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102 Cards in this Set

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