Trachte- Structure and Function

Question 1

How do gasses move across the blood gas interface?

Answer 1

By diffusion

from HIGH pressure to LOW pressure)

Question 2

How does oxygen move from air to blood?

Answer 2

Pp oxygen in the air = 150 mmHg

Pp oxygen in venous blood (pulmonary arterial) = 40 mmHg

SO oxygen wants to move from air to venous blood

Question 3

How does Carbon dioxide move from blood to air?

Answer 3

Pp of CO2 in air = almost zero

Pp of CO2 in venous blood = 46 mmHg

CO2 wants to diffuse from BLOOD to AIR

Question 4

Gas movement across a barrier depends on what two characteristics?

Answer 4

CROSS SECTIONAL AREA of the barrier

Inversely proportional to the THICKNESS of the barrier

Question 5

What is the cross sectional area of the barrier?

Answer 5

50- 100 m2

Capillaries wrapped around 500 million alveoli (tiny sacs containing air)

Question 6

What is the thickness of the alveolar walls?

Answer 6

exceptionally small!

Less than 1 u

Question 7

Describe the path of the pulmonary airway.

Answer 7

Trachea
right and left bronchi
lobar bronchi
segmental bronchi
terminal bronchioles (smalles airways w/out alveoli)

Question 8

What are the conducting airways composed of? What are they involved in?

Answer 8

trachea to the terminal bronchioles

Conduct air but are NOT involved in GAS EXCHANGE

Question 9

What are the gas concentrations in the conducting airways that are essentially anatomic dead space?

Answer 9

about 150 ml

similar to atm except that the air is humidified

Question 10

What is the respiratory zone?

Answer 10

TERMINAL BRONCHIOLES divide into respiratory bronchioles

Respiratory bronchioles lead to ALVEOLAR DUCTS (completely lined with alveoli

Question 11

What initiates airflow in the lungs and what path does it follow?

Answer 11

Expansion of thoracic cavity (diapragm and intercostals contract)>
air flows down to the terminal bronchioles>
distal sections rely on DIFFUSION of gases

Question 12

Where will dust settle?

Answer 12

In the terminal bronchioles NOT the alveoli

Question 13

Describe the compliancy of the lung.

Answer 13

VERY compliant (change in V/change in P)

500 ml/3 cm water (2.1 mmHg)

Flow rate is 1 L/sec only experiences a drop in pressure of 2 cm water

since P = flow x resistance, this means R = 2 cm water/L/sec

Question 14

What is the blood flow in the lung?

Answer 14

Pulmonary artery>
capillaries>
pulmonary veing

Question 15

Why is the lung vasculature susceptible to damage? What causes damage?

Answer 15

the walls are THIN

Increased CAPILLARY PRESSURE

increased ALVEOLAR PRESSURE

Question 16

How much time do RBCs spend in pulmonary capillaries?

Answer 16

Less than a SECOND but they can equilibrate almost completely in that time span!

Question 17

What is the source of bronchial circulation?

Answer 17

Systemic side (aorta) and supplies the conducting airways

Question 18

What prevents alveoli from collapsing?

Answer 18

SURFACTANT reduces surface tension and prevents alveolar collapse

Alveoli are 500 million bubbles that WANT to COLLAPSE when they are SMALL.

Question 19

What happens to inhaled particles?

Answer 19

They’re filtered through the NOSE

Can be moved toward the mouth by a MUCOUS CILIARY ELEVATOR

Can be engulfed by MPHAGES (usually in alveoli)