[1] Review of Normal Structure and Function of the Lung Flashcards
Mucociliary Clearance is under Sympathetic or Parasympathetic Control?
Parasympathetic
Composition of Mucus
95% Water
3% Mucin
1% Lipid
< 0.3% DNA
Bonds present in Mucus
Disulfide Bonds
Calcium Ion Bonds
Why should you increase water intake when mucus is hard to expectorate?
Increase in the Sol Layer
Liquid Volume of Sol Layer is determined by?
NaCl Amount
What produces the Sol Layer?
Epithelial Serous Layer
Amount of Alveoli in a Human Body
300 Million
Diameter of an Alveoli
1/3mm.
Area of Alveoli
85 square meters
Width of Blood-Gas Barrier
<0.5 microns
What maintains patency of the alveolar cells?
Surfactants
What mainly produces surfactants?
Alveolar Type II Cells
Technical name of Surfactant
Phospholipid Dipalmitoyl Phosphatidyl Choline
DPPC
What is Laplace’s Law?
Larger the surface area, the smaller the surface tension
Formula for Compliance
Compliance = P / V
Effect of Emphysema on Lung Compliance
Decreased elastic recoil -> High Compliance
Effect of Fibrosis on Lung Compliance
Low Compliance
Effect of Expiration on Pleural Pressure
Becomes less negative
Space that lies between the epithelial basement membrane and the vascular basement membrane
Interstitium
How does exercise help unmask hypoxemia?
Shortens transmit time giving RBCs less time to complete gas exchange
Which part of the lung is more perfused?
Which part is more ventilated?
Both are the lower part of the lung because of the lower pleural pressure that allows it to expand
Expansion is greater at the Apex of the Lung or the Base?
Base
Ventilation / Perfusion ratio is greater at which part of the lung?
The Top since the Ventilation would become greater than the Perfusion
(Keep in mind that in both cases, ventilation and perfusion are still greater at the base of the lung)
How come Bacilli prefer the top of the lung better than the bottom?
More ventilation than perfusion
What do you call situations with high flow but no perfusion?
Shunt
Most potent vasoconstrictor of Pulmonary Blood Vessels?
Lack of Oxygen
Is CO2 more or less soluble in liquid compared to O2?
More soluble, by 20x
Is there CO2 present usually in alveolar area?
No
Receptors Mainly Important for Detecting Elevated PCO2 Levels
Carotid Artery Surroundings
5 Mechanisms Causing Hypoxemia
- Low Inspired O2
- Ventilation-Perfusion Mismatch (Most Common)
- Shunting
- Decrease in Diffusing Capacity
- Hypoventilation
Hallmark of Alveolar Hypoventilation
Pa CO2 Always Increased
Increase in PACO2 triggers hyperventilation, since CO2 is very diffusible, it will cause the increase
Effect of Supplemental O2 on PaO2
PaO2 does not improve significantly because of shunted blood causing no perfusion
How come Adult Respiratory Distress Syndrome mimics a Shunt?
The alveoli are full of liquid already resulting in no ventilation, and since it cannot ventilate the perfusion is also affected
(Perfusion does still occur, making it different from shunts)
The only time a Ventilation Abnormality is obstructive?
Airway Problem
Everything else is restrictive
Most pulmonary diseases manifest with?
Cough and Dyspnea
Level of the Larynx
C4-C6
Level of the Carina
Expiration
Inspiration
E: T5
I: T6
Aspirated material is more likely to enter the right or left lung?
The right, since the main bronchus is less sharply angled here as compared to the left
Anatomic Division of Upper and Lower Respiratory Tract in Adults
Vocal Cords
Anatomic Division of Upper and Lower Respiratory Tract in Children
Cricoid Cartilage
Conducting Zone spans which generations of airway?
1st 16 generations
Where are the chief sites of greatest resistance?
Medium-sized Bronchi (5th-7th Generations)
What is the Reid Index
Ratio between thickness of submucosal glands and wall thickness between epithelium and cartilage that covers bronchi
Normal Reid Index
<0.4
Is there gas exchange in the Transitional Zone?
Yes
Is air flow turbulent or laminar in the Central Airways?
Turbulent Bulk Flow
Which provides more airway resistance? Central or peripheral airways?
Central: 80
Peripheral: 20
Effect of Cystic Fibrosis on the Mucus Layer
Abnormal Cl- channels cause lack of water in the sol layer and in the end causing very thick mucous
What are responsible for secretion of surfactant precursors in the Type II Pneumocytes?
Cytosomes
When is Equal Point Pressure achieved?
When intrapleural pressure equals airway pressure
Most potent vasoconstrictor of pulmonary blood vessels
Lack of O2
Situations that would cause a right shift of Hemoglobin-O2 Binding Curve
CO2 Acidity DPG Exercise Temperature
Where is the respiratory center located?
Medulla Oblongata
