Respiratory System

Question 1

Which structures are involved in pulmonary defense systems?

Answer 1

Olfaction, filtration (cilia and mucus), alveolar macrophages and neutrophil recruitment

Question 2

Regions of the tracheobronchial tree NOT involved in gas exchange

Answer 2

Trachea, bronchi, bronchioles, terminal bronchioles

Question 3

Regions of the tracheobronchial tree that ARE involved in gas exchange

Answer 3

Respiratory bronchioles, alveolar ducts, alveolar sacs

Question 4

Layers to pass through for gas exchange

Answer 4

Thin epithelium of alveoli, parenchyma and blood vessel wall (goes through via diffusion)

Question 5

Factors that affect rate of gas diffusion

Answer 5

Diffusion coefficient of the gas, membrane thickness, surface area of membrane, partial pressure difference between sides of membrane

Question 6

What is shunt flow?

Answer 6

The flow of blood to supply the pulmonary system (lungs and alveoli). It is not exposed to gas exchange.
It is also the act of shifting where blood flow goes in result to lack of gas exchange

Question 7

What is Dalton’s Law (state and describe in cases of dry and humid)

Answer 7

Px = (Pb) * Fx   ---- Dry
Px = (Pb - 47mmH [water vapor pressure]) * Fx   ----- Humid

Know that PO2 in humid environment (during inspiration) is less than in the dry environment

Question 8

Draw the lung volume and capacity chart describing volumes of air in lungs

Answer 8

Should include: inspiratory reserve volume, expiratory reserve volume, residual volume, tidal volume, inspiratory capacity, vital capacity, functional residual capacity, and total lung capacity

Question 9

Intrapulmonary pressure

Answer 9

Pressure within the pleural cavity (where gas exchange occurs)

Question 10

Intrapleural pressure

Answer 10

Pressure within pleural cavity (between lung and thoracic wall)

Question 11

Transpulmonary pressure

Answer 11

Difference between Intrapulmonary and Intrapleural pressure

Question 12

Pressure balances at rest

Answer 12

Pressure along tracheobronchial tree is atmospheric
Recoil of lung and chest are equal but opposite (wall wants expansion, lung wants contraction)
Intrapleural pressure is negative
Transpulmonary pressure = 0

Question 13

Pressure balance during inspiration

Answer 13

Alveolar pressure (intrapulmonary pressure) becomes lower, forcing chest to expand (but increases during inhalation)
Transpulmonary pressure is more negative
Intrapleural pressure is more negative

Question 14

Pressure balance during exhalation

Answer 14

Recoil of lung causes alveolar pressure to increase
Transpulmonary pressure is less negative
Intrapulmonary pressure increases but begins to decrease
Intrapleural pressure increases (less negative)

Question 15

Define compliance and give equation

Answer 15

Measure of lung expandability
C = dV/dP
More compliant = easier to inhale, more difficult to exhale (emphysema)
Less compliant = more difficult to inhale, easier to exhale (fibrosis)

Question 16

What is surfactant and what is its purpose?

Answer 16

Produced by alveolar type II cells
Decreases surface tension and prevents collapse at the end of expiration
Allows for structural dependence

Question 17

Describe structural independence

Answer 17

Surfactant allows the local reduction of surface tension to allow an alveolus that may have a smaller radius (and therefore increased pressure and harder to inflate) to be easier to inflate. Allows a sort of equilibrium between alveoli with each one maintaining its size and ability to participate in gas exchange.

Question 18

Pressures during forced expiration

Answer 18

Intrapulmonary pressure decreases
Intrapleural pressure increases (less negative and becomes positive)
Transpulmonary pressure increases to force air out
Chance of collapse where intrapleural pressure = intrapulmonary pressure
(when transpulmonary pressure = 0)

Question 19

Describe COPD

Answer 19

Chronic obstructive pulmonary disorder
Loss of alveolar wall = decreased elastic recoil and increased compliance
Increased chance of collapse during expiration

Question 20

Series of events that occur during airway obstruction concerning ventilation-perfusion relationships

Answer 20

In response to reduced ventilation without change in perfusion (hypoxia), hypoxic vasoconstriction reduces the local blood flow. The local reduced blood flow shunts more blood to areas of lungs that can still participate in gas exchange.

Question 21

What are the primary causes of hypoxia

Answer 21

1. Reduced inspired O2
2. Reduced diffusion through alveolar membrane (asbestosis)
3. CO (greater affinity to Hb than O2)
4. Anemia (tissue hypoxia)
5. Anemia + CO
6. Physiologic shunt

Question 22

How does anemia result in tissue hypoxia?

Answer 22

The saturation of Hb is the same – arterial PO2 does not decrease

Volume of O2 held and therefore transferred to tissue lowers – not as much oxygen is being given to tissue = tissue hypoxia

Question 23

How are levels of breathing controlled under normal conditions?

Answer 23

Controllers: neural circuitry required to generate each breath
Effectors: muscles of respiration
Sensors: regulate rate of ventilation

Question 24

Example of breathing controllers

Answer 24

Cerebrum, brainstem, spinal cord, reflexes

Question 25

Examples of breathing effectors

Answer 25

Diaphragm, lungs

Question 26

Example of breathing sensors

Answer 26

Central medullary (CO2 - brainstem neurons) and peripheral (O2 - carotid and aortic bodies)