Respiratory Pathophysiology

Question 1

Functional anatomy can be divided into 3 categories

Answer 1

Conducting zone: tube for gas exchange sites
(Includes all respiratory structures that do not participate in gas exchange)
Respiratory zone: site of gas exchange
Respiratory muscles: diaphragm and other muscles that promote ventilation

Question 2

Conducting Zone Structures

Answer 2

Trachea: R/L main bronchi
Each main bronchus enters the hilum of one lung
Each main bronchus branches into lobar (secondary) bronchi
Each lobar bronchus branches into segmental (tertiary) bronchi

Question 3

Respiratory Zone Structures

Answer 3

Respiratory bronchioles, alveolar ducts, alveolar sacs (clusters of alveoli)
300 million alveoli account for most of the lungs’ volume and are the main site for gas exchange

Question 4

Atmospheric pressure (Patm)

Answer 4

Pressure exerted by the air surrounding the body

760 mm Hg at sea level

Question 5

Respiratory pressures are described relative to Patm… -, +, 0

Answer 5

Negative respiratory pressure is less than Patm
Positive respiratory pressure is greater than Patm
Zero respiratory pressure = Patm

Question 6

Intrapulmonary (intra-alveolar) pressure (Ppul)

Answer 6

Pressure in the alveoli
Fluctuates with breathing
Always eventually equalizes with Patm

Question 7

Intrapleural pressure (Pip)

Answer 7

Pressure in the pleural cavity
Fluctuates with breathing
Always a negative pressure (<Ppul)

Question 8

The transpulmonary pressure

Answer 8

(Ppul – Pip) = transpulmonary pressure
Keeps the lungs open
The greater the transpulmonary pressure, the larger the lungs

Question 9

Atelectasis (lung collapse) is due to either

Answer 9

Lack of air delivery: Plugged bronchioles lead to collapse of alveoli
Lack of integrity of the pleura: Wound that allows air entry into pleural cavity (pneumothorax)

Question 10

Boyle’s Law

Answer 10

Inspiration: As volume increases pressure decreases (must be active)
Expiratoin: As volume decreases, pressure increases (can be passive)

Question 11

Inspiratory muscles overcome three factors that hinder air passage and pulmonary ventilation

Answer 11

Airway resistance
Alveolar surface tension
Lung compliance

Question 12

Dalton’s Law of Partial Pressures

Answer 12

Total pressure exerted by a mixture of gases is the sum of the pressures exerted by each gas
P1+P2= total pressure

Question 13

Henry’s Law

Answer 13

Gas will dissolve in a liquid in proportion to its partial pressure

The amount of gas that will dissolve in a liquid also depends on it’s solubility and temp of the liquid:
CO2 is 20 times more soluble in water than O2
Very little N2 dissolves in water

Question 14

high CO2 bronchioles

Answer 14

dilate

Question 15

Low CO2 bronchioles

Answer 15

constrict

Question 16

In arterial blood % of saturated hemoglobin.

Answer 16

Po2 = 100 mm Hg

Hb is 98% saturated

Question 17

% of saturated hemoglobin In venous blood

Answer 17

Po2 = 40 mm Hg

Hb is 75% saturated

Question 18

CO2 is transported in the blood 3 ways

Answer 18

Dissolved in plasma (7-10%)
Bound to hemoglobin (carbaminohemoglobin) (20%) (Binds on a different site compared to O2)
Transported as bicarbonate ions (HCO3–) in plasma (70%)

Question 19

Transport and exchange of CO2 in the pulmonary capillaries

Answer 19

HCO3– moves into the RBCs and binds with H+ to form H2CO3
H2CO3 is split by carbonic anhydrase into CO2 and water
CO2 diffuses into the alveoli

Question 20

Haldane Effect

Answer 20

The amount of CO2 transported is affected by the Po2

The lower the Po2 and hemoglobin saturation with O2, the more CO2 can be carried in the blood