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Phys. Exam 3 Respiratory
Respiratory Phys.
172
Physiology
Graduate
11/02/2010
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Term
Functions of the Respiratory System:
 Definition
- pulmonary gas exchange: matching of ventilation and profusion
- maintenance of partial pressures of gases in tissues (diffusion)
- Immune system defense via IgA
- Blood sieve- removes clots
- Blood reservoir
- substrate conversion- Angiotension I to Angiotension II by ACE (also bradykinin, serotonin,prostoglandin E and F)
Term
ventilation is related to ___ and ___ of breathing.
 Definition
- frequency
- depth
Term
perfusion is dependent on:
 Definition
cardiac output from the right ventricle
Term
ventilation and profusion are closely matched, ideally air volume= blood volume
 Definition
Term
Mucociliary escalator is made of ___ cells lining the ___ ____ down to ___ ___. The cilia beat synchronously to carry mucus up the trachea. If particles reach the alveoli they are engulfed by ____.
 Definition
- ciliated
- respiratory tree
- terminal bronchioles
- macrophages
Term
Gas exchange is ONLY at the ____ level.
 Definition
alveoli
Term
Normal alveoli have ___ fibers around them.
 Definition
- elastin
Term
With Emphysema, the alveoli brake down, so you have decreased ___, so decreased ___ __.
 Definition
- surface area
- gas exchange
Term
equation for relating radius to resistance.
 Definition
resistance = (viscosity x length)/ r^4
Term
___ and ____ ___ both decrease effective diameter.
 Definition
Bronchospasms
intraluminal secretions
Term
Asthma:
 Definition
inflammation,secretions, smooth muscle constriction> difficult to breathe out
Term
Lungs are covered with ___ pleura while the thorax is lined with ____ pleura. Space b/w these is intrapleural space.
 Definition
- visceral
- parietal
Term
What creates the negative intrapleural pressure?
 Definition
- lungs pulling in and wanting to contract, while the chest wall is pulling out and wanting to expand
Term
The balance of the force of the lungs pulling in against the force of the chest wall pulling out determines the ___ ___ ___ of the system.
 Definition
- function residual capacity (FRC)
Term
Elastin allows for :
 Definition
recoil
Term
term for lung tissue:
 Definition
- parenchyma (rich in elastin)
Term
___ is the active phase of breathing. Describe features of this phase.
 Definition
- Inspiration= active
- neural activity (phrenic nerve) needed
- thoracic cavity expands
- external intercostals move rips in cephalic direction
- lung expands passively due to decreased intrapleural pressure
- air flows in the equalize pressure
Term
___ changes drive air flow.
 Definition
pressure
Term
During inspiration the ___ ___ muscles move the ribs in a ___ direction.
 Definition
- external intecostal
- cephalic
Term
____ is normally a passive phase of breathing. Chest wall muscles ____. Pleural and alveolar pressure ____, and aire flows ___ of lungs.
 Definition
- Expiration
- relax
- increases
- out
Term
with expiration what pressures increase?
 Definition
- pleural pressure
- alveolar pressure
Term
Dalton's Law of Partial Pressures:
 Definition
Total pressure of gases= sum of partial pressures
Term
see slide 11 and know the normals for ambient dry air and moist tracheal air
 Definition
Term
PO2 of inspired air, is the same as saying saturated air, how do you calculate this?
 Definition
PB (760 mmHg) x Fraction of O2 in air (21%)

(760 - 47) x 0.21 = 150 mmHg
Term
what is the fraction of oxygen in the air?
 Definition
21%
Term
what is the constant pressure of water vapor for tracheal air?
 Definition
47 mmHg
Term
see slide 13 and know these normals, will be on test.
 Definition
Term
When you go to higher altitudes, the ___ of ___ is the same, but the ___ ___ decreases, causing ___ to drop.
 Definition
Higher altitude:
- fraction of O2 is same
- barometric pressure decreases
- PO2 decreases
Term
So at a higher altitude, air is still 21% oxygen, but due to the decrease in barometric pressure, the partial pressure of oxygen of is less.
 Definition
Term
mixed venous blood is deoxygenated and is found in the pulmonary artery on the way to the lungs.
 Definition
Term
Considering that the pulmonary artery has deoxygenated blood, what are the partial pressures of oxygen and co2 in this vessel?
 Definition
- PO2= 40 mmHg
- PCO2= 46 mmHg
Term
TLC:
 Definition
total lung capacity, usually 6 liters

IRV + TV + ERV + RV= TLC

IC + ERV + RV = TLC

VC + RV = TLC

IC + FRC = TLC
Term
FRC:
 Definition
- functional residual capacity
- it is how much you can blow out on your own (ERV) plus the amount that would still be left after that (VC)
- ERV + VC = FRC
Term
what measure of lung function correlates to the stroke volume of the heart?
 Definition
tidal volume
Term
TV:
 Definition
- tidal volume
- how much you breathe in and out when breathing normally
Term
IRV:
 Definition
- inspiratory reserve volume
- what you can breathe in above and beyond tidal volume
Term
IC:
 Definition
- inspiratory capacity
- what you breathe in normally (TV), plus what you can breathe in above and beyond that (IRV)
Term
So IRV excludes tidal volume, while IC includes tidal volume.
 Definition
Term
ERV:
 Definition
- expiratory reserve volume
- once you have breathed out your normal about, it is how much more you can breathe out above and beyond your normal amount
- ERV= FRC- RV
- ERV + RV = FRC
Term
VC:
 Definition
- vital capacity
- the total amount of air you can MOVE with maximal inspiration and maximal expireation, does not include reserve volume b/c you can move RV
Term
How is vital capacity different than total lung capacity?
 Definition
- vital capacity is the air you can move if inspire as much as possible and expire as much as possible
- total lung capcity is this plus the air you cant move called residual volume
Term
what lung volume can a spirometer not measure?
 Definition
- residual volume
Term
FVC:
 Definition
- forced vital capacity
- the amount of air you can expire after a maximal inspiration
- after FVC only residual volume is left in your lungs
Term
When you work out to your maximum, your PO2 and PCO2 stay constant. How is this possible?
 Definition
- metabolism increases a lot
- O2 consumption has increased to meet metabolic needs
- to do this you are breathing more than tidal volume, you are going into IRV and ERV, but not all of VC but a lot of it
Term
formula for vital capacity:
 Definition
VC= TV + IRV + ERV

around 4800 mL
Term
FEV1:
 Definition
- forced expiratory volume
- amount of air that can be forcefully expired in the first second
Term
FVC:
 Definition
- forced vital capacity
- amount of air that can be forcefully expired after maximal inspiration
Term
FEV1 should be __% of FVC.
 Definition
- 78-83%
Term
With obstructive disease, the ratio of FEV1 to FVC would ____ because these people have trouble ___. Give examples of obstructive diseases.
 Definition
- decrease
- expiring
- COPD, emphysema, chronic bronchitis
Term
With obstructive diseases, lung volume is ____, residual volume is ___, TLC is usually ___, vital capacity is ___, and the ratio of of FEV1 to FVC is ___.
 Definition
- lung volume is increased
- residual volume is increased
- TLC usually increased
- Vital capacity is decreased
- FEV1 to FVC is decreased
Term
Obtructive disease is an alveolar problem, restrictive disease is an airway problem.
 Definition
Term
Restrictive disease:
 Definition
- causes troubles with inspiration
- thickened airways or alveolus due to increased interstitium
- increased resistance, so decreased flow
- seen in people exposed to asbestos, cole miners, etc.
Term
Gas exchange is impaired with emphysema (obstructive) b/c alveolar break down. Gas exchange is also impaired with restrictive disease, but only b/c alveolar walls may become thicker which makes diffusion more difficult.
 Definition
Term
With obstructive disease the FEV1 to FVC will be ___, with restrictive disease this ratio will be ___.
 Definition
- obstructive- decreased
- restrictive - increased
Term
FEF25-75%:
 Definition
- forced midexpiratory flow rate ( normal is 4-5L/second)
Term
FRC (functional residual capacity), is a point of ____ between the elastic recoil of the lungs and the outward movement of the chest wall.
 Definition
- equillibrium
Term
what two lung volumes cannot be measured with spirometry?
 Definition
- FRC
- RV
Term
Total lung capacity is ___ with restrictive diseases but ___ with obstructive diseases. ____ ___ is decreased in both types of diseases.
 Definition
- decreased
- increased
- vital capacity
Term
with obstructive lung diseases, the residual volume is increased which causes the ____ to be much higher for FRC.
 Definition
- equillibrium
Term
what value does not change much with obstructive disease and decreases a little with restrictive disease?
 Definition
- tidal volume
Term
When no air is flowing, alveolar pressure is equal to __.
 Definition
zero
Term
During inspiration, which is active, the diaphragm is contracting and the thoracic cavity is becoming larger, this makes the negative intrapleural pressure more ____ resulting in suction that, so alveolar pressure becomes more ___ compared to barometric pressure, and since there is a pressure gradient the air flows in.
 Definition
- negative
- negative
Term
As air goes into the alvoeli during inspiration, the alveolar pressure ___ with the barometric pressure. So the periord between inspiration and expiration, you have an alveolar pressure of 0, so there is no pressure gradient, so there is no flow.
 Definition
- equillibrates
Term
As you begin to expire, alveolar pressure becomes ___ relative to barometric pressure, so you have a pressure gradient and air is flowing out.
 Definition
- positive
Term
During normal breathing, pleural pressure is always negative, it just gets more/less negative depending
 Definition
Term
During pulmonary function test you maximally inspire so the pleural pressure gets much more ____. Alveolar pressure also gets much more negative, until you stop breathing in, at which point it is 0. Then you blow out as fast as you can, so pleural pressure is becoming more ___ and alveolar pressure is becoming more ___.
 Definition
- negative
- positive
- positive
Term
look at charts on slide 23 and understand
 Definition
Term
look at graph on slide 24 and understand
 Definition
Term
___ is the relationship between volume and pressure.
 Definition
compliance
Term
compliance:
 Definition
the amount of volume change you get for a given change in pressure
Term
With restrictive disease, lungs are more/less compliant.
 Definition
less compliant
so for a given pressure change you have less of a volume change
Term
people with obstructive diseases have more/less compliance.
 Definition
more
Term
three things increased with obstructive disease:
 Definition
TLC
FRC
compliance
Term
Fibrosis, a restrictive disease, results in decreased:
 Definition
TLC
FRC
Compliance
Term
asthma increases:
 Definition
FRC
Term
pulmonary compliance is decreased by:
 Definition
- high lung volume
- fibrotic disease
- alveolar edema (decreased surfactant)
- vascular congestion
Term
pulmonary compliance is increased by:
 Definition
- destruction of elastic tissue (emphysema)
Term
equation for total minute ventilation:
 Definition
total minute ventilation= tidal volume x respiratory rate
Term
know formulas on slide27
 Definition
Term
anatomic dead space:
 Definition
- air through nose, mouth, pharynx, larynx, trachea, bronchi, bronchioles
- little/ no gas exchange
- measure with Fowler's method
- normally 150 ml (about 2 ml/kg body weight)
Term
what is a clinical setting in which anatomic dead space is increased?
 Definition
- on a ventilator b/c of the dead space in the tubing
Term
physiologic dead space:
 Definition
- anatomic dead space + alveolar volume not exchanging gas
- wasted ventilation, everyone has a little bit
- observed in patients with disease and describes a deviation from ideal ventilation and blood flow
- measure with Bohr's method (volume of lung that does not eliminate CO2)
Term
You measure anatomic dead space with ___ method, but physiologic dead space with ___ method, which measures the volume of lung that does not eliminate CO2.
 Definition
- Fowler's
- Bohr's
Term
physiologic dead space is also called alveolar dead space
 Definition
Term
what condition would increase physiologic dead space?
 Definition
- pulmonary embolis
Term
Under normal conditions, the minute ventilation of the dead space is a function of the ___.
 Definition
frequency
Term
With tachypnea, or fast breathing, total ventilation is ___, but the breaths are fast and shallow, so the tidal volume is ___, the dead space ventilation is ___, and the alveolar ventilation is ___. So PO2 is ___ and PCO2 is ____, so is this hyper/hypoventilation.
 Definition
- unchanged
- decreased
- increased
- zero
- decreasing PO2
- increasing PCO2
- hypoventilation even though breathing fast
Term
relationship between arterial PCO2 to VCO2 and Alveolar Ventilation:
 Definition
- PaCO2- arterial PCO2
- VCO2- correlates with metabolism, as metabolism increases, VCO2 increases
- Va- alveolar ventilation

PaCO2= VCO2/Va

- so as metabolism increases, VCO2 increases, and PaCO2 increases
- But as alveolar ventialtion, Va, increases, PaCO2 decreases
Term
Hypo/hyperventilation is defined based on if ____ is increasing or decreasing.
 Definition
PaCO2
Term
increasing PaCO2=
 Definition
hypoventilation
Term
decreasing PaCO2=
 Definition
hyperventilation
Term
With hyperventilation ___ ___ is greater than ___ so you get decreased PaCO2.
 Definition
- alveolar ventilation
- metabolism
Term
With exercise, you double metabolism, so you double ___, so to keep PaCO2 constant, ___ ____ must increase.
 Definition
- PVO2
- alveolar ventilation
Term
up to 70% max exercise PaCO2 is constant because you have increased PVO2 and increased alveolar ventilation.
 Definition
Term
Hyperventilation results in ____.
 Definition
- alkalosis
Term
Hypoventilation results in ____.
 Definition
acidosis
Term
LaPlace's Law:
 Definition
- pertains to surface tension

pressure = tension/ radius

- smaller alveolus has higher presure
- air flows from smaller alveolus to larger alveolus
Term
according to law of LaPlace, smaller alveoli have ____ pressures, and air flows from ___ alveoli to ___ alveoli.
 Definition
- higher
- small
- large
Term
Surfactant is a special phospholipid (dipalmitoyl phosphatidyl choline) that acts to reduce ___ ___ created by air water interface. It is made by ___ ___ ___ cells to minimize the ___ pressure needed for ___.
 Definition
- surface tension
- type 2 alveolar cells
- intrapleural pressure
- inspiration
Term
surfactant acts to stabilize lung size by giving alveoli variable tension. Increases tension for high volumes and decreases tensions for low volumes.
 Definition
Term
When alveolus gets smaller, surfactant gets ___ to reduce the surface tension.
 Definition
thicker
Term
advantages of surfactant:
 Definition
- decreases muscular effort needed to expand lungs
- lowers elastic recoil and thus prevents alveolar collapse
- stabilizes alveoli that tend to deflate at different rates
Term
describe effort dependent flow:
 Definition
- airflow determined by degree of effort subject makes during expiration
Term
Effort independent:
 Definition
airflow determined by degree of pulmonary elastic recoil due to dynamic compression of airway
Term
explain hypoxic vasoconstriction:
 Definition
- when an alveoli is hypoxic, the blood vessels around it constrict and the blood is shunted to an alveoli with more oxygen
- this is different than tissues or muscles being hypoxic which results in vasodilation
Term
With emphysema, you have generalized hypoxia, so you get ___ ___, which can lead to ___ ___ heart failure b/c the resistance caused by constriction leads to increased pressures.
 Definition
- pulmonary hypertension
- right sided heart failure
Term
Pulmonary vascular resistance is affected by alveolar effects and extralveolar effects. explain each:
 Definition
- alveolar effects: as lungs fill, blood vessels are compressed> increased resistance, so as lungs fill alveolar affects cause increased resistance
- extralveolar effects: as you fill the lungs, the pleural pressure is more negative which tends to dilate the blood vessels, so as you fill the lungs, extralveolar affects decrease vascular resistance
- net pulmonary vascular resistance is a function of the two
Term
Alveolar effects ___ pulmonary vascular resistance during inspiration, while extralveolar effects ___ resistance during inspiration.
 Definition
- increase
- decrease
Term
The net pulmonary vascular resistance is a function of alveolar effects and extralveolar effects and is lowest near the __ ___ ___.
 Definition
- functional residual capacity (FRC)
Term
PVR (pulmonary vascular resistance) is ___ at high and low lung volumes.
 Definition
- increased
Term
V/Q matching:
 Definition
Ventilation, Profusion matching, not perfect
normal =0.8

find it by doing Va liters/ CO liters
Term
Blood flow is greatest at the ___ of the lungs b/c of gravity. Air is not as affected by gravity, but still there is more ventilation at the ___ of the lung. V/Q is less than 1 at the base b/c more blood at base than air. V/Q matching is much better in the ___ of the lungs.
 Definition
base
base
middle
Term
It is easier to oxygenate blood to the max at the ___ b/c this is where V/Q is high, but there is not as much blood here.
 Definition
- apex
Term
At TLC, alveolar pressure is ___ and and pleural pressure is its __ ___.
 Definition
- zero
- most negative
Term
P(A-a)O2 gradient:
 Definition
A= alveolar
a= arterial
- talking about blood with oxygen from lungs before any oxygen has left the blood
- difference between equillibrated PO2 in alveolus and what you pull out in arterial sample
- in a health person it should be low, but not 0 b/c some blood doesn't get oxygenated and VQ matching isn't perfect

P(A-a)O2 gradient of 10-15 is normal
Term
formula for calculating P(A-a)O2 gradient:
 Definition
alveolar gas equation:

PAO2 = PIO2 - (PACO2/RQ)

- PIO2= inspired oxygen
- RQ= respiratory quotient, usually 0.8
Term
calculate P(A-a)O2 gradient:

Example: Blood gas from a patient are
PaO2 = 90 mmHg R = 0.8
PACO2 = 40 mmHg
Pbar = 760 mmHg
 Definition
PAO2 = PIO2 - (PACO2 / R)
= 150 - (40 / 0.8)
= 150 - (50)
= 100 mmHg
Therefore, A-a gradient is 100 – 90 = 10 mmHg (normal)
Term
With emphysema, surface area is impaired, so there is an ___ A-a gradient and reduced diffusion. Putting patient on oxygen, shifts up ___ ___ and alveolar PO2, so you get higher ___ in the blood. But this does not fix the A-a gradient problem and diffusion problem, but better PO2 so tissues oxygenated better.
 Definition
- increased
- inspired oxygen
- PO2
Term
To increase O2 content for a given PO2, you need ____.
 Definition
hemoglobin= oxygen carrier
Term
Hemoglobin has ___ oxygen binding ___ groups that combine with oxygen reversible to make ___.
 Definition
- 4
- heme
- oxyhemoglobin
Term
O2 saturation definition:
 Definition
amount of O2 bound relative to the total amount that could be bound

bound O2/total O2
Term
PO2 is NOT hemoglobin saturation, but PO2 ___ hemoglobin saturation.
 Definition
- determines
Term
PO2 (partial pressure of O2) determines oxygen's affinity for binding ____.
 Definition
hemoglobin
Term
PO2 of 90-100 is normal.
95-100% is normal saturation.
 Definition
Term
So with a PO2 of 90-100, the __ is high, so the ____ is high.
 Definition
- affinity
- saturation
Term
As partial pressure goes down, ___ goes down, so ____ goes down. Thus, at high altitudes ___ is decreased, and ____ is decreased even though ___ is normal.
 Definition
- affinity
- saturation
- PO2
- saturation
- hemoglobin
Term
As O2 binds to hemoglobin, the affinity ___ ____.
 Definition
increases exponentially
Term
Upper flat part of O2 dissociation curve ensures:
 Definition
- high arterial O2 content, safety factor
Term
Middle portion of oxygen dissociation curve allows :
 Definition
- release of large quantities of O2 for a small decrease in PO2
Term
___ ____ shows how effectively you are oxygenating the blood in the lungs. List three conditions that would increase this.
 Definition
A-a gradient
emphysema
fibrosis
shunting
Term
PO2 can decrease quite a bit before oxygen saturation is significantly changed. From PO2 of 60-100, you will have a pretty steady oxygen saturation.
 Definition
Term
at rest Normal PaO2 and SaO2:
 Definition
PaO2= partial pressure of O2 in arteries= 90-100 mm Hg

SaO2= oxygen saturation in arteries, 95-100%
Term
at rest normal PVO2 and SVO2:
 Definition
PVO2: 40 mm Hg
SVO2: 70-75%
Term
A PaO2 of 60 mmHg correlates with what saturation?
 Definition
90%
Term
normal p50 is
 Definition
27mm Hg
Term
During modest exercise, how do your PaO2, SaO2, PvO2, and SvO2 change?
 Definition
- PaO2 stays 100
- SaO2 stays 95-100%

PvO2 decreases to less than 40 mm Hg and SvO2 decreases to less than70-75%

this is because metabolism has increased in tissues, so more oxygen is given up to the tissues
Term
Metabolic bi-products affect hemoglobin affinity. On the PO2-oxygen saturation curve, a rightward shift favors ___ of oxygen. What are some metabolic bi-products that would encourage this?
 Definition
- unloading of oxygen
encouraged by increased PCO2, increased H+, decreased pH, increased temperature, increased 2,3-DPG (glycolysis in RBC),
Term
When there is a rightward shift on the O2 saturation curve, which favors unloading of oxygen, the P50 ____, meaning there is ___ O2 saturation for a given PO2. There is also a decreased hemoglobin affinity so that there is more unloading of oxygen at a given PO2.
 Definition
- increases
- less
Term
Factors affecting P50 on oxygen saturation curve that result in a leftward shift, which favors oxygen saturation.
 Definition
- decreased H+
- decreased CO2
- increased pH
- decreased 2,3 DPG
- presence of fetal hemoglobin
Term
So with a leftward shift on the oxygen saturation curve, P50 ____, meaning there is an ___ in O2 saturation for a given PO2. This also means affinity for hemoglobin has increased.
 Definition
- decreases
- increase
Term
formula for oxygen content:
 Definition
O2 content = [O2 on hemoglobin] + [O2 in plasma]
Term
O2 carrying capacity Hb:
 Definition
1.34 ml/gm
Term
O2 carrying capacity of blood:
 Definition
g of Hb normally (15 g/dL)x 1.34 ml/g= 20 ml/dl
Term
oxygen content:
 Definition
how much total oxygen in blood is being taken to the tissue
Term
With a normal hemoglobin of 15 g/dL, you have 20 ml/dl oxygen content, this is at or near 100% saturation. So if you drop oxygen saturation to 50%, then your oxygen content is ___.
 Definition
10 ml/dl
Term
A patient comes in with a hemoglobin of 7.5 g/dL, so their oxygen content when fully saturated is ___. But there saturation will still show ___ even though this person is profoundly anemic
 Definition
10ml/dl
100%
Term
What is arterial O2 content of patient with:
PaO2 = 60 mmHg
Hb = 15 g/dl
O2 saturation = 80%
 Definition
16 ml/dl
Term
When hemoglobin decreases by 50%, oxygen content ____ even though ___ is normal.
 Definition
- decreases
- PO2
Term
CO poisoning;
 Definition
- CO binds the hemoglobin and displaces the oxygen
- CO has affinity 250 x greater for hemoglobin
- acute decrease in oxygen carrying capacity
- normal PO2 and Hb
- large decrease in oxygen content
- large decrease in venous PO2
Term
Anemic patients will can have a normal arterial PO2 but usually have a decreased venous PO2.
 Definition
Term
With CO poisoning, ___ and ___ are normal, but there is a big decrease in ___ ___ and ___ ___.
 Definition
- PO2 and Hb
- oxygen content
- venous PO2
Term
results of Hemoglobin decreasing 50%:
 Definition
- decreased oxygen content
- normal arterial PO2
- decreased venous PO2
- normal saturation
Term
average CO2 produced:
 Definition
200 ml/min
Term
Mechanisms of CO2 transport:
 Definition
1. 8% is dissolved
2. HCO3- in plasma (57%), and RBCs (24%)
3. Carbaminohemoglobin (11%)
Term
CO2 is different, more is dissolved, most of it is converted to bicarbonate, which is how it becomes involved acid-base balance. Carbaminohemoglobin- co2 bound to hemoglobin
MOST IMPORTANT IS IT IS PRIMARILY CARRIED AS BICARBONATE
 Definition
Term
Human body favors uptake of oxygen into the blood at the alveoli and favors release of O2 at the tissues.
 Definition
Term
Central chemoreceptors are located at the surface of the ___ ___ on the floor of the ___ ____. They are sensitive to ___ and ___, not ___.
 Definition
- ventrolateral medulla
- fourth ventricle
- PCO2 and H+
- not oxygen
Term
Peripheral chemoreceptors are located on the ___ and ___ bodies and are sensitive to ___, ___, and __. They are innervated by the ___ __ ___, which is a branch off of __ __ ___.
 Definition
- carotid and aortic
- PO2, PCO2, and ph
- carotid sinus nerve
- CN IX (glossopharyngeal)
Term
central chemoreceptors are NOT sensitive to ___.
 Definition
oxygen
Term
As arterial CO2 increases what happens to alveolar ventialtion?
 Definition
increases
Term
what happens when there is decreased O2?
 Definition
alveolar ventilation increases
Term
Are we more sensitive to O2 or CO2?
 Definition
CO2
Term
normal value for PACO2:
 Definition
PACO2= 40 mm Hg at 5L/min
Term
hyperventilation ___ CO2. Hypoventilation ___ CO2.
 Definition
- lowers
- increases
Term
High ___ defines hypoventilation.
 Definition
PCO2
Term
As alveolar ventilation is doubled, ___ should be ____.
 Definition
PACO2
halved
Term
When PaCO2 is increased, chemoreceptors sense the increase and provoke an inreased ventilation to blow off the excess CO2 (negative feedback control)
PaCO2 determines the “drive to breathe” and thus, determines alveolar ventilation as a reflex response.
 Definition
Term
factors affecting CO2 control:
 Definition
Basal level of PaCO2
Arousal state
Affected by PO2
Hyperventilation effect
Hypoventilation effect
Term
When we sleep, we have a ___ PaCO2.
 Definition
higher
Term
Factors affecting oxygen control:
 Definition
Basal level of PaO2
NOT O2 CONTENT
Affected by PaCO2
Arousal state--not much
Term
Central sleep apnea:
 Definition
-- Periodic Loss of airflow
-- Concomitant loss of central drive
-- Lack of inspiratory (diaphragmatic) efforts = EMG
-- Small % of sleep apnea (<5%)
Term
Obstructive sleep apnea:
 Definition
Periodic Loss of airflow
-- No loss or transient loss of central drive
-- Inspiratory (diaphragmatic) efforts = EMG
-- Most apneas are OSA
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