Respiratory, Topnotch + CDB Flashcards
End of conducting zone
Terminal bronchioles
How many generations of airways in the respiratory system
23
How many alveoli are in the respiratory system
300 million
Effect of SY nervous system on airways and via what receptor
Bronchodilation via b2
Effect of PSY nervous system on airways and via what receptor
Bronchoconstriction via M
% Type I pneumocyte in lungs
97%
Histology of type I pneumocytes
Squamous
Histology of type II pneumocytes
Cuboidal
Purpose of Type I pneumocytes
Gas exchange
Purpose of Type II pneumocytes (3)
1) Surfactant production
2) Turn into type I when needed
3) Proliferate during lung damage
Special cells in the lungs in patients with CHF
Alveolar macrophages that have become siderophages/hemosiderin-laden macrophages
Disease entity where goblet cells and submucous glands undergo hypertrophy and hyperplasia
COPD
Cells that may play a role in epithelial regeneration, secrete component of surfactant, degrade toxins, and act as reserve cells
Clara cells
Histology of Clara cells
Non-ciliated columnar
Where pulmonary veins return
Left atrium
Bronchial circulation receives ___% of cardiac output
1-2
Where bronchial circulation drains (2)
1) 1/3 R atrium via bronchial veins
2) 2/3 L atrium via pulmonary veins
Tidal volume in normal adult
500mL
IRV
3000mL
ERV
1200mL
RV
1200mL
Total volume of lung that does not participate in gas exchange
Physiologic dead space
Formula of physiologic dead space
Anatomic dead space + alveolar dead space
Air in conducting zone corresponds to
Anatomic dead space
Increase or decrease: Anatomic dead space during mechanical ventilation
Increase
Normal volume in conducting zone
150mL
Normal volume in alveolar dead space
0mL
Volume of air moved into and out of the lungs per unit time
Ventilation rate
Total rate of air movement in/out of lungs
Minute ventilation
Minute ventilation corrected for physiologic dead space
Alveolar ventilation
Formula for minute ventilation
Tidal volume x breaths per minutes
Formula for alveolar ventilation
(Tidal volume - Physiologic dead space) x breaths/min
Increased vs decreased: FEV1 and FVC in obstructive and restrictive lung diseases
Decreased
FEV1/FVC in normal healthy person
70%
FEV1/FVC ratio in restrictive disease
Increased or normal
FEV1/FVC ratio in obstructive disease
Decreased
Muscle involved in normal inspiration
Diaphragm
Muscle involved in normal expiration
None; passive process
Change in volume required for a fractional change of pulmonary pressure
Compliance
Pressure required for a fractional change of lung volume
Elastance
Pressure-volume work performed in moving air into and out of the lungs
Work of breathing
Property of matter that makes it resist deformation
Elastance
3 primary sources of resistance encountered during inspiration
1) Airway resistance
2) Compliance resistance
3) Tissue resistance
Airway resistance accounts for __% of work of breathing
20
Work that must be performed to overcome the intrinsic elastic recoil of the lungs
Compliance resistance/work
Compliance resistance accounts for __% of work of breathing
75
Law that implies that small changes in airway diameter have dramatic impact on airflow resistance because resistance is inversely related to the r^4
Poiseuille’s Law
Large vs small airways: Arranged in series, resistance additive
Large
Large vs small airways: Arranged in parallel, resistance added reciprocally
Small
Forced Inspiration vs Expiration: External intercostals
Inspiration
Forced Inspiration vs Expiration: Internal intercostals
Expiration
FEV1
Maximum volume of air that can be exhaled in 1 second after maximal inspiration
Increased vs decreased: FRC in emphysema
Increased
Increased vs decreased: FRC in pulmonary fibrosis
Decreased
Force exerted by water in an air-fluid interface that minimizes surface area
Surface tension
Emphysema: Destruction of elastic tissue is mediated by
Neutrophil-derived elastases
Examples of restrictive lung disease (2)
1) Silicosis
2) Asbestosis
Increased tendency of alveoli to collapse on expiration as radius decreases
Law of Laplace
Predisposing factors for atelectasis in preterm babies
1) Small alveolar radius (50 um) compared to adult (100 um)
2) Lack of mature surfactant
Composition of surfactants
1) Lipids (90%)
2) Proteins (10%)
Active component of surfactant
DPPC
Mechanism for DPPC in reducing surface tension
Amphipathic nature
Start of surfactant production
24th week AOG
Maturation of surfactant
35th week AOG
L:S ratio that indicates lung maturation
> 2.0
Transpulmonary pressure =
Alveolar pressure - Intrapleural pressure
Positive vs Negative: Transpulmonary pressure in expanded lungs
Positive
Positive vs Negative: Transpulmonary pressure in collapsed lungs
Negative
Ability of respiratory membrane to exchange gas
Diffusion capacity
Diffusion capacity of O2 at rest
21 mL/min/mmHg
Diffusion capacity of O2 at maximal exercise
65 mL/min/mmHg
Diffusion capacity for CO2 at rest
400-450 mL/min/mmHg
Diffusion capacity of CO2 at maximal exercise
1200-1300 mL/min/mmHg
Forms of gas in solutions
1) Dissolved
2) Bound
3) Chemically modified
Only form of gas that contributes to partial pressure
Dissolved gas
Difference between PAO2 and PaO2
A-a gradient
A vs a: Higher O2
Alveolar (A)
Why A is slightly higher than a
Due to blood that bypasses the alveoli (physiologic shunt)
2 types of alveolar-blood gas exchange
1) Perfusion-limited
2) Diffusion-limited
Characteristics of perfusion-limited gas exchange (2)
1) Gas equilibrates with the pulmonary capillary near the start of the pulmonary capillary
2) Diffusion increased only by increasing blood flow
Characteristic of diffusion-limited gas exchange
Gas does not equilibrate
O2 transport at rest
Perfusion-limited
O2 transport during exercise and disease states (emphysema, fibrosis)
Diffusion-limited
Percentage of dissolved O2
2%
Percentage of O2 bound to Hgb
98%
Hgb with iron in the ferric form hence does not bind with O2
Methemoglobin
Which hgb chain is abnormal in sickle cell anemia
Beta chain
Hgb increases the O2-carrying capacity of blood ___-fold
70
Shape of O2-Hgb dissociation curve
Sigmoidal
% saturated: PO2 of 25 mmHg
50% (P50)
% saturated: PO2 of 40 mmHg
75%
% saturated: PO2 of 100 mmHg
Almost 100%
Characteristic of O2-Hgb dissociation curve where binding of first O2 molecule increases affinity for 2nd O2 molecule and so forth
Positive cooperativity
Causes of shift to the left in the O2-Hgb dissociation curve
1) CO
2) HbF
90% (CDB: 70%) CO2 in blood is in the form of
HCO3-
5% (CDB: 7%) CO2 in blood is in the form of
Dissolved CO2
3% (CDB: 23%) CO2 in blood is in the form of
CarbaminoHgb
Cl-HCO3 exchange in the RBC
Chloride shift using Band 3 protein
O2 affecting affinity of CO2/H to Hgb INVERSELY
Haldane effect
CO2/H affecting affinity of O2 to Hgb INVERSELY
Bohr effect
Phenomenon normally encountered after a meal wherein there is a temporary increase in pH
Alkaline tide
Substances that cause bronchoconstriction
Leukotrienes
Effect of hypoxia (low pAO2) on pulmonary arterioles
Vasoconstriction
Zone of the lung: Local alveolar capillary pressure is less than alveolar air pressure THROUGHOUT the cycle
Zone 1
Zone of the lung: Local alveolar capillary systolic pressure > alveolar air pressure during systole but less than that during diastole
Zone 2
Zone of the lung: Local alveolar capillary pressure > alveolar air pressure THROUGHOUT the cycle
Zone 3
Lung zone seen with severe hemorrhage and positive-pressure ventilation
Zone 1
Normal V/Q ratio
0.8
V/Q in ventilated area of the lungs with (-) perfusion
Infinity
Disease entity where V/Q = infinity
Pulmonary embolism
V/Q in lungs with perfusion but no ventilation
0
Disease entity where V/Q = 0
Shunt/airway obstruction
Conversion of CO2 to carbonic acid as it reacts with water is catalyzed by what enzyme
Carbonic anhydrase
Structure that is defective in congenital diaphragmatic hernia
Pleuroperitoneal membrane
Anterior diaphragmatic hernia
Morgagni
Posterior diaphragmatic hernia
Bochdaleck
Accessory inspiratory muscles (3)
1) SCM
2) Scaleni
3) Serratus anterior
Accessory expiratory muscles
1) Internal intercostals
2) Abdominal recti
Pleural pressure at the beginning of inspiration
-5 cm H2O
Pleural pressure at the end of inspiration
-7.5 cm H2O
Flail chest (2)
1) 2 or more contiguous ribs
2) 2 or more fracture points
Driving force for inspiration
Negative intrapleural pressure created by diaphragm and external intercostals
Driving force for expiration
1) Increase in intrapleural pressure
2) Alveolar recoil
Alveolar ventilation at rest
4L/min
Mechanisms of maintaining V/Q matching (2)
1) Hypoxia-induced vasoconstriction
2) Changes during exercise (recruitment and distention)
Blood that bypasses the lungs or for another reason does not participate in gas exchange
Shunt
Anatomic shunt of the respiratory system
Blood bypasses lungs
Examples of anatomic shunt of the respiratory system (2)
1) Fetal blood flow
2) Intracardiac shunting
Physiologic shunt of the respiratory system
Blood flows to unventilated portions of lungs
Examples of physiologic shunt of the respiratory system (3)
1) Bronchial circulation
2) Pneumonia
3) Pulmonary edema
Causes the arterial PO2 to decrease from 104 to 95mmHg
Bronchial circulation
Regulators of respiration (5)
1) Cerebral cortex
2) Midbrain and pons
3) Central and peripheral chemoreceptors
4) Mechanoreceptors
5) Respiratory muscles
Central controller of breathing that can override the autonomic brainstem centers
Cerebral cortex
Creates the basic respiratory rhythm
Medulla
Modifies the basic respiratory rhythm
Pons
Inspiratory center
DRG
Overdrive mechanism during exercise
VRG
Prolongs inspiratory phase > decreases RR
Apneustic
Limits time for inspiration > increases RR
Pneumotaxic phase
Central chemoreceptors for respiration are found in the
Ventral medulla
Regulators of respiration: Ventral medulla responds directly to
CSF H+
Regulators of respiration: Response of ventral medulla to acidosis
Increases RR
Where peripheral chemoreceptors of respiration are found
Carotid and aortic bodies
Peripheral chemoreceptors of respiration respond mainly to
PaO2
Response of peripheral chemoreceptors of respiration to decrease on PaO2
Increases RR
Mechanoreceptors of respiration
1) Lung stretch receptors
2) Joint and muscle receptors
3) Irritant receptors
4) J receptors
Stimulus to lung stretch receptors
Lung distension
Response of lung stretch receptors
Hering-Breuer reflex
Hering-Breuer reflex
Decreases RR by prolonging expiratory time
Regulators of respiration: Stimulus to joint and muscle receptors
Limb movement
Regulators of respiration: Response of joint and muscle receptors
Increases RR during exercise
Stimulus to irritant receptors of respiration
Noxious chemicals
Regulators of respiration: Response of irritant receptors (2)
1) Bronchoconstriction
2) Increases RR
Responsible for dyspnea in left-sided heart failure
J receptors
Stimulus to J receptors
Pulmonary capillary engorgement
Response of J receptors
Rapid shallow breathing
Only gas in inspired air found exclusively in dissolved form
Nitrogen
