Respiratory Flashcards
Conducting Zone
Trachea, Bronchi, Bronchioles, terminal bronchioles
- No gas exchange
- Cartillage to Bronchi
- All lined with pseudostratified ciliated epithelium
- Goblet cells to Bronchi
- Clara Cells in bronchioles
Clara (Club) cell
Secrete GAGs, toxin degredation, can divide into pseudostratified epithelium
-Large ER secretory capacity
Respiratory Zone
Respiratory Brochioles (Cuboidal Epithelium) -Alveoli squamous and cubidal
Type 1 pneumocytes
Make the majority of the surface of lung. Simple Squamous
Type 2
Secrete surfactant, clusters, cuboidal
-Also can divide in response to injury
Collapsing pressure
Surface tension/radius
-Smaller radius means more likely to collapse. Residual volume prevents collapse
Surfactant
Amphipathic and reduces hydrogen bonds and surface tension, decreases collapsing pressure
- Phosphatydlcholine most common
- 2:1 phosphatydal choline to sphingmyelin ratio signals maturity
- Begin production around 26 weeks and complete by 36 weeks.
- Prematurity means immature lungs. Can give steroids to increase maturity
Diaphragmtic structures
IVC at T8 in central tendon
- Esophagus, vagus at T10
- Aorta, thoracic duct, aygous at T12
Lung relations
R bronchus is straight down, more likely to lodge in left lower lobe
Bronchi to pulmonary artery
Right side has three lobes so pulmonary artery is anterior to bronchi
-Left side has 2 lobes, so artery is superior to bronchi
Accessory respiration
- External Intercostals, Scalene, SCM: Inspiration
- Internal Intercostals, abdominal : Expiration
Anatomic Dead Space
-Volume of air in the conducting zone,
Does not participate in gas exchange
Physiologic Dead Space
- Volume of air in the alveoli that does not particiate in gas exchange
- generally from V/Q mismatches
Total Dead Space Calculation
- If perfect ventilation and no dead space, all alveolar CO2 will be expired CO2. In realiy, anatomic and physiologic dead space dilute the expired air
- Must make assumption that PaCO2 = PACO2
- Equation will be: (PACO2-PECO2)/(PACO@) essentially a dilution factor
- Using assumption allows for practical measurment
- (PaCO2-PECO2)/(PaCO2) * Vt
- There will always be dead space, so PECO2 will always be less than PaCO2
Alveolar Ventialation Equation
- Remember that PACO2 = PaCO2
- Under steady state, PaCO2 is inversely proportional to alveolar ventilaiton rate. All CO2 produced is ventilated (Steady state assumption)
- PAO2 or alveolar oxygen deliver is thus dependent on alveolar ventilation and inspired oxygen concentration
- More rapid ventilation (Hypervetilation) leads to drop in PaCO2 and
- Slowed or hypoventilation leads to increased PaCO2
- A correction factor is uniformaly provided
-PAO2 = PIO2 - (PaCO2/.8)
Lung and Chest Wall
- Elastic forces predominate, combination of system
- X interept is FRC, point where atmospheric and lung pressures are equal, end expiration of tidal volume.
- All graph motions are a function of the tissue to behave independently of external forces
- Lung always wants to collapse, chest wall changes
- At FRC tendency is for chest wall to expand and lung to collapse and forces are balanced (Highest blood flow)
- At a forced expiration the tendency of the chest wall to expand will be even more and the system will expand
- At forced inspiration, the chest wall is strethed more than it is comfortable with and will have a compressive force leading to exhalation
Compliance
- Chest wall curve is more or less fixed
- Compliance of lungs can chage
- Compliance defined as volume change for a given unit of pressure change
- Increased compliance as seen in emphysema will lead to decreased compressive forces of the lungs and a higher FRC
- Decreased compliance as seen in restuctive lung disease will cause an increase in collapsing force and drop in FRC
Airway Resistance
R= nl/r^4
- Largest radius is in smaller airways because of large numbers
- Medium radius in traches
- Smalles radius in medium sized bronchi
- Larger lung volumes also have larger radius and have decreased resistance to flow
- Small lung vlumes have increased resistance to flow
- ANother purpose or residual volume
Hemoglobin
- Methemoglobin is Fe 3+ and can’t bind O2. Oxidizing drugs (nitrates and sulfonamides)
- HgF has decreased affinity for 2,3BPG and leads to increased O2 affinity
Dissociation Curves
- COoperative binding allows sigmoidal curve
- R is relaxed and capable of binding O2, T is taught and lower affinity for O2
- In tissues pushed into T form by (H-deoxyhemoglobin, CO2-carbamino, increaesed T, increased 2,3BPG) altidude causes increased in 2,3 BPG
- In lungs exchange leads to opposite effects
- CO binding to O2 leads to a left shift because of cooperativity of O2 and CO occuring at a lower O2 concentration, but the shift will also be pushed down beause binding sites are occupied
CO2 transport
- Minor portion is dissolved
- Some in carbamino form which will decreasd O2 affinity
- Majority as bicarb. CA catalyzed reaction. HCO3 leaves the cell in exchange for Cl (Band 3), H stays in cells and is buffered by deoxyhemoglobin
- Reverse occurs in lungs
- In tissues H+ and Cl into cells and HCO3 out of cells, opposite occurs in lungs
Lung Embry
Conducting zone develops first with the respiratory later
- Alveoli are prodced during saccular phase and mature during alveolar phase
- Surfactant secretion mature at the end of sacular phase around 36 weeks
TE Fistula
Associaed with VACTERL
- Midline Defects
- Vertebral, Anal atreais, cardiac, TEF, renal, limb
Congenital Diaphragmatic Hernia
- Failure of left pleuroperitioneal folds to close
- GI into thorax and lung hypoplasia occurs
Hyaline Membrane Disease
- Premature infant without surfactant leads to widespread atelectasis
- Fibrin cellular debris and red cells make up hyaline membranes
- Give steroids and surfactant
RALS
Right anterior and Left superior. Is the relatinship of the pulmonary artery to the bronchi
Diaphragm structures
T8 is IVC
T10 is esophagus and vagus
T12 is Aorta, thoracic ducts, and azygous
Intercostal NAV
NAV from inferior to superior. Wil hit nerve first, artery closest to the rib
-Do thoracocentsis on upper border of rib
Olfactory
Superior coanae is respiratory epithelum
-Sensry cells are bipolar and can regenerate
Pulmonary vascular reistance
- At high lung volumes arteries will be compressed by alveolar pressure
- At low lung volumes there will be inadequate traction and closure (Atelectasis has closed arteries, kinda)
- Best flow is at FRC, atomospheric pressure leads to minimal compression from either
- Contriction with acidosis, endothelin and SANS
- Dilation with PG, NO, PANS, His
Respiratory control
Apneustic and chemotactic centers in pons
-Medullary centers integrate information
Obstructive Diseaes
Characterized by increasing TLC (air trapping) and decreased FEV1, FVC, and FEV1/FVC ratio
-Can see pulsus paradoxus
Chronic Bronchitis
- Caused by longterm bronchiole iritation leading to mucus cell hyperplasis (in bronchioles) Ried Index
- Hypermucus secretion leads to narrowing of Bronchi and high resistance to flow, air trapping may occur
- Mucus causes hypoventalation and there is often times hypoxemia (Blue Bloaters)
- Hypoxemia induces vasoconstriction leading to cor pulmonale
- Also mucus predisposes to infection
- Treatement can be supplemental O2 to decrease hypoxic vasoconstriction and decrease cor pulmonale
- Also can treat with steroids for acute attack and albuterol too
- DLCO will be normal
- Hypoventalation leads to VQ mismatiching and hypoxemia, can be corrected with O2
Emphysema
- Destruction of parenchyma of lung due to imbalance in pro elastase and anti-elastase functions
- Panacinar associated with congenital decrese in alpha 1 antitrypsin (Piz is mutatnt, heterozygote is risk, homo wil get, often accompanied by cirrhosis) will see PAS positive misfolded proteins in ER of Hepatocytes
- Cetnriacinar: chronic inflammation from smoking leads to destruction of lung parenchyma
- Destruction leads to loss of elastic recoil and increaed compliance
- Destruction also leads to loss of radial traction
- Combination leads to an obstructive pattern
- Parenchymal loss leads to decreased surface area, so there will be impaired DLCO
- Pink puffers do not get hypoxemia because of loss of vasculature along with alveoli
- Treatment is stop smoking and beta 2 agonists can be helpful for some patients.
- Patietns will breathe through puresed lips. This will decrase resistance to flow because airway radius is increased. It will also prevent collapsing as radius is increased