Respiratory Physiology Flashcards
What are the 2 zones to the airway tree
which zone is the site of gas exchange
conducting zone and repiratory zone
what is the conducting zone
-what kind of air is in here
the trachea and 1st 16 generations of branching
-warm, humidify, and clean air
what is the respiratory zone?
last 7 generations of branching
-site of gas exchange
how man alveoli do the lungs contain
300-500 x 10^6 alveoli
what is barometric pressure
760 mmHg
- sum of partial pressure of the gases in the atmosphere
- daltons law of PP
- Nitrogen ~ 78%, oxygen 21%, Co2 0.04% and water ~0.5%
what is boyle’s law?
at constant temperature, pressure of a gas varies inversely w/ volume
ex. P=1/V
what is pleural pressure
space between visceral and parietal
what is transpulmonary
alveolar minus pleural
what are the pressures associated w/ breathing
pleural, alveolar. transpulmonary
at rest, what is pleural pressure? what is alveolar pressure?
pleural is slightly negative
alveolar is zero
pulmonary pressure changes during the breathing cycle:
when does air flow into lungs
when does air flow out of lungs
what is pleural pressure
P atm > P alveoli
P atm < P alveoli
always negative
during inspiration, how is pressure diff?
pressure is more negative
less pressure in pleural space
what is pneumothorax
what happens to the pleural space
air in lungs
open pleural space = to normal pressure
NOT NEGATIVE ANYMORE
what is a tension pneumothroax
(piece of lung tissue can form a one way valve that allows air to enter the pleural cavity from the lung but not to escape resulting in increasing pleural pressuure w/ each breath)
- can lead to severe shortness of breath as well as circulatory collapse
- can be caused by CPR compressions
what is atelectasis
-air is absorbed following what?
collapse of part or all of a lung by blockage of the air passage (bronchus or bronchioles)
- air is absorbed following obstruction of bronchopulmonary segment
- change in auscultation when tapped: resonting => dull
what is needed for the inflation of lungs
negative pressure
what is tidal volume
volume of air leaving the lungs during a single breath (~500mL)
-exhale
what is total lung capacity
max volume of air in lungs at end of maximal inhalation (~6L)
-deepest breath you can take
what is functional residual capacity
volume of air remaining in lungs at end of normal expiration
-sum of residual volume + expiratory reserve vol
what is vital capacity
max vol of air that can be exhaled after a max inspiration (~4.6 L)
what is forced vital capacity
expiration performed rapidly and forcefully as possible
what is a spirometer
a volume recorder consisting of a double walled cylinder in which an inverted bell is immersed in water to form a seal. a pulley attaches the bell to a marker that writes on a rotating drum. when air enters the spirometere, the bell rises
what do insects and shit use to breath
spiracle inside wall
-air is pumped in and out
when is compliance the greatest?
when is compliance the lowest?
moderate lung volume
high/low levels
what is lung compliance
lung distensibliity (malleability) C L = change volume / change pressure
what is lung compliance affected by
lung volume,
size,
surface tension inside alveoli,
lung elasticity
what kind of curve does compliance have? why?
pressure-volume curve is nonlinear
-compliance is not the same at all lung volumes
what happens w/ low compliance
high compliance?
low-stiff lungs, restrictive
high-overstretched lungs, emphysema, chronic obstructive pulmonary disease
how does alveolar surface tension contribute to compliance
what is the equation for the rel’n btwn surface tension and pressure inside alveoli
surface tension pulls inwardly and creates internal prssure
law of Laplace: P=2T/r
P=pressure inside alveolus, T=surface tension, r=radus
what is neonatal respiratory distress syndrome
immature lungs dont have enough surfactant
(pressure will be too high inside alveoli)
-surfactant contains phospholipids and proteins
-hydrophobic end and hydrophillic end (amphipathic)
what is work
force x dist
W = P x changeV
-change in lung volume (dist) x change in transpulmonary pressure (force)
what is th energy needed for breathing at rest in healthy people
how about during heavy exercise
5% of total energy expenditure
20% during exercise
waht is work required for
to expand lungs and overcome airway resistnace
what moves respiratory gases across alveolar-capillary membrane?
diffusion
what is the equation for partial pressure
PP=barometric presssure x fractional concentration of gas
what is the PP of oxygen when it is inspired?
what is it PP of oxygen when it is in the lungs?
what is the PP of oxy in the systemic veins? (R herat)
what is the PP of CO2 in the systemic veins? (R heart)
160
102 (# lowers bc barometic pressure is lower)
40
46
what happens to the fractional concentration of oxygen w/ a chnage in altitude?
what happnes to the partial pressure of oxygeN?
it does not change.
%age of oxy is the same at 30,000 ft and sea level
-decrease at altitude due to reduced barometric pressure
what is gas diffusion in lungs defined by
fick law
-volume of gas diffusing per minute across a membrane (Vgas) is directly proportional to the membrane surface area, the diffusion coefficient of the gas (D) and the partial pressure diff of the gas (changeP) and is inversely proportional to membrane thickness (T)
oxygen is transported to tissues in 2 forms, what are they
combined w/ hemoglobin (98%)
dissolved in the blood (2%)
what is the oxyhemoglobin equilibrium curve
relationship btwn partial pressure oxygen, oxygen saturation, and oxy content
hemoglobin has how many heme sites and globular protein units
4 oxy binding heme sites and 4 globular protein units
how does oxygen bind to hemoglobin
rapidly and reversibly
when the oxyhemoglobin curve shifts to the right (partial pressure where 50% of hemoglobin saturated), what happens
increase in temp, PCO2, hyopia
decrease in pH
Bohr effect
when the oxyhemoglobin curve shits to the left what happens
increases affinity of hemoglobin for oxygen
-fetal hemoglobin
how does 2,3 diphosphoglycerate (DPG) affect the hemoglobin oxygen saturation
-what is it
shifts to the right
glycolytic intermediate that affects hemoglobin oxygen saturation
what does hypoxia due to lung disease or high altitude result in
adaptive rise in the concentrations of DPG and an improvement in the quantity of oxygen delivered to the tissues
-tissue metabolize at a higher rate
what is the mechanism for hyopia due to lung diesease
in binding partially deoxygenated hemoglobin, DPG allosterically upregulates the release of the remaining oxy molec bound to the hemoglobin, thus enhancing the ability of RBCs to release oxy near tissues that need it most
changes conformation to unbind from hemoglobin more readily
what are levels of DPG high in RBCs
bc they don’t have mit
-anaerobically metabolize
what does fetal hemoglobin and myoglobin do to the oxyhemoglobin curve
shifts to the left
fetal carries more what than adult hemoglobin?
more oxygen at a low partial pressure for oxygen
-conc. of hemoglobin is 20% higher than in adults
what is myoglobin more abundant in
red muscle fibers that depend heavily on aerobic metabolism
-store oxygen in muscle
where is haemoglobin’s saturation curve compared to myoglobin
to the right of myoglobin
why does carbon dioxide readily displace oxygen from hemoglobin
bc of the much greater affinity it has for hemoglobin (200x that of oxygen)
how does carbon dioxide thicken the blood
by stimulated production of fibrinogen
what is the oxygen content of a pt w/ anemia who has 1/2 the normal hemoglobin content but normal partial pressure PO2
oxygen content that is reduced by half
carbon dioxide is transported in 3 manners
- dissolved in plasma (10%)
- bound to Hb (30%)
- as bicarbonate in RBC cytoplasm and plasma (60%)
- cayalyzed by action of carbonic anhydrase
what is a chloride shift
antiport of bicarbonate in exchange for chloride out of the RBC into plasma
-carbon dioxide indirectly transported out of cell through this mech
what is the haldane effect
- co2 equiv of bohr effect, acting in reverse manner
- low po2 shifts the co2 dissociation curve to the LEFT so that the blood is able to pick up more CO2 in the tissue
- in lungs, there’s a higher PO2 so blood gives up its CO2
what is hypoxemia
what is it cuased by
deficient oxygenation of the blood
- high altitude
- hypoventilation
- diffusion defect, such as fibrosis
what is hypoxia
deficiency of O2 reaching the tissues
- decreased cardiac output
- anemia
- CO poisoning
- cyanide poisoning
how does cyanide poisoning decrease oxygen
decrease o2 utilization by blocking cytochrome C in the electron transport chain
- stops transport of electrons to oxygen
- prevents H ions from fueling ATP synthase to produce ATP and starves the cell of energy
why can consumption of very high levels of cassava root lead to weakness and even paralyssi
CN poisoning, increased blood cyanide levels
-although its the 3rd largest source of carbs for human food in the world….
what is the volume of pulmonary circulation? what is the amount of blood in the pulmonary capillaries?
volume of PC is 500 mL
70mL
what is angiotensin-converting enzyme in?
what does it do?
pulmonary endothelial cells
converts angiotension 1 to angiotension 2 (which is a highly potent vasoconstrictor)
how is pulmonary circulation in flow, pressure, and resistnace?
high flow
low pressure
very low resistance
what is the mean arterial pressure? what is it in the pulmonary system?
90-95 mmHg
15mmHg
what happens to pulmonary ciruclation when there is low oxygen
resistance is increassed
-if there is low O2 in certain parts of the lung, the blood will be shunted elsewhere
when standing, where is flow greater
how is blood flow when supine
flow is greater in the base (zone 3) than at the top
(zone 1)
uniform
how is the pressure relationship in zone 1
alveolar pressure >arterial pressure>venous pressure
-bc alveolar > arterial, this creates resistance to blood flow
how is pressure relationship in zone 2
arterial pressure>alveolar>venous
how is the pressure rel’n in zone 3
arterial pressure>venous>alveolar
what triggers inspiratory activity in DRG and VRG?
where is it located?
release of inhibition of central inspiratory activity (CIA) integrator
-medullary reticular formation
what does the dorsal respiratory group (DRG) do?
DRG primarily inspiration
-influences VRG by way of sensory input from the vagus and glossopharyngeal
what does ventral respiratory group (VRG) do?
both inspiration and expiration
-vagus nerve keeps larynx open during expiration
what does the pontine respiratory group do
turns off inspiratory neurons in the VRG to start expiration
-may integrate other autonomic functions
what can do cerebral cortex do
can override everything bc of its voluntary/conscious control
what is the medullary reticular formation in the brainstem?
where do they synapse onto?
a grouping of interconnected nuclei
synapse onto motor neurons C3, 4, 5
what primarily controls ventilation
medulla, but w/ some input from the pons
what are the dorsal respiratory group (DRG) neurons involved in
alterting the pattern for ventilation in response to the physiological needs of the body for O2 and CO2 exchange and for blood acid-base balance
what do pulmonary stretch receptors do
as the lungs/airways stretch, various nerves will signal the CNS to trigger expiration
-in the smooth muscles of the airway
what do irritant receptors do
- where are they
- what are they triggered by
contribute to reflex hypernea (rapid breathing) and broncoconstriction and may trigger the cough reflex
- w/in epithelium of large conducting airways
- by touch, dust, smoke
where are j receptors
what are they stimulated by
what do they lead to
in alveolar walls near capillaries and in bronchi
- stimulated by lung injury, large inflation, and acute vascular congestion
- lead to rapid, shallow breathing
if someone is in an acidotic state, what happen to the chemoreceptive cells in the medulla?
they don’t monitor acidity directly
- H ions in the blood can’t get directly to the chemoreceptive cells
- when acidity increases, co2 lvls also increase
where are chemoreceptors
where are baroreceptors
carotid and aortic body
carotid and arotic sinus
peripheral chemoreceptors respond to a change in…
PO2 not O2
ex. anemia or CO poisoning won’t have effect on response cause they dont affect PCO2
what are aortic arch receptos innervated by
what are carotid receptors innervated by
vagus nerve
glossopharyngeal nerve
what is hyperventilation stimulated by
metabolic acidosis through peripheral chemoreceptors
what is cheyne-strokes breathing
occurs frequently during sleep, esp in lowlanders new to high altitudes
-central sleep apnea can happen (w/o breathing)
see in people w/ heart disease or people from sea lvl who relocate to high altitiudes
what is kussmaul breathing
fall in blood pH in diabetic ketoacidosis that is accompanied by a characteristic increase in ventilation
-hyperventilation, quick respiratory rate
what is agonal breathing
- shallow, slow (3-4 per min), irregular inspirations followed by irregular pauses due to cerebral ischemia
- seen shortly before death
in adaptation to high altitudes, why is alveolar PO2 reduced?
due to decreased barometric prsesure which results in lower arterial PO2
how is the ventilation rate in an adaptaion to high altitude
hyperventilation due to hyoxemia which will lead to respiratory alkalosis bc the starting blood isnt acidtic
why will hb concentration increase in adaptation to high altitude
why sill 2,3,DPG levles (in RBCs) increase
why will pulmonary vascular resistnace increase
polycythemia (increased RBCs)
Bohr effect
bc of reduced PO2
what is acute mountain sickness
related to CSF pressure differences but depends on rate of ascent.
