Module 1 Lecture 6

Question 1

What is the atmospheric pressure at sea level?

Answer 1

The atmospheric pressure at sea level is 760 mmHg

Question 2

Before inspiration?

Answer 2

Equilibrated - no net movement of air, the preinspiratory size of lungs (760)

Question 3

During inspiration?

Answer 3

Size of the thorax on the contraction of inspiratory muscles (expands), the size of the lungs as they are stretched to fill the expanded thorax

Question 4

Expiration?

Answer 4

Size of thorax - smaller, relaxation of the inspiratory muscle, size of the lungs as they recoil? bigger?

Question 5

What is airflow?

Answer 5

airflow is the volume of air flowing through the lungs at a given point

Question 6

What is airflow directionally proportional to?

Answer 6

Airflow is directionally proportional to the pressure gradient between external atmospheric and alveoli and inversely proportional to resistance airway passages

Question 7

What is the formula for airflow?

Answer 7

F ∝ pressure gradient/resistance

Question 8

What has the biggest influence on airflow?

Answer 8

During normal quiet breathing, pressure gradient has the biggest influence on air flow

Question 9

Why are liquid molecules strongly attached to each other?

Answer 9

Liquid molecules are strongly attached to each other, it creates tension called surface tension

Question 10

What is surfactant?

Answer 10

It is a detergent-like mixture of lipids and proteins decreases in water cohesiveness

Question 11

What does detergent do to water?

Answer 11

surfactant reduces attraction between water molecules, it reduces surface tension of alveolar fluid and reduces tendency to recoli/alveolar collapse

Question 12

Why are premature babies at risk?

Answer 12

Premature babies are at risk because they lack sufficient surfactant and alvoli which may collapse between breathes

Question 13

How does a change in lung volume occur?

Answer 13

Change in lung volume occurs with a change in transpulmonary pressure, the greater the lung compliance, the greater the expansion at any given transpulmonary pressure.

Question 14

How is lung compliance determined?

Answer 14

Lung compliance is determined largely by two factors. Distensibility of lung tissue ( increase in lung compliance) alveolar surface tension (decrease in lung compliance)

Question 15

Note

Answer 15

Lung distensibility is generally high and surfactant keeps alveolar surface tension low, healthy lungs have a high compliance for efficient ventilation - thoracic respiratory compliance is also affected by thoracic wall compliance

Question 16

Draw and lable the respiratory volumes

Answer 16

–

Question 17

Define tidal volume

Answer 17

It is the amount of air that moves in and out during normal quiet breathing

Question 18

Define inspiratory reserve

Answer 18

it is the amount of air that can be breathed in forcibly beyond TV

Question 19

Define expiratory reserve

Answer 19

is the amount of air that can be breathed out forcibly beyond TV

Question 20

Define residual volume

Answer 20

Amount of air remaining after forced expiration helps to keep alveoli open

Question 21

What is inspiratory capacity?

Answer 21

Inspiratory capacity is the total amount of air that can be inspired after normal tidal volume expiration -> TV and IRV

Question 22

What is functional residual capacity?

Answer 22

The functional residual capacity is the amount of air remaining in lungs after a normal tidal volume expiration –> RV and ERV

Question 23

What is vital capacity?

Answer 23

It is the amount of exchangeable air –> TV, IRV and ERV

Question 24

What is totoal lung capity?

Answer 24

Total lung capacity is the sum of all lung volumes

Question 25

What is dead space?

Answer 25

it is some inspired air never contributed to gas exchange, this air fills the conducting respiratory passageways, if TV is 500ml, only 350ml is actually involved in alveolar ventilation

Question 26

Ventilation equation?

Answer 26

pulmonary/minute ventilation (ml/min) = tidal volume (ml/breath) x respiratory rate (breaths/mins)

Question 27

Alveolar ventilation?

Answer 27

TV - dead space (ml/breath) x respiratory rate (breaths/min)

Question 28

What affects alveolar ventilation?

Answer 28

Depth of breathing affects alveolar ventilation more than respiratory rate

Question 29

What is spirometry?

Answer 29

it measures respiratory function (lung volumes) and monitors progression of certain respiratory diseases, it does not provide a specific diagnosis but can distinguish between obstructive and restrictive lung diseases

Question 30

What do volume lopp and vitagraph provide?

Answer 30

Provides additional information related to the rate at which gas moves in and out of the lungs

Question 31

What is FEV1?

Answer 31

Forced expiratory volume is the amount of air exhaled in the first second during a force rapid exhale after a deep breath (forced vital capacity FVC) - FEV1 /FVC ratio

Question 32

Define a obstructive lung disease? and draw

Answer 32

Increased airway resistance: chronic bronchitis, athsma and emphysema

Question 33

Define an restrictive lung disease and draw

Answer 33

Restrictive lung disease = reduced lung compliance - tuberculosis, lung fibrosis (asbestos)

Question 34

What is gas exchange?

Answer 34

Gas exchange: O2 and CO2 need to move between the lungs and other body cells - it’s transported in blood and exchanged by passive diffusion

Question 35

What is the partial pressure gradient?

Answer 35

The patial pressure gradient difference in particual pressure between blood and surrounding structures (Alveolar air and pulmonary capillary blood, systemic capillary blood and surrounding cells –> gases move from high to low)

Question 36

What is partial pressure?

Answer 36

Partial pressure (P gas) is the pressure exerted by a particular gas relative to the total gas pressure (applies to gasses dissolved in liquid)

Question 37

What factors influence gas exchange by diffusion?

Answer 37

Thickness and SA of exchange membrane: shorter distance and greater SA for diffusion = greater rate of diffusion = greater rate of diffusion

Question 38

What is ventilation-perfusion coupling? DRAW DIAGRAM

Answer 38

Ventilation perfusion coupling is a close match between ventilation (amount of gas reaching alveoli) and perfusion (blood flow in pulmonary capillaries)