Ventilation

Question 1

what is the function of the respiratory system?

Answer 1

to bring oxygen into the body from the environment and rid the body of the carbon dioxide produced by tissue metabolism

Question 2

what is a spirometer?

Answer 2

the key tool used to measure respiration
- includes a cylinder of water with a floating drum in it
- inspiration = moves drum down = recording pen moves up
- expiration = drum moves up = recording pen moved down

Question 3

what do the wave measurements mean in this graph from a spirometer mean?

Answer 3

Question 4

what is inspiratory reserve volume (IRV)?

Answer 4

the volume of air from the end of normal inspiration (peak of resting tidal volume) to maximal amount of inspiration
= inspiratory capacity - resting tidal volume

Question 5

what is resting tidal volume (RTV)?

Answer 5

the volume of air you can breathe in and out with no extra effort
= inspiratory capacity - inspiratory reserve volume

Question 6

what is expiratory reserve volume (ERV)?

Answer 6

the volume of air you expire from the end of normal expiration to maximal expiration; the volume of forced expiration
= functional residual capacity - residual volume

Question 7

what is residual volume (RV)?

Answer 7

the remaining air in your lungs that you cannot expel
= functional residual capacity - expiratory reserve volume

Question 8

what is inspiratory capacity (IC)?

Answer 8

the sum of inspiratory volumes
= inspiratory reserve volume + resting tidal volume

Question 9

what is functional residual capacity (FRC)?

Answer 9

the sum of the expiratory volumes; the total amount of volume remaining in the lungs at the end of quiet expiration
= expiratory reserve volume + residual volume

Question 10

what is vital capacity (VC)?

Answer 10

the capacity of the lungs in which we are capable of inspiring and expiring
= inspiratory reserve volume + resting tidal volume + expiratory reserve volume

Question 11

what is total lung capacity (TLC)?

Answer 11

the sum of all 4 basic volumes; the total volume of air the lungs can hold, inspire, and expire

Question 12

what is a capacity?

Answer 12

the sum of 2 or more volumes

Question 13

what are the average male values of lung volumes and capacities?

Answer 13

Question 14

what is the significance of functional residual capacity (FRC)?

Answer 14

= RV + ERV
- it is the volume left in the lungs at the end of quiet expiration
- is the equilibrium point of respiratory system***
- requires no muscular effort
- balanced mechanical forces

Question 15

what is minute ventilation?

Answer 15

generally is the expired volume in a given amount of time

Question 16

what is dead space (Vd)?

Answer 16

the volume within the respiratory system where no gas exchange takes place
- not all of the inspired air goes to the alveoli so there is a lot of dead space in the lungs

Question 17

what is the physiologic dead space?

Answer 17

the volume within the respiratory system where no gas exchange takes place
= anatomic + alveolar dead space
- is a greater value in older people

Question 18

what is anatomic dead space?

Answer 18

• the volume of the conducting airways (bronchi, bronchioles, etc)
  ≈ an individual’s body weight in mL
  i.e. 150 lb person = 150 mL of dead space
• in younger people, anatomic dead space ≈ total dead space

Question 19

what is alveolar dead space?

Answer 19

• the volume of the alveoli that are not perfused by pulmonary blood and therefore do not participate in gas exchange
• this volume increases as you get older so total dead space increases

Question 20

how does respiratory mechanics work? (basic)

Answer 20

• to move air you need a pressure gradient between atm and alveoli (high to low)
• so when you inspire: barometric pressure has to be greater than alveolar pressure
• when you expired: alveolar pressure has to be greater than barometric pressure

Question 21

what is the pleural space and its components?

Answer 21

Question 22

what happens during inhalation (inspiration) to change the pressure gradient?

Answer 22

the diaphragm contracts and moves downward and outward to push the chest wall outward thus decreasing the pressure

Question 23

what happens during exhalation (expiration) to change the pressure gradient?

Answer 23

the diaphragm relaxes and moves upward which decreases the volume in the ribcage, thus increasing the pressure to move air out

Question 24

general mechanism of inspiration

Answer 24

Question 25

what muscles are used during quiet breathing?

Answer 25

only “regular” muscles
- inspiration: diaphragm and external intercostals (btwn ribs)
- expiration: none - just relaxation

Question 26

what muscles are used during forced inspiration and expiration?

Answer 26

regular and accessory muscles
- inspiration: scalenes, SCM, and trap
- expiration: internal intercostals, abdominal muscles

Question 27

what is the primary muscle of breathing?

Answer 27

diaphragm

Question 28

what is the action of the external intercostal muscles?

Answer 28

lift the ribs that lay below the muscle

Question 29

how do we measure respiratory pressure?
units? relative to what?

Answer 29

• units: cm H2O
• pressure is relative to barometric pressure so if it’s positive it’s greater than barometric and if it’s negative then its less than barometric

Question 30

what are the mechanical forces that influence respiration?

Answer 30

RECOIL (in the lungs and chest wall) and negative pressure (in the intrapleural space)

Question 31

which direction do recoil forces go?

Answer 31

lung = inward recoil forces
chest wall = outward recoil forces
- these forces help make the intrapleural pressure more negative

Question 32

what happens to the pressure during inspiration?

Answer 32

inspiration creates more negative pressure in the intrapleural space