Pulmonary physiology Flashcards
What is the purpose respiratory system overview?
-Maintain systemic arterial blood gas levels
-O2 uptake and CO excretion=O2 use and CO production by cellular respiration
Ventilation
the amount of air moved in or out of the lungs per minute
tidal volume
amount of air moved per breath (during normal respiration)
what is the normal breathing frequency
12-20
What are the four steps of respiration
- pulmonary ventilation
- alveolar gas exchange
- gas transport
- systemic gas exchange
what is pulmonary ventilation
Air containing O2 coming into lungs
air containing CO2 going out of the lungs
What is alveolar gas exchange
O2 moves into blood and CO moves into alveoli
What is gas transport
blood containing O2 towards tissues
blood containing CO2 towards lungs
What is systemic gas exchange
O2 moves into systemic cells
CO2 moves into blood
Ventilation is synonymous with perfusion?
False
What is the alveolar vs dead space ventilation
-alveolar ventilation is also where gas exchange occurs
-dead space ventilation is purely ventilation
what is perfusion of the lungs
the amount of O2/blood brought to the lungs
What are the muscles of inspiration?
Diaphragm (descends during contractions to increase volume)
Accessory:
-sternocleidomastoid
-scalenes
-external/internal intercostal
What are the muscles of expiration?
Accessory muscles (at rest it is passive)
-internal intercostals
-external abdominal oblique
-transverse abdominis
rectis abdominis
What are the pressures that influence respiration
atmospheric pressure
alveolar pressure
intra pleural perssure
What are the conducting zones of the lungs
Trachae
primary bronchus
bronchial tree
terminal bronchioles
What are the respiratory zones of the lungs
Respiratory bronchioles
alveolus
What is Boyle’s law
volume of a gas varies inversely with its pressure
What is Dalton’s law
each gas in a mixture exerts a partial pressure that is proportional to its concentration
What is Charles’ law
gas volume and temperature are directly related
Henry’s law
volume of dissolved gas is proportional to partial pressure
Apnea
no breathing
bradypnea va tachypnea
- <10
- > 20
hypoventilation
inadequate ventilation results in increased material PCO2 - hypercardbia/hypercapnia (increased CO2 levels)
hyperventilation
excessive ventilation results in decreased arterial PCO2- hypocarrbia/hypocapnia (why you breath in a bag)
dsypnea
subjective sensation of Short of breath
Tidal volume
amount of air inhaled or exhaled in one breath during quiet breathing
Inspiratory reserve volume (IRV)
amount of air in excess of tidal volume that can be inhaled with maximum effort (extra air in)
expiratory reserve volume (ERV)
amount of air in excess of tidal volume that can be exhaled with maximum effort (extra air out)
residual volume (RV)
amount of air remaining in the lungs after maximum expiration; that is the amount of air that can never be voluntarily exhaled
Vital capacity (VC)
amount of air that can be forcefully exhaled following a maximum inspiration (VC=ERV+TV+IRV)
Inspiratory capacity (IC)
maximum amount of air that can be inhaled following a normal expiration (IC=TV+IRV)
Functional residual capacity (FRC)
amount of air remaining in the lungs following normal expiration (RV+ERV)
Total lung capacity (TLC)
maximum amount of air in the lungs at the end of a maximum inspiration (TLC=RV+VC)
what drives air flow
pressure gradients between mouth and alveolar
what contributes to the work of breathing
compliance and resistance
(compliance is the ability to inflate the lungs or chest-elastic property)
(resistance is the gas flow along the airway)
Where is the best compliance
resting lung volume or FRC
What are the requirements for O2 to move from air to cells (systemically)
-ventilation of perfused alveoli with atmospheric O2 (air coming into alveoli)
-diffusion of O2 and binding to hemoglobin
-balance between ventilation and perfusion (needs time to bind to hemoglobin
-adequate blood flow to tissues
-unloading of O2 from hemoglobin
Describe regional differences in perfusion(V/Q)
at the bas of the lung blood flow>ventilation (V/Q<1.0)
at the apex of the lung ventilation< blood flow (V/Q>1.0)
What happens when alveolar pressure is greater than the arterial and venous pressure,
perfusion is prevented (zone 1)
What happens when alveolar pressure is greater than venous but not arterial
blood flow is impeded (but not stoped) (zone 2) the optimal spot
what happens when arterial and venous pressures are greater than alveolar
blood flows freely (zone 3)
Describe the oxygen-hemoglobin dissociation curve
-this is how much O2 is bound to hemoglobin due to partial pressure
Rule of thumb:
-40 mmHg = 70% O2 sat
-50 mmHg=80%O2 sat
-60 mmHg = 90% O2 sat
what happens when there is a rightward shift in the oxygen-hemoglobin dissociation curve
there is decrease in O2 sat and O2 gets released to tissues at a higher pressure (gets released quicker = lower affinity)
what happens when there is a leftward shift in the oxygen-hemoglobin dissociation curve
there is an increase in O2 sat and O2 gets released at lower pressures (affinity increases)
How does CO2 get transported
-dissolved in plasma
-Co2+H2O (carbonic anhydrase) –> H2CO3 –> HCO3- + +H
compare myoglobin and hemoglobin dissociation curves
myoglobin has a higher O2 affinity and therefore is towards the left and is also steeper (myoglobin unloads at lower pressures- meaning that it takes a huge drop in pressure for O2 to be released)
How does the pulmonary system work for acid-base balance
-pulmonary ventilation removes H+ from blood by the HCO3- reaction
-increased ventilation and decreased ventilation
-exhaling gets rid of H+/CO2
what are the effects of pH on Oxygen hemoglobin dissociation curve
-a drop in pH results in the Bohr effect meaning that hemoglobins affinity for O2 decreases
-a raise in pH will result in a left shift meaning that hemoglobin has a higher O2 affinity
what are the effects of Temperature and 2,3-DPG
- a decrease in Temperature causes a left shift (more loading/higher affinity)
-an increase in temperature causes a right shift (more unloading/lower affinity)
Where is breathing initiated
medulla and pons initiate the breathing pattern
What are inputs to the medulla and pons
-negative feedback to maintain arterial Pco2 and PO2 and pH
-sensory feedback regarding mechanical state of lung and chest wall (what’s the expansion)
-sensory receptors feedback from joints and muscles
-sympathetic nervous system integration (breathing with talking and swallowing)
-conscious control (can over rule)
Explain central chemoreceptors and peripheral chemoreceptors
central chemoreceptors: ventral surface of medulla and they respond to changes in CSF not blood pH (CO2 concentration)
peripheral chemoreceptors: in carotid bodies of common carotid and aortic bodies in aortic arch (O2 and pH)
how do the chemoreceptors control ventilation
-by O2 and pH by the peripheral chemoreceptors
-by CO2 is through central chemoreceptors
Increase in ventilation is initiated by
-increase in arterial pCO2 or decrease in arterial pO2
-reduced arterial blood pH (increase acidity)
-arterial CO2 predominates this control
-PO2 must drop below 60 mmHg to have significant influence in ventilation
acidemia stimulates
hyperventilation to reduce H+
alkalemia stimulates
hypoventilation but only slightly affects ventilation because the result would be an increased arterial pCO2 which Is prevented by the feedback described above
what are some other examples of peripheral input
-stretch receptors In airway (mechanoreceptors (can initiate hearing-breuer reflex - increases breathing frequency to prevent hyperinflation and get rid of excess air)
-pulmonary J receptors in blood vessels (initiate increased ventilation from lung edema)
-input from muscles and joints (sends input about workload)
What happens to respiratory muscles during exercise
-diaphragm becomes the generator of flow and controls the volume
-the rib cage muscles control the pressure
explain the effects of exercise on ventilation in transition from rest to sub maximal exercise like walking ?`
-pulmonary ventilation increase rapidly as the start of exercise before plateauing due to a plateau of O2 and CO2 concentrations
What are the effects of exercise on ventilation in hot/humid evnironments?
during prolonged sub maximal exercises ventilation drifts upward during prolonged activity
(ventilation gradually increases even though CO says around the same)
Explain the difference between an untrained athlete and a trained athlete in their response to incrememntal exercise?
-for trained athletes ventilation increases linearly as O2 uptake increases until about 75% of O2 max and then it increases exponentially
-arterial PO2 decreases 30-40 mmHG at near maximum exercise levels in 40-50% of athletes
-Untrained maintain arteiral O2 within 10-12 mmHG of resting levels
-pH drops significantly in untrained athletes
-overall it takes a higher intensity for trained athletes to increase exponentially
What is the effect of rising PCO2 on ventilation
a direct linear relationship, (increase in ventilation)
effects of decreases in arterial PO2 on minute ventilation
-as O2 levels drop respiration raises
-arterial PO2 changes do not significantly affect ventilation until arterial PO2 reaches the hyopxic threshold (60-75mmHg)`
-K+ can also trigger the carotid bodies and impact ventilation rate
Effects of training on exercise ventilation
-endurance trained athletes have about 20-30% reduction in exercise ventilation rates
-can be due to aerobic capacity changes in skeletal muscle which decreases the amount of H+ and signals from the muscle receptors
-together this dulls the response of the central respiratory center to increase ventilation
-trained athletes take more intensity to get to Vo2 max
what is the ventilatory threshold
the point in which a trained athlete starts to increase exponentially
