anatomy of chest wall and mechanics of breathing

Question 1

what are the 4 gas laws?

Answer 1

1. Boyle’s law
2. Dalton’s law
3. Charles’ law
4. Henry’s law

Question 2

what does Boyle’s law state?

Answer 2

pressure exerted by a gas is inversely proportional to its volume (P = 1/V)

Question 3

when talking about the pressure and volumes of gas, what does the volume refer to?

Answer 3

the volume of the container that the gas is in

Question 4

what is core body temperature?

Answer 4

37^oC

Question 5

what is ventilation?

Answer 5

movement of air in and out of the lungs

Question 6

in terms of pressure, where does air always move?

Answer 6

from areas of high pressure to areas of low pressure

Question 7

if the pressure in the lungs is more than the atmosphere, where does the air move?

Answer 7

from the lungs to the atmosphere (out of the body)

Question 8

what shape is the diaphragm?

Answer 8

domed shaped

Question 9

what happens when the diaphragm contracts?

Answer 9

it flattens which increases the volume of the thoracic cavity

Question 10

what is the pleural cavity critical for?

Answer 10

maintaining the inflation state of our lungs

Question 11

what is A?

Answer 11

aorta

Question 12

what is B?

Answer 12

left lung

Question 13

what is C?

Answer 13

pleural membranes

Question 14

what is D?

Answer 14

left pleural cavity

Question 15

what is E?

Answer 15

pericardial cavity

Question 16

what is F?

Answer 16

right pleural cavity

Question 17

what is G?

Answer 17

right lung

Question 18

what is H?

Answer 18

oesophagus

Question 19

what does the pleural cavity contain?

Answer 19

5mm of pleural fluid

Question 20

what is the pleural cavity unique to?

Answer 20

each lung, they do not join

Question 21

what does the inside and outside of the pleural membrane line?

Answer 21

ribs and outer tissue of the lungs

Question 22

what are the 2 pleural membranes called?

Answer 22

• visceral pleural membrane: lines lungs
• parietal pleural membrane: lines ribs

Question 23

what are some functions of pleural fluid?

Answer 23

lubricant: allowing the two membranes to glide across each other as the lungs expand and contract

creates a force that stops the separation of the lungs from the rib cage, so when the rib cage moves so does the lungs

Question 24

what is pleurisy?

Answer 24

inflammation of pleural membranes

Question 25

what is the pressure of the pleural cavity when the lungs are at rest?

Answer 25

-3mmHg

Question 26

where does the rib cage and lungs naturally want to move?

Answer 26

rib cage wants to move outwards and the lungs want to recoil inwards

Question 27

what happens to the intrapleural pressure when the lung is punctured?

Answer 27

becomes equal to atmospheric pressure and the lung collapses

Question 28

what is the end of expiration a balance between?

Answer 28

lung wanting to retract inwards and the ribcage wanting to expand outwards

Question 29

what creates the negative pressure of the pleural cavity?

Answer 29

lung wanting to retract inwards and the ribcage wanting to expand outwards

Question 30

what is intrapleural pressure?

Answer 30

negative pressure inside the pleural cavity

Question 31

what gas law is the mechanics of breathing based on?

Answer 31

Boyle’s law

Increase in volume decreases pressure

Decrease in volume increases pressure

Question 32

what are the mechanics of breathing?

Answer 32

1. thoracic cavity changes volume
2. this changes the pressure (Boyle’s law)
3. air moves from area of high pressure to low pressure

Question 33

what muscles does inspiration use?

Answer 33

intercostal muscles

diaphragm

Question 34

what muscles does expiration use?

Answer 34

passive at rest, but during severe respiratory load uses:

internal intercostal muscles

abdominal muscles

Question 35

what is A?

Answer 35

sternocleidomastoids

Question 36

what is B?

Answer 36

scalenes

Question 37

what is C?

Answer 37

external intercostals

Question 38

what is D?

Answer 38

diaphragm

Question 39

what is E?

Answer 39

abdominal muscles

Question 40

what is F?

Answer 40

internal intercostals

Question 41

where do external intercostals run between and what happens when they contract?

Answer 41

ribs

when they contract they lift the rib cage upwards and outwards

Question 42

where do internal intercostal muscles run between, and what do they do when they contract?

Answer 42

ribs

when they contract they lift they pull the ribcage inwards and downwards

Question 43

what happens when abdominal muscles contract?

Answer 43

they bring abdominal organs upwards, which push against the diaphragm and decreases thoracic volume

Question 44

what does the diaphragm do during inspiration?

Answer 44

contracts and flattens which increases thoracic volume

Question 45

what does the diaphragm do during expiration?

Answer 45

relaxes which decreases thoracic volume

Question 46

what can thoracic volume increasing due to rib movement be compared to?

Answer 46

bucket handle shows increase in lateral dimensions

pump handle shows increase in anterior-posterior dimensions

Question 47

what is asthma?

Answer 47

over reactive constriction of bronchial smooth muscle, increasing resistance

Question 48

why do asthma sufferers struggle during expiration but not inspiration?

Answer 48

physical forces pull airways open during inspiration but not expiration

Question 49

what is pneumothorax?

Answer 49

collapsed lung, occuring due to air leaking into the pleural cavity and altering the pressure (equal to atmospheric pressure)

Question 50

what happens during pneumothorax?

Answer 50

rib cage expands slightly

lung collapses to unstretched size

(due to no longer being attached by the force created by the pleural cavity)

Question 51

why does a pneumothorax happen?

Answer 51

punctured pleural cavity causes loss of negative pressure (as it becomes equal to the atmosphere)

(force that attaches lungs to rib cage is no longer present and so the lung collapses to unstretched size)

Question 52

what are 3 relative pressures?

Answer 52

• intra-thoracic (alveolar) pressure, P_A
• intra-pleural pressure, P_IP
• transpulmonary pressure, P_T

Question 53

what is intra-thoracic (alveolar) pressure, P_A?

Answer 53

pressure inside the thoracic cavity (inside lungs)

may be negative or positive

Question 54

what is intra-pleural pressure, P_IP?

Answer 54

pressure inside the pleural cavity

always negative

Question 55

what is transpulmonary pressure, P_T?

Answer 55

pressure difference between the alveolar and intra-pleural pressure

P_T = P_A - P_IP

always positive because intra-pleural pressure is always more negative than alveolar pressure

Question 56

what is intra-pleural pressure compared to alveolar pressure?

Answer 56

always more negative

Question 57

how does pressure change during the respiration cycle?

Answer 57

during inspiration alveolar pressure goes negative then back to 0 and intrapleural pressure goes more negative

during expiration alveolar presure goes positive and then back to 0 and intrapleural pressure goes closer to 0

Question 58

what formula describes the flow of air?

Answer 58

directly proportional to the difference between atmospheric and alveolar pressure and inversely proportional to airway resistance:

F = (P_ATM - P_A / R

Question 59

how does alveolar pressure compare to atmospheric pressure at the end of an unforced expiration?

Answer 59

P_ATM = P_A

Question 60

why are the dimensions of the thoracic cage stable after an unforced expiration?

Answer 60

opposing elastic forces are equal, creating subatmospheric intrapleural pressure and a transpulmonary pressure that opposes the forces of elastic recoil

Question 61

what is the most important thing affecting airway resistance?

Answer 61

radii of airway