L9&10 - Pulmonary System

Question 1

how is the respiratory system organized for breathing?

Answer 1

organized like a tree, each section branches into smaller sections

Question 2

what allows bronchioles to alter diameter?

Answer 2

they have a considerable amount of smooth muscle and are controlled by the sympathetic nervous system

Question 3

describe pulmonary ventilation?

Answer 3

Q= ΔP/R
air flows from area of higher pressure to area of lower pressure which then causes changes in the volume of the lungs

Question 4

how does Boyle’s Law apply to inhalation?

Answer 4

during inspiration, diaphragm contracts - volume of thorax increases and pressure within it falls allowing air to flow from outside into the lungs

Question 5

how does Boyle’s Law apply to exhalation?

Answer 5

the inhalation process is reversed aided by the elastic recoil tendency of the lungs, therefore expiration is passive

Question 6

what is lung compliance?

Answer 6

for a given change in pressure, there is a large change in volume - compliance reduced the work of breathing

Question 7

give an example of lung over-compliance and under-compliance

Answer 7

over-compliance = emphysema
under-compliance = fibrosis

Question 8

what is surfactant?

Answer 8

liquid produced by certain alveolar cells and lines the inner surface of the alveoli

Question 9

when does production of surfactant start?

Answer 9

in utero

Question 10

what are the 3 functions of surfactant?

Answer 10

1. reduces surface tension - high surface tension would allow collapse of alveoli
2. helps to keep airways open and therefore increases lung compliance
3. presence of surfactant reduces the work of breathing

Question 11

what is tidal volume?

Answer 11

the volume of air moved in and out of the lungs during a normal breath

Question 12

what is the formula for minute volume?

Answer 12

TV x RR

Question 13

what is expiratory reserve volume?

Answer 13

the volume of extra air breathed out after a normal exhalation

Question 14

what is inspiratory reserve volume?

Answer 14

the volume of extra air breathed in after a normal inhalation

Question 15

what is forced vital capacity?

Answer 15

strongest exhale over 1 second - recorded on a peak flow meter

Question 16

what is functional residual capacity?

Answer 16

the volume of air in the lungs after a normal exhalation

Question 17

what is residual volume?

Answer 17

volume of air left in the lungs after a maximum exhalation

Question 18

what is vital capacity?

Answer 18

maximum amount of air that can be moved in and out of the lungs in a single breath

Question 19

what is partial pressure?

Answer 19

each gas in the air exerts an indiviaual partial pressure
PN2 Po2 Pco2 PH2O
total atmospheric pressure of 760mmHg

Question 20

what is nitrogen’s atmospheric pressure compared to alveolar pressure?

Answer 20

597mmHg vs 573mmHg

Question 21

what is oxygen’s atmospheric pressure compared to alveolar pressure?

Answer 21

159mmHg vs 100mmHg

Question 22

what is carbon dioxide’s atmospheric pressure compared to alveolar pressure?

Answer 22

0.3mmHg vs 40mmHg

Question 23

what is water vapour’s atmospheric pressure compared to alveolar pressure?

Answer 23

3.7mmHg vs 47mmHg

Question 24

what 4 factors influence the diffusion of respiratory gasses across the respiratory membrane?

Answer 24

1. surface area available
2. thickness of the respiratory membrane and its permeability
3. partial pressure gradient of the gases
4. lipid solubility

Question 25

describe the intake of O2 during gas exchange

Answer 25

O2 diffuses down its concentration gradient across the respiratory membrane from the alveoli into the pulmonary capillaries, where most of it is transported around the circulation bound to haemoglobin
a small amount of it is dissolved in plasma

Question 26

describe the uptake of CO2 into the alveoli to be exhaled during gas exchange

Answer 26

CO2 diffuses down its concentration gradient across the respiratory membrane from the pulmonary capillaries into the alveoli to be exhaled