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59 Cards in this Set
- Front
- Back
Respirations 4 major functions
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1) pulmonary ventilation 2) diffusion of O2 and CO2 btwn alveoli and blood 3) transportation of O2 and CO2 in blood and body fluids 4)regulation of ventilation
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how are lungs expanded
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downward movement of diaphragm and elevation of ribs
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what causes slight suction btwn parietal pleura and lung
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lymphatic channels
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Pleural pressure definition
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pressure of fluid btwn lung pleura and chest wall pleura (slight neg pressure)
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pleural pressure at beginning of inspiration and end inspiration
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negative 5 cm of water and negative 7.5 cm of water
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zero reference pressure in the airways
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atmospheric pressure (0 cm h2o)
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alveolar pressure during inspiration and expiration
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negative 1 cm water and positive 1 cm water
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transpulmonary pressure
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difference btwn alveolar and pleural pressure - measure of elastic forces in lungs
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compliance of lungs
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extent to which the lungs will expand for each unit increase in transpulmonary pressure (~200 mL of air per cm of water)
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inspiratory compliance curve
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slow to fill lungs at first, then more rapid
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expiratory compliance curve
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rapidly exits at first, then slower
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Tissue elastic forces
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represents 1/3 of the total lung elasticity
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Fluid-air surface tension
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represents 2/3 of the total lung elasticity
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surfactant
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reduces surface tension of water
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what secretes surfactant
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type II alveolar cells
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what is in surfactant
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phospholipids, proteins, and ions (most important are dipalmitoylphospatidylcholine, surfactant apoproteins, and calcium ions)
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How does dipalmitoylphospatidylcholine work?
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partially dissolves - part remains on surface (surface has 1/12 to 1/2 tension of pure water)
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pressure in occluded alveoli
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2 times surface tension/radius of alveolus (about 4 cm of water in average alveolus with surfactant)
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alveolar pressure in premature infants
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double normal due to small radius, also less/no surfactant production
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compliance of lungs including thoraxic cage
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half the compliance of lungs alone
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Work of inspiration-3 components
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1) expand lungs against elastic forces 2) overcome viscosity of lung and chest structures - tissue resistance 3) overcome airway resistance
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Quiet respiration energy expenditure
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3 to 5 percent total energy
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Tidal volume
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volume inspired/expired with each noraml breath (~500 mL in adult male)
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Inspiratory reserve volume
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extra volume of air that can be inspired above tidal volume with full force (~3000 mL)
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expiratory reserve volume
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max extra volume of air that can be expelled by forceful expiration (~1100 mL)
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residual volume
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volume air remaining in lungs after most forceful expiration (~1200 mL)
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Inspiratory capacity
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tidal volume plus inspiratory reserve volume (~3500 mL)
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functional residual capacity
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expiratory reserve volume plus residual volume (~2300 mL); amount left in lungs after normal expiration
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vital capacity
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inspiratory reserve volume plus tidal volume plus expiratory reserve volume (4600); max amount of air that can be expired
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total lung capacity
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vital capacity plus residual volume; max expansion with greatest possible effort (~5800 mL)
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capacity in men vs woman
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20-25 percent less in women than men
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measuring functional residual capacity (FRC)
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helium dilution (FRC = (initial He concentration/final He concentration -1)*initial volume spirometer
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minute respiratory rate
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total amount of new air entering respiratory passages each minute; about 6L/min normal…can go up to 200L/min (tidal volume times resp rate/min)
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alveolar ventilation
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rate at which new air reaches alveoli
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dead space
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air that enters respiratory passage, but never enters alveoli (generally ~150 mL)
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measuring dead space
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measure changes in nitrogen concentration after taking deep breath of pure O2
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calculating dead space
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Vd = (VO2*Vexpired)/(VN2+VO2)
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physiological dead space
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dead space + alveolar dead space
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alveolar ventilation rate
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resp frequency * (tidal volume - physiologic dead space); noramal about 4200 mL/min
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composition of trachea and bronchi btwn catilage plates
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Smooth muscle
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walls of bronchioles
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almost entirely smooth muscle
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walls of respiratory bronchioles
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pulmonary epithelium plus few smooth muscle fibers
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Many obstructive diseases result in narrowing of what
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smaller bronchi and larger bronchioles
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Where is the greatest amount of resistance to airflow
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larger bronchioles and bronchi near trachea (few in comparison to terminal branches)
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Smaller bronchioles are easily occluded by…
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1) muscle contration in walls 2) edema in walls 3) mucus collection in lumens
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sympathetic stimulation location
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few fibers penetrate central portions of lungs, but respond to norepinephrine and epinephrine released by adrenal medulla into blood
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sympathetic stimulation effect
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dilation of bronchial tree (beta-adrenergic receptors)
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parasympathetic stimulation
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penetrate lung parenchyma, cause mild/moderate constriction
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What can be used to block parasympathetic acetylcholine release
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atropine
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Substances in lungs that cause bronchiolar constriction
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histamine and slow reactive substance of anaphylaxis (released by mast cells)
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where does ciliated epithelium end
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as far down as terminal bronchioles
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carina
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point where trachea splits into bronchi
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cough reflex caused mainly by what nerve
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vagus
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cough sequence
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2.5 L air rapidly inspired; epiglottis closes and vocal cords shut tight; abdominal muscle contract forcefully; vocal cords and epiglottis open widely
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sneeze reflex
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like cough reflex except through nasal passageways
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nerve mainly responsible for sneeze reflex
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trigeminal
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function of nasal passageways
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1) warm air 2) moisten air 3) filter air
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Size of particles that can pass normal nasal passageways
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almost no particles greater than 6 um (smaller than RBCs)
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where do most small dust particles settle in the lungs
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smaller bronchioles (result of gravitational precipitation) - unless smaller than 0.5 um (go to alveoli)
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