RESPIRATORY Flashcards
The volume inspired or expired with each normal breath
Tidal volume (Vt)
Volume that can be inspired over and above the tidal volume
used during exercise
Inspiratory reserve volume (IRV)
The volume that can be expired after the expiration of a tidal volume
Expiratory reserve volume
The vlume that remains in the lungs after a maximal expiration
cannot be measured by spirometry
Residual volume
2 types of dead space
Anatomic
Physiologic
The volue of the conducting pathways
Anatomic pathway (approximately 150 mL)
functional measurement
defined as the volume of the lungs that does not participate in gas exhange,
approximately equal to the anatomic dead space in normal lungs.
Physiologice dead space
- may be greater than the anatomic dead space in lung diseases in twhich there are V/Q defects
Physiologic dead space can be calcutated by this equation
Lung volumes and capacity
Minute ventilation is expressed as _______
Minute ventilation = Vt x RR
Alveolar Ventilation (VA) is expressed as ________
VA = (VT - VD) x RR
The sum of tidal volume and IRV
Inspiratory capacity
Sum of ERV and RV
the volume remaining in the lungs after a tidal volume is expired
Includes RV, cannot be measured by spirometry
Functional residual capacity (FRC)
Sum of tidal volume, IRV, ERV
the volume of air that can be forcibly expired after a maximal inspiration
Vital capacity, or forced vital capacity
Sum of all four lung volumes.
The volume in the lungs after a maximal inspiration
includes RV, so it cannot be measured by spirometry
Total lung capacity
the volume of air that can be expired in the first second of a forced maximal expiration
Forced expiratory volume (FEV1)
normally 8% if the forced vital capcacity
(FEV1 / FVC) = 0.8
in obstructive disease, such as asthma and COPD, FEV1 and FVC are ______
Reduced
- FEV1 is reduced more than FVC
- FEV1/FVC = decreased
In restrictive lung disease, such as fibrois, both FEV1 and FVC are _______
Reduced
- FVC is reduced more
- FEV1/FVC = increased
The most imporatnt muscle of inspiration
Diaphragm
- when the diaphragm contracts, the abdominal contents are pushed downward, and the ribs are lifted upward and outward, increasing the volume of the thoracic cavity
Not used for inspiration during normal quiet brething
used during exercise and in respiratory distress
External intercosatal and accessory muscles
Expiration is (active or passive)
Passive
Push the diaphragm up and push air out of the lungs
Abdominal muscles
Pull the ribs downward and inward
Internal intercostal muscles
Analogous to capacitance in the CVS
Distensibility of the lungs and chest walls
Compliance
Compliance is ______ related to elastance
Inversely
Compliance of the lungs
- Transmural pressure is alveolar pressure minus intrapleural pressure
- Whenthe pressure outside the lungs is negattive, lung lungs EXPAND and lung volume INCREASES
- In the middle range of pressures,
- Compliance is GREATEST and the lungs are most distensible
- At high expanding pressures
- Compliance is lowest, the lungs are least distensible and the curve Flattens
Inflation of the lungs follows a different curve than deflation of the lungs (expiration); this difference is called ___________
hysteresis
- due to the need to overcome surface tenson forces when inflating
Compliance of the combined lung-chest wall system
- Compliance of the lung chest wall system is less than of the lungs alone or the chest wall along (slope is flatter)
- At rest, Lung volume is at FRC and the pressure in the airways and lungs is qual to atmospheric pressure (0)
- collapsing force of the lungs
- expanding force of the chest wall
- interpleural pressure is NEGATIVE
In a patient with emphysema, lung compliance is _____________
Increased
- higher FRc
- patient’s chest becomes barrel shaped
In a patient with fibrosis, lung compliance is _______
Decreased
- lower FRC
Results from the attractive forces between liquid molecules lining the alveoli at the air liquid interface
Surface tension
Cretaes a collapsing pressure that is directly proportional to surface tension and iversely proportional to alveolar radius
Laplace’s Law
Large alveoli have ______ collapsing pressures and are easy to open
low
Small alveoli have ______ collapsing pressure
high
- In the absence of surfactant, the small alveoli have a tendency to collapse (atelectasis)
Reduces surface tension by disrupting the intermolecular forces between liquid molecules.
Increases co,piance
Surfactant
Surfactants are synthesized by
Type II alveolar cells
Surfactants are primarily cosnsists of the phospholipid
dipalmitoylphosphatidylcholine (DPPC)
In the fetus, surfactant synthesis is variable. Surfactant may be present as early as week ______ and is almost always present by gestation week ______
24
35
LEcithin: sphingomyelin ration greater than _____________ in amniotic fluid reflects mature levels of surfatant
2:1
driven by and is directly proporional to the pressure difference between the mouth(or nose) and the alveoli
Airflow
- Inversely proportional to airway resistance.
Resistance of the airways is described by ____________
Poiseuille’s law
- Notice the powerful inverse fourth power relationship between resistance and the size (radius) of the airway
Mahor site of airway resistance is the ________-
Medium sized bronchi
- Why not the smallest airways?
- Parallel arrangemetn
Factors that change airway resistance
- Contraction or relaxation of bronchial smooth muscles
- Lung volume
- Viscosity or density of inpired gas
________________stimulation, irritants, and the slow reacting substancce of anaphylaxis (asthma) constrict th airways, decrease the radius and inrease the resistance to airflow
Parasympathetic stmulation
_________-__stimualtion dilate the airways via B2 receptors, increases the radius and decrease the resistance to airflow
Sympathetic
________associated with greater traction on airways and decreased airway resistance.
high lung volumes
- patients with increased airway resistance learn to breathe at higher lung volumes to offset the high airway resistance associated with their disease
_____________ are associated with less traction and increased airway resitance, even to the point of airway collapse
Low lung volumes
During a deep-sea dive, both air density and resistane to airflow are ___________
increased
breathing a low density gas, such as helium __________ the resistance to airflow
reduces
Breathing cycle`
- At rest
- Alveolar pressure = atmospheric pressure
- Interpleural pressure is negative
- pressure can be measured in the esophagus
- Lung volume is FRC
- During inspiration
- Inspiratory muscles contract and cause the volume of the thorax to increase
- Lung volume increase, alveolar pressure decrease
- the pressure gradient causes air to flow
- Intrapleural pressure becomes more negative
- Lung volume increase by one Vt
- peak of inspiration
- Inspiratory muscles contract and cause the volume of the thorax to increase
- Expiration
- Alveolar pressure becomes greater than atmospheric pressure
- Intrapleural pressure returns to its resting value
- lung volumes returns to FRC
During forced expiration, intrapleural pressure actually becomes _____________
Positive
Obstructive disease in which expiration is impaired
Characterized by decreased FVC, decreased FEV1
Air trapping and increased FRC
Asthma
- decreased FEV1/FVC ratio
Combiantion of chronic bronchitis and emphysema
Obstrucive disese with increased lung compliance in which expiration is impaired
Decreased FVC and FEV1
Barrel shaped chest
Increased FRC
COPD
- Decreased FEV1/FVC ratio`
mild hypoxemia
normocapnia
Pink puffers
Primarily emphysema
Severe hypoxemia with xyanosis
hypercapnia
Blue bloaters
Restrictive disease with decreased lung compliance
decreased in all lung volumes
FEV1/FVC is increased or may be mormal
Fibrosis
Dalton’s law of partial pressures
as exchange
Partial pressure = Total Pressure x fractional gas concentraion
- In dry inspired air, partial pressure of O2 can be calculated
- TP and Fractional O2 is 0.21
- PO2 = 760 mmHg x 0.21
- 160 mmHg
- Humidified tracheal air at 37 degrees, the calculation is odiefied to correct fot the partial pressure of H2O which is 47 mmHg
- 760 -47 mmHg = 713
- 713 x 0.21
- 150 mmHg
Approximately 2% of the systemic cardiac output bypasses the pulmonary circulation
Physiologic shunt
- the admixture of the venous blood and arterial blood makes the PO2 of arterial blood slightly lower han that of alveolar air
The amount of gas dissolved in a solution is proportional to its __________
Partial pressure
- The units of concentration of a dissolved gas are mL gas/100 mL blood
The diffusion rates of O2 and CO2 depend on the ____________ across the membrane and the area available fo diffusion
partial pressure difference
Gas diffusion across the alveolar-pulmonary capillary barrier occurs according to __________
Fick’s law
- DL or lung diffusing capacity id the equivaent of permeability of the alveolar-pulmonary capilalry barrier and is proportional to diffusion coefficient of the gas and surface area and inversely proportional to thckness of the barrier
DL is measured with ___________
carbon monoxide
DL ________ during excercise
Increases
- there are more open capillaries and thus more surface area for diffusion
DL ________ in emphysema
Decreases
- because of decreased suface area and in fibrosis and pulmonary edema (because of increased diffusion distance)
the gas equilibrates early along the length of the pulmonart capillary.
The partial pressure of the gas in arterial blood becomes equal to the partial pressure in alveoalar air
Perfusion- limited exchange
- Illustrated by N2O and O2 under normal conditions
- diffusion of the as in the arterial blood can be increased only if blood flow increases
The gas does not equilibriate by the time blood reacehs the end of the pulmonary capillary
The partial pressure difference of the gas between alveolar air and pulmonary capilalry blood is maintained.
Diffusion-limited exhange
- Diffusion contines as long as the aprtial pressure gradient is maintaine
Oxygen is carried in two forms:
Dissolved or bound
Hemoglobin
- globular protein of four subunits
- Ferrous state
- each subunit has a polypetide chain
- 2 alpha chains
- 2 beta chains
B chains are replace by y-cahins
Fetal hemoglobin
The oxygen affinity of fetal oxygen is _______________ than adult oxygen
Higher
- becaue of 2,3 diphosphoglycerate (DPG) binds less avidly to the y-chains of fetal hemoglobin
- Oxygen movement from mother to fetus is facilitated
Iron is in the Fe3+ state
Does not bind Oxygen
Methemoglobin
Causes sickle cell disease
The alpha subunits are normal and the B subunits are abnormal
hemoglobin S
- In the deoxygenated form, deoxyhemoglobin forms a sickle shaped rods that deform red blood cells (RBCs)
maximum amount of Oxygen that can be bound to hemoglobin
Limits the amount of oxygen that can be carried in blood
Measured at 100% saturation
Oxygen binfing capacity of hemoglobin
- expressed in units of mL O2/g hemoglobin
The total amount of oxygen carried in blood, including bound and dissolved oxygen.
depends on the hemoglobin concentration, the Oxygen binding capacity of hemoglobin, the PO2 and the P50 of Hgb
Oxygen content of blood
Hemoglobin combines rapidly and reversibly with oxygen to form_______
oxyhemoglobin
At a PO2 of 100mmHg(arterial blood) _________
hemoglobin is 100%saturated; oxygen is bound to all four heme groups on all hemoglobin molecules
At PO2 of 40 mmHg _______
hemoglobin is 75% saturated, which means that on average, 3/4 heme groups on eah hemoglobin molecule have O2 bound
at PO2 of 25 mmHg __________
Hemoglobin si 50% saturated
The PO2 at 50% is the P50. 50% saturation means that on average, 2/4 heme groups of each hemoglobin molecule have oxygen bound
The __________ shape of the HODC is the result of a chanfe in the affinity of hemoglobin as each successive oxygen molecule binds to a heme site
Sigmoid
(Positive coperativity)
- Binding of the first Oxygen molecule increases the affinity for the second molecule, and so forth
The HODC is almost flat when the PO2 is between ______________
60-100 mmHg
Humans can tolerate changes in atmospheric pressure (and PO2) without compromising the oxygen carryng capacity of hemoglobin
Shifts to the right of HODC
- affinity of hemoglobin is decreased
- P50 is increased
- Inrease in PCO2 or decrease in pH
- BOHR EFFECT
- Increase in temperature (during exercise)
- Increase in 2,3 DPG concentration
- adaptation to chronic hypoxemia
Shift to the left of HODC
- affinity of hemoglbin to oxygen is increased
- P50 is decreased
- Decreased PCO2
- Increassed pH
- decreased temperature
- decreased 2,3-DPG
- HbF
- Carbon monoxide
Effect of carbon monoxide poisoning to the HODC
- CO competes for oxygen binding sites on hemoglobin
- the affnitity for CO is 200x
- shify to the left
Decreased in arterial PO2
caused by deceased PAO2, diffusion defect, V/Q defects, and right to left shunts
Hypoxemia
can be used to compare causes of hypoxemia
A-a gradient
Normal A-a gradient is ______
0-10 mmHg
A-a gradient is _________ if Oxygen does not equlibriate between alveolar gas and arterial blood
Increased
- Diffusion defect
- V/Q defect
- Right to left shunt
- PAO2 is greater the PaO2
Decreased oxygen delivery to the tissue
caused by decreased blood flow, hypoxemia, decreased hemoglobin concentration, CO poisoning, and cyanide poisoning
hypoxia
- Oxygen delivery
- O2 delivery = Cardiac output x Oxygen content of blood
oxygen content of blood depends on _________
- Oxygen binding capacity of hemoglobin
- PO2
Cause of hypoxia
Is a growth factor that is synthesized in the kidneys in response to hypoxia
Decreased Oxygen delivery to the kidney causes increased production of hypoxia inducible facto 1a
Erythropoeitin
Produced in the tissues and carried to the lungs in the venous blood
Carbon dioxide
- 3 forms
- Dissolved
- Carbaminohemoglobin
- HCO3 (major form)
In the RBCs, carbon dioxide combines with water to form H2CO3, a reaction cataluzed by ___________
Carbonic anhydrase.
_________leaves the RBCs in exchange for Chloride (chloride shift) and is transported to the lungs in the plasma.
HCO3
H+ is buffered inside the RBCs by ______
Deoxyglobin
Pressures are much ______ in the pulmonary circulation than in he systemic circulation
- lower
Resistance is much ________ in the pulmonary circulation than in systemic circulation
lower
Cardiac output of the right ventricle is _______
Pulmonary blood flow
- equal to cardiac output of the left ventricle
- Although pressures int hepulmonary circulation are low, they are sufficient to pump the cardiac output because resistance of the pulmonary circulation is proportionately low
When a person is _____ blood flow is nearly uniform throughout the lung
supine
When a peron is ____ blood flow is unevenly distributed
standing
- Due to the effect of gravity
- lowest at the apex (zone 1)
- highest at the base (zone 3)
Zone _____
Blood flow is lowest
Alveolar pressure > arterial pressure > venous pressure
1
- Th higher alveolar pressure may compress the capillaries and reduce the blood flow in zone 1
- This situation can occure if arterial BP is decreased as a result f hemorrhage or if alveolar pressure is increased because of PPP
Zone ______
blow flow is medium
Arterial pressure > alveolar pressure > venous pressure
2
- Moving down the lung, arterial pressure progressively increases because of gravitational effects on arterial pressure
- Arterial pressure is greater than alveolar pressure in zone 2, and blood flow is driven by the difference between arterial pressure and alveolar pressure
Zone_______
Blood flow is highest
Arterial pressure > venous pressure > alveolar pressure
3
- Moving down toward the base of the lung, arterial pressure is highest because of gravitational effects, and venous pressure finally increases to the point where it exceeds alveolar pressure
- Blood flow is driven by the difference between arterial and venous pressures as in most vascular beds
in the lungs, hypoxia causes _________
vasoconstriction
Right to left shunts
- normally occur to a small extent
- seen in TOF
- decrease in arterial PO2
- admixture of venous blood with arterial blood
Left to right shunts
- more common that right to left shunts
- pressure are higher on the left side of the heart
- congenital abdonormalities (PDA) or taumatic injuries
- Do not result in decrease in arterial PO2.
- PO2 will be elevated on the right side of the hear because there has been admixture of arterial blood with venous blood
Ration of alveolar ventilataion to pulmonary blood flow
V/Q ratio
- if the RR, tidal volume, cardiac output are normal, the V/Q is approximatly 0.8
- this V/Q results in an arterial PO2 of 100 mmHg and an arterial PCO2 of 40 mmHg
Blood flow or perfusion is ____a_____at the apex and _____b_____in the base
A: Lowest
B: Highest
- because of gravitational effects on arterial pressure
Ventilation is _______at the apex and _______at the base
A : lower
B: higher
- Gravitaional effect in the upright lung
- regional differences for ventialtion are not as great as for perfusion
V/Q ration is higher at the __________
Apex
If the airways are completely bloockedm the ventilation is zero. If bblood flow is normal then _____
V/Q is zero
Called a shunt
- no gas exchange in a lung that is perfused but not ventialted
- the PO2 and PCO2 of pulmonary capilalry blood will approach their values in mixed venous blood
- increased A-a gradient
If blood flow is completely bcoked, then the blood flow to that lung is zero. If ventilation is normal then _____
V/Q is infinite
Dead space
- No gas excahnge
- PO2 and PCO2 of alveolar gas wil aproach their values in inspired air
Sensory information (PCO2, lung stretchm irritants, muscle spindles, tendons, and joints) is coordination in the _______
Brain stem
Medullary respiratory center is located in the ____________
reticular formation
primarily for inspiration and generates the basic rhythm for breathing.
Dorsal respiratory group
Input to the dorsal respiratory group comes from the ____ and _____ nerves
Vagus and Glossopharyngeal
- Vagus = from peripheral chemoreceptors and mechanoreceptors
- Glossopharyngeal nerve = from peripheral chemoreceptors
Output from the dorsal respiratory group travels via ______________
Phrenic nerve
Priamarily responsible for expiration
not active during normal, quiet breathing, when expiration is passive
Ventral respiratory group
Apneustic center is located in the _______
lower pons
Stimulates inspiration, producing deep and prolonged inspiratory gasp
apneustic center
Pneumotaxic center is located in the _______
upper pons
Inhibits inspiration and, therefore regulates inspiratory volume and respiratory rate
Pneumotaxic center
Central chemoreceptors in the medulla are sensitive to the _____ of the CSF.
pH
Decrease in the pH of the CSF produce ________ in breathing rate
increase (hyperventilation)
The _______ are located at the bifurcation of the common carotid arteries
Carotid bodies
The ______ are located above the aortic arch
Aortic bodies
Decrease ina rterial PO2 stimulate the peripheral chemoreceptors and __________ breathing rate
Increase
PO2 must decrease to ________ before breathing is stimulated.
<60 mmHg
__________ in arterial PCO2 stimulate peripheral chemoreceptors to increase breathing rate
Increase
- Potentiate the stimulation of breathing caused by hypoxemia
The respnse o the peripheral chemoreceptors is _______ important than is the responsse of the central chemoreceptors to CO2 or H+
less
In _____________.(Metabolic/respiratory ; acidosis/alkalosis) breathing rate is increased
Metabolic acidosis
located in the smooth muscle airways
when these receptor ae stimulatedm they produce a decrease in breathing frequency
Lung stretch receptors
(HERING-BREUER REFLEX)
Located between the airway epithelial cells
stimulated by noxious substances
Irritant receptors
Located in the alveolar walls, close to the capillaries.
Engorgement of the pulmoanry capillaries, such as that may occur with left heart failure stimulates this receptors, which then cause rapid, shallow breathing
J receptors
activated during movement of limbs
Involved in the early stimulation of breathing during exercise
joint and muscle receptors
Summary of respiratory response to exercise
Summary of adaptation during High altitudes
The mean values for PO2 and PCO2 _____________during exercise
Do not
- arterial pH does not change during moderate exercise, although it may decrease during strenuous excercise because of lactic acidosis
Venous PCO2 ______ during exercise beause the excess CO2 produced by exercising muscle is carried to the lungs in venous blood
Increases
Pulmonary blood flow ________ during exercise
Increases
- because cardiac out increases duringe xercise. As a result, more pulmonary capillaries are perfused, and more gas exchanged occurs.
- Decrease in the physiologic dead space
Alveolar PO2 is ____ at high altitude
Decreased
- barometric pressure is decreased.
Hyperventilation produces respiratory alkalosis, which can be treated by administering ________
Acetazolamide
2,3 DPG conentrations are _______ in high altitudes
Increased
______________is a result of hypoxia. there is increase in pulmonary arterial pressure, increased work of the right sisde of the heart against the higher resistance, and hypertrophy of theright ventricle
Pulmonary vasoconstriction
