Pulmonary Flashcards
the ventilatory system is subdivided into zones of ventilation
conducting zones
transitional and respiratory zones
what is the conducting zones
trachea and terminal bronchioles
considered anatomic dead space
functions of the conducting zone
air transport humidification warming particle filtration vocalization immunoglobulin secretion
what is the transitional respiratory zones
bronchioles alveolar ducts and alveoli
functions of the transitional and respiratory zones
gas exchange surfactant production molecule activation and inactivation blood clotting regulation and endocrine function
more then ____ million alveoli provide the surface for gas exchange between lung tissue and blood
600
characteristics of the alveoli
elastic
thin walled
surface for gas exhcnage
pore of kohn - surfactant
what is surfactant
resistance to expansion of the ling cavity and alveoli increases during inspiration from the effect of surface tension
surfactant consists of a ____
lipoprotein mixture of phospholipids proteins and calcium ions produced by alveolar epithelial cells that reduces surface tension, this reduces the energy required for alveolar inflation and deflation
ficks law of diffusion states
that the rate of transfer of a gas through a tissue is directly proportional to the partial pressure differential between the two sides tissue surface area a diffusion constant and inversely proportional to the tissue thickness
volume of gas diffused is proportional to
partial pressure
surface area
diffusion constant
volume of gas diffused is inversely proportional to
the thickness of the tissue through which the gas is moving
what are static lung volumes
tidal volume inspiratory reserve volume expiratory reserve volume total lung capacity residual lung volume forced vital capacity inspiratory capacity functional residual capacity
total lung capacity =
RLV + FVC
phases of inspiration
diaphragm contracts, flattens, and moves downward toward the abdominal cavity
elongation and enlargement of the chest cavity expands the air in the lungs causing its intrapulmonic pressure to decrease to slightly below atmospheric pressure
lungs inflate as the nose and mouth suck air inward
finishes when thoracic cavity expansion ceases, causing equality between intrapulmonic and ambient atmospheric pressure
during exercise the scaleni and external intercostal muscles between the ribs contract causing
the ribs to rotate and lift up and away from the body
inspiratory action _____ during exercise when the diaphragm ____ the ribs swing upward and the sternum thrusts outward
increases
descends
athletes often bend forward at the waist to facilitate breathing following exercise because
promotes blood flow back to the heart
minimizes antagonistic effects of gravity on the usual upward direction of inspiratory movements
during rest and light exercise represents a passive process of air movement out of the lungs resulting from
natural recoil of the stretched lung tissue and relaxation of the inspiratory muscles
what are the phases of expiration
sternum and ribs drop diaphragm rises decreasing chest cavity volume and compressing alveolar gas so air moves from respiratory tract to atmosphere
ends when the compressive force of expiratory muscles ceases and intrapulmonic pressure decreases to atmospheric pressure
diring exercise internal intercostal and abdominal muscles act powerfully on the ribs and abdominal cavity to
reduce thoracic dimensions
by reducing the dimensions exhalation becomes more rapid and extensive
what is tidal volume
air moved during inspiratory or expiratory phase of each breathing cycle 0.4-1L of air per breath
what is inspiratory reserve volume
inspiring as deeply as possible following a normal inspiration 2.5-3.5L above inspired tidal air
what is expiratory reserve volume
after a normal exhalation continuing to exhale and forcing as much as a possible from the lung 1-1.5L
what is forced vital capacity
total volume of air voluntarily moved in one breath includes TV plus IRV and ERV
4-5L in young men and 3-4 L in young women
what is residual lung volume
air volume in the lungs after exhaling as deeply as possible
what is the average for residual lung volume
0.8-1.2L for collage aged women 0.9-1.4L for collage aged men and increases with age
what does the residual lung volume allow
an uninterrupted exchange of gas between the blood and alveoli to prevent fluctuations in blood gases during phases of the breathing cycle
RLV plus FVC constitutes ___
total lung capacity
effects of previous exercise on RLV
RLV temporarily increases from an acute bout of either short term or prolonged exercise due to
closure of the small peripheral airways
increase in thoracic blood volume
dynamic ventilation depends on
maximum stroke volume of the lungs (FVC)
speed of moving a volume of air (breathing rate)
determined by lung compliance or the resistance of the respiratory passages to air and the stiffness imposed by the chest and lung
FEV1.0/FVC indicates
pulmonary airflow capacity
healthy people average __ of FVC in 1 second
85%
obstructive diseases result in significantly lower
FEV1
restrictive diseases result in normal or above normal ___ but the volume of air moved is reduced
FEV1
two ways to view pulmonary ventilation
volume of air moved into or out of total respiratory tract each minute = minute ventilation
air volume that ventilates only alveolar chambers each minute = alveolar ventilation
what is minute ventilation
volume of air breathed each minute (VE)
= tidal volume x breath rate
= o.5L x 12 breaths/min
= 6Lmin
what is alveolar ventilation
remember that anatomic dead space averages 150-200mL
therefore only about 350-300mL of the 500mL TV enters alveoli
anatomic dead space increases
despite the increase in dead space, increases in TV result in more effective alveolar ventilation
dead space ___ with tidal volume ( to a less degree)
increases
hyperventilation
an increase in pulmonary ventilation that exceeds O2 needs of metabolism
hyperventilation ___ PCO2 and H
decreases
dyspnea
subjective distress in breathing
during exercise respiratory muscles may fatigue, resulting in shallow, ineffective breathing and increased dyspnea
volume of gas diffused is proportional to
ficks law
partial pressure
surface area
diffusion constant
volume of gas diffused is ____ to the thickness of the tissue through which the gas is moving
inversely proportional
bodys supply of oxygen depends on
concentration of ambient air
pressure of ambient air
what is the concentration of ambient air
- 93% O2
- 04% N2
- 03% CO2
what is torr
the pressure of air molecules that raises a column of mercury in a barometer to a height of 760mm
1 torr equals the pressure necessary to raise
a 1mm column of mercury 1mm high at 0 degrees celcius against the standard acceleration of gravity at 45 degrees north latitude
the molecules of each specific gas in a mixture of gases exert
their own partial pressure
partial pressure computes as follows
partial pressure = percentage concentration of specific gas / total pressure of gas mixture
partial pressures of gases in dry ambient air at sea level
PO2 = 159mm Hg
PCO2 = 0.2mm Hg
PN2 = 600mm Hg
partial pressure =
% of [gas] x total pressure of mixture
symbols for gas pressure
P = PARTIAL PRESSURE S = SATURATION A = ALVEOLAR a = arterial blood v = mixed venous blood
o2 and co2 in the environmental inspired air
o2 = 159
co2 = 0.2-0.3
air in the trachea becomes saturated air with humidity what are the o2 and co2 values
o2 = 149 co2 = 0.3
alveolar air is diluted with carbon dioxide coming out of the blood
PAO2 and PACO2 values
PAO2 = 100 PACO2 = 40
what is the o2 and co2 in venous blood
PVO2 = 40 PVCO2 = 46
what is the o2 and co2 in arterial blood
PaO2 = 100 PaCO2 = 40
what is the o2 and co2 in contracting muscle
PO2 = 40 PCO2 = 46
at rest blood tends to move through the capillaries in ___ seconds. at max exercise that transient time is as short as ___ seconds, even so that is sufficient time for the blood to become fully saturated in a healthy lung with large alveolar area
- 75 seconds
0. 40 seconds
what is henrys law
the mass of a gas that dissolves in a fluid at a given temperature varies in direct proportion to the pressure of the gas over the liquid
what factors in henrys law govern the rate of gas diffusion into a fluid
the pressure differential between the gas above the fluid and the gas dissolved in the fluid
the solubility of the gas in the fluid
o2 travels from a __ to ___ pressure as it dissolves and diffuses through the alveolar membranes into the blood
higher to lower pressure
co2 exists under a slightly greater pressure in returning venous blood then in the ____ causing net diffusion of co2 from the ___ into the ____
alveoli
blood into the lungs
N2 ___ in alveolar-capillary gas
remains essentially unchanged
alveolar gas-blood gas equilibrium takes place in ___seconds
1/4
factors that impair gas transfer capacity at the alveolar capillary membrane
buildup of a pollutant layer that thickens the alveolar membrane
reduction in alveolar surface area
each factor extends the time before alveolar-capillary gas equilibrates
for individuals with impaired lung function the added demand for rapid gas exchange in exercise compromises
aeration
negatively affecting exercise performance
the blood carriers oxygen in two ways
in physical solution dissolved in the fluid portion of blood
in loose combination with hemoglobin the iron-protein molecule within the red blood cell
oxygens relative insolubility in water keeps its
concentration low within bodily fluids
functions of oxygen transported in solution
establishes the po2 of the plasma and tissue fluids
helps to regulate breathing
determines oxygen loading of hemoglobin in the lungs and subsequent release in tissues
hemoglobin is
the iron containing globular protein pigment
hemoglobin carries ___ times more oxygen than normally dissolves in plasma
65-70
each of the four iron atoms in the hemoglobin molecule can
loosely bind one oxygen molecule
Hb4+4O2Hb4O8
the partial pressure of oxygen dissolved in physical solution dictates the
oxygenation of hemoglobin to oxyhemoglobin
what is the oxygen carrying capacity of hemoglobin in men and women
15g/dL of blood for men
14g/dL of blood for women
the sex difference in oxygen carrying capacity of hemoglobin explains
the lower aerobic capacity of women relative to men
mens higher hemoglobin concentrations relate to the stimulating effects on red blood cell production of testosterone
each gram of hemoglobin combines loosely with ___mL of oxygen
1.34
with full oxygen saturation and with normal hemoglobin levels hemoglobin carriers ____mL of oxygen in each dL of whole blood
20
what is anemias affect on oxygen transport
the bloods oxygen transport capacity changes only slightly with normal variations in hemoglobin content
iron deficiency anemia causes a significant decrease in the iron content of red blood cells reduces the bloods oxygen carrying capacity which diminishes a persons capacity to sustain even mild-intensity aerobic exercise
what is cooperative binding
the binding of an O2 molecule to the iron atom in one of the four globin chains progressively facilitates the binding of subsequent molecules
what is the term affinity mean
is used to describe oxygens attraction to hemoglobin binding sites
affinity of Hb can be shifted by changes in - pH - temperature - CO2 2,3-DPG
what does the flat portion of the curve allow for in the oxyhemoglobin dissociation curve. what about the steep portion of the curve
safety
diffusion gradient
unloading
what is the bohr effect
in presence of CO2 the O2 affinity for dissociation of hemoglobin decreases
increase CO2
decreased pH
affinity increases with __ temperature
and
affinity decreases with __ temperature
decreasing
increasing
there is an increased 2,3-DPG shifts curve to the right usually in conjunction with
changes in pH CO2 and temperature
barometric pressure ___ with altitude
decreases
a red blood cell derives its energy solely from
the anaerobic reactions of glycolysis because they contain no mitochondria causing them to produce the compond 2,3-DPG
2,3DPG binds loosely with subunits of the hemoglobin molecule which
reduces its affinity for oxygen causing greater oxygen release to the tissues for a given decrease in po2
increased levels of red blood cell 2,3DPG occur in those with __disorders and those who live
cardiopulmonary
live at high altitudes to facilitate oxygen release to the cells
during strenuous exercise 2,3DPG aids in
oxygen transfer to muscles
myoglobin has a __x higher affinity for o2 than does hemoglobin
240
myoglobin is
an iron containing globular protein in skeletal and cardiac muscle fibers. it resembles hemoglobin because it also combines reversibly with oxygen, but each myoglobin molecule contains one iron atom while hemoglobin contains four iron atoms
compared with the oxygen saturation curve for hemoglobin, the curve for myoglobin shows
that it much more readily binds and retains oxygen at low po2, the greatest quantity of oxygen releases from MbO2 when tissue PO2 declines below 5mm Hg.
acidity carbon dioxide and temperature do/do not affect myoglobins oxygen binding affinity
do not affect
ventilation of carbon dioxide: once carbon dioxide forms in the cell, ___ and ____ in the venous blood provides the only means for its escape through the lungs
diffusion
subsequent transport
the blood carries carbon dioxide in three ways
in physical solution in plasma (5%)
combined with hemoglobin within the red blood cell (20%)
as plasma bicarbonate (60-80%)
how is carbon dioxide carried in physical solution
5% of the co2 formed during energy metabolism moves into physical solution in the plasma as free carbon dioxide
the random movement of this small quantity of dissolved carbon dioxide molecules establishes the PCO2 of the blood
CO2 transport as carbamino compounds
at the tissue level, carbamino compounds form when carbon dioxide reacts directly with the amino acid molecules of blood proteins
the globin portion of hemoglobin which carriers about 20% of the bodys carbon dioxide forms a carbamino compound
what is the Haldane effect
a decrease in the plasma PCO2 in the lungs reverses carbamino formation causing carbon dioxide to move into solution and enter the alveoli as oxygenation of hemoglobin reduces its ability to bind carbon dioxide
carbon dioxide transport as bicarbonate
carbon dioxide in solution slowly combines with water to form carbonic acid
once carbonic acid forms in the tissues most of it ionizes into hydrogen ions and bicarbonate ions
60-80% of the total carbon dioxide exists as plasma bicarbonate
what is the plasma bicarbonate reaction and what is it facilitated by
co2+ h2oh2co3h+hco
facilitated by carbonic anhydrase
what are the three basic elements of respiratory control
sensors = chemoreceptors, lungs and other send input to the
central controller = pons medulla and other parts that sends output to
effectors = respiratory muscles
complex mechanisms adjust breathing rate and depth to the body metabolic needs….
intricate neural circuits relay information from higher brain centers lungs and other sensors throughout the body to coordinate ventilatory control
the gaseous and chemical states of the blood that bathes the medulla and aortic and carotid artery chemoreceptors also mediate alveolar ventilation
the control mechanisms of pulmonary ventilation maintain
relatively constant alveolar gas pressures throughout a broad range of exercise intensities
what are the three controls of breathing
central controller - ventral lateral medulla and pons
intrinsic pacemaker neurons, network for pattern gen
efferent motor output
- cranial and spinal nerve innervation of upper airway bronchial smooth muscle and respiratory pump muscles
sensory
- medullary and carotid chemoreceptors
mechanoreceptors
normal breathing controlled by circuits in the
pons and medullar (pontomedullary circuit)
ventral lateral medulla has pacemaker neurons linked to a pattern generator,ablation of this area or the rostral pons
disrupts normal breathing
both areas are required
rhythm generation from pontomedullary neuronal circuit is directed to the
phrenic intercostal and abdominal motor nerves
efferent motor output well patterned output during normal breath expiration is ___ and inhalation is governed
passive
by diaphragm (phrenic n) external intercostals (intercostal n)
peripheral sensory input
chemoreceptor
- peripheral chemoreceptors
- medullary receptors
highly pH sensitive esp due to co2
responds to PaCO2 strongly in steady state - negative feedback
Co2 influences ___ to a large extent
minute ventilation
sensitivity to reduced oxygen pressure resides in the ____
peripheral chemoreceptors
the carotid bodies monitors the state of ____ just before it perfuses the ____
arterial blood
brain
decreased arterial PO2 ___ alveolar ventilation through aortic and carotid chemoreceptor stimulation
increases
these receptors alone protect the organism against reduced oxygen pressure in inspired air
peripheral chemoreceptors also stimulate ventilation in exercise because of
increases in temperature acidity and carbon dioxide sand potassium concentrations
at rest carbon dioxide pressure in arterial plasma provides the most
important respiratory stimulus
small increases in PCO2 in inspired air trigger
large increases in minute ventilation
plasma acidity which varies with the bloods carbon dioxide content exerts
command over minute ventilation
a fall in blood pH signals acidosis and reflects
carbon dioxide retention and carbonic acid formation
as arterial pH declines and hydrogen ions accumulate inspiratory activity
increases to eliminate carbon dioxide and reduce arterial levels of carbonic acid
if a person breath holds after a normal exhalation it takes about ___seconds for the urge to breath cause inspiration
40 seconds
the stimulus to breath when holding your breath comes primarily from
increased arterial pco2 and h concentration
the breakpoint for breath holding =
50mm Hg PCO2
hyperventilation before breath holding causes
alveolar PCO2 to decrease to 15 mmHg
a larger than normal quantity of carbon dioxide leaves the blood and arterial PCO2 decreases
extends breath holding duration until arterial PCO2 and/or H concentration cause the urge to breath
mechanical sensoty afferent feedback provided by vagus n. limits
end-inspiratory lung volume
responses as a stimulus during lung deflation
stretch receptors
respiratory muscle feedback relayed by
group 3 mechanical
group 4 chemical
what are the 4 regulation of breathing during exercise
chemical control
- no single chemical mechanism responsible for hypernea during exercise
neurogenic factors
- cortical influence
- peripheral influence
temperature has little influence on respiratory rate during exercise
humoral factors
- chemical state of blood
combined and simultaneous effects pf several chemical and neural stimuli initiate and modulate
exercise alveolar ventilation
ventilation phases during exercise and recovery :
phase 1 = neurogenic stimuli from cerebral cortex and feedback from active limbs stimulate the medulla to abruptly increase ventilation
phase 2 = after a brief plateau ventilation rises exponentially to achieve a steady rate related to metabolic gas exchange demands
phase 3 = fine tuning of steady rate ventilation through peripheral sensory feedback mechanisms
ventilation in steady rate exercise during light to moderate exercise
increases linearly with O2 consumption and co2 production
non steady rate ventilation in exercise
VE rises sharply and the ventilatory equivalent rises as high as 35-40L of air per liter of oxygen
ventilatory threshold
lactate threshold
onset of blood lactate accumulation
the point of ventilatory threshold occurs at a work rate when ___
the lactate threshold occurs at this point however blood lactate remains
VE and VO2 deviate from being linear
low at this point as it is only starting to accumulate
lactate threshold describes the ____
highest oxygen consumption or exercise intensity achieved with less than a 1 mm increase in blood lactate concentration above the pre exercise level
the onset of blood lactate accumulation is defined as the
exercise intensity when blood lactate levels exceed 4mm
this event technically occurs after the lactate threshold has passed because it takes some time for the lactate to accumulate to a level high enough to detect in a blood test
lactate accumulation reflects changes in
pH
bicarbonate and H concentrations
co2 production via buffering
together can provide indirect assessment
the measurement of lactate threshold serves three important functions
provides a sensitive indicator of aerobic training status
predicts endurance performance often with greater accuracy then VO2max
establishes an effective training intensity geared to active muscles aerobic metabolic dynamics
what are three different indicators of lactate threshold
fixed blood lactate concentration
ventilatory threshold
blood lactate exercise v02 response
major variables contributing to oxygen transport and use, vo2 max is traditionally used to predict
performance but OBLA may also be an excellent tool
increased H concentration from carbon dioxide production and lactate formation during strenuous exercise makes
pH regulation progressively more difficult
acid based regulation becomes exceedingly difficult during repeated brief bouts of all out exercise that
elevate blood lactate values to 30 mm or higher
humans temporarily tolerate pronounced disturbances in
acid base balance during maximal exercise
a plasma pH below 7 can cause
nausea headache and dizziness
the chemical buffering system consists of
a weak acid and salt of that acid
when H concentration remains elevated the reaction __ in contrast when H concentration the buffering reaction moves
produces the weak acid
in the opposite direction and releases H
chemical buffers that provide the first line of defense
second line of defense; when does this buffering function occur
bicarbonate buffers
phosphate buffers
protein buffers
secondary = pulmonary and renal systems
occurs when a change in pH has already occurred
what is the ventilatory buffer
when H in extracellular fluid and plasma increases it stimulates the respiratory center to increase alveolar ventilation which reduces alveolar co2 and causes co2 to be blown off which reduced plasma co2 levels accelerate the recombination of H and HCO lowering H concentration in plasma
what is renal buffer
renal tubules regulate acidity through complex chemical reactions that secrete ammonia and H into urine and reabsorb alkali chloride and bicarbonate
does ventilation limit aerobic power and endurance
healthy individuals overbreathe at higher levels of o2 consumption
at max exercise there usually is a breathing reserve
ventilation in healthy individuals is not the limiting factor in exercise
little relationship exists among diverse lung volumes and capacities and exercise performance
aerobic training produces considerably less adaption in
pulmonary structure and function then in cardiovascular and neuromuscular adaptations
during strenuous exercise healthy individuals
overbreath at higher levels of oxygen consumption
this hyperventilation response decreases alveolar pco2 and slightly increases alveolar po2
during max exercise a breathing reserve exists because
VE at vo2max is only 60-85% of a healthy persons MVV
pulmonary function does not form a weak link in the
oxygen transport system of healthy individuals with average to moderately large aerobic capacities
the oxygen requirement of breathing remains ___ at rest and during ligh to moderate exercise
relatively small at rest and during light to moderate exercise
for exercise ventilations up to about 100L min oxygen cost averages ___per liter of air breathed each minute or __% of the total oxygen consumption in moderate exercise and 8-11% for minute ventilations at vo2max
1.5-2mL
3-5%
for highly trained endurance athletes with minute ventilations of 150L min and higher the cost of exercise hyperpnea can be
> 15% of total oxygen consumption
in chronic obstructive pulmonary disease the added expiratory resistance can
triple the normal cost of breathing at rest
in severe pulmonary disease the cost of breathing attains __% of the total exercise oxygen consumption
40%
competition between the oxygen blood flow needs of locomotor and respiratory muscles encroaches on the
oxygen available to the active non-respiratory muscles
for endurance athletes the pulmonary system…
lags behind the cardiovascular and aerobic muscular adaptations
exercise induced arterial hypoxemia is
an impaired ventilation, perfusion during high intensity exercise may compromise arterial saturation and oxygen transport
possible causes for arterial desaturation include
inequality in ventilation - perfusion within the lungs
shunting of blood between venous and arterial circulations
failure to achieve end capillary equilibrium
