Respiratory - First Aid Flashcards
Large airways consist of…
nose, pharynx, larynx, trachea and bronchi.
Small airways consist of…
bronchioles and terminal bronchioles (large numbers in parallel give the least resistance).
The conducting zone acts to…
warm, humidify and filter air but it does not participate in gas exchange. It is anatomic dead space.
Cartilage and goblet cells extend to…
the end of the bronchi.
Pseudostratified ciliated columnar cells (which beat mucus up and out of the lungs) extend to…
the beginning of the terminal bronchiles and then transitions to the cuboidal cells.
Airway smooth muscles extend to…
the end of terminal bronchioles and is sparse beyond this point.
The respiratory zone consists of…
respiratory bronchiles, alveolar ducts and alveoli. These participate in gas exchange.
The respiratory zone is mostly made of…
cuboidal cells in respiratory bronchioles and then is simple squamous cells up to the alveoli. No cilia.
Type I pneumocytes make up…
97% of the alveolar surfaces. They line the alveoli. Squamous. Thin for optimal gas diffusion.
Type II pneumocytes secrete…
pulmonary surfactant which leads to decreased alveolar surface tension and prevention of alveolar collapse (atelectasis). They are cuboidal and clustered.
Type II pneumocytes also serve as…
precursors to type I cells and other type II cells. They proliferate during lung damage.
Clara (club) cells are…
nonciliated; columnar/cuboidal with secretory granules.
Clara cells secrete…
a component of surfactant and degrade toxins.
Collapsing pressure =
2(surface tension)/radius
Alveoli have increased tendency to collapse on…
expiration as radius decreases.
Pulmonary surfactant is a complex mixture of…
lecithins, the most important of which is dipalmitoylphosphatidylcholine.
Surfactant synthesis begins around…
week 26 of gestation but mature levels are not achieved until around week 35.
Lecithin to sphingomyelin ratio that indicates fetal lung maturity is…
> 2.
Right lung has…
3 lobes. Left Lobe has Less and Lingula.
The more common site for inhaled foreign bodies is…
the right lung bc the right main stem bronchus is wider and more vertical than the left.
Aspiration while upright ends up in the…
lower portion of the right inferior lobe.
Aspiration while supine ends up in the…
superior portion of the right inferior lobe.
The relation of the pulmonary artery to the bronchus at each lung hilus is described by…
RALS - Right Anterior; Left Superior.
Structures perforating the diaphragm:
-At T8: IVC -At T10: esophagus, vagus -At T12: aorta, thoracic duct, azygous vein
The diaphragm is innervated by…
C3, 4 and 5 (phrenic nerve).
Pain from diaphragm irritation can be referred to..
the shoulder (C5) or the trapezius ridge (C3, 4).
Inspiratory Reserve Volume (IRV)
air that can still be breathed in after normal inspiration
Tidal Volume (TV)
air that moves into the lung with each quiet inspiration (about 500 mL)
Expiratory Reserve Volume (ERV)
air that can still be breathed out after normal expiration
Residual Volume (RV)
air in lung after maximal expiration; cannot be measured on spirometry
Inspiratory capacity (IC)
IRV + TV
Functional Residual Capacity (FRC)
RV + ERV (volume in lungs after normal expiration)
Vital Capacity (VC)
TV + IRV + ERV; maximum volume of gas that can be expired after a maximal inspiration
Total Lung Capacity (TLC)
IRV + TV + ERV + RV; volume of gas present in lungs after a maximal inspiration
V(D) =
physiologic dead space = anatomic dead space of conducting airways plus functional dead space in the alveli (volume of inspired air that does not participate in gas exchange)
Equation for V(D) =
VT x (PaCO - PECO)/PaCO
The largest contributor of functional dead space is…
the apex of a healthy lung.
Minute ventilation (V(E))
total volume of gas entering the lungs per minute V(E) = V(T) x RR
Alveolar ventilation (V(A))
volume of gas per unit time that reaches the alveoli V(A) = (VT-VD) x RR
The lungs have a tendency to…
collapse inward and the chest wall has a tendency to spring outward.
At FRC, the inward pull of the lung is…
balanced by outward pull of the chest wall and the system pressure is atmospheric.
Elastic properties of the chest wall and lungs determine their…
combined volume.
At FRC, airway and alveolar pressures are…
0 and intrapleural pressure is negative (which prevents pneumothorax). PVR is at minimum.
Compliance is…
the chang in lung volume for a given change in pressure.
Compliance is decreased in…
pulmonary fibrosis, pneumonia and pulmonary edema.
Compliance is increased in…
emphysema and normal aging.
Hemoglobin (Hb) is composed of…
4 polypeptide subunits (2 alpha and 2 beta) .
Hb exists in 2 forms:
- T (taut) form has a low affinity for O2 2. R (relaxed) form has a high affinity for O2
Hb exhibits..
positive cooperativity and negative allostery.
Factors that favor the taut form of Hb
-increased Cl -increased H+ -CO2 -2,3-BPG -Temperature
Factors that favor the taut form of Hb cause…
the dissociation curve to shift to the right leading to increased oxygen unloading
Fetal Hb (2 alpha and 2 gamma) has lower affinity for…
2,3-BPG and thus higher affinity for O2.
Methemoglobin is…
the oxidized form of Hb (ferric, Fe3+) that does not bind O2 as readily but has increased affinity for cyanide.
Methemoglobinemia may present with…
cyanosis and chocolate-colored blood.
To treat cyanide poisoning, use…
nitrites to oxidize Hb to methemoglobin which binds the cyanide. Then use thiosulfate to bind this cyanide forming thiocyanate which is renally excreted.
Methemoglobinemia can be treated with…
methylene blue.
Carboxyhemoglobin is a…
form of Hb bound to CO in place of O2. This causes decreased oxygen binding capacity with a left shift in the oxygen hemoglobin dissociation curve and decreased O2 unloading in tissues.
The affinity of CO for Hb is…
200x greater than O2.
The oxygen-Hb dissociation curve has a…
sigmoidal shape due to the positive cooperativity (tetrameric Hb can bind 4 O2 molecules and has higher affinity for each subsequent O2 molecule bound).
Myoglobin does not show positive cooperativity bc…
it is monomeric. Curve lacks sigmoid shape.
When the oxygen-hemoglobin curve shifts to the right, there is…
decreased affinity of Hb for O2. (facilitates unloading of O2 to tissue)
An increase in all factors of the O2-Hb curve cause…
a shift of the curve to the right.
The curve for fetal Hb is…
shifted to the left.
Factors that cause right shift (BAT ACE):
B - BPG A - Altitude T - Temperature A - Acid (H+) C - CO2 E - Exercise
Cyanosis results when…
deoxygenated Hb > 5 g/dL.
Pulmonary circulation is normally…
low-resistance, high-compliance system.
In the lungs, a decrease in PaO2 causes…
a hypoxic vasoconstriction (opposite of most tissues) that shifts blood away from poorly ventilated regions of the lung to well-ventilated regions.
Perfusion limited
-O2 (normal health) -CO2 -N2O
In perfusion limited exchange, gas will…
equilibrate early along the length of the capillary and diffusion can be increased only if blood flow increases.
In diffusion limited exchange, gas…
does not equilibrate by the time blood reaches the end of the capillary.
Diffusion limited
-O2 (emphysema, fibrosis) -CO
An increase in the A-a gradient may occur in…
hypoxemia; causes include shunting, V/Q mismatch, fibrosis
Situations with normal A-a gradient despite Hypoxemia
-high altitude -hypoventilation
Hypoxemia with increased A-a gradient (3)
-V/Q mismatch -diffusion limitation -right to left shunt
Causes of hypoxia (4)
- decreased CO 2. hypoxemia 3. anemia 4. CO poisoning
V/Q in the apex of the lung =
3 (wasted ventilation)
V/Q at the base of the lung =
.6 (wasted perfusion)
Both ventilation and perfusion are greater at…
the base of the lung than the apex.
V/Q approaches 1 with…
exercise because there is vasodilation of apical capillaries resulting in a V/Q ratio that approaches 1.
Organisms that thrive in high O2 will…
flourish in the apex (TB).
V/Q approaches zero in…
airway obstruction (shunt). 100% O2 will not improve PO2.
V/Q approaches affinity in…
blood flow obstruction. 100% O2 will improve PO2.
CO2 is transported from tissues to the lungs in 3 forms:
- HCO3- (90%) 2. Carbaminohemoglobin (HbCO2) (5%) 3. dissolved CO2 (5%)
Haldane effect
In the lungs, oxygenation of Hb promotes dissociation of H+ from Hb. This shifts equilibrium toward CO2 formation. Therefore, CO2 is released from RBCs.
Bohr effect
In peripheral tissues, increased H+ from tissue metabolism shifts the curve to the right unloading O2.
Decreased atmospheric oxygen leads to…
decreased PaO2 which increases ventilation which decreases PaCO2.
Chronic changes in response to high altitude
-decreased PaCO2 -increased ventilation -increased erythropoietin -increased 2,3-BPG -increased mitochondria -increased renal excretion of HCO3- (to compensate for respiratory alkalosis)
Increased erythropoietin leads to…
increased hematocrit and Hb