Mechanics of breathing

Question 1

what is the partial pressure of 02 in the air?

Answer 1

21kPa / 160mmHg

Question 2

what is the partial pressure of 02 in the alveoli?

Answer 2

100mmHg / 13kPa

Question 3

what is the partial pressure of C02 in the alveoli?

Answer 3

40mmHg / 5kPa

Question 4

What is residual volume?

Answer 4

the amount of air remaining in the lungs after maximal expiration

Question 5

what is function residual volume?

Answer 5

the amount of air left in the lungs after passive exiration

Question 6

what is inspiratory capacity defined as?

Answer 6

the maximum amount of air that can be inspired

TV + IRV

Question 7

what is vital capacity defined as?

Answer 7

The maximum amount of air that can be expired from a maximum inspiration
TV+IRV+ERV

Question 8

what is the normal volume for Vital capacity?

Answer 8

4600ml

Question 9

what is the normal volume for tidal volume?

Answer 9

500ml

350 from inspired air and 150ml from dead space

Question 10

how effective is breathing?

Answer 10

70% effective because 150ml of the 500ml tidal volume is kept as anatomical dead space

Question 11

what is total lung capacity defined as?

Answer 11

the total capacity of the lungs - maximum inspiration and maximum expiration + residual volume.
VC+RV

Question 12

what is the average inspiratory reserve volume and expiratory reserve volume?

Answer 12

3000ml IRV

1100ml ERV

Question 13

why does vital capacity decrease with age?

Answer 13

as muscles weaken and the lungs become less elastic

Question 14

what is the capacity of volume of air that each lung can hold ?

Answer 14

3litres per lung

therefore 6 litres In total

Question 15

what is the volume of the anatomical dead space?

Answer 15

150ml

Question 16

what zone is the trachea known as?

Answer 16

conductance zone as gas exchange doesn’t occur

Question 17

what zone is the alveoli known as?

Answer 17

respiratory zone

Question 18

what accessory muscles are involves in inspiration?

Answer 18

(external intercostal and diaphragm)

sternocleoidmastoid and scalene muscles

Question 19

what accessory muscles are involves in expiration?

Answer 19

expiration is passive unless there is extreme expiratory load
muscles involves are internal intercostal and abdominal wall muscles

Question 20

what does Pip stand for?

Answer 20

partial pressure of intra pleural cavity

Question 21

what is the value of Pip?

Answer 21

-3mmHg

Question 22

what recess provides space into which the lungs can expand on inspiration?

Answer 22

costodiaphragmatic

Question 23

what is the main determinant of airway resistance?

Answer 23

radii of airways
large diameter = high resistance
small diameter = low resistance
(this is due to the total surface area available)

Question 24

what is the difference between alveolar pressure and intrapleural pressure defined as?

Answer 24

transpulmonary pressure (Pt)

Question 25

is the transpulonary pressure always positive or negative?

Answer 25

positive

Question 26

is the intra pleural pressure always positive or negative?

Answer 26

negative

Question 27

is the intrathoracic pressure always positive or negative?

Answer 27

it can be positive or negative (depending on the stage of respiration)