Respiratory Physiology Flashcards
The conducting zone transports gas to the lungs and is from the nose to the:
Terminal bronchioles
The respiratory zone is the site of gas exchange and consists of:
respiratory bronchioles, alveolar ducts, alveolar sacs
How many generation of airways do you find int he respiratory system?
23
How many alveoli are present in the respiratory system?
500 million
What is the sympathetic and parasympathetic effect on the smooth muscles of the airways?
Sympathetic: smooth muscle relaxation via B2 receptors
Parasympathetic: smooth muscle contraction via muscaric receptors
Type of pneumocyte which composes 96-98% of surface area, and is for gas exchange
Type I pneumocytes
Type of pneumocyte which composes 2-4% of surface area, and is for surfactant production
Type II pneumocytes
Alveolar macrophages can convert into what in CHF:
Siderophages/ Hemosiderin-laden macrophages
Cells that produce mucus:
Goblet cells, submucosal glands
May play a role in epithelial regeneration after injury by secreting protective GAGs
Clara cells/Club cells
What is the Reid’s index?
Ratio of submucosal gland layer to the alveolar wall.
In COPD, Reid’s index is >0.4 indicating hyperplasia and hypertrophy of the submucosal gland layer
Dual blood supply of the lungs:
- Pulmonary (deoxygenated blood) circulation
- Bronchial (oxygenated blood) circulation (1/3 returns to R atrium via bronchial veins, 2/3 returns to L atrium via pulmonary veins)
Amount of air inspired/expired during quiet breathing
Tidal volume
Maintains oxygenation between breaths
Residual volume
Sum of IRV, TV, ERV
Vital capacity
Sum of ERV and RV
Functional residual capacity
Sum of IRV and TV
Inspiratory capacity
Sum of all 4 lung volumes
Total lung capacity (Normal: 6L)
Cannot be measured directly by spirometry
Residual volume (and all lung capacities that include residual volume)
Equilibrium/resting volume of the lung
Functional residual capacity
Marker for lung function
Functional residual capacity
Difference in lung volumes/capacities among sexes
Lung volumes and capacities 20-25% lower in females
Factors that increase vital capacity
Body size, male sex, conditioning, youth
Total volume of the lungs that does not participate in gas exchange; anatomic dead space + alveolar dead space
Physiologic dead space
Air in the conducting zone is called the anatomic dead space. What is the normal value in healthy humans?
150mL
Air in the alveoli not participating in gas exchange due to V/Q mismatch.
Alveolar dead space (Normal value in healthy humans is 0 mL)
Total rate of air movement in/out of the lungs
Minute ventilation
MV = VT x RR
Minute ventilation corrected for physiologic dead space
Alveolar ventilation
VA = (VT-VD) x RR
25/M, healthy, 70kg with a RR of 20bpm. What is the minute ventilation and alveolar ventilation?
MV = 500mL x 20 = 10, 000mL or 10L VA = (500mL - 150mL) x 20 = 7,000mL or 7L
50/M with TV = 500mL, RR = 20bpm, PCO2 arterial = 40mmHg, PCO2 expired air = 30mmHg. What is the minute ventilation? What is the alveolar ventilation? What percent of TV reaches the alveoli? What percent of TV is dead space?
MV = 500mL x 20 = 10,000 mL or 10L
Physiologic dead space = (0.5L) x (40mmHg - 30mmHg)/40mmHg = 0.125L
VA = (0.5L - 0.125L) x 20 = 7.5L
Percent reaching the alveoli: (0.5 - 0.125)/0.5 = 0.75 = 75%
Dead space: 0.125/0.5 = 0.25 = 25%
What happens to FEV1 and FVC in patients with obstructive and restrictive lung diseases?
Decrease
What is the FEV1/FVC ratio of a healthy person?
0.8 / 80%
What happens to the FEV1/FVC ratio in patients with obstructive and restrictive lung diseases respectively?
Obstructive: Decrease
Restrictive: Normal to increase
Normal inspiration is an active process carried out by what muscle?
Diaphragm
Predominant muscle in forced expiration
External intercostals
Normal expiration is a passive process. However, forced expiration is predominantly done by what muscle:
Internal intercostals
In obstructive lung disease, the decrease in FEV1 is ___ than decrease in FVC
greater
In restrictive lung disease, the decrease in FEV1 is ___ than decrease in FVC
less
In emphysema: Pathology is: loss of \_\_\_\_\_ fiber Compliance: \_\_\_\_\_\_\_\_\_\_\_ Elasticity: \_\_\_\_\_\_\_\_\_\_\_ FRC: \_\_\_\_\_\_\_\_\_\_\_ Effects: \_\_\_\_\_\_-shaped chest
elastic increased decreased increased barrel
In fibrosis: Pathology is: \_\_\_\_\_\_ of lung tissue Compliance: \_\_\_\_\_\_\_\_\_\_\_ Elasticity: \_\_\_\_\_\_\_\_\_\_\_ FRC: \_\_\_\_\_\_\_\_\_\_\_
stiffening
decreased
increased
decreased
Force cause by water molecules at the air-liquid interface that tends to minimize surface area
Surface tension
2 reasons why preterm babies have large collapsing pressure and are prone to atelectasis:
Alveolar radius is 50 micrometers (adult = 100 micrometers)
Lack mature surfactant
Cells that produce surfactant
Type II pneumocytes
Main component of surfactant
Water
Active component of surfactant
Dipalmitoyl-phosphatidylcholine (DPPC)
Mechanism for DPPC reducing surface tension
Amphipathic nature
Effects of surfactant on lung compliance
Increase
Start of surfactant production
24th week AOG
Maturation of surfactant
35th week AOG
Test for surfactant
Amniotic L:S ratio
Treatment for newborn RDS
Steroids, surfactant
Ability of the respiratory membrane to exchange gas between the alveoli and the pulmonary blood
Diffusing capacity
Diffusing capacity for O2:
At rest: _____
Maximal exercise: _____
At rest: 21 mL/min/mmHg
Maximal exercise: 65 mL/min/mmHg
Diffusing capacity for CO2:
At rest: _____
Maximal exercise: _____
At rest: 400 - 450 mL/min/mmHg
Maximal exercise: 1200 - 1300 mL/min/mmHg
What are the forms of gases in solutions?
Dissolved gas, bound gas, chemically modified gas
What is the only form of gas that contributes to partial pressure?
Dissolved gas
What is the only gas in inspired air found exclusively as dissolved gas?
Nitrogen
Difference between PAO2 (alveolar PO2) and PaO2 (arterial PO2)
A-a gradient (Normal: not zero; PAO2 > PaO2)
Nitrogen, oxygen and CO2 under normal condition exhibit what kind of gas exchange?
Perfusion -limited gas exchange (gas equilibriates with the pulmonary capillary near the start of the pulmonary capillary)
CO2 and O2 during strenuous exercise and disease states (emphysema, fibrosis) exhibit what kind of gas exchange?
Diffusion-limited gas exchange (gas doe not equilibriate even until the end of the pulmonary capillary)
O2 transport in high altitude is fast or slow?
Slow
Equilibration of O2 at sea level is ___ length of the pulmonary capillary
1/3 length
Equlibration of O2 at high altitude is ___ length of the pulmonary capillary
2/3 length
Percentage of dissolved O2
2%
Percentage of O2 bound to Hgb
98%
Hgb with attached O2
Oxyhemoglobin
Hgb without attached O2
Deoxyhemoglobin
Hgb with Fe3+ and doesn’t bind O2
Methemoglobin
A2Y2, higher affinity for O2
Fetal hemoglobin
A2B2, sickled RBCs, less affinity for O2
Hemoglobin S
Max O2 binding with Hgb
O2 binding capacity
Percent of blood that gives up it O2 as it passes through the tissues
Utilization coefficient
O2-Hgb dissociation curve is sigmoidal in shape. What is the PO2 at the following percent saturation:
50% saturated, 75% saturated, 100% saturated
50% = 25 mmHg (p50) 75% = 40 mmHg 100% = 100 mmHg
Binding of first O2 molecule increases affinity for second O2 molecule and so forth
Positive cooperativity
Shift to the right or shift to the left?
Increased P50
Right
Shift to the right or shift to the left?
Increased unloading of O2 to Hgb
Right
Shift to the right or shift to the left?
Increased CO2
Right
Shift to the right or shift to the left?
Increased 2,3 BPG
Right
Shift to the right or shift to the left?
Increased temperature, exercise
Right
Shift to the right or shift to the left?
Acidosis
Right
Shift to the right or shift to the left?
Increased binding of O2 to Hgb
Left
Shift to the right or shift to the left?
Decreased p50
Left
Shift to the right or shift to the left?
Increased Carbon monoxide, HbF
Left
90% of chloride in the blood
HCO3-
5% of CO2 in the blood
Dissolved CO2
3% of CO2 in the blood
Carbamino Hgb
Cl-HCO3 exchange in the RBC
Chloride shift (using Band 3 protein)
O2 affecting affinity of CO2/H+ to Hgb
Haldane effect
CO2/H+ affecting affinity of O2 to Hgb
Bohr effect
Haldane effect happens in the:
Lungs
Bohr effect happens in the:
Tissues
Pressure in the pulmonary circulation is ___ than systemic circulation
less
Resistance in the pulmonary circulation is ___ than systemic circulation
less
Cardiac output in the pulmonary circulation is ___ than the systemic circulation
equal to
Pulmonary blood flow in a supine position is lowest at the apex and highest at the base or same through the entire lung?
same through the entire lung
Pulmonary blood flow in a standing position is lowest at the apex and highest at the base or same through the entire lung?
Lowest at the apex and highest at the base
Effect of hypoxia (low PAO2) on pulmonary arterioles
vasoconstriction
Causes of pulmonary global hypoxic vasoconstriction
high altitude, fetal circulation
Called the slow reactive substances of anaphylaxis and causes bronchoconstriction in asthma
Leukotriene C4, D4 and E4
Lung zone:
Local alveolar capillary pressure
Zone 1
Lung zone:
Local alveolar capillary systolic pressure > alveolar air pressure during systole but less than that during diastole;
Intermittent blood flow
Zone 2
Lung zone:
Local alveolar capillary pressure > alveolar air pressure throughout the cycle;
Continuous blood flow
Zone 3
What lung zones do we see in the apex of the lungs at rest?
Zone 2 and 3
What lung zones do we see in the base of the lungs at rest?
Zone 3
What lung zones do we see in a supine position, or during exercise throughout the lungs?
Zone 3
What lung zones do we see in cases of pulmonary hemorrhage or positive pressure ventilation?
Zone 1
Site of highest ventilation
Base of the lungs
Site of highest perfusion
Base of the lungs
Site of highest V/Q ratio
Apex of lungs
Ventilated area of the lungs with no perfusion (V/Q = infinity)
Dead space (eg. pulmonary embolism)
Perfusion of lungs with no ventilation (V/Q = zero)
Shunt
Alveolar gas has same composition as humidified inspired air (PAO2 = 150 mmHg and PACO2 = 0)
Dead space
Pulmonary capillary blood has same composition as mixed venous blood: PaO2 = 40mmHg and PaCO2 = 46mmHg
Shunt
Creates the basic respiratory rhythm; contains the dorsal respiratory group, ventral respiratory group, central chemoreceptors
Medulla
Modifies the basic respiratory rhythm; contains the apneustic and pneumotaxic centers
Pons
Inspiratory center; control basic rhythm; for normal respiration
Dorsal respiratory group
Overdrive mechanism during exercise; for forced inspiration and expiration
Ventral respiratory group
Found in the lower pons; for prolonged duration of inspiration –> decreases RR
Apneustic center
Found in the upper pons; shorten duration of inspiration –> increases RR
Pneumotaxic center
Found in the ventral medulla, respond directly to CSF H+ (increases RR)
Central chemoreceptors
Responds mainly to PaO2
Peripheral chemoreceptors
Stimulated by lung distention
Lung stretch receptors
Decreases RR by prolonging expiratory time; prevent overinflation of the lungs
Hering-Breuer reflex
Stimulated by limb movement; causes anticipatory increase in RR during exercise
Joint and muscle receptors
Stimulated by noxious chemicals; causes bronchoconstriction and increases RR
Irritant receptors
Found in juxtacapillary areas; stimulated by pulmonary capillary engorgement; causes rapid shallow breathing and responsible for the feeling of dyspnea
J receptors