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Respiratory
From BRS physiology 5th
42
Physiology
Professional
10/02/2011

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Term
Tidal Volume (TV)
Definition
the volume inspired or expired with each normal breath.
Term
Inspiratory reserve volume (IRV)
Definition
is the volume that can be inspired over and above the tidal volume.
is used during exercise.
Term
Expiratory reserve volume (ERV)
Definition
is the volume that can be expired after the expiration of a tidal volume.
Term
Residual volume (RV)
Definition
is the volume that remains in the lungs after a maximal expiration.
cannot be measured by spirometry.
Term
Anatomic Dead Space
Definition
volume of conducting airways
normally ~150mL or patients wt in lbs
Term
Physiological Dead Space
Definition
is a functional measurement
is the volume of the lungs that do not participate in gas exchange
Term
Dead Space Equation
Definition
V(dead) = V(total) * [ (PAco2 - PEco2)/(PAco2) ]
PAco2 is alveolar CO2 partial pressure
PEco2 is expired CO2 partial pressure
Term
Inspiratory Capacity (IC)
Definition
IC = IRV + TV
Term
Functional Residual Capacity (FRC)
Definition
FRC = ERV + RV
cannot be measured by spirometry
Term
Total Lung Capacity (TLC)
Definition
TLC = IRV + TV + ERV + RV
cannot be measured by spirometry
Term
Vital Capacity (VC)
Definition
VC = IRV + TV + ERV
or
VC = IC + ERV
Term
Minute Ventilation
Definition
Tidal Volume * Breaths/min
Term
Alveolar Minute Ventilation
Definition
(Tidal Volume - Dead Space) * Breaths/min
Term
Respiratory Compliance
Definition
C = V/P
Describes distensibility of lungs and chest wall
inversely related to stiffness/elastance (both of which depend on elastic tissues)
dV/dt
Term
Lung Compliance
Definition
Transmural Pressure = Palveolar - Pintrapleural
Term
Intrapleural Pressure is (sign)
Definition
negative
Term
A patient with emphysema shows
A patient with fibrosis shows
Definition
increased lung compliance, which eventually results in a new, higher FRC - patients may exhibit a barrel-chest
decreased lung compliance, and eventually a new lower FRC
Term
Law of Laplace
Definition
P = 2T/r
P is collapsing pressure on alveolus
T is surface tension
r is the radius of the alveolus
Term
Application of Law of Laplace to large and small alveoli
Definition
Large alveoli have low collapsing pressures and are easy to keep open
Small alveoli have high collapsing pressures and have a tendency to collapse (atelectasis)
Term
Surfactant
Definition
lines the surface of alveoli, reducing surface tension
is synthesized by type II alveolar cells and is primarily dipalmitoyl phosphatidylcholine (DPPC - a phospholipid)
Term
Neonatal Respiratory Distress Syndrome
Definition
prematurely born infants lack surfactant, which leads to lung collapse (atelectasis) as well as a difficulty in reinflating the lungs (decreased compliance) and hypoxemia (as a result of decreased V/Q)
Term
Airflow
Definition
Q = dP/R

Q is airflow
dP is a pressure gradient
R is airway resistance
Term
Poiseuille's law and airway resistance
Definition
R = [8(eta)L] / [(pi)r^4]
eta = viscosity of inspired gas
L = length of airway
r = Airway Resistance
Term
Bronchial Smooth Muscle Contraction
Definition
Parasympathetic Stimulation, Irritants, and asthma inducing substances constrict the airways, reduce radii, and increase resistance to flow
Term
Bronchial Smooth Muscle Relaxation
Definition
Sympathetic stimulation and Sympathetic agonists (isoproterenol) dialate airways via beta-2 receptors, increasing radii and decreasing airway resistance.
Term
Lung Volumes and Airway Resistance
Definition
High LV leads to decreased airway resistance - used as a compensatory mechanism for patients with asthma
Low LV leads to increased airway resistance, and potentially even collapse
Term
Inspired Gas Voscosity/Density
Definition
alters airflow
during deep-sea diving air density and resistance are increased
low-density gases reduce airflow resistance
Term
Graphs of Breath Volume (L), (Intrapleural Pressure (cm H20), and Alveolar pressure
Resemble what from inspiration to expiration?
Definition
vol - cos^2(x) from -pi/2 to pi/2 (sharper slope during inspiration)
lowercase greek nu
sin(x) from -pi to pi
Term
Chronic Obstructive Pulmonary Disease (COPD)
Definition
Increased airway resistance leads patients to expire slowly with pursed lips
Term
Asthma
Definition
obstructive disease which impares expiration
decreased FVC, decreased FEV1 and decreased FEV1/FVC
FRC is increased as a coping mechanism, but during distress, air which should leave may become trapped
Term
COPD
Definition
combination of chronic bronchitis and emphysema
obstructive disease with increased lung compliance and impaired expiration
decreased FVC, decreased FEV1, decreased FEV1/FVC
Air that should be expired is not. Increased FRC can result in barrel chest
Term
COPD types
Definition
pink puffers - primarily emphysema - mild hypoxemia, normal levels of Pco2 (since alveolar ventilation is maintained
blue bloaters - primarily bronchitis - severe hypoxemia with cyanosis. alveolar ventilation is not maintained, therefore they exhibit hypercapnia (high alveolar Pco2) - right ventricle failure and systemic edema are common
Term
Fibrosis
Definition
Restrictive disease, decreased lung compliance due to impaired inspiration.
decrease in ALL lung volumes.
FEV1 is decreased less than FVC therefore FEV1/FVC may be normal or increased
Term
Chronic Hyopxemia
Definition
living at high altitude where external Po2 is decreased leads to increased synthesis of 2,3-DPG which binds hemoglobin and facilitates unloading of O2 in the tissues
Term
Fetal Hemoglobin
Definition
does not interact strongly with 2,3-DPG
therefore the curve has an increased o2 affinity, decreased p50 and is shifted left
Term
Medullary respiratory center
Definition
located in reticular formation
Term
Dorsal Respiratory Group
Definition
responsible for inspiration and basic rhythm of breathing
inputs from vagas (relays mechano and chemo receptor of lung) and glossopharyngeal (relay chemo receptor outside lung)
output follows phrenic nerve
Term
Ventral Respiratory Group
Definition
responsible for expiration
inactive during normal breathing
activated for exercise
Term
Apneustic center
Definition
located in lower pons
stimulates inspiration as prolonged deep gasps
Term
Pneumotaxic center
Definition
upper pons
inhibits inspiration - regulates inspiratory volume and respiratory rate
Term
Cerebral Cortex
Definition
Breathing under voluntary control
Hypoventilation leads to increased Pco2 and decreased Po2. A previous period of hyperventilation extends the period of breath holding.
Term
High Altitude Adaptations
Definition
Hypoxemia -> hyperventilation, erythropoietin and 2,3-DPG production, and pulmonary vasoconstriction
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