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116 Cards in this Set
- Front
- Back
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Two types of air passages |
*conducting zone *respiratory zone |
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Describe the progression of air in the conducting zone |
nose/mouth > oropharynx > glottis with vocal folds > layrynx > trachea > primary bronchus > 23 branches of bronchiole tree > terminal bronchioles |
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What are the physical characteristics of the bronchioles? |
no cartilage and an opening of 1mm |
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Define aspiration |
anything besides air going into the lungs |
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How is the R side main bronchus different than the left? What are the consequences of these differences? |
*wider and more vertical. *the more likely site of aspiration pneumonia |
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Functions of the conducting zone (3) |
*conducts air to respiratory zone *warms and humidifies inspired air *mucociliary escalator |
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Describe the mucociliary escalator? |
*mucous filters and cleans inspired air by trapping stuff in mucous *rhythmic beating of cilia pushes mucous and trapped particles toward the pharynx, to be swallowed or expectorated |
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Two things that can paralyze cilia |
*cigarette smoke *dehydration |
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Key conditions for quality gas exchange |
*large surface area *tiny area to diffuse across (2 cell widths) |
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Function of respiratory zone |
*gas exchange between air and blood |
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Components of the respiratory zone |
respiratory bronchioles, alveolar sacs, and alveoli |
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3 separate, related functions that make up respiration |
*ventilations *gas exchange *oxygen utilization/cellular respiration |
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What do you call a machine helping a patient breathe? |
*ventilator (NOT respirator), as it is only helping with ventilations |
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Where does gas exchange occur? |
At both the interface between alveoli and capillaries (blood) and the interface between capillaries (bood) and other tissues |
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Define cellular respiration |
The utilization of oxygen to breakdown macronutrients to generate ATP |
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Define ventilation |
the mechanical process of moving air in and out of the lungs |
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How does gas exchange between air and blood occur? |
diffusion |
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Why is diffusion rapid in the lungs? |
large surface area and small diffusion distance |
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How many alveoli are there and how much surface area do they provide? |
300 million alveoli providing a surface area of 60 to 80 square meters |
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What type of cells make up the alveoli? |
epithelial cells |
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Describe the two types of alveolar cells |
*Alveolar type 1: structural *alveolar type 2: secrete surfactant |
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What is another cells types other than the alveolar cells present? |
macrophages, they are impaired by smoking |
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What causes the constant sticking/contact between the parietal and visceral pleura? Why do the lungs expand along with the thoracic cavity? |
a vacuum (negative pressure) |
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What kind of space is the intrapleural space and what is there? |
It is a potential space containing serous fluid |
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Define intrapulmonary pressure. How do the values of this pressure vary? |
also called intra-alveolar pressure, it is pressure inside the alveoli. It varies from neutral to negative to positive based on which part of ventilation. |
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Define intrapleural pressure. How do the values of this pressure vary? |
*the pressure inside the intrapleural space *it varies depending on which part of the ventilation cycle, but is always negative |
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Other terms that can be used for "vacuum" |
*negative pressure *subatmospheric |
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What are the pressures during inspiration? |
*intrapulmonary: negative *intrapleural: more negative |
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What are the pressures during exhalation? |
*intrapulmonary: positive *intrapleural: negative |
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What are the pressures at the rest time in the ventilation cycle |
*intrapulmonary: neutral *intrapleural: negative |
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What generates and what is the effect of negative pressure in the intrapulmonary space? |
negative pressure is generated by increased lung volume, resulting in air being drawn into the lung (inspiration) |
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What generates and what is the effect of a positive pressure in the intrapulmonary space? |
positive pressure is generated by decreased lung volume, resulting in air being pushed out of the lung (expiration) |
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Boyle's law |
the pressure of gas is always inversely proportional to its volume. Breathing follows Boyle's law |
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Define transpulmonary pressure |
The pressure difference across the wall of the lung intrapulmonary pressure - intrapleural pressure |
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In a normal/healthy human, what should the value of transpulmonary pressure be |
a positive number in all phases of respiration. The pressure in the alveoli has to be greater than than the intrapleural space in order to stay inflated |
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How is an atelectasis different form a pneumothorax |
*An atelectasis is usually due to interference with natural forces that promote lung expansion *An atelectasis is treatable with physical therapy |
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Treatment of atelectasis (3) |
*wait and see *deep breathing exercises (using an incentive spirometer) *chest physical therapy |
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What are the PT techniques for treatment of atelectasis? |
*postural drainage *percussion *vibration |
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Define pneumothorax |
partial or whole lung collapse due to collection of air or gas in the intrapleural space |
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Define atelectasis. What is a common cause? |
*partial or whole lung collapse due to interference with natural forces that promote lung expansion *fluid collecting in inferior lungs due to sustained bedrest and gravity |
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One way to identify pneumothorax on Xray |
*more rib expansion, due to elastic recoil of rib cage unapposed by visceral pleura |
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What is the treatment for a pneumothorax? where is it usually placed? |
A chest tube is usually placed on the midaxillary line between rib 4 and 5 |
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Can a patient with a chest tube be mobilized? |
Yes, the chest tube is sutured in, but it is a medical emergency if it is disturbed |
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3 properties of the lung that are critical for function |
*compliance *elasticity *surface tension |
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What is compliance a measure of |
distensibility |
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Define compliance |
change in lung volume per change in transpulmonary pressure |
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What factors reduce compliance? |
*factors that produce resistance to distension *ex. pulmonary fibrosis, pneumonia |
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What factors increase compliance? |
*factors that decrease resistance to distension *ex: emphysema, age |
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What is the relationship between compliance and elasticity? |
The are inverse |
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Definition of elasticity |
tendency to return to initial size after distension |
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What allows for the elasticity of lung tissue |
high concentration of elastin |
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When is elastic tension increased and decreased? |
Elastic tension is increased during inspiration and reduced by recoil during expiration |
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What prevents lungs from collapsing after each breath due to their high elasticity? |
Positive transpulmonary pressure |
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How does emphysema affect compliance/elasticity? |
*severely decreases elasticity
*lungs and the chest wall expand somewhat unopposed (creating barrel chest) |
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Define surface tension |
*force that resists distension that is exerted by a thin layer of fluid in the alveoli |
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What direction of force is produced by surface tension in the alveoli? What law communicates that potential problem with this force? |
*surface tension exerts an inward force within alveoli *Law of Laplace shows that if these forces are unopposed, and small alveolus would collapse as the pressure is lower in larger alveoli. |
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What does the lung produce to deal with the potential consequences of surface tension? |
Surfactant |
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What is surfactant? How is it produced? |
Surfactant is a phospholipid produced by alveolar type II cells, starting in late fetal development |
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How does surfactant lower surface tension? |
It interferes with the hydrogen bonds between molecules. The effect increases as the radius of alveoli decreases, negating the consequences of the Law of Laplace. |
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Muscles of inspiration |
Primary: diaphragm Main accessory: sternocleidomastoid and scalenes other: external/parasternal intercostals, traps, pecs, erector spinae |
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Muscles of expiration |
Primary: none Accessory: internal intercostals, abdominals |
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What is bucket handle motion? What ribs move this way? |
Lower ribs move in this matter: ribs elevate to increase in transverse diameter |
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How do upper thoracic ribs move? |
Usually increased in anterior/posterior diameter |
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How do the lungs increase in volume during quiet inspiration (an active process)? |
*diaphragm actively contracts to increase thoracic volume vertically *parasternal and external intercostals actively contract to increase thoracic volume laterally |
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How do lungs decrease in volume during quiet exhalation (a passive process)? |
*the stretched diaphragm and accessory muscles and lungs recoil |
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How is pulmonary function assessed clinically? |
spirometry |
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What does spirometry measure? |
How much and how quickly air can be exhaled |
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What is the purpose of pulmonary function tests? |
*test for obstructive and restrictive disease *document progression of disease *document effectiveness of treatment *evaluate pt prior to surgery *evaluate pt ability to be weaned from ventilator |
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Define tidal volume |
amount of air expired with each breath during normal quiet breathing 500mL |
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define vital capacity |
maximum amount of air that can be forcefully exhaled after maximum inhalation |
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Define volume and capacity |
volume = discrete amount capacity = sum of two or more volumes |
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What volume cannot be measured by spirogram? |
residual volume |
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study terms on p. 19 and hand out |
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Factors that affect PTF norms |
Age: decrease with age Sex: male = larger Body height/size: tall = larger, obese = smaller Race |
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What altered spirometry measures define restrictive disorders? |
*vital capacity is reduced *various flow rates are normal |
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What altered spirometry measures define obstructive disorders? |
*vital capacity is normal *FEV1 is reduced |
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What is the diagnostic result that indicates an obstructive disorder? |
Post bronchodilator FEV1/FVC of less than 70% |
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clinical examples of restrictive disorders |
*lobectomy *pulmonary fibrosis (restrictive to inhalation = less functional lung available) |
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Define dead space |
volume of airways and lungs that does not participate in gas exchange |
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what structures make up anatomical dead space? How big is it? |
conducting zone, 150mL |
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What happens when fresh air is inhaled and mixes with anatomical dead space |
amount of "fresh" air (high in O2, low in CO2) that reaches the alveoli is less than tidal volume |
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How is anatomical dead space affected by increasing tidal volumes? |
It stays the same, so the percentage of fresh air reaching alveoli increases |
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Define alveolar ventilation |
the actual removal and replacement of gas within alveoli (takes dead space into account) frequency (f) x (tidal volume - dead space) |
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What is Dalton's law? |
the total pressure of a gas mixture is the equal to the sum of the pressures that each gas in the mixture would exert independently total pressure = sum of partial pressures |
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Define partial pressure |
pressure that a particular gas in a mixture exerts independently |
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What are the first variables that have to be considered to find PO2 in the air? |
*percent oxygen (21%) *pressure based on altitude (760mmHg at sea level) |
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What variables have to be considered to find PO2 in the conducting zone and alveoli? |
*humidifiation of air (reduces PO2) *dead space (reduces PO2) |
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What are the values of PO2 in *normal atmosphere *conducting zone *respiratory zone *arteries |
*159mm Hg *150mm Hg *105mm Hg *100mm Hg |
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How is oxygen carried in the blood |
*dissolved in plasma (<2%) *bound to hemoglobin (98%) |
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In what form can oxygen exert a partial pressure? |
dissolved in plasma |
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Henry's law |
the amount of O2 dissolved is proportional to its partial presssure |
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What form of oxygen is available to diffuse into tissues? |
dissolved in plasma |
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Where is Hemoglobin (Hb) found? |
RBCs |
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Describe the protein structure of hemoglobin |
4 polypeptide chains and 4 heme groups |
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What is a heme group? What does it do? |
1 iron molecule that can combine with 1 molecule of O2 |
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How many molecules of O2 can be held by one hemoglobin? How many hemoglobins per RBC? |
*4 *280 million |
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Names for hemoglobin in its various states of oxygenation |
*oxyhemoglobin *deoxyhemoglobin |
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How is hemoglobin production controlled |
Via erythropoeitin produced by the kidneys. Release is stimulated when oxygen delivery to tissues is lower than normal |
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What is loading/unloading of O2 from hemoglobin dependent on? |
*PO2 of environment *affinity between hemoglobin and O2 |
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Where does unloading of oxyhemoglobin occur? Where does loading of deoxyghemoglobin occur? |
*tissue capillaries/areas of lower PO2 *lung capillaries |
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PO2 in arteries PO2 in veins |
~100mm Hg ~40mm Hg |
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Describe fluctuations of PaO2 |
*arterial blood values are relatively constant |
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Why are arterial blood values clinically significant? |
they reflect lung function |
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3 things that oxygen content in the blood depends on |
*PO2 (elevation, supplemental oxygen) *Number of RBCs (erythropoietin, kidneys) *hemoglobin content (erythropoietin, kidneys, iron) |
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What does the steep portion of the oxygen dissociation curve indicate? |
small changes in PO2 produce large differences in %Hb saturation |
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What does the flat portion of the oxygen dissociation curve indicate? |
Large changes in PO2 have very little affect on Hb saturation |
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What does the oxyhemoglobin dissociation curve illustrate? |
How PO2 in the environment dictates whether or not O2 will bind to hemoglobin |
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What does a 'right shift' of the oxyhemoglobin curve indicate? What causes a right shift? |
*Hb has decreased affinity for O2, making it easier to unload into tissues *increase in PCO2 and decrease in pH *increase in temperature *increase in glycolytic products (results of exercise) |
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What does a 'left shift' of the curve indicate? What causes a left shift? |
*Hb has increased affinity for O2, making unloading into tissues harder *alkylosis *carbon monoxide poisoning |
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What is the abbreviation for arterial oxyhemoglobin saturation? What does it indicate? |
*SaO2 *how oxygenated arterial blood is |
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What is the gold standard for measuring SaO2? What is often used instead? |
*repeated sampling of arterial blood via indwelling catheter *pulse oximetry |
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Physiological relevance of the following points on the curve in normal, healthy person: *PO2 100mmHg, Hb 98 *PO2 60mmHg, Hb 90% *PO2 40mmHg, Hb 75% *PO2 20mmHg, Hb 35% |
*arterial blood *critical cut off point for exercise *veins at rest *intense exercise |
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What does pulse oximetry measure? |
ratio of oxyhemoglobin to deoxyhemoglobin |
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Describe issues with pulse oximetry in patient with normal oxygenation? |
*responds to pulsatile nature of arterial blood flow *only an estimate for SaO2 *<2% error at normal saturation and perfusion *motion artifact *skin pigment *poor peripheral circulation *nail polish |
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When are pulse oximeters less accurate? In what way are they inaccurate? |
*SaO2 < 80% *values are likely to be in error by 5% at SaO2 < 80% *values are usually an overestimate |
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Values for various levels of hypoxemia |
*mild: 90-94% *moderate: 75-89% *severe: <75% |
