respiratory physiology

Question 1

what is intrapleural pressure relative to intrapulmonary pressure (pressure within the alveoli)

Answer 1

-4 drops to -6 on inspiration which decreases intrapulmonary pressure by -1. this increases the volume by 500mls

Question 2

describe how the pressure changes

Answer 2

decreases on inspiration and increases on expiration

Question 3

what is the equation linking airflow to airway resistance

Answer 3

flow = change in pressure / resistance

Question 4

what is work of breathing

Answer 4

energy required to

contract muscle

stretch elastic components

overcome airway resistance

overcome friction and inertia

Question 5

where is the greatest resistance to airflow found

Answer 5

segmental bronchi

low cross sectional area and high airflow and turbulence

Question 6

what is compliance

Answer 6

the ease of distensibility of the lung tissue when an external force is applied

the change in volume of the chest for a given change in pressure

determined by elastic components and alveolar surface tension

healthy = 1L per kPa

Question 7

how can you change compliance?

Answer 7

decrease: pulmonary fibrosis

blocking smaller resp passages

increases surface tension

decreasing flexibility of the thoracic cage

increase: emphysema by reducing surface tension. also poor deflation leading to trapped air and barrel chest

lung compliance also changes with lung volume which explains differences between the base and apex. the base volume is less so more compliant

Question 8

what produces surfactant

Answer 8

type 2 alveolar cells

made of phospholipids

prevents alveolar collapse and increases compliance

Question 9

what are the 4 lung volumes

Answer 9

expiratory reserve volume

inspiratory reserve volume

tidal volume

residual volume

Question 10

what are the 4 lung capacities

Answer 10

vital capacity

total lung capacity

inspiratory capacity

functional residual capacity

Question 11

what is dead space

Answer 11

anatomical: parts of airways not involved in gas exchange
functional: anatomical plus alveolar where gas exchange is suboptimal

Question 12

describe a vitalograph reading for a restrictive lung disease

Answer 12

FEV1 is reduced

FEV1 divided by FVC is normal

Question 13

describe a vitalograph from an obstructive airway disease

Answer 13

FEV1 is reduced

Question 14

where are the respiratory centres located

Answer 14

medulla and pons

Question 15

what are the two pontine centres

Answer 15

pneumotaxic

apneustic

Question 16

what are the two medullary centres

Answer 16

inspiratory- upper part of medulla aka DRG

expiratory in the anterolateral part aka VRG

Question 17

pneumotaxic centre function and location

Answer 17

upper pons

controls medullary resp centres esp DRG

Question 18

location of the apneustic centre and function

Answer 18

lower pons

increases the depth of inspiration by acting on the DRG

Question 19

what afferent nerves are involved in respiration

Answer 19

vagus and glossopharyngeal

Question 20

what information does the resp centre receive

Answer 20

chemoreceptor and info about movement of the thorax

Question 21

what higher centres can influence the respiratory centres

Answer 21

cerebral cortex, limbic, hypothalamus

Question 22

what is the Hering breur reflex

Answer 22

when the lung inflates neurones send impulses to the DRG which prevents over inflation

Question 23

what a J receptors aka pulmonary C fibres

Answer 23

juxtacapillary receptos present in the walls of the alveoli

stimulated in oedema, congestion, pneumonia and histamine

induces apnea and rapid shallow breathing

Question 24

what do irritant receptors do

Answer 24

situated on the walls of bronchi and bronchioles

stimulated by harmful chemicals

induces rapid shallow breathing and long deep breaths to reverse slow lung collapse

Question 25

what do proprioceptors do

Answer 25

found in chest wall, joints, tendons, muscle spindles

stablises ventilation

Question 26

what do thermoreceptors do

Answer 26

stimulates hyperventilation to the cerebral cortex

Question 27

what do pain receptors do`

Answer 27

signal to resp centre, signals hyperventilation

Question 28

what does the cough reflex do

Answer 28

stimulates vagus nerve

forced expiration against closed glottis due to irritants

Question 29

what is the sneezing reflex

Answer 29

irritation of nasal mucous membranes

forceful expiration with open glottis

Question 30

what is the deglutition reflex

Answer 30

swallowing apneoa

Question 31

what do chemoreceptors detect

Answer 31

hypoxia

hypercapnia

ph

Question 32

where are central chemoreceptors found

Answer 32

medulla oblongata close to DRG

sensitive to increase in H+

H+ cannot cross BBB but CO2 can which forms H+

sensitive due to low buffering in CSF

Question 33

where are peripheral chemoreceptors found

Answer 33

carotid sinus and aortic arch

carotid bodies more important in respiration

detects O2, CO2, pH, blood flow and temp

Question 34

describe some diseases affecting ventilation

Answer 34

CNS trauma

stroke

poliomyelitis

diptheria

botulism

Duchennes muscular distrophy