Respiratory Flashcards
Tidal volume =
Volume of air drawn in and out of the lungs during NORMAL breathing
Usually 500ml (0.5L)
Inspiratory reserve volume =
Volume of air that can be inspired at the end of a normal inspiration (difference between resting inspiration and maximum inspiration)
Expiratory reserve volume =
Volume of air that can be expired at the end of a normal expiration (difference between resting expiration and maximum expiration)
Residual volume =
Volume of air remaining in the lungs after maximal expiration
Vital capacity =
Maximum tidal volume when an individual breathes in and out as far as possible
IRV + TV + ERC
Total ventilation =
tidal volume x respiratory rate
Anatomical deadspace =
Anatomical dead space is represented by the volume of air that fills the conducting zone of respiration made up by the nose, trachea, and bronchi.
(anything not aveoli)
Alveolar dead space =
Refers to alveoli incapable of gas exchange
(minimal in health)
Physiological dead space =
sum of anatomical and alveolar dead space
Ventilation (V) =
flow of gas
Perfusion (Q) =
flow of blood
Dead space V/Q mismatch
Lung region with normal alveolar ventilation but absent perfusion e.g. PE
Q = 0, V/Q = infinity
True shunt V/Q mismatch
Lung region with normal perfusion but absent alveolar ventilation
Caused by complete collapse or consolidation of a lung region
V = 0, V/Q = 0
Difference between type I & type II alveolar pneumocytes?
Type II secrete surfactant
At all volumes which bit of the lung has greatest compliance?
Base
Actions of surfactant in the lungs (3)
Prevent alveolar collapse, increase lung compliance and prevents transudation of fluid into alveoli
Receptors that mediate brochoconstriction
Muscarinic receptrs
Receptors that mediate bronchodilation
B2 adrenoreceptors
Partial pressures of PO2 and PCO2 in inhaled air
21.2
0.0(4)
Partial pressures of PO2 and PCO2 in inspired air in the airways (humidified)
19.1
0.0
Partial pressures of PO2 and PCO2 in alveolar air (after equilibrium with pulmonary capillaries)
13.3
5.3
Partial pressures of PO2 and PCO2 in exhaled air
15.5
4.3
Rate of gas transfer is limited by what? (2)
Diffusion or perfussion
Respiratory centre(s) in which parts of the brain stem
Pons & medulla
3 major respiratory groups of neurons
dorsal respiratory group (medulla) , ventral RG (medulla) & pontine RG
Which respiratory group of neurones initiates respiration?
dorsal respiratory group
Which respiratory group of neurones determines the rhythm of breathing?
dorsal respiratory group
What excites the DRG during exercise?
Apneustic centre in the pons
What does the DRG stimulate? (2)
Phrenic nerve -> diaphragm
Thoracic nerves -> Ex. ICMs
What inhibits the DRG?
Pneumotaxic centre
When is the VRG activated?
action
Forced expiration
Inhibits the apneustic centre
Respiratory voluntary control comes from?
Via cortical motor neurones in pyramidal tract
Central respiratory chemoreceptors are detecting?
pH of CSF (controlled by pCO2, which is diffusing into the CSF)
Where are peripheral respiratory chemoreceptors found?
Innervated by?
Carotid body which lies at the bifurcation of the common carotid arteries
&
Aortic bodies at the aortic arch
Glossopharyngeal nerve
&
Vagus nerve
Where are central respiratory chemoreceptors found?
Medulla
Stretch receptors in the lungs are located where?
Smooth muscle of bronchial walls
What does activation of pulmonary stretch receptors do?
Delays next inspiratory cycle and causes short, shallow breaths
Which receptors are involved in tachynpnoea due to odema, emboli or inflammation
J receptors
Stimulation of pulmonary irritant receptors causes?
Reflex bronchial and laryngeal constriction
