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102 Cards in this Set
- Front
- Back
What are two phsyiological challenges humans face?
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they need a large exchange surface that is moist to allow gases to pass from air into solution and yet most be protected from drying out as a result of exposure to air
-dehydration |
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how do we overcome dehydration?
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using an internalized respiratory epithelium which creates a humid environment for the exchange of gases with the blood and protects the delicate exchange surface from damage
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what does air flow require?
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a muscular pump to create pressure gradients
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the respiratory system consists of 2 separate components
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muscle-driven pump (musculoskeletal structure of the thorax in humans) and a thin, moist exchange surface
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the primary functions of the respiratory system are:
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-exchange of gases between the atmosphere and the blood
-homeostatic regulation of body pH, the lungs alter body pH by retaining or excreting CO2 -protection from inhaled pathogens and irritating substances -vocalization |
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the respiratory system is a significant source of
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water loss and heat loss from the body which must be balanced using homeostatic compensations
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bulk flow of air
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exchange of air btw environment and interior air spaces of lungs
1) from high to low pressure 2) muscular pump creates pressure gradients 3) resistance to air flow is influenced primarily by the diameter of the tubes |
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what is the difference btw air flow and blood flow?
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air is compressible mixture of gases
blood is a noncompressible liquid |
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the respiratory system can be divided into two groups
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cellular respiration: intracellular reaction of oxygen with organic molecules to produce CO2, water, and ATP energy
-external respiration: movement of gases between the environment and the body's cells |
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external environment
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movement of gases btween the environment and the body's cells
1) exchange of air btw atmosphere and lungs 2) exchange of O2 and CO2 btw the lungs and blood 3)transport of O2 and CO2 by the blood 4)exchange of gases btw blood and the cells |
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ventilation is
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breathing
the exchange of air btw the atmosphere and lungs |
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inspiration
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movement of air into lungs
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expiration
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movement of air out of the lungs
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external respiration requires the coordinated functioning of both
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respiratory and circulatory systems
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the respiratory system consists of structures involved in ventilation and gas exchange
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1) conducting system of passages (airways) lead from external environment to exchange surface of lungs
2)alveoli 3) bones and muscles of the thorax (chest cavity) and abdomen that assist in ventilation |
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alveoli
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a series of interconnected sacs that collectively form the exchange surface, where oxygen moves from inhaled air to the blood, and CO2 moves from the blood to the air that is about to be exhaled
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the respiratory system can be divided into two tracts
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upper respiratory tract
lower respiratory tract |
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upper respiratory tract consists of
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mouth
nasal cavity pharynx larynx |
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lower respiratory tract
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trachea
two primary bronchi their branches lungs |
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the thorax is bounded by what
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the bones of the spine and the rib cage + their associated muscles
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the thorax is sealed container with 3 sacs
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1 pericardial sac for the heart
2 pleural sacs contain the lungs |
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pleural sacs enclose the lungs
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each lung is surrounded by a double-walled pleural sac
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each pleural membrane (pleura) contains several layers of elastic connective tissue and numerous capillaries
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nothing
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the opposing layers of pleural membrane is held together by
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pleural fluid which serves to create a moist, slippery surface so that the opposing membranes can slide across one another as the lungs move witin the thorax
-holds the lungs tight against the thoracic wall |
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what happens from the trachea to the bronchioles
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the diameter of the airways becomes progressively smaller
-the numbers increase -total cross-section increases! |
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what is the site of gas exchange?
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alveoli- make up the bulk of lung tissue
-primary function: exchange of gases btw themselves and the blood |
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2 types of epithelial cells are found in the alveoli occurring roughly in equal numbers
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type II alveolar cells
type I alveolar cells |
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type II alveolar cells
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synthesize and secrete surfactant
-help minimize the amount of fluid present in the alveoli by transporting solutes, followed by water, out of the alveolar air space |
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surfactant
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mixes with thin fluid lining of the alveoli to aid lungs as they expand during breathing
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type I alveolar cells
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very thin so that gases can diffuse rapidly through them
-small amount of interstitial fluid |
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the thin walls of the alveoli do not contain
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muscle because muscle fibers would block rapid gas exchange
-as a result lung tissue itself cannot contract |
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connective tissue btw
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the alveolar epithelial cells contains many elastin fibers that create elastic recoil when lung is stretched
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what is essential for rapid exchange of gases
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close proximity of capillary blood to alveolar air
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muscles of inspiration
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scalenes
external intercostals diaphragm sternocleidomastoids? |
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muscles of expiration
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abdominal muscles
internal intercostals |
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the number of lobes in the lungs
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right has 3
left has 2 |
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pulmonary ciruclation contains about __ liter of blood or ___ total blood volume
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.5 liters
10% -the majority is found in pulmonary arteries and veins |
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the rate of blood flow through lungs versus other tissues
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the rate is much higher through the lungs because the lungs receive the entire cardiac output of the right ventricle: 5 L/min
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pulmonary blood pressure is? high or low
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low 25/8 mm Hg which is much lower than the average systemic pressure of 120/80 mm Hg
-the right ventricle doesn't pump as forcefully bc of short distance btw blood vessels and arterioles |
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why does congestive heart failure arrise?
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right heart is a more effective pump than the left heart
-blood accumulates in the pulmonary circulation, increased volume increases pulmonary blood pressure and capillary hydrostatic pressure |
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gas laws
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total pressure of a mixture of gases is the sum of the pressures of the individual gases
-gases, singly or in a mixture, move from areas of higher pressure to areas of lower pressure -increase volume, decrease pressure |
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what does water vapor do to pressure
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is dilutes it
meaning increasing humidity will decrease pressure -increasing temperature will also decrease pressure |
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this causes alternating conditions of high and low presure in lungs
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movement of the thorax
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when the chest volume increases
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alveolar pressure falls
air flows into the respiratory system because atmospheric pressure is higher than alveolar pressure |
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lung volumes
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tidal volume
inspiratory reserve volume expiratory reserve volume residual volume |
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tidal volume
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breathe quietly
single inspiration or expiration 500 ml |
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inspiratory volume
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3000 ml
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expiratory volume
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1100 ml
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residual volume
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cannot be measure directly
1200 ml |
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lung capacities
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vital capacity: sum of inspiratory volume, expiratory reserve volume, and tidal volume
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total lung capacity
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vital capacity plus residual volume
-or inspiratory capacity + functional residual capacity |
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inspiratory capacity
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tidal volume + inspiratory RV
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functional residual capacity
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ERV + residual volume
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what do the airways do?
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-warm air to body temperature
-adding water vapor until the air reaches 100% humidity -filtering out foreign material |
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filtration takes place where?
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trachea
bronchi -airways are lined with ciliated epithelium that secrete both mucus and dilute saline solution |
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what happens when diaphragm contracts?
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thoracic volume increases
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what happens when diaphragm relaxes?
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thoracic volume decreases
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pressure in the respiratory system can be measured in?
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the air spaces of the lungs (alveolar pressure)
pleural fluid (intrapleural pressure) |
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how can air move into the lungs?
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increase teh volume will cause a decrease in pressure to the point which pressure inside is lower than atmospheric pressure
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volume change is caused by
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60-75% of the inspiratory volume change is causes by contraction of diaphragm
25-40% by movement of the rib cage |
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pump handle increases the
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anterior-posterior dimension of the rib cage
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bucket handle motion increases
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lateral dimension of rib cage
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alveolar pressure
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is at 0 btw breaths which makes sense because atmospheric = alveolar pressure
-during inspiration, contraction of diaphragm causes volume to increase, meaning pressure decreases |
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why is alveolar pressure lowest halfway through inspiration?
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because thoracic volume changes faster than air can flow
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expiration occurs when?
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alveolar pressure exceeds atmospheric pressure
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during expiration what happens to volume and pressure
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the volume decreases and thus pressure increases above 0
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which part of the muscle group doesnt have antagonistic muscles?
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the diaphragm
-abdominal muscles contract during active expiration to supplement the activity of the internal intercostals |
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why is intrapleural pressure subatmospheric?
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combo of outward pull of the thoracic cage and the inward recoil of the elastic lungs
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why does the intrapleural pressure never equilibrate with atmospheric pressure?
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the pleural cavity is a closed compartment
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2 factors that have the greatest influence on the amount of work needed for breathing are
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stretchability of the lungs
resistance of the airways to air flow |
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restrictive lung disease
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energy required for less-compliant lungs far exceeds energy needed for normal
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saline-filled v. air-filled
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saline-filled are much easier to inflate
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what property of air-filled makes them harder to inflate?
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surface tension created by thin fluid layer btw alveolar cells and the air
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Law of laplace
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p = 2t/r
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surfactants reduce
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surface tension, decreases resistance of the lung to stretch, makes it easier to infalte the smaller alveoli
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primary determinant of airway resistance
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diameter
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primary paracrine that affects bronchiolar
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CO2 dilation
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primary neural control
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parasymphathetic neurons constriction
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histamine
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paracrine that is constrictor
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epinephrine
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dilation
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total pulmonary ventilation
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minute volume
= ventilation rate x tidal volume 12 breaths/min x 500 ml/breath = 6000 ml/min |
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anatomic dead space
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150 ml
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alveolar ventilation
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a more accurate measure of the amount of fresh air that reaches the alveoli each minute
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hyperventilation
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alveolar ventilation is above normal levels
-alveolar P02 rises to 120 mm and CO2 falls to 20 |
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hypoventilation
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less fresh air into alveoli
o2 decreases and co2 increases |
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total pulmonary ventilation
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remains the same regardless of titdal volume and ventilation rate
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what happens if you increase tidal volume
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you decrease ventilation rate and thus increase fresh air to alveoli and increase alveolar ventilation
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what happens if you decrease tidal volume from 500 to 350
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you increase ventilation rate and decrease fresh air to alveoli and decrease alveoli ventilation
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eupnea
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normal quiet breathing
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hyperpnea
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increased respiratory rate and/or volume in response to increased metabolism (exercise)
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hyperventilation
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increased respiratory rate and/or volume without increased metabolism (blowing up a balloon)
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tachypnea
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rapid breathing, usually increased respiratory rate with decreased depth (panting)
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dyspnea
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difficulty breathing (air hunger)
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apnea
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cessation of breathing (voluntary breath-holding)
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why are capillaries inthe lungs unusual?
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because they are collapsible
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bronchiolar diameter is mediated primarily by?
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CO2 levels
-increase in co2 of expired air causes bronchioles to dilate |
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what happens if ventilation of alveoli in one area of the lung is diminished?
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po2 in that area decreases and arterioles respond by constricting
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increase Pco2
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bronchioles dilate
pulmonary arterioles constrict systemic artioles dilate |
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decrease Po2
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bronchioles dilate
pulmonary arterioles constrict systemic artioles dilate |
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bronchioles constrict
pulmonary arterioles dilate systemic artioles constrict |
CO2 decreases
PO2 increases |
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what happens if ventilation decreases in a group of alveoli
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co2 increases and o2 decreases
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these are bronchoconstrictors that are released during the inflammatory response
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leukotrienes
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