Ventilation and Lung Mechanics

Question 1

What walls(position) does the diaphragm arise from?

Answer 1

Lateral and posterior of the body cavity

Question 2

What is the diaphragm?

Answer 2

Dome shaped muscle which lungs rest on

Question 3

What happens to muscles during inspiration?

Answer 3

diaphragm and muscles contract and ribs elevate

Question 4

What happens to muscles during expiration?

Answer 4

muscles relax and elastic properties of lungs allow it to relax

Question 5

For air flow in the lungs where does there have to be a pressure difference?

Answer 5

between internal enviroment of lungs and external enviroment - similiar to flow of fluids

Question 6

How can the flow rate be measured?

Answer 6

Pressure at point 1 minus pressure at point 2 divided by resistance to flow

Question 7

What is the pressure in the alveoli described as?

Answer 7

When the pressure of gas is inversely proportional to the volume (when one increases other decreases, always constant)

Question 8

How can pressure in alveoli be measured?

Answer 8

Pressure is the number of moles of gas x gas constant x absolute temp / volume

Question 9

What are the 2 reasons lungs would collapse?

Answer 9

Elastic recoil - elastic properties of alveolar walls

Surface tension - droplets forming in the alveoli cause alveolar membranes to be drawn together

Question 10

What prevents collapse of the lung?

Answer 10

Surfactant and intrapleural pressure

Question 11

Where is surfactant created?

Answer 11

From the alveolar epithelium and contains a mixture of lipoproteins

Question 12

With surfactant what is the force produced by surface tension? what would it be without surfactant?

Answer 12

4mm Hg, 20-30mm HG

Question 13

During expiration what pressure will the intrapleural pressure drop to?

Answer 13

2mm Hg below atmospheric pressure

Question 14

What is atmospheric pressure?

Answer 14

760mm Hg

Question 15

Elastic recoil prevents lung collapse by balancing what?

Answer 15

Negative intrapleural pressure

Question 16

What is the compliance of the lungs and thorax referred to as?

Answer 16

the ability to expand

Question 17

How is compliance measured?

Answer 17

Increased lung volume per unit of change in intrapulmonary pressure

Question 18

What is compliance expressed as?

Answer 18

Litres per cm of water L/cm

Question 19

What is the normal compliance of the lungs and thorax?

Answer 19

0.13L/cm

Question 20

What pressure needs to increase for lung volume to increase by 0.13L?

Answer 20

1cm increase in intrapulmonary pressure

Question 21

What tool can measure the flow of air in and out of lungs?

Answer 21

Spirometer

Question 22

What is air flow examined by?

Answer 22

The pulmonary volumes and capacities

Question 23

What are the pulmonary volumes a measure of?

Answer 23

Tidal volume, Inspiratory reserve volume, Expiratory reserve volume and Residual volume

Question 24

What is the tidal volume?

Answer 24

volume of air passes in and out of lungs during normal inspiration and expiration 500ml

Question 25

What is inspiratory reserve volume?

Answer 25

Amount of air that can be inspired on top of the tidal volume 3000ml

Question 26

What is the expiratory reserve volume?

Answer 26

Volume of air that can be exhaled forcefully 1100ml

Question 27

What is the residual volume?

Answer 27

volume of air still remaining in lungs after forcible expiration 1200ml

Question 28

What is the pulmonary capacities a measure of?

Answer 28

2 or more pulmonary volumes combined

Question 29

What is the inspiratory capacity?

Answer 29

normally 3500ml

Question 30

What is the functional residual capacity?

Answer 30

measure of total air left in lungs after normal expiration 2300ml

Question 31

What is the vital capacity?

Answer 31

total amount of air that can be exhaled after maximum inspiration 4600ml

Question 32

What is the total lung capacity?

Answer 32

Most air you can inspire in your lungs

Question 33

What is the minute respiratory volume?

Answer 33

total volume of air that passes through the respiratory system per minute usually 6L

Question 34

What is the dead air space?

Answer 34

region of respiratory system where gas exchange does not occur

Question 35

What can dead air space be divided into

Answer 35

Anatomical and physiological dead air spaces

Question 36

Where is the anatomical dead space?

Answer 36

Volume taken up by nasal cavities to terminal bronchioles 150ml

Question 37

What is the physiological dead air space?

Answer 37

anatomical dead air space and volume of non-functional alveoli

Question 38

what is the alveolar ventilation rate how is it calculated?

Answer 38

volume of air available for gas exchange per minute | Respiratory rate x (tital volume - dead air space)