phys 3

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what is anatomic dead space?: URT is equivalent to it, it includes all the anatomical tubes which connect the external environment with respiratory units (alveoli)
define vapor pressure: pressure exerted on the walls of a container due to the kinetic energy of the molecules evaporated into the gaseous phase (in mmHg or torr)
define vapor: water (or any liquid) in the gaseous state
define absolute humidity: mass or weight of water vapor per volume of gas AH= mg of water /L of gas think of it as the number of molecules per volume of gas...as the temp of a gas increases then the gas has the capacity to hold more water vapor so the potential absolute humidity increases.
define relative humidity: actual number of water molecules in the gaseous phase/maximum number of water molecules at given temperature change in RH depends on if there is water being added to the system as temperature increases
what factors increase humidity?: temperature, surface area (larger surface area increases the ability ot humidify by increasing the area for evaporation), pressure over the liquid (inhalation is caused by a pressure difference...this pulls water molecules from the wall of the airway into the inspired gas) and presence of a continuous gradient (old gas is replaced by new gas that has less humidity)
what are the consequences if you fail to humidify air?: impaired ciliary function, impaired mucous function, inflammation and necrosis, retained secretions; microbial colonization, atelectasis and pneumonia
define ventilation: mechanical process of moving air into/out of the lungs
what are the 4 things required for ventilation?: patent airway, functional muscles, unrestricted movement of pumps and associated structures and central neural control to initiate/modify ventilation
what is TV (or Vt): tidal volume=the volume of air leaving/leaving the nose/mouth per breath
what is the resting end point?: when the entire ventilatory system is at an equilibrium point where all the forces system acting on the system are balanced-no muscles are contracting at this phase
how do you calculate minute volume?: tidal volume x frequency
what is IRV?: inspiratory reserve volume (air that inspired with max inspiratory effort after inspiring a tidal volume
what is ERV?: expiratory reserve volume
what is RV?: residual volume-helps the lungs from collapsing at low lung volume
what is IC?: inspiratory capacity IC=TV + IRV
what is FRC?: functional residual capacity FRC=ERV + RV
what is VC?: vital capacity VC=IRV+TV+ERV
what is TLC?: total lung capacity TLC=IRV+TV+ERV+RV
what is the difference between a restrictive and obstructive disease?: restrictive-limit expansion of the lungs (primarily affect inspiration more than experiation) examples: fibrosis of the lungs and/or chest wall, spinal deformities, advanced pregnancy, neuromuscular disease obstructive-limits airflow (affects expiration more than inspiration) examples: emphysema, chronic bronchitis, asthma, airway tumors
what is anatomic dead space volume?: volume of gas taken in that does not equilibriate with blood, approximated as 1 cc/lb of body weight
what is physiologic dead space?: anatomic dead space + alveolar dead space
what is the most important volume of air measured?: pulmonary or alveolar ventilation--this is the portion of tidal volume that is fresh air which reaches the alveoli and actually exchanges with blood. this is constantly being regulated and is acheived by adjusting the tidal volume
what would the gases look like with hypoventilation?: increased carbon dioxide, decreased oxygen (looks more cellular)
what would the gases look like with hyperventilation?: increased oxygen and decreased carbon dioxide
what are the primary muscles for inspiration in the thoracic pump?: the external intercostals-changes the diameter of the thoracic cylinder
what are the accessory muscles associated with inspiration?: major and minor pecs scalenes SCMs part of serratus
what muscles are involved with expiration?: note-expiration is usually passive but may be active and use internal intercostals, rectus abdominis, rectus oblique and transverse abdominis
what muscle (s) moves about 2/3rds of the tidal volume during inspiration?: diaphragms-changes the length of the thoracic cylinder
how can we measure Ppl clinically?: measure pressure in the esophagus
what is Ptp?: the pressure difference across the alveolar wall-on the either side of the alveolar or pulmonary wall Ptp=Pa minus Ppl if its positive-favors opening of the alveoli if its negative-favors closing of the alveoli
does active deflation decrease or increase central venous pressure?: increases CVP--less of a gradient---less venous return--less cardiac output
is the lung volume/transpulmonary pressure relationship linear? direct?: it is NONlinear and DIRECT this is also an example of hysteresis (taking different paths but beginning and ending at the same points)---this takes way more pressure to have the same lung volume during inspiration versus expiration
what is compliance?: a measure of the stiffness of the lung or its distensibility or ease of inflation C=V/P
what is atelectasis?: collapse of alveoli
why does anesthesia promote alveolar collapsing?: hypoventilation-you get alveoli collapsing-alveolar interdependence is lost
how do COPD patient's cope and modify their breathing?: slow, purse-lipped breathing
how are FRC and RV tested clinically?: cannot do them by routine spirometry-need to do indirect measurement such as the Fick principle
What is the relationship between work, pressure and volume?: W=PxV
what is more important with gas exchange....partial pressure gradient or concentration?: partial pressure gradient!! because of solubility differences (if they are at the same concentration but one is more soluble, the more soluble gas with have a lower partial pressure)
what are we more suceptible to change in, PO2 or PCO2?: PCO2-should be around 40 mmHg
how thick is the alveolar capillary barrier?: about 0.5 u if this becomes thicker (because of disease) exchange and diffusion become impaired
what is the definition of hypoxia?: low PO2 in the inspired air or decreased PO2 in blood or tissues
what is hypoxemia?: low O2 in arterial blood
what is hyperoxia?: high PaO2
what is hypercapnia?: high PaCO2 or retained CO2
what is hypocapnia?: low PaCO2
what is hyperventilation?: increased alveolar ventilation (respiratory gases approach ambient) causes: changes in psychic state, pain and in response to metabolic acidosis
what is hypoventilation?: decreased alveolar ventilation (respiratory gases approach cellular) causes: CNS depression, neurological problems, thoracic cage injuries or neuromuscular disease
clinically, how do we measure normal diffusion?: have a patient inhale a single breath of a gas mixture that contains CO and calculate the rate of uptake
what does P50 mean?: at P50 there is 50% saturation of Hgb at physiological pH, temp and PaCO2
what does a right shift in P50 mean?: this means the P50 is occuring at a higher PaO2 level so there is favoring of unloading of oxygen this happens with exercise, or any condition which increases CO2 (Bohr effect), so an increase in H+, increase in temp and an increase in 2,3 DPG
what does a left shift in P50 mean?: this favors loading of O2
what does an ABG tell us?: it ONLY tells us about the adequacy of gas exchange b/t the lungs and blood and only relfects the amount of O2 in the dissolved state---so you also need to assess the oxygen carrying capacity by doing a CBC
what are the three ways that CO2 is transported?: dissolved, HCO3- (primary) and carbamino cmpds
what is the Haldance effect?: when there is an increase in the PO2--there is a decreased affinity of Hgb for CO2-this promotes elimination of CO2 in the lungs and enhances transport away from the tissues
what is the Hering-Breuer relfex?: the inflation reflex that is activated more as lungs are inflated, increased activation as the lungs inhale more
what is eupnea?: normal breathing (12-16/min)
what is hyperpnea?: increased ventilatory volume (hyperinflation) or deep breaths at a fast rate (>20/min) this happens with exercise, anxiety, etc
what is tachypnea or polypnea?: shallow rapid breathing or many breaths/minute (>20/min) this term only refers to the rate of breathing and not the adequacy of breathing
what is bradypnea?: slow rate of breathing (< 12/in) this is most common with neurogenic disorders, electrolyte imbalance, response to pain or infection
what is hypoventilation?: decreased alveolar ventilation-causes the ABGs to approach cellular levels
what is hyperventilation?: increased alveolar ventilation-results in ABGs approaching the values in the ambient or surrounding environment-this is NOT rapid breathing or tachypnea
what is apnea?: cessation of breathing
what is dysnpea?: labored or difficult breathing
what is Cheyne-Strokes respiration or periodic breathing?: a breathing pattern characterized by bursts of tidal volumes that increase and then decrease in depth followed by intervals of apnea-"waxing and waning" pattern this is thought to maybe be due to altered sensitivity of the central chemoreceptors to changes in PaCO2 or impaired feedback in ventrilatory control
what is Biot's breathing or cluster breathing?: this is a disorganized pattern of breaths with irregular apnea caused by lesions in the pons or medulla-a typical pattern consists of 2-3 deep breaths followed by a period of apnea
what is Kussmaul's respiration?: this is a fast (>20/min) breathing pattern of deep sighing types of breaths but no pauses-it is often characterized as labored breathing and associated with renal failure or metabolic acidosis
what is apneusis?: cessation of breathing in the inspiratory phase or breath holding
what is apneustic breathing?: ventilation is arrest in the inspiratory phase with only periodic expirations
what is ataxic breathing?: irregular breathing pattern with both deep and shallow breaths occuring in no organized pattern--most associated with lesions in the medulla

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