26/5 Breathing Rates & Mechanisms Flashcards
During inhalation, describe how the diaphragm and external intercostals move
Diaphragm: contracts, moves inferiorly
External intercostals: contract, moves ribs up and out
What are the accessory muscles involved in forced inhalation
Scalenes
Sternocleidomastoids
Pectoralis minors
During inhalation, how does the lung volume change
increases
During inhalation, how do the intrapleural and intrapulmonary pressures change
Intrapleural: more subatmospheric/ negative
Intrapulmonary: becomes negative (relative to atmospheric pressure)
How do the diaphragm and external intercostals move during exhalation
Diaphragm: Relaxes, moves superiorly
External intercostals: relax, rib cage descends due to recoil of costal cartilages
What are the accessory muscles involved in forced exhalation
Abdominal wall muscles (transverse & oblique)
Internal intercostals
How does the volume of the lungs change during exhalation
decreases
During exhalation, how do the intrapleural and intrapulmonary pressures change?
Intrapleural: less subatmospheric (more positive)
Intrapulmonary: Becomes positive (relative to atmospheric pressure)
Define respiratory rate
frequency of breathing
Define Respiratory Minute Volume (VE) aka Minute Ventilation Rate and give its equation.
Amount of air moved via Tidal Ventilation each minute
VE= VT x f
Define Alveolar Ventilation(VA) and give its equation
Amount of air reaching the alveoli each minute
VA = (VT - VD) x f
What does tidal volume (VT) mean?
Volume of air inhaled / exhaled during 1 normal breath
What does dead space (VD) mean?
Amount of air in the conudcting zone that does not take part in gas exhange/ transfer
-> there is always a small volume of air that will re-enter the alveoli
Define Expiratory Reserve Volume (ERV)
Volume of additional air that can be expired after a normal quiet expiration-> beyond tidal volume
Define Inspiratory Reserve Volume (IRV)
Volume of additional air that can be inspired after a normal quiet inhalation -> beyond tidal volume
Define residual volume (RV)
Air left in lungs after maximum forced expiration
-> air that can’t be breathed out and cannot be measured by spirometer
What is Inspiratory capacity (IC) and what is its equation
Volume of air that can be inspired after a normal quiet expiration
IC= VT + IRV
Define Functional Residual capacity
Total air remaining after a normal quiet expiration
Define Vital Capacity (VC) and give its equation
Max air moving into/ out of lungs.
-> VC = ERV + VT + IRV
Define Total lung capacity )TLC) and give the equation
Total air in the lungs after a forced inspiration
TLC = RV + ERV + VT + IRV
What are the 3 routes of CO2 to the lungs
- dissolved in plasma
- bound to Hb
- Bicarbonate-ion form
How does the majority of CO2 travel to the lungs
in the form of bicarbonate ions in the blood
What enzyme changes CO2 to a bicarbonate ion and what is the other ion formed in the process? State the full equation
Carbonic anhydrase
H+
CO2 + H2O H2CO3 H+ + HCO3-
What is the difference between ventilation (V) and perfusion (Q)
Ventilation: flow of air into and out of alveoli
Perfusion: flow of blood to alveolar capillaries
Describe the three zones of Ventilation-Perfusion ratios in the regional pulmonary blood flow
Zone 1: capillary pressure never more than alveolar air pressure, no blood flow, V/Q ratio= infinity
Zone 2: capillary pressure > alveolar air pressure during systole, intermittent blood flow (flows during systolic), V/Q = normal
Zone 3: capillary pressure always > alveolar air pressure, constant blood flow, V/Q still normal but lower than zone 2
