Overview of Respiratory Physiology

Question 1

What is the primary function of the respiratory system?

Answer 1

Exchange of O2 and CO2 between the body and the environment

Question 2

What are the five secondary functions of the respiratory system?

Answer 2

1) maintenance of acid-base balance
2) heat exchange
3) voice production
4) smell
5) filtering and activation/inactivation of circulating substances

Question 3

What are the mechanisms by which the respiratory system is organized?

Answer 3

1) Central controlling mechanism for regulating ventilation
2) Air pump that delivers fresh air to the lungs
3) A surface for gas exchange (lungs)
4) A circulatory system
5) Regulating ventilation and perfusion
6) System for carrying O2 and CO2 in the blood

Question 4

What components of the nervous system control breathing?

Answer 4

1) Central pattern generator
2) Outputs that stimulate muscles of respiration
3) central and peripheral chemoreceptors for pH, PaCO2, PaO2
4) Integrating that processes feedback from chemoreceptors

Question 5

What is the driving force of respiration?

Answer 5

The PaCO2

Question 6

What is the typical desired condition of the chest wall?

Answer 6

Expanded

Question 7

What is the typical desired condition of the lungs?

Answer 7

Contracted

Question 8

What is the result of the difference in desired conditions between the chest wall and the lungs?

Answer 8

A negative pleural pressure begins and the lungs are forced to expand

Question 9

What are the relationships between the alveolar and atmospheric pressures that induces inhalation?

Answer 9

The pressure of air in the atmosphere is higher than the pressure in the alveoli

Question 10

What are the relationships between the alveolar and atmospheric pressures that induces expiration?

Answer 10

The pressure of air in the alveolar is higher than the pressure in the atmosphere

Question 11

How do the lungs express compliance?

Answer 11

Lungs and the chest wall should expand when air is inhaled

Question 12

How does resistance appear in the respiratory system?

Answer 12

If any portion of the bronchial tree has a smaller radius, the resistance through that vessel will be higher.

Question 13

How is compliance calculated?

Answer 13

Change in volume/change in pressure

Question 14

How is resistance calculated?

Answer 14

change of pressure/change of flow

Question 15

What is the effect of pulmonary fibrosis on the lung’s compliance?

Answer 15

It will reduce compliance

Question 16

What is the effect of asthma on the lung’s resistance?

Answer 16

It will increase resistance

Question 17

What is the effect of emphysema on the lung’s compliance?

Answer 17

It will increase compliance

Question 18

What is the effect of ALS on the lung?

Answer 18

It decreases the capacity to decrease pleural pressure by weakening the diaphragm

Question 19

How should ventilation and perfusion be coordinated in the lung?

Answer 19

Ventilation and perfusion in the lung are matched–blood and air will be in the same place at the same time

Question 20

How is oxygen carried in the blood?

Answer 20

Attached to hemoglobin

Question 21

How is carbon dioxide carried in the blood?

Answer 21

1) Direct solution in the blood
2) Attached in carbaminos
3) Dissolved as bicarbonate

Question 22

What are the four main volumes of the lung?

Answer 22

1) Tidal volume—air moved in normal breathing
2) Forced expiratory–air that can be pushed out of the lungs in addition to regular tidal volume
3) Forced inspiratory–air that can be inhaled beyond its regular tidal volume
4) Residual volume–Amount of air that cannot be forced out of the lungs in any way

Question 23

How is total lung capacity measured?

Answer 23

Sum of forced expiratory, forced inspiratory, tidal volume, and residual volume

Question 24

What is functional residual volume?

Answer 24

The amount of air left in the lung after a tidal breath out, or the sum of forced expiratory and residual volume

Question 25

What is the inspiratory capacity?

Answer 25

The amount of air that can be forced into the lungs beyond its normal flow. Equal to total lung capacity minus the functional residual volume

Question 26

What is vital capacity?

Answer 26

The amount of air that can be moved through lungs in general; equal to total lung capacity minus the residual volume

Question 27

How does the helium dilution method work?

Answer 27

- the patient breathes in a given quantity of helium - after allowing the helium to spread in lungs in given quantity, patient breathes out - Total Lung capacity can be calculated based on exhaled helium

Question 28

How does the nitrogen wash out method work?

Answer 28

Patient will breathe pure O2 for 7 minutes | Exhaled gases are measured and volume determined based on N2 concentrations

Question 29

What is the limit to the helium dilution or nitrogen wash out method?

Answer 29

It assumes that flow in the lungs is equal and undisrupted

Question 30

How does body plethysmography work?

Answer 30

Patient breathes in an airtight box; as air is moved in and out, patient changes the volume and then the pressure of the container. Using Boyle's law, the volume of the lungs at inspiratory stage can be calculated.

Question 31

How is body plethysmography calculated?

Answer 31

``` P*VL=(P–ΔP)*(VL+ ΔVL) P=atmospheric pressure VL=Functional Reserve Capacity deltaP=measured by mouthpiece deltaV=determined by the changes in pressure in the chamber ```

Question 32

What can FEV1 tell?

Answer 32

If FEV1 is decreased, it is indicative of obstructive lung disease

Question 33

What is minute ventilation?

Answer 33

The total amount of air leaving the lungs in each minute= | Respiratory rate * Tidal Volume

Question 34

What is dead space? What are the two components? What are normal values in men and women?

Answer 34

The amount of air in the lungs that does not participate in gas exchange. It is made of anatomic dead space and the alveolar dead space. In males, it is 150 mL; in females, it is 100 mL

Question 35

What is anatomic dead space?

Answer 35

The amount of air in the passageways that does not rest near alveoli

Question 36

What is the alveolar dead space?

Answer 36

The amount of air in the alveoli that does not engage in gas exchange

Question 37

How is alveolar ventilation calculated?

Answer 37

Respiratory rate * (tidal volume-dead space)