Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
121 Cards in this Set
- Front
- Back
|
What are the zones of the respiratory tree? |
- Conducting zone
- Respiratory zone |
|
|
What large airway structures contribute to the conducting zone of the respiratory tree?
|
- Nose
- Pharynx - Larynx - Trachea - Bronchi |
|
|
What small airway structures contribute to the conducting zone of the respiratory tree?
|
- Bronchioles
- Terminal bronchioles |
|
|
What minimizes airway resistance?
|
Large numbers of terminal bronchioles IN PARALLEL
|
|
|
What is the function of the conducting zone of the respiratory tree?
|
Warms, humidifies, and filters air but does not participate in gas exchange
|
|
|
What is the other term for the air in the conducting zone of the respiratory tree?
|
"Anatomic Dead Space" because it does not participate in gas exchange
|
|
|
Cartilage and goblet cells are in what part of the respiratory tree?
|
Cartilage and goblet cells extend to the end of the bronchi (not found in bronchioles)
|
|
|
What kinds of cells line the conducting zone of the respiratory tree? Function?
|
Pseudostratified Ciliated Columnar Cells:
- Beats mucus up and out of lungs - Extends to beginning of terminal bronchioles Cuboidal cells - Line the terminal bronchioles |
|
|
Airway smooth muscle is in what part of the respiratory tree?
|
Extends to the end of the terminal bronchioles (sparse beyond this point)
|
|
|
What are the components of the respiratory zone of the respiratory tree?
|
Lung parenchyma: respiratory bronchioles, alveolar ducts, and alveoli
|
|
|
What is the function of the respiratory zone of the respiratory tree?
|
Participates in gas exchange
|
|
|
What kinds of cells line the respiratory zone of the respiratory tree?
|
- Mostly cuboidal cells in respiratory bronchioles
- Simple squamous cells up to alveoli - No cilia - Alveolar macrophages clear debris and participate in immune response |
|
|
What kinds of cells in the respiratory zone clear debris and participate in the immune response?
|
Alveolar macrophages
|
|
|
What types of cells line the alveoli? Which takes up the majority of the surface area?
|
- Type I cells: 97% of alveolar surface
- Type II cells: remaining alveolar surface area - Club (Clara) cells |
|
|
What type of cells are type I pneumocytes? Function?
|
- Squamous cells
- Thin for optimal gas diffusion/exchange - 97% of surface area of alveoli |
|
|
What type of cells are type II pneumocytes? Function?
|
- Cuboidal and clustered cells
- Secrete pulmonary surfactant → ↓ alveolar surface tension and prevention of alveolar collapse (atelectasis) - Also serve as precursors to type I cells and other type II cells |
|
|
What type of cells proliferate during lung damage to replace damaged cells?
|
Type II pneumocytes
|
|
|
What type of cells are Club (Clara) cells? Functions?
|
- Nonciliated, low-columnar/cuboidal with secretory granules
- Secrete component of surfactant, degrade toxins - Act as reserve cells |
|
|
What is the tendency of the alveoli during expiration? Why?
|
Alveoli have increased tendency to collapse on expiration because radius is ↓
Law of Laplace: Collapsing pressure (P) = 2* Surface Tension / Radius |
|
|
What is pulmonary surfactant made of?
|
Complex mix of lecithins, the most important of which is dipalmitoylphosphatidylcholine
|
|
|
When does surfactant begin being synthesized? When does it reach mature levels?
|
- Synthesis begins at week 26 of gestation
- Mature levels are not reached until week 35 |
|
|
What measurement indicates fetal lung maturity?
|
Lecithin-to-Sphingomyelin ratio >2.0 in amniotic fluid indicates maturity of fetal lungs
|
|
|
How many lobes does each lung have?
|
- Right lung has 3 lobes
- Left has Less Lobes (2) + Lingula |
|
|
Which side is the Lingula on? What is it a homolog of?
|
Lingula is on the Left side
- Homolog of the R middle lobe |
|
|
Which lung is a more common site for an inhaled foreign body? Why?
|
Right lung - because the right main stem bronchus is wider and more vertical than the left
|
|
|
If you are upright and aspirate a peanut, what is the most likely location?
|
Lower portion of R inferior lobe
|
|
|
If you are supine and aspirate a peanut, what is the most likely location?
|
Superior portion of R inferior lobe
|
|
|
Why does the left lobe not have a middle lobe?
|
The left lung has the heart
|
|
|
What is the relation of the pulmonary arteries to the bronchus at each lung hilus?
|
RALS:
- Right: pulmonary artery is Anterior to bronchus - Left: pulmonary artery is Superior to bronchus |
|
|
What structures pass through the diaphragm? At what level?
|
Structures perforating the diaphragm:
- T8: IVC - T10: esophagus and vagus (CN X) - T12: aorta, thoracic duct, azygos vein I (IVC) ate (8) ten (10) eggs (esophagus) at (aorta) twelve (12) Also "At T-1-2 it's the red, white, and blue" (red = aorta, white = thoracic duct, and blue = azygos vein) |
|
|
What innervates the diaphragm?
|
C3, 4, and 5 = Phrenic Nerve
C3, 4, 5 keeps the diaphragm alive |
|
|
What can irritate the diaphragm? Where will this pain be referred to?
|
- Air or blood in the peritoneal cavity
- Refers to shoulder (C5) and the trapezius ridge (C3 and C4) |
|
|
What lung volume represents the air that can still be breathed in after a normal inspiration?
|
Inspiratory Reserve Volume (IRV)
|
|
|
What lung volume represents the air that moves into lungs with each quiet inspiration? What volume?
|
Tidal Volume (TV) - typically 500 mL
|
|
|
What lung volume represents the air that can still be breathed out after a normal expiration?
|
Expiratory Reserve Volume (ERV)
|
|
|
What lung volume represents the air that is still in the lung after a maximal expiration?
|
Residual Volume (RV)
|
|
|
What lung volume represents the air that cannot be measured directly on spirometry?
|
Residual Volume (RV)
|
|
|
What lung volume consists of the inspiratory reserve volume + tidal volume?
|
Inspiratory Capacity (IC)
|
|
|
What lung volume consists of the residual volume + expiratory reserve volume (volume in lungs after normal expiration)?
|
Functional Residual Capacity (FRC)
|
|
|
What lung volume represents the maximum volume of gas that can be expired after a maximal inspiration (TV + IRV + ERV)?
|
Vital Capacity (VC)
|
|
|
What lung volume represents the total volume of gas present in the lungs after a maximal inspiration (IRV + TV + ERV + RV)?
|
Total Lung Capacity (TLC)
|
|
|
When you see the term "capacity" what does that mean?
|
It is a sum of ≥2 volumes
|
|
|
How do you calculate the physiologic dead space?
|
VD = Vt * (PaCO2 - PeCO2) / (PaCO2)
VD = dead space volume Vt = tidal volume PaCO2 = arterial PCO2 PeCO2 = expired air PCO2 |
|
|
What does the physiologic dead space represent?
|
- Anatomic dead space of conducting airways + functional dead space in alveoli
- Volume of inspired air that does not take part in gas exchange |
|
|
What part of a healthy lung is the largest contributor to the functional dead space?
|
Apex of healthy lung
|
|
|
What is the "minute ventilation"? How do you calculate it?
|
Total volume of gas entering the lungs per minute
Ve = Vt * Respiratory Rate Ve = minute ventilation Vt = tidal volume |
|
|
What is the "alveolar ventilation"? How do you calculate it?
|
Volume of gas per unit time that reaches the alveoli
VA = (Vt - VD) * RR VA = alveolar ventilation Vt = tidal volume VD = physiologic dead space volume RR = respiratory rate |
|
|
What is the natural tendency of the lungs and the chest wall?
|
- Lungs: tendency to collapse inward
- Chest wall: tendency to spring outward |
|
|
At what lung volume is the inward pull of the lungs balanced by the outward pull of the chest wall? What is the system pressure?
|
At the Functional Residual Capacity (FRC)
- The system pressure is atmospheric |
|
|
What determines the combined volume of the lung-chest wall system?
|
The elastic properties of both the chest wall and the lungs
|
|
|
What is the pressure in the airway and alveoli when at the Functional Residual Capacity?
|
Airway and alveolar pressures are 0
|
|
|
What is the intrapleural pressure when at the Functional Residual Capacity?
|
Intrapleural pressure is negative (prevents pneumothorax)
|
|
|
What is compliance?
|
Change in lung volume for a given change in pressure
|
|
|
When is the compliance of the lungs decreased?
|
- Pulmonary fibrosis
- Pneumonia - Pulmonary edema |
|
|
When is the compliance of the lungs increased?
|
- Emphysema
- Normal aging |
|
|
What are the components of Hemoglobin?
|
4 polypeptide subunits (2 α and 2 β)
|
|
|
What are the forms Hemoglobin can be in? What is the relative affinity for O2 of each form?
|
- T (taut) - low affinity for O2
- R (relaxed) - high affinity for O2 (300x higher) |
|
|
What factors favor the taut form (decreased affinity for O2) over the relaxed form (increased affinity for O2)? What happens to the dissociation curve?
|
- ↑ Cl-
- ↑ H+ (↓ pH) - ↑ CO2 - ↑ 2,3-BPG - ↑ Temperature These shift the dissociation curve to the right, leading to ↑ O2 unloading |
|
|
What are the characteristics of fetal hemoglobin?
|
- 2 α and 2 γ subunits
- Lower affinity for 2,3-BPG than adult Hb and thus has higher affinity for O2 |
|
|
Which form of hemoglobin predominates in the tissues? In the respiratory tract? Implications?
|
- Tissues: Taut Hb → low affinity for O2 → O2 unloading
- Respiratory tract: Relaxed Hb → high affinity for O2 → O2 loading |
|
|
What are the similar effects of Methemoglobin and Carboxyhemoglobin?
|
Leads to tissue hypoxia from ↓ O2 saturation and ↓ O2 content
|
|
|
What is different about Methemoglobin?
|
Oxidized form of Hb (ferric Fe3+) that does not bind O2 as readily, but has ↑ affinity for cyanide
|
|
|
What is the normal state of iron in Hb?
|
Hb is normally in reduced state (ferrous, Fe2+)
|
|
|
How might a patient with methemoglobin present?
|
- Cyanosis
- Chocolate-colored blood |
|
|
How can you treat a patient with cyanide poisoning?
|
- Use nitrites to oxidize Hb to methemoglobin, which binds cyanide
- Use thiosulfate to bind this cyanide, forming thiocyanate, which is renally excreted |
|
|
How can you treat a patient with methemoglobinemia?
|
Methylene blue
|
|
|
What can cause methemoglobin formation?
|
Nitrites cause poisoning by oxidizing Fe2+ to Fe3+ (form in methemoglobin)
|
|
|
Which form of hemoglobin is bound to CO instead of O2?
|
Carboxyhemoglobin
|
|
|
What are the implications of Carboxyhemoglobin?
|
- Causes ↓ O2-binding capacity with a left shift in the O2-hemoglobin dissociation curve
- ↓ O2 unloading in tissues |
|
|
What is the affinity of CO relative to O2 for Hb?
|
CO has 200x greater affinity than O2 for Hb
|
|
|
What shape does the oxygen-hemoglobin dissociation curve have? Why?
|
Sigmoidal shape due to positive cooperativity (ie, tetrameric Hb molecule can bind 4 O2 molecules and has higher affinity for each subsequent O2 molecule bound)
|
|
|
What shape does the oxygen-myoglobin dissociation curve have? Why?
|
Myoglobin is monomeric and does not show positive cooperativity, thus curve lacks sigmoidal appearance
|
|
|
What happens when the oxygen-hemoglobin dissociation curve shifts to the right? Examples of causes of this?
|
↓ Affinity of Hb for O2 (facilitates unloading of O2 to tissues)
Caused by increased BAT ACE: - BPG (2,3-BPG) - Altitude - Temperature - Acid - CO2 - Exercise (↑ acid) |
|
|
What happens when the oxygen-hemoglobin dissociation curve shifts to the left? Examples of causes of this?
|
↑ Affinity of Hb for O2 (facilitates binding of O2 to Hb)
Caused by Fetal Hb |
|
|
How do you calculate the "O2 content" of the blood?
|
O2 content = (O2 binding capacity * % saturation) + Dissolved O2
|
|
|
Normally 1 g of Hb can bind how much O2? What is the normal amount of Hb in the blood?
|
- 1 g Hb can bind 1.34 mL O2
- Normal amount of Hb in blood: 15 g/dL |
|
|
When does cyanosis occur?
|
When there is >5 g/dL of deoxygenated Hb (doesn't matter how much Hb you have)
|
|
|
What is the typical O2 binding capacity?
|
~ 20.1 mL O2 / dL
|
|
|
How is O2 content, O2 saturation, and arterial PO2 affected by levels of Hb?
|
As Hb falls:
- ↓ O2 content - O2 saturation and arterial PO2 stay the same |
|
|
How do you calculate the O2 delivery to the tissues?
|
O2 delivery = Cardiac Output * O2 Content of blood
|
|
|
What happens to the following levels with CO poisoning:
- Hb level - % O2 saturation of Hb - Dissolved O2 (PaO2) - Total O2 content |
- Hb level: normal
- % O2 saturation of Hb: ↓ (CO competes with O2) - Dissolved O2 (PaO2): normal - Total O2 content: ↓ |
|
|
What happens to the following levels in anemia:
- Hb level - % O2 saturation of Hb - Dissolved O2 (PaO2) - Total O2 content |
- Hb level: ↓
- % O2 saturation of Hb: normal - Dissolved O2 (PaO2): normal - Total O2 content: ↓ |
|
|
What happens to the following levels with polycythemia:
- Hb level - % O2 saturation of Hb - Dissolved O2 (PaO2) - Total O2 content |
- Hb level: ↑
- % O2 saturation of Hb: normal - Dissolved O2 (PaO2): normal - Total O2 content: ↑ |
|
|
What are the characteristics of the pulmonary circulation?
|
- Low resistance
- High compliance |
|
|
What are the effects of PO2 vs PCO2 on the pulmonary and systemic circulation?
|
They have opposite effects:
- ↓ PAO2 causes a hypoxic vasoconstriction that shifts blood away from poorly ventilated regions of lung to well-ventilated regions of lung |
|
|
Which type of gases are perfusion limited? Characteristics?
|
Perfusion limited: O2 (normal health, CO2, and N2O
- Gas equilibrates early along the length of the capillary - Diffusion can only be increased if blood flow increases |
|
|
What are the characteristics of gas equilibration and diffusion in a patient with emphysema or fibrosis?
|
Diffusion limited: O2 (emphysema, fibrosis) and CO
- Gas does not equilibrate by the time the blood reaches the end of the capillary |
|
|
What is a consequence of pulmonary hypertension?
|
Cor pulmonale and subsequent right ventricular failure (jugular venous distention, edema, hepatomegaly)
|
|
|
How do you calculate the volume of a gas that diffuses?
|
Vgas = (A / T) * Dk (P1 - P2)
A = area T = thickness Dk (P1 - P2) = difference in partial pressures |
|
|
What happens to diffusion ability in a patient with emphysema?
|
Decreases because Area of diffusion decreases
Vgas = (A / T) * Dk (P1 - P2) A = area T = thickness Dk (P1 - P2) = difference in partial pressures |
|
|
What happens to diffusion ability in a patient with pulmonary fibrosis?
|
Decreases because Thickness of wall increases
Vgas = (A / T) * Dk (P1 - P2) A = area T = thickness Dk (P1 - P2) = difference in partial pressures |
|
|
How do you calculate the Pulmonary Vascular Resistance?
|
PVR = (P-pulmonary artery - P-left atrium) / (cardiac output)
Remember ΔP = Q * R, so R = ΔP/Q R = (8ηl) / (π r^4) η = viscosity of blood l = vessel length r = vessel radius |
|
|
What does the pulmonary wedge pressure equal?
|
Pressure in the left atrium
|
|
|
How do you calculate the alveolar PAO2?
|
PAO2 = PIO2 - (PaCO2 / R)
PAO2 ≈ 150 - (PaCO2 / 0.8) PAO2 = alveolar PO2 PIO2 = PO2 in inspired air PaCO2 = arterial PCO2 R = respiratory quotient = CO2 produced / O2 consumed |
|
|
How do you calculate the A-a gradient? What is it normally?
|
A-a gradient = PAO2 - PaO2 = 10-15 mmHg
|
|
|
What can increase the A-a gradient (PAO2 - PaO2)?
|
Increases in hypoxemia
- Causes include shunting, V/Q mismatch, fibrosis (impairs diffusion) |
|
|
What could cause a hypoxemia (↓PaO2) with a normal A-a gradient?
|
- High altitude
- Hypoventilation |
|
|
What could cause a hypoxemia (↓PaO2) with a ↑ A-a gradient?
|
- V/Q mismatch
- Diffusion limitation - Right-to-left shunt |
|
|
What could cause hypoxia (↓ O2 delivery to tissue)?
|
- ↓ Cardiac output
- Hypoxemia - Anemia - CO poisoning |
|
|
What can cause ischemia (loss of blood flow)?
|
- Impeded arterial flow
- ↓ Venous drainage |
|
|
How does the V/Q change throughout the lung?
|
- Apex of lung: V/Q = 3 (wasted ventilation)
- Base of lung: V/Q = 0.6 (wasted perfusion) Both ventilation and perfusion are greater at the base of the lung than at the apex of the lung |
|
|
Where is the V/Q ratio highest?
|
Zone 1: Apex of lung (~3) because there is not enough perfusion for the amount of ventilation
|
|
|
Where is the V/Q ratio lowest?
|
Zone 3: Base of lung (~0.6) because there is too much perfusion to this area relative to the amount of ventilation
|
|
|
What can cause the V/Q ratio to approach 1 (ideal = ventilation matches perfusion)?
|
With exercise (↑ cardiac output), there is vasodilation of apical capillaries, resulting in a V/Q ratio that approaches 1
|
|
|
What part of the lung has the highest O2 concentration? What kind of organisms thrive in this location?
|
- Apex of lung
- Obligate aerobes flourish here (eg, TB) |
|
|
What can cause the V/Q ratio to approach 0?
|
When there is an airway obstruction (shunt)
- In shunt, 100% O2 does not improve PO2 |
|
|
Under what circumstance would giving a patient 100% O2 fail to improve their PO2?
|
In a patient with an airway obstruction (shunt)
|
|
|
What can cause the V/Q ratio to approach infinity?
|
Blood flow obstruction (physiologic dead space)
- Assuming <100% dead space, 100% O2 improves PO2 |
|
|
In what forms is CO2 transported from the tissues to the lungs?
|
- HCO3- (90%)
- Carbaminohemoglobin or HbCO2 (5%) - Dissolved CO2 (5%) |
|
|
What is Carbaminohemoglobin? Characteristics?
|
HbCO2
- CO2 bound to Hb at N-terminus of globin (not heme) - CO2 binding favors taut form (O2 unloaded) |
|
|
What is the effect of oxygenation of Hb in the lungs?
|
Promotes dissociation of H+ from Hb; this shifts equilibrium toward CO2 formation; therefore CO2 is released from RBCs (Haldane effect)
|
|
|
What is the Haldane effect?
|
- In lungs, oxygenation of Hb promotes dissociation of H+ from Hb
- This shifts the equilibrium toward CO2 formation; therefore CO2 is released from RBCs |
|
|
What is the effect of H+ in the peripheral tissues?
|
Increased H+ from tissue metabolism shifts the curve to the right, unloading O2 (Bohr effect)
|
|
|
What is the Bohr effect?
|
In peripheral tissue, ↑ H+ from tissue metabolism shifts curve to right, unloading O2
|
|
|
How is the majority of blood CO2 carried?
|
Carried as HCO3- in the plasma (90%)
|
|
|
What is the effect of high altitude on ventilation?
|
↓ Atmospheric O2 → ↓ PaO2 → ↑ Ventilation → ↓ PaCO2
Chronic ↑ in ventilation |
|
|
What is the effect of high altitude on the kidneys?
|
- ↑ Erythropoietin production → ↑ Hematocrit and Hb (chronic hypoxia)
- ↑ Renal excretion of HCO3- (eg, can augment by use of acetazolamide) to compensate for the respiratory alkalosis |
|
|
What is the effect of high altitude on 2,3-BPG?
|
↑ 2,3-BPG (binds to Hb sot hat Hb releases more O2)
|
|
|
What is the effect of high altitude on cells?
|
Increased mitochondria
|
|
|
What is the effect of high altitude on the heart?
|
Chronic hypoxic pulmonary vasoconstriction results in RV hypertrophy
|
|
|
What happens in response to exercise?
|
- ↑ CO2 production
- ↑ O2 consumption - ↑ Ventilation rate to meet O2 demand - V/Q ratio from apex to base becomes more uniform - ↑ Pulmonary blood flow due to ↑ cardiac output - ↓ pH during strenuous exercise (2° to lactic acidosis) - No change in PaO2 and PaCO2, but ↑ in venous CO2 content and ↓ in venous O2 content |
