Pulmonary Respiration — Chapter 10

Question 1

Function of the pulmonary respiratory system

Answer 1

1. Provides a means of gas exchange between the environment and the body.
2. Regulation of acid-base balance during exercise.

Question 2

Definitions – ventilation and diffusion

Answer 2

Ventilation – the mechanical process of moving air into and out of lungs.

Diffusion – Process by which O2 moves out of lungs into the blood, and CO2 moves from blood into lungs.

Question 3

Purpose of the different zones of the respiratory system

Answer 3

Divided into 2 functional zones

Conducting Zone:

1. Conducts (moves) air through the trachea, bronchi, bronchioles, and terminal bronchioles to the respiratory zone.
2. Humidifies, warms, and filters the air (via mucus and macrophages)
   No exchange of gases b/t lungs and blood here

Respiratory Zone:

1. Exchange of gases between lungs and blood occurs in alveoli of respiratory bronchioles and in alveolar sacs.

Question 4

How many alveoli are estimated to exist in the lungs?

Answer 4

About 300 million alveoli

Question 5

Importance of the diaphragm for ventilation

Answer 5

Diaphragm initiates the pressure change inside lungs. It stimulates contraction several times per minute.

Question 6

Active vs. passive phases of ventilation

Answer 6

Inspiration (Active)
o Lowering the diaphragm expands the volume of the chest cavity, intrapulmonary pressure is decreased (2-3 mmHg below atmospheric pressure of 760 mmHg or 757 mmHg)

o Create a “vacuum”, allows air to flow into the bronchial passages.

Expiration (Passive)
o Diaphragm relaxes, elastic recoil of the alveoli raises the intrapulmonary pressure (about 763 mmHg)

o Air is forced out of lungs

Question 7

Average tidal volume and breathing frequency for healthy adult

Answer 7

0.5 L x 15 = 7.5 L/min

Question 8

Alveolar vs. dead-space ventilation

Answer 8

1. Alveolar ventilation (Va) (about 0.35 L out of 0.5 L)
   o Volume of “fresh air” that reaches the respiratory zone each minute.
2. Dead Space ventilation (Vd) (about 0.15 L out of 0.5 L)
   o Not all air that passes the lips reaches the respiratory zone (remains in conducting zone); this unused ventilation is called dead space ventilation.
    Inflammation = increases Vd

Question 9

Dalton’s law of partial pressures

Answer 9

The total pressure of a gas mixture is = to the sum of the pressure that each gas would exert independently.
o O2 = 20.93  159 mmHg
o CO2 = 0.03  0.3 mmHg
o N2 = 79.04  600.7 mmHg
Total = 100  760 mmHg

Question 10

Definition of diffusion

Answer 10

Random movement of molecules from high to low concentration.
o Gases diffuse from high to low partial pressure

Question 11

Definition of diffusion

Answer 11

Random movement of molecules from high to low concentration.
o Gases diffuse from high to low partial pressure

Question 12

Fick’s law of diffusion – factors that influence gas movement in the body

Answer 12

Rate of gas transfer across tissues depends on :
o Vgas = rate of diffusion
o A = tissue area
o T = tissue thickness
o D = diffusion coefficient of gas
o P1-P2 = difference in partial pressure of the gas on the 2 sides of the tissue