Respiratory P1 Flashcards
Potential Space Makeup
parietal pleura
visceral pleura
pleural cavity
Conducting zone makeup
trachea
primary bronchus
bronchial tree
terminal bronchioles
Path of air
Nose/Mouth
Pharynx
Glottis
Trachea
Primary bronchi
bronchial tree
respiratory bronchioles
alveolar sacs
alveoli
Makeup of respiratory zone
respiratory bronchioles
alveolar sacs
alveoli
Aspiration
when anything besides air goes down the trachea
Carina
inferior termination of trachea into R and L mainstem bronchi
at level of sternal angle
Which lung is more common to experience pneumonia?
Right
the bronchi on the right side are straighter and wider vs the left, allowing more to enter the lungs
Functions of conducting zone
- conducts air to respiratory zone
- warms and humidifies inspired air
- filters and cleans the inspired air
Mucociliary Escalator
-cilia on epithelial cells lines the conducting zones
-they beat in unilateral and coordinated way to move mucus toward pharynx
-leads germs to be either swallowed or expectorated
What is something that paralyzes cilia?
smoking
Functions of respiratory zone
Region of gas exchange between air and blood
Gas exchange occurs by diffusion from alveolus to capillary
Respiration steps
Ventilation
Gas Exchange
O2 utilization
Ventilation
-mechanical process of moving air in and out of lungs
-O2 is greater in air vs O2 in blood, so it follows a gradient, moving from air to blood
-CO2 in blood is greater than in lungs, goes from blood to lungs
Gas Exchange
-occurs entirely by diffusion through lung tissue
-diffusion is very rapid because of the large surface area and small diffusion distance
-occurs between air/blood/lungs/other tissues
Alveoli
very thin
have alveolar type 1 (structural), alveolar type 2 (secrete surfactant)
Lungs and and thoracic cavity
-during breathing, lungs remain in contact with chest wall
-vacuum keeps them together
-lungs expand and contract with thoracic cavity
Intrapulmonary pressure
pressure inside the alveoli
Intrapleural pressure
pressure inside intrapleural space
Intrapulmonary pressure and ventilation
Inspiration = less than atmospheric pressure (about 3 mmHg)
Expiration = greater than atmospheric pressure (about 3 mmHg)
Boyle’s gas
pressure of gas is inversely proportional to its volume
1. increase in lung volume decreases intrapulmonary pressure (air moves in).
2. decrease in lung volume raises intrapulmonary pressure above atmosphere (air moves out)
Transpulmonary Pressure
pressure difference across the wall of the lung
Intrapulmonary pressure - intrapleural pressure = transpulmonary pressure
in healthy adults, this pressure will be positive because pressure within alveoli is greater than pressure outside of alveoli
Atelectasis
partial or whole lung collapse
due to interference w/forces that promote lung expansion
treatment includes deep breathing, mobility
Pneumothorax
partial or whole lung collapse
due to collection of air or gas in intrapleural space, so pressure outside is greater than inside
chest tube is the treatment
Chest tube
tube placed between the ribs and into the intrapleural space to drain air/blood to allow the lungs to re-inflate
Physical aspects of ventilation
Compliance
Elasticity
Surface tension
Compliance
- measure of distensibility
- change in lung volume per change in transpulmonary pressure
- C = V/P or P = V/C
Compliance is decreased by
factors that produce resistance to distension
pulmonary fibrosis, alveolar edema
Compliance is increased by
factors that decrease resistance to distension
aging, emphysema
elasticity
- tendency to return to initial size after distension
- high concentration of elastin protein allows for high elasticity and recoil ability
- tension increases during inspiration
- potential space helps lungs to not collapse
Emphysema
decreased elasticity, increased compliance. lungs lose recoil ability. barrel chest
Pneumothorax
unopposed elasticity
lung collapses in, thorax goes out
Surface tension
force that resists distension
exerted by a thin layer of fluid in each alveolus
surfactant helps to lower surface tension by decreasing attraction between H2O
Law of Laplace
pressure in alveoli is directly proportional to surface tension and inversely proportional to radius of alveoli
Tidal volume
how much you move in resting breath
Diaphragm is the
resting muscle of inhalation
muscles of inspiration
SCM
scalenes
external intercostals
diaphragm
Muscles of expiration
no resting muscle of expiration, passive movement
internal intercostals
abdominal obliques
transversus abdominis
rectus abdominis
Uses of accessory muscles
exercise
pathology (increased RR or TV)
Bucket-handle motion
how lower ribs move as you breathe
Quiet Inspiration, Active process
diaphragm contraction increases thoracic volume vertically
contraction of parasternal/external intercostals increases thoracic volume laterally
Expiration, passive process
diaphragm, thoracic, thorax, lungs recoil after being stretched by contraction
decrease in lung volume raises pressure above atmosphere
Expiration pressure changes
Intra-alveolar = -3 to +3
Intrapleural = -6 to -3
Transpulmonary = 3 - -3 = 6 mmHg
Inspiration pressure changes
Intra-alveolar = 0 to -3
Intrapleural = -4 to -6
Transpulmonary = -3 - -6 = 3 mmHg
Pulmonary function tests
assessed clinically by spirometry
measures how much and how quickly air can be exhaled by an individual
subject breathes into a closed system attached to spirometer, results displayed in spirograms
Purposes of PFTs
screen for obstructive and restrictive diseases
document progression of disease
document effectiveness of intervention
evaluate prior to surgery
evaluate pt ability to be weaned from ventilator
Tidal volume
amount of air expired with each breath during quiet breathing
about 500 mL
Vital capacity
max amount of air that can be exhaled after max inhalation
Lung volumes
Tidal volume
inspiratory reserve volume
expiratory reserve volume
residual volume
Inspiratory reserve volume
additional air that can be inhaled after normal TV is inhaled
Expiratory reserve volume
additional air that can be exhaled after normal TV is exhaled
Residual volume
volume of air remaining in lungs after max expiration
cannot be directly measure w/spirometry
Lung Capacities
Total lung capacity
vital capacity
inspiratory capacity
functional residual capacity
Total lung capacity
total amount of air in lungs after max inspiration
cannot be directly measured with spirometry
Inspiratory capacity
max amount of air that can be inspired after normal tidal expiration
Functional residual capacity
amount of air remaining in lungs after normal tidal expiration
cannot be directly measured with spirometry
PFTs variables are based on
age (increasing, PFT values decrease)
sex (males have larger PFT)
Body height/size (taller is larger PFT, obese is lower PFT)
FVC
forced vital capacity
FEV1
forced expiratory volume in 1 second
FEV1/FVC
% of FVC expelled from lungs in 1st second of forced exhalation
Restrictive Disorders
spirometry is required to make these broad diagnoses
vital capacity is reduced
flow rates are usually normal
lobectomy and pulmonary fibrosis
Obstructive disorders
VC is normal
decreased rates of expiration
COPD, emphysema, asthma
post bronchodilator FEV1/FVC <70% confirms the presence of persistent airflow limitation
Dead space
volume of airways and lungs that does not participate in gas exchange
for those without pathology, dead space is anatomical
Anatomical dead space
about 150 mL
stays constant
conducting zone
fresh air mixes with it
volume of air in space remains the same, if you increase TV, % of fresh air increases that enters alveoli
Physiological dead space
parts of lungs not participating in gas exchange
those with pathology will have larger ones
Alveolar ventilation
represents the actual removal and replacement of gas within alveoli, takes into account the dead space
f x (TV - DS)
(f is frequency of breathing)
Dalton’s law
total pressure of a gas mixture is equal to the sum of the pressures that each gas in the mixture would exert independently
total pressure of a gas mix = sum of partial pressures of constituent gases
Partial pressure
pressure that a particular gas in a mixture exerts independently
partial pressure = total pressure X fraction of gas in mix
PO2 at sea level
760 mmHg x 21% (fraction of O2 in air) = 159 mmHg
PO2 at high altitudes
total pressure decreases, so PO2 decreases
Calculating PO2 in alveoli
air in alveoli is 100% saturated with water vapor, which contributes to partial pressure
you have to subtract water vapor pressure in order to get pressure within alveoli
about 150 mmHg
dead air mixes with this, end up with about 105 mmHg
ways in which Oxygen is carried in blood
dissolved in plasma, 2% (only form that produces partial pressure)
bound to hemoglobin, 98%
Hemoglobin
found within RBCs, produced by erthropoietin (produced in kidneys)
1 Hb can combine with 4 O2
pulse oximetry measures how much O2 is bound to Hb
Loading and unloading of Hb depends on
POs of environemnt
affinity between Hb and O2
Unloading of Hb occurs
tissue capillaries
Loading of Hb occurs
in lung capillaries
PaO2 normal value at rest
100 mmHg
PO2 in systemic veins at rest
40 mmHg
venous values are not clinically useful because they are much more variable
PO2 in veins during exercise
can drop to 20 mmHg
Oxygen content in blood depends on 3 things
PO2
Hemoglobin
Hematocrit
Oxy-Hb dissociation curve
curve is steep and then flattens
as Hb sat falls below 90%, PO2 drops rapidly
Right shift of Oxy-hb curve
hb has decreased affinity for O2, unloading is easier
increase in PCO2 and decrease in pH
increase in temp
occurs during exercise, low pH
Left shift of oxy-Hb curve
Hb has increased affinity for O2, unloading is harder
occurs with CO2 poisoning, high pH
SaO2
arterial oxy-hb saturation
indicates how oxygenated arterial blood is
catheter measures it
Pulse Ox and Pathology
performance of pulse ox deteriorates when SaO2 decreases below 80%, usually overestimation
dyshemoglobins, low perfusion state, skin pigmentation, nail polish, excessive motion, anemia are all limitations. also has response delay
