Lect 5-Mechanics & Gas Exchange Flashcards by Rachel Leigh

conducting zone

brings air into and out of lungs

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respiratory zone

where gas exchange occurs

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structures comprising conducting zone

nose/mouth, pharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles

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main conducting airway

trachea

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innervation of what neurons/receptors leads to relaxation and dilation of the airways?

sympathetic adrenergic neurons, B2 receptors

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innervation of what neurons/receptors leads to contraction and constriction of airways?

parasympathetic cholinergic; M3 receptors

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area of most airway resistance

bronchioles

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where are club “clara” cells and what do they do

bronchioles; secrete protective glycosaminoglycans

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epithelial cell phenotype in bronchi

ciliated columnar

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epithelial cell phenotype in bronchioles

ciliated columnar

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epithelial cell phenotype in respiratory bronchioles

cuboidal ciliated

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structures of respiratory zone

respiratory bronchioles, alveolar ducts, alveolar sacs

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type I pneumocytes

gas exchange; squamous; nonreplicating

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type II pneumocytes

make surfactant; columnar, can differentiate into type I

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function of alveolar macrophages

keep alveoli free of debris (no cilia); found in inter-alveolar septum

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pulmonary coupling=

alveoli + vasculature

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blood supply to lungs

pulmonary artery + branches

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when standing, where is pulmonary blood flow focused?

lower lobes (gravity)

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which side of the heart is assoc w lungs

right side (deox blood travelling to lungs)

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bronchial circulation is the blood flow to the…

conducting zone

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does bronchial blood flow participate in gas exchange?

no… except for a few respiratory bronchioles; the blood just perfuses the lungs themselves

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pulmonary function test

measure volume of gas in lungs at a given time

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tidal volume

amt of air that can be inhaled/exhaled during one resp cycle (300-500mL)

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inspiratory reserve volume

additional volume that can be forcibly inspired above tidal volume (3000mL)

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expiratory reserve volume

additional volume that can be forcibly expired below tidal volume (1200mL)

residual volume

volume of air remaining in lungs after maximal exhalation (1000-1200mL) can only be indirectly measured

capacities contain ____ or more lung volumes

inspiratory capacity

tidal volume + inspiratory reserve volume (500+3000)

functional residual capacity

expiratory reserve volume + residual volume (1200+1200) the volume remaining in lungs after a normal, passive exhale

vital capacity

inspiratory capacity + expiratory reserve (3500 + 1200)

total lung capacity

vital capacity + residual volume (4700+1200)

total average lung capacity

6L (includes theoretical amt of capacity)

how many L is a normal functional residual capacity

at FRC, the airway pressure is >, =, < than atmospheric pressure?

EQUAL

dead space

volume of air that is inhaled but does not participate in gas exchange because it remains in conducting airways

anatomic dead space

volume of conducting airways (150mL)

alveolar dead space

sum of volumes of alveoli that have no blood flow; ventilated but not perfused

physiological dead space

(total dead space) =anatomic + alveolar

in a healthy individual, what is the ratio of anatomic: physiologic dead space?

roughly equal physio ds= anatomic ds + alveolar ds

ventilation rate

volume of air moved into and out of lungs per unit time

minute ventilation

total rate of air movement =tidal volume x RR

alveolar ventilation

corrects for physiologic dead space and only considers am of air capable of gas exchange =(tidal v-physio ds) x RR

in a normal person, FEV1/FVC is about...

0.8L

____% of the vital capacity can be expired in the first second of forced expiration

80%

accessory muscles for inspiration

external intercostals, sternocleidomastoid, scalenes

what happens to intrathoracic V and P when the diaphragm contracts?

increase in V, decrease in P so air flows in

accessory muscles for expiration

abdominals, internal intercostals

transmural pressure

the pressure inside a compartment relative to outside compartment (alveolus)

transpulmonary pressure

difference between intraalveolar pressure and intrapleural pressure

intra-alveolar pressure is always (greater/equal/less than) intrapleural pressure

greater than

alveolar surfactant produced by

type II pneumocytes; it acts as a soap to reduce surface tension

surfactant (incr/decr) compliance?

increase

a pneumothorax occurs when air enters the _______

intrapleural space... pressure becomes equal to atmospheric... atelectasis

airflow is __________ to resistance of the airways

inversely proportional; more resistance, less flow

the pressure gradient in the thoracic cavity is accomplished by...

contraction of inspiratory muscles

3 phases of breathing cycle

rest/pause, inspiration, expiration

at rest... alveolar pressure? intrapleural? transmural?

alveolar= equals atmospheric intrapleural= negative transmural= positive, keeping alveoli open (alv pressure - intrapleural)

during inspiration, alveolar pressure? intrapleural pressure?

alveolar- falls as volume increases intrapleural- more negative

during expiration, intrapleural pressure? alveolar?

intrapleural- less negative alveolar- becomes positive as elastic forces compress

forced expiration raises what type of pressure?

intrapleural

resistance is determined by

Poiseuille law

what part of the respiratory tract has the highest airway resistance?

medium-sized bronchi... due to their directional changes

alveolar interdependence

alveoli tend to hold each other open thru mechanical tethering

dalton's law

total pressure is sum of partial pressures

henrys law

amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid

transfer of gasses across cell membranes occurs by

simple diffusion

fick's law states

the rate of diffusion is directly proportional to diffusion coefficient, surface area, partial pressure differences (driving force), thickness of membrane

lung diffusing capacity

measures how well the lungs move gas from air into bloodstream; uses CO

diffusing capacity of lung for CO

(DLCO), technique that helps to measure lung diffusing capacity

emphysema

destruction of alveoli, decrease in surface area; net decrease in lung diffusion capacity

pulmonary fibrosis or edema

increase in alveolar membrane thickness; net decrease in lung diffusion capacity

carbonic anhydrase

converts CO2 to HCO3-

most CO2 is carried in the blood as...

HCO3-

physiological shunt

small % of blood that bypasses the alveoli and drains directly into left ventricle

strenuous exercise (incr O2 demand) can cause periods of ...

diffusion limitation

altitude effects on perfusion

pressure reduced, lower pressure, slower diffusion rate