Respiratory Flashcards
What makes up the Conducting Zone?
Large airways: Nose, Pharynx, Trachea, Bronchi
Small airways: Bronchioles and Terminal Bronchioles
Function of Conducting Zone
Warms and humidifies air but does not participate in gas exchange
Anatomical Dead Space
Cartilage extends until
Bronchi
Goblet cells extend until
End of Bronchi
Pseudostratified, ciliated, columnar cells extend until
What is the cilia’s function?
End of Terminal Bronchioles to beat mucus up and out of lung
Smooth muscle in airway wall extends until
terminal bronchioles
What makes up the respiratory zone?
= Lung Parenchyma. Respiratory bronchioles, alveolar ducts and alveoli
participates in gas exchange
What kind of cells are in the Respiratory zone?
Cuboidal cells in respiratory bronchioles, then simple squamous cells up to alveoli
Type I Pneumocytes
Percentage of alveolar surface
Kind of cell
Function
97% of alveolar surface. Squamous cells optimal for gas diffusion
Type II Pneumocytes
Kind of cell
Function
Clustered cuboidal cells. Secrete surfactant and act as precursors
Collapsing Pressure Formula
P = 2 (surface Tension) / Radius
When are alveoli most likely to collapse?
On Expiration
Function of surfactant
Decreased alveolar surface tension to prevent atelectasis
Composition of surfactant
Complex mix of lecithins. The most important of which is dipalmitoylphasphatidylcholine
When does surfactant production begin in the fetus? When does it reach mature levels? What indicates maturity?
Begins at week 26. Mature by week 35. Mature when Lecithin/Sphingomyelin > 2
Clara Cells:
Location
Appearance
Function
In Terminal and Respiratory Bronchioles. Non ciliated columnar cells with secretory granules. Secrete components of surfactant, degrade toxins and act as reserve cells
of lobes in each lung?
R: 3, L: 2 + Lingula
Foreign body most likely to be lodged in
R lung because R mainstem bronchus is wider and more vertical than L
Aspirate a peanut:
While upright?
While supine?
Upright: Lower Portion of R Inferior Lobe
Supine: Superior Portion of R Inferior Lobe
Relationship bet Pul Artery to the Bronchus?
RALS
Right: Anterior, Left Superior
Structures perforating the Diaphragm
I ate 10 eggs at 12
T8: IVC
T10: Vagus and Esophagus
T12: Aorta, Azygous, Thoracic duct (Red White and Blue)
What innervates the Diaphragm? Where is pain from the Diaphragm referred?
C3, 4, 5 keeps you alive
Pain referred to shoulder (C5) and Trapezius ridge (C3, C4)
Muscles of respiration (quiet and exercise)
Inspiration: Quiet –> Diaphragm, Exercise –> SCM, Scalene, External Intercostals
Expiration: Quiet –> Passive, Exercise –> Obliques (Internal and External), Abdominis (Rectus and Transversus) Internal Intercostals
Inspiratory Reserve Vol
Air that can be breathed in after normal inspiration
Tidal Vol
500mL. Air that moves into the lung on quiet inspiration
Expiratory Reserve Vol
Air that can still be breathed out after a normal expiration
Reserve Volume
Air left in lung after maximal expiration
Inspiratory capacity
TV + IRV
Function Residual Capacity
RV + ERV
Vital Capacity
TV + IRV + ERV
Total Lung Capacity
IRV + TV + ERV + RV
Physiological Dead Space
Definition
Calculation
Vol of inspired air that does not participate in gas exchange
VD = Anatomical Dead Space of conducting airways + functional dead space in alveoli
VD = TV [(PaCO2 -PECO2)/PaCO2] Taco Paco Peco Paco
Largest contributor to functional dead space?
Apex of Lung
The tendency is for the lung to … and for the chest wall to …
Lung wants to collapse, Chest wall wants to spring outward
@ FRC: What is happening with the lung - chest wall system? What is the P in the alveoli and airway? What is the P in the Intrapleural space?
@ FRC: Inward pull of lung = outward pull of chest wall and system pressure is atmospheric. P in the alveoli and airway = 0. P in the Intrapleural space is negative to prevent pneumothorax
Alveolar transmural pressure is …
Always positive. Meaning always tending to collapse
What determines the elastic properties of both the chest wall and lungs?
Their combined volume
What is compliance?
What increases compliance?
What decreases compliance?
Change in lung vol for a given change in pressure
Increases in emphysema and normal aging
Decreases in fibrosis, pneumonia and edema
Hemoglobin
Composed of
Exists in 2 forms
Exhibits
Composed of 2 alpha and 2 beta subunits
Exists in Taut form in tissues (low affinity) and Relaxed form in lungs (high affinity)
Exhibits positive cooperativeity and negative allostery
What shifts Hemoglobin dissociation curve to the R (towards T form)
CADET! Turn R!
CO2 and Cl, Acidosis and Altitude, BPG, Exercise, Increased Temp
Fetal Hemoglobin
Consists of
Different affinities?
Consists of 2 alpha and 2 gamma subunits
Lower affinity for BPG = higher affinity for O2 –> curve shifted to the L
Methemoglobin What is it ? Change in affinity? Shift in curve? Treat with
Oxidized Iron 3+ (ferric) instead of Iron 2+ (ferrous)
Lower affinity for O2, Higher affinity for cyanide
Shifts curve to R
Treat with Methylene Blue
Nitrite poisoning causes
Oxidization of Fe2+ to Fe3+
How to treat cyanide poisoning?
Use nitrites to oxidize Hemoglobin to methemoglobin. MetHem with bind cyanide and allow cytochrome oxidase to function. Then use Thiosulfate to bind cyanide –> forms thiocynate which is renally excreted
Carboxyhemoglobin
What is it
Affect on O2 binding curve
Hemoglobin bound to CO
Shifts curve to L –> decreased O2 unloading in tissues
Appearance of Hemoglobin O2 binding curve?
Sigmoidal because of cooperativity
Pulmonary Circulation Re Resistance and Compliance
Low Resistance and High Compliance
How does a decrease in PA02 (= increase in PACO2) affect pulmonary circulation?
Vasoconstriction to shift blood away from poorly ventilated areas
Which gases are perfusion limited? What does that mean?
O2 (normally), CO2, N2O. Diffusion Increases if Blood Flow Increases
Which gasses are diffusion limited? What does that mean?
O2 (in fibrosis or emphysema), CO. Gas does not equilibrate by the time the blood reaches the end of the capillary.
Gas diffusion equation
What happens in Emphysema?
What happens in Fibrosis?
Vgas = (A/T) x D(P1-P2)
Emphysema –> Area decreases
Fibrosis –> Thickness increases
Pulmonary artery pressure: Normal? PHTN?
Normal: 10-14mmHg, PHTN: >/= 25 (rest) or >/= 35 (exercise)
PHTN affect on pulmonary artery
Arteriosclerosis, Medial Hypertrophy, Intimal Fibrosis
Cause of Primary PHTN
Inactivation of BMPR2 gene which normally functions to inhibit vascular smooth muscle proliferation
What causes secondary PHTN? What is the course of the disease?
COPD (destruction of lung parenchyma), Mitral Stenosis (Increased resistance –> increased P), Recurrent thromboemboli (decreased cross sectional area of pulmonary vascular bed), autoimmune disease, L –> R shunt (increased sheer stress –> endothelial injury), Sleep Apnea, Living at high altitude
Respiratory distress –> Cyanosis and RVH –> cor pulmonale –> death
Pulmonary Vascular Resistance formula
PVR = (P pulmonary artery - P left atrium) / CO
O2 content of blood formula
What is normal O2 binding capacity?
O2 binding capacity x saturation + dissolved O2
O2 binding capacity normally 20ml/dL
1g Hb can bind how much O2?
How much Hb is normally in blood?
When does cyanosis occur?
1.34mL
15 g Hb/dL
Cyanosis occurs when deoxygenated Hb > 5g/dL
What happens to O2 content of blood, O2 sat and PaO2 when Hb decreases?
O2 content decreases but O2 sat and PaO2 remain the same
Formula for oxygen delivery to tissues
CO x O2 content of blood
Alveolar gas equation
PAO2 = PIO2 - PaCO2/R PAO2 = 150 - PaCO2/.8 R = CO2 produced/O2 consumed
A-a gradient
Normal value
Increased in?
Causes?
Normal A-a gradient = 10-15mmHg
Increased in hypoxemia due to lesion in Lung
Causes: Shunting, V/Q mismatch, Fibrosis