mechanisms of breathing (W3) - part 1

Question 1

when is atmospheric and alveolar pressure equal

Answer 1

at the end of a normal breath

Question 2

how do we get balance at the end of a normal breath?

Answer 2

elastic recoil

Question 3

where does the chest wall and lung want to recoil

Answer 3

chest wall - outward
lungs - inward

Question 4

how to move gas into lungs?

Answer 4

pressure greater outside lungs than inside

Question 5

which intercostal muscles are involved in inspiring

Answer 5

external

Question 6

why is expiration a passive process

Answer 6

lung elastic recoil is inward, alveolar pressure higher than atmospheric

Question 7

which is quicker - inspiration or expiration - and why

Answer 7

inspiration because it is an active process

Question 8

which muscles take part in forced expiration (active process)

Answer 8

abdominal muscles, internal intercostal muscles

Question 9

what is tidal volume

Answer 9

difference in volume between inspiration and expiration

Question 10

what is respiratory frequency/rate

Answer 10

breaths per minute

Question 11

what condition does dynamic hyperinflation occur in

Answer 11

COPD

Question 12

what causes SOBOE in COPD

Answer 12

decreased lung elastic recoil
obstructive airways disease
static and dynamic hyperinflation
inability to efficiently increase tidal volume

Question 13

what does SOBOE stand for

Answer 13

shortness of breath on exertion

Question 14

what is static and dynamic hyperinflation

Answer 14

?

Question 15

how may inspiration and expiration be disrupted

Answer 15

airflow obstruction (eg COPD, asthma)
weakness of respiratory muscles
lung tissue damage
thoracic cage disorders (AS, kyphoscoliosis)

Question 16

which part of the brain causes a complete stop in breathing if removed

Answer 16

medulla

Question 17

which part of the brain controls voluntary breathing

Answer 17

cortex

Question 18

which part of the brain controls automatic breathing

Answer 18

brainstem

Question 19

what do inspiratory neurones cause

Answer 19

contraction of inspiratory muscles
activation of expiratory neurones

Question 20

effect of expiratory neurones on inspiratory neurones

Answer 20

inhibiting

Question 21

effect of large inspiration on expiratory neurons

Answer 21

larger activation expiratory neurons cause contraction of expiratory muscles (active process)

Question 22

breath stacking in COPD

Answer 22

more inspiration than expiration, leads to inability to get more air into lungs

Question 23

environmental factors that change basic breathing pattern

Answer 23

inhaled noxious substances
speech/volition
sleep
exercise

Question 24

lung receptors?

Answer 24

slowly adapting receptors
rapidly adapting receptors
C-fibre endings

Question 25

2 types of chemoreceptors that input to the respiratory rhythm - what do they sense

Answer 25

peripheral chemoreceptors - sense changes in arterial blood
central chemoreceptors - sense changes in cerebrospinal fluid

Question 26

which nerve carries afferent nerve fibres from lung receptors

Answer 26

vagus nerve (CN10)

Question 27

what happens if the nerve containing afferent nerve fibres is cut or stimulated

Answer 27

cut - breathing pattern has greater amplitude, smaller frequency
stimulated - breathing pattern has smaller amplitude and greater frequency

Question 28

another name for slowly adapting receptors

Answer 28

stretch receptors

Question 29

what type of receptors are SARs (slowly adapting receptors

Answer 29

mechanoreceptors

Question 30

where are SARs situated

Answer 30

close to airway smooth muscle

Question 31

what are SARs stimulated by

Answer 31

stretching of airway walls during respiration

Question 32

what do SARs help do?

Answer 32

initiate expiration and prevent overinflation of the lungs

Question 33

which reflex does SARs initiate? what is this?

Answer 33

Hering-Breuer inflation reflex
prolonged inspiration produces prolonged expiration

Question 34

another name for RARs

Answer 34

irritant receptors

Question 35

where are RARs located

Answer 35

airway epithelium

Question 36

what type of receptors are RARs

Answer 36

mechanoreceptors

Question 37

what do RARs respond to

Answer 37

rapid lung inflation, chemicals, smoke, dust

Question 38

where are RARs most useful and why

Answer 38

trachea and large bronchi - if something hits your large airway its your first opportunity to expel it

Question 39

what can RARs initiate

Answer 39

cough, mucus production, bronchoconstriction (stops anything getting further in)

Question 40

why do RARs initiate bronchoconstriction and why can this be bad?

Answer 40

stops anything from getting further in, but can be pathologically activated eg in COPD

Question 41

what are C fibres

Answer 41

unmyelinated nerve fibres

Question 42

what can C fibres be stimulated by

Answer 42

increased interstitial fluid (oedema) and various inflammatory mediators (histamine, prostaglandins, bradykinins)

Question 43

where are C fibres found

Answer 43

further out in alveoli and bronchioles

Question 44

2 types of C fibre endings

Answer 44

bronchial (in airway epithelium)
pulmonary (close to pulmonary capillaries)

Question 45

what do peripheral chemoreceptors respond to and is it fast or slow

Answer 45

fast response to arterial pO2, pCO2, H+

Question 46

what do central chemoreceptors respond to and is it fast or slow

Answer 46

slow response to arterial pCO2