asthma

Question 36

What is alpha-1 antitrypsin deficiency?

Answer 36

a disease that carries a genetic predisposition (mutation in SERPINA 1 with M, Z, S alleles), but smoking is what makes it happen. Smoking increases presence of neutrophils, neutrophils create the elastase (this is the really bad stuff), and the alpha-1 antitrypsin inhibits elastase. So an lapha-1 antitrypsin deficiency is bad.