Block 5 Exam Flashcards
Key components of respiratory system
An air pump
Mechanisms for carrying O2 and CO2 in the blood
A surface for gas exchange
A circulatory system
A mechanism for locally regulating the distribution of ventilation and perfusion
A mechanism for centrally regulating ventilation
What does magnitude of inspiratory reserve volume depend on?
Current lung volume Lung compliance Muscle strength Comfort Flexibility of the skeleton Posture
Total lung capacity
Sum of all four volumes
Functional residual capacity
Sum of ERV and RV
Inspiratory capacity
Sum of IRV and TV
Vital capacity (VC)
Sum of IRV, TV, and ERV
Dalton’s law
Total pressure is the sum of the individual partial pressures
Henry’s law
The concentration of O2 dissolved in water is proportional to PO2 in the gas phase
BTPS
Body temperature and pressure, saturated with water vapor
ATPS
Ambient temperature and pressure, saturated with water vapor
STPD
Standard temperature and pressure/dry
Bronchi
Generations 1-10
Contain cartilage
Bronchioles
Begin at generation 11
Cartilage free
Conducting airways
Nose and lips to alveoli free bronchioles
Terminal bronchioles
Most distal conducting airways
Anatomic dead space
Small fraction of total lung capacity
What happens with increasing generation?
Cartilage, mucus, and linear velocity decrease
Cross sectional area increases
Lung elastic recoil
inward
Chest wall/diaphragm elastic recoil
outward
P(AW)
Airway pressure
P(TM)
Transmural pressure
P(TP)
Transpulmonary pressure
Static component
Controls lung volume
P(IP)
Intrapleural pressure
Relative vacuum
P(A)
Alveolar pressure
Dynamic component
Controls airflow
Primary muscles of inspiration
Diaphragm
External and internal intercostal muscles
Most important muscle of inspiration
Diaphragm
Secondary (accessory) muscles of inspiration
Scalenes
Sternocleidomastoids
Neck and back muscles
Upper respiratory tract muscles
Scalenes
Lift the first two ribs
Sternocleidomastoids
Lift the sternum outward
Contributing to the water-pump handle effect
Neck and back muscles of inspiration
Elevate the pectoral girdle and extend the back
Upper respiratory tract muscles
Decrease airway resistance
Primary muscles of expiration
NONE
Accessory muscles of expiration
Abdominal muscles
Intercostals
Neck and back muscles
Abdominal muscles
Increases intra-abdominal pressure and forces the diaphragm upward into the chest cavity
Decreasing the rostral-caudal diameter of the thorax and increasing P(IP)
Intercostals
Reduce both the anterior-posterior and the transverse diameters of the thorax
Important for coughing
Neck and back muscles in expiration
Lowering of pectoral girdle reduces the cross-sectional area of the thorax, whereas flexion of the trunk reduces the rostral-caudal diameter
Hysteresis
Different curves are followed during inspiration and expiration
Harder to open a collapsed airway than to keep an airway open
Static compliance (C)
Property of the alveoli
Decreases with increasing lung volumes
Obstructive disease effects
More compliance
Less elastic recoil
Increased volume
Can’t exhale
Restrictive disease effects
Less compliance
More elastic recoil
Decreased lung volume
Can’t inhale or exhale
Pulmonary surfactant
Made by type II pneumocytes
Role of pulmonary surfactant
Easier to inhale Promotes more uniform alveolar diameters Reduces surface tension Increases compliance Minimizes fluid accumulation in alveolus
Stages of V(L) during reinflation
Stable V(L)
Opening of airways
Linear expansion of open airways
Limit of airway inflation
What to optimize during cardiorespiratory transition from fetus to neonate
Continuous breathing
Pulmonary vasorelaxation
Resorption of lung fluid
What to avoid during cardiorespiratory transition from fetus to neonate
Apnea
Pulmonary vasoconstriction
Retention of lung fluid
What leads to inhibition of fetal respiratory activity
Hypoxia (through adenosine) Placental unity (prostaglandin) Descending pontine inhibition Hyperthermia Non-REM sleep
What drug is used for late preterm delivery with surfactant therapy
Betamethasone
Saturated phosphatidylcholine in pulmonary surfactant
50%
Unsaturated phosphatidylcholine in pulmonary surfactant
20%
Neutral lipids in pulmonary surfactant
8%
Phosphatidylglycerol in pulmonary surfactant
8%
Other phospholipids in pulmonary surfactant
6%
What causes BPD/CLD
Low gestation Genetic susceptibility Low birthweight Baro/volutrauma Increased inspired O2 Sepsis/inflammation Nutritional deficit
Neonatal contributors to altered airway function
Modulated neural output
Parenchymal (alveolar) injury
Airway dysfunction
How does hypoxia affect pulmonary vessel diameter
Causes pulmonary vasoconstriction
Ductus Venosus
Shunts blood from the umbilical vein to the inferior vena cava
Bypasses the liver
Foramen Ovale
Shunts blood from right atrium to left atrium
Bypasses the lungs
Ductus Arteriosus
Shunts blood from the pulmonary artery to the aorta
Bypasses the lungs
What taste is associated with ENaCs
Salt
What cells contain ENaCs in the kidney
Principal cells in the kidney
Release of what endogenous hormone is thought to be associated with the transition of the ENaCs at birth
Glucocorticoids/cortisol
Why is betamethasone used?
Can cross the placental barrier
What is considered late preterm infant?
34-36 weeks
What is the primary component of pulmonary surfactant
Saturated phosphatidylcholine
Contributing factors to neonatal respiratory distress syndrome
Surfactant deficiency
Inefficient fluid absorption (37-38 weeks)
Treatment of Neonatal respiratory distress syndrome
Glucocorticoids
Artificial surfactant therapy
CPAP
Intubation
Impact of C-section on Neonatal respiratory distress syndrome
Increases risk of neonate respiratory distress by showing lower SpO2
What can happen when you don’t have sufficient surfactant
Atelectasis
Atelectasis
Alveoli collapse
What are the two roles of glucocorticoids that were discussed?
Promotes resorption of fluid
Increases production of surfactant
What leads to a right shift of O2-Hb curve
Increased temp Increased [H+] Decreased pH Increased [CO2] Increased [2,3-DPG]
What leads to left shift of O2-Hb curve
Decreased temp Decreased [H+] Increased pH Decreased [CO2] Decreased [2,3-DPG] HbF
CO2 transport in blood
Dissolved CO2
HCO3 -
Carbamino compounds
Spirometer
Measures changes in V(L)
Doesn’t measure RV
Can measure FEV1
He Dilution
Measures absolute volumes
Can measure RV, FRC, TLC
Closed system
Volume of distribution approach
N2 washout
Measures absolute volumes
Can measure RV, FRC, TLC
Open system
Volume of distribution approach
Plethysmograph
Air tight telephone booth
Use Boyle’s law
Estimates RV
Measures changes in volume and pressure
Aggregate lung volume
5-6 L
Laplace’s law
P= 2T/r
What increases R(AW)
COPD/Emphysema/Chronic Bronchitis
Vagal tone => parasympathetic activity
Histamine => Bronchoconstriction
Reduced lung volumes
Change of 1 unit in pH
10x in [H+]
Change in 0.3 unit of pH
2x change in [H+]
Buffering power
Amount of OH-/H+ (mM) needed to change the pH by one unit
Cause of respiratory acidosis
Increased PCO2
respiratory acidosis leads to
decreased blood pH
Clinical causes of respiratory acidosis
Decreased alveolar ventilation
Decreased lung diffusing capacity
Ventilation/perfusion mismatch
Compensation of respiratory acidosis
Metabolic alkalosis
Cause of respiratory alkalosis
Decreased PCO2
respiratory alkalosis leads to
increased pH
clinical causes of respiratory alkalosis
Increased alveolar ventilation
Hypoxia
Anxiety
Compensation of respiratory alkalosis
Metabolic acidosis
Cause of metabolic acidosis
Decreased HCO3 -
metabolic acidosis leads to
Decreased pH
Clinical causes of metabolic acidosis
Decreased urinary secretion of H+
Ketoacidosis
Lactic acidosis
Severe diarrhea
Compensation of metabolic acidosis
Respiratory alkalosis
Cause of metabolic alkalosis
Increased HCO3 -
metabolic alkalosis leads to
increased pH
Clinical causes of metabolic alkalosis
Increased HCO3 - load
Severe vomiting
Compensation of metabolic alkalosis
Respiratory acidosis
Intracellular metabolic acidosis response
Stimulate acid extruders
Inhibit acid loaders
Intracellular metabolic alkalosis response
Stimulate acid loaders
Inhibit acid extruders
