Effects of Blood PO2 on Ventilation

Under normal conditions, blood Po2 affects breathing only indirectly, by influencing the chemoreceptor sensitivity to changes in PcO2- Chemoreceptor sensitivity to PCO>2 is augmented by a low PO2 (so ventilation is increased at a high altitude, for example) and is decreased by a high PO2. If the blood PO2 is raised by breathing 100% oxygen, therefore, the breath can be held longer because the response to increased PCO2 is blunted.

When the blood PCO2 is held constant by experimental techniques, the PO2 of arterial blood must fall from 100 mmHg to below 50 mmHg before ventilation is significantly stimulated (fig. 16.31). This stimulation is apparently due to a direct effect of PO2 on the carotid bodies. Since this degree of hypoxemia, or low blood oxygen, does not normally occur at sea level, PO2 does not normally exert this direct effect on breathing.

In emphysema, when there is a chronic retention of carbon dioxide, the chemoreceptor response to carbon dioxide becomes blunted. This is because the choroid plexus in the brain (chapter 8)

%CO2

%CO2

Chemoreceptors Graph Pco2

6420

6420

â–  Figure 16.31 Comparing the effects of blood CO2 and O2 on breathing. The graph depicts the effects of increasing blood concentrations of CO2 (see the scale at the top of the graph) on breathing, as measured by the total minute volume. The effects of decreasing concentrations of blood O2 (see the scale at the bottom of the graph) on breathing are also shown for comparison. Notice that breathing increases linearly with increasing CO2 concentration, whereas O2 concentrations must decrease to half the normal value before breathing is stimulated.

secretes more bicarbonate into the cerebrospinal fluid, buffering the fall in cerebrospinal fluid pH. The abnormally high PCO2, however, enhances the sensitivity of the carotid bodies to a fall in PO2. For people with emphysema, therefore, breathing may be stimulated by a hypoxic drive rather than by increases in blood PCO2. Over a long period, however, the chronic hypoxia reduces the sensitivity of the carotid bodies in people with emphysema or other forms of chronic obstructive pulmonary disease, exacerbating their breathing problems.

The effects of changes in the blood PCO2, pH, and PO2 on chemoreceptors and the regulation of ventilation are summarized in table 16.6.

A variety of disease processes can produce cessation of breathing during sleep, or sleep apnea. Sudden infant death syndrome (SIDS) is an especially tragic condition that claims about I in 1,000 babies under 12 months in the United States annually. Victims are apparently healthy 2-to-5-month-old babies who die in their sleep for no obvious reason—hence, the layperson's term "crib death." These deaths seem to be caused by failure of the respiratory control mechanisms in the brain stem and/or by failure of the carotid bodies to be stimulated by reduced arterial oxygen. Since 1992, when the American Academy of Pediatrics began a campaign recommending that parents put infants to sleep on their backs rather than on their stomachs, the number of infants dying from SIDS has dropped by 38%.

Was this article helpful?

0 0
Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

Get My Free Ebook


Responses

  • annie
    How po2 effects on respiration?
    8 years ago
  • aatos savonheimo
    How abnormally high PC02 enhances sensitivity of carotid bodies to fall in P02.?
    8 years ago
  • Heike Beike
    Is hypoxic drive to breath from pco2 or po2?
    8 years ago
  • PIIA-NOORA
    Why doesnt change in po2 effect repiration?
    8 years ago
  • natsnet abrha
    Why emphysema causes low po2 and high pco2?
    8 years ago
  • fastolph
    How does blood ph and pco2 and po2 affect ventilation?
    8 years ago
  • gerda
    What condition was stimulated with Pco2 was raised?
    8 years ago
  • Zahra
    Does increased blood pco2 decreased ventilation?
    7 years ago
  • Nibs
    How does emphysema affect po2?
    7 years ago
  • michael
    Is PCO2 or PO2 controlling the ventilation at sea level?
    7 years ago
  • antje rothschild
    How does ventilation impact blood CO2 at high altitude?
    7 years ago
  • Divo
    How does ventilation affect arterial po2?
    7 years ago
  • mariam
    Why does COPD effect Arterial PO2 and PCO2?
    7 years ago
  • Eric
    What condition was simulated when the PCO2 was raised?
    7 years ago
  • Caramella Hogpen
    How does blood co2 effect ventilation?
    7 years ago
  • benjamin
    Why does PaCO2 elevate with emphysema?
    7 years ago
  • marigold
    How does emphysema affect your Pco2 levels?
    7 years ago
  • DOMINIK
    How is blood chemistry related to ventilation?
    7 years ago
  • SARA
    Does oxygen affect ventilation?
    7 years ago
  • matta boffin
    How does arterial p02 affect emphysema'?
    7 years ago
  • Faizan
    Why does a severe drop in oxygen below 50mmHg reduced ventilation?
    7 years ago
  • Gilly
    What are the effects of high pco2?
    7 years ago
  • jan
    How does copd affect pco2 levels?
    6 years ago
  • semere
    How does hypoxia affect alveolar po2?
    6 years ago
  • angela
    Why does a high pco2 drive ventilation more than low po2?
    5 years ago
  • Celendine
    How pulmonary ventilation influenced by the changes of in blood PO2, PCO2 and pH?
    4 years ago
  • Rebecca
    Does PO2 effect minute ventilation?
    4 years ago
  • keiran johnstone
    How does arterial p02 affect minute ventilation?
    4 years ago
  • carly
    WHAT CANGES TO VENTILATOR WHEN PCO2 IS HIGH AND PO2 IS HIGH?
    4 years ago
  • Eila
    Does po2 affect breathing?
    4 years ago
  • valentin
    How is pulmonary ventilation influenced by the changes in arterial PO2, PCO2, pH Explain mechanisms?
    4 years ago
  • PRISCILLA
    What increases ventilation during high blood po2?
    4 years ago
  • Cain
    How to reduce pco2 in blood naturally?
    4 years ago
  • Mandy Kunze
    What is the effects of arterial PO2 on alveolar ventilation?
    3 years ago
  • kinfe
    How does increased p02 affect minute ventilation?
    3 years ago
  • riley sutherland
    How are pulmonary ventillation influenced by Po2, Pco2 and ph?
    3 years ago
  • amiee
    How to change pCO2 on vent?
    3 years ago
  • Gloriana
    How to release po2 on ventilator?
    3 years ago
  • rasmus
    What effect will reduced ventilation have on the PO2 of arterial blood?
    3 years ago
  • STEPHEN
    What is the effect of decreased po2 in lungs?
    3 years ago
  • konsta
    How to affect pco2 on vent?
    3 years ago
  • miska
    How does p02 relate with pco2?
    3 years ago
  • karoliina v
    How PO2 decreases in blood affects the alveoli ventilation?
    3 years ago
  • fiorenzo
    How does increased PO2 affect the release of oxygen?
    3 years ago
  • SHERI
    How to change po2 and pco2 in ventilator?
    3 years ago
  • Jessika
    What happen PO2 increased?
    3 years ago
  • iago
    How does blood and alveolar o2 and co2 affect ventilation?
    3 years ago
  • elena
    What condition was stimulated when the pco2 is higher?
    3 years ago
  • DONNA
    Is the sensitivity of Pco2 ventilation increased by hypoxia?
    3 years ago
  • tytti
    How the increase of PO2 affect the release of oxygen?
    3 years ago
  • JOONA
    DOES BICARBONATE AFFECT PO2 VENTILATOR?
    3 years ago
  • awet
    How does a ventilator affect hco3?
    3 years ago
  • steve
    How increase in po2 effect human body?
    2 years ago
  • leah eichel
    Which fruit decrease po2 in body?
    2 years ago
  • Delfina
    When the po2 level is increased what is treatment?
    2 years ago
  • gualtiero
    Why emphysema lowers blood po2?
    2 years ago
  • THAD
    What is the pco2 volume in the human body?
    2 years ago
  • TULLIA
    How does increased pco2 affect the release of oxyzen?
    2 years ago
  • tiia
    What does a low pco2 indicate in a neonate?
    2 years ago
  • Kauko
    How to decrease high pco2 levels?
    2 years ago
  • Birgit
    How does emphysema affect blood ph levels?
    2 years ago
  • Maik
    What increases pO2 levels?
    2 years ago
  • nina
    How chemorecepters manage pO2 and pCO2 level?
    2 years ago
  • leea salpa
    HOW HIGH IS A PCO2 BEFORE DEATH?
    2 years ago
  • tiffany
    How will emphysema affect patient's blood ph?
    2 years ago
  • victor
    What is effect of decrease ph on pulmonary ventilation?
    2 years ago
  • mattiesko
    What happens when pco2 reduces graphs?
    2 years ago
  • isengrim
    How do changes in po2 pco2 and ph influence the respiratory movement?
    2 years ago
  • floyd
    Do emphysema has high po2 level and low co2 level?
    2 years ago
  • bertha phillips
    Which vent parameters affect po2?
    2 years ago
  • jali
    How does pco2 affect hypertension?
    2 years ago
  • matthias
    Why does baby p02 high?
    2 years ago
  • Jarno Katajisto
    Which of the following blood chemistry changes will cause an increase in ventilation?
    2 years ago
  • Giuseppa
    How quickly does PaO2 respond to changes in PO2?
    2 years ago
  • rose goodchild
    When ventrilation patient po2 is incress then what i do?
    1 year ago
  • Catone
    What happens at low po2?
    1 year ago
  • dahlak
    What does a low po2 indicate?
    1 year ago
  • veera
    How much does PO2 have to change to have physiological effect?
    1 year ago
  • cody
    How to correct someones po2 if it is low?
    1 year ago
  • iggi girma
    What is the response to increased levels of PO2?
    1 year ago
  • edda
    How do you treat Pco2?
    1 year ago
  • rosamunda
    Does the rate on a ventilator affects ph levels?
    1 year ago
  • Cassandra
    How does oxycontin affect arterial po2, co2, and ph?
    1 year ago
  • tammi
    How fast do ventillator changes affect ABG?
    1 year ago
  • anton anderson
    Why would po2 be so low?
    1 year ago
  • Pinja Sutinen
    Does high PO2 cause overcirculation to the lungs?
    1 year ago
  • Leanna Wilson
    What happens when you have low po2 levels and high pco2 levels in patients with copd?
    1 year ago
  • ciara
    What effects will low Pc02 have on breathing?
    1 year ago
  • tanta
    Can someone have a pO2 of 24 mmHgand live?
    1 year ago
  • CORNELIA
    What role does pao2 have on ph?
    1 year ago
  • richard
    What would cause an impact on minute ventilation?
    1 year ago
  • john
    When would po2 be a stimulus for ventilation?
    1 year ago
  • tanja
    Why is pao2 high on ventillator?
    1 year ago
  • birikti
    How does hypozia affect blood ph?
    1 year ago
  • Lisa
    What happens to arterial pco2 at altitude?
    1 year ago
  • Diana
    What are negative effects of high paO2?
    1 year ago
  • cesarina
    How does minute ventilation related to paco2?
    1 year ago
  • david
    How does emphysema impact blood ph?
    1 year ago
  • meneaduc hornblower
    What happens to aolveolar PO2 with increasing exercise?
    12 months ago
  • furio
    How does arterial oxygen affect ventillation?
    12 months ago
  • tesmi
    How does anaphylaxis affect arterial blood PO2?
    12 months ago
  • Brent
    How does mechanical venting affect ph of the blood?
    12 months ago
  • Rosaura
    Why would ph be high and pao2 and paco2 be low?
    12 months ago
  • goytiom awate
    What happens to po2 while sleeppin at altitude?
    12 months ago
  • veikko
    What can make the PO2 arterial very high?
    12 months ago
  • Tarsha Price
    Does a person with emphesyma have increase pO2 levels?
    12 months ago
  • ambrogio
    What to do if your patient has a high pO2 off the vent?
    11 months ago
  • tewelde
    How does pressure support affect pco2?
    11 months ago
  • fantino lombardi
    How to explain increased po2 on a vent?
    11 months ago
  • dina
    How does alveolar air volume relate to ph levels in blood?
    11 months ago
  • germana
    What affect does high po2 venous have?
    11 months ago
  • CARMEN
    What is po2 arterial high glood guauges?
    11 months ago
  • eric
    How do changes in PaCO2 drive ventilation?
    11 months ago
  • marmaduke
    How the changes in alveolar structure cause a decrease in blood oxygen levels in emphysema?
    11 months ago
  • karri
    What is considered a high pco2?
    10 months ago
  • Anita
    How do you increase the pao2 in a neonate?
    10 months ago
  • anne
    Which organ controls the level of pco2 in the blood?
    10 months ago
  • Florence
    Why mightpatient have a low pco2 in trauma?
    10 months ago
  • terenzio
    How does po2 affect respiratory rate?
    9 months ago
  • Rorimac T
    What ways does the body have of increasing or decreasing PO2 levels in the blood?
    9 months ago
  • flora
    What causes increases in PaO2?
    9 months ago
  • osman
    What is the normal level of Po2 in arterial blood?
    9 months ago
  • maximilian
    What is the physiological explanation for a high minute ventilation but normal pao2?
    9 months ago
  • samuel amanuel
    Why does minute ventilation increase when ph decreases?
    9 months ago
  • Frodo
    How to correct elevated pO2 level ABG?
    9 months ago
  • richard
    What if paO2 is high on ventilated patient?
    9 months ago
  • Anke
    Can high Po2 make CO2 rise?
    9 months ago
  • dominik
    Does body position improve po2?
    9 months ago
  • kaisa
    What makes po2 arterial high?
    9 months ago
  • pia
    How do physiological changes affect ventilation?
    9 months ago
  • Brenda
    How does po2 and pco2 change in shunt?
    9 months ago
  • jamila
    What effects respiratory rate in asmatics pao2?
    8 months ago
  • erik
    How does arterial ph affect oxygen in blood?
    8 months ago
  • Kati
    Is po2 lower at high altitudes?
    8 months ago
  • Corrado Greece
    How does alveolar PO2 affect the movement of oxygen?
    8 months ago
  • eeva
    What if the PO2 is really h igh?
    8 months ago
  • JOHN LANE
    What will cause the arterial po2 levels to increase?
    8 months ago
  • Jo Lightfoot
    Is high po2 dangerous?
    8 months ago
  • Berhane
    What is the most likey side effect of low PCO2?
    8 months ago
  • ricky
    Is PO2 of 13 compatable with life?
    8 months ago
  • Felix
    How can i achieve a higher p02 respiratory?
    8 months ago
  • Rayyan
    How does this change in ph affect oxygen binding at the lungs when po2 is decreased?
    7 months ago
  • SILKE
    Why don't changes in po2 drive respiration?
    7 months ago
  • Michael
    How does altered blood chemistry change ventilation rates ?
    7 months ago
  • aman
    How does PCO2 effect minute breathing?
    7 months ago
  • Aman Medhanie
    What does the body due in response to low alveolar po2?
    7 months ago
  • Merimas
    How does pao2 effect abg?
    7 months ago
  • george eddy
    What is the expected Po2 for aeteriol blood?
    7 months ago
  • Holfast
    How p02 is maintained in a human athlete?
    7 months ago
  • jessika
    How high can you raise arterial po2?
    7 months ago
  • rosanna
    What happens to pco2 during high altitude?
    7 months ago
  • Karin Aachen
    How does pao2 affect the movement of oxygen in the blood?
    6 months ago
  • Semhar Senay
    Can Po2 arerial increase beause of bipap?
    6 months ago
  • RUDIGAR
    What is the effect of increased ventilation on PaO2?
    6 months ago
  • tristan
    How to reduce PCO2 in ventilator?
    6 months ago
  • Joel
    How does emphysema effect arterial PaO2 and PaCO2.?
    6 months ago
  • frances goldsmith
    Why is po2 high on abg on room air patient?
    5 months ago
  • Cassidy
    How do po2 and pco2 change during hypoxia?
    5 months ago
  • Rebecca Palerma
    What level is to high for oxygen Po2?
    5 months ago
  • ciriaca
    Why does PO2 go over 100?
    4 months ago
  • jana beike
    WHAT WILL po2 be if vent is overcompensated?
    4 months ago
  • elizabeth martin
    Can a high pao2 make you acidotic?
    3 months ago
  • nelma
    How does the altitude affect pb, ph, pco2, p02, hco3?
    3 months ago
  • bisrat
    Does PAO2 drop before CO2 rises?
    3 months ago
  • rachel ford
    Why does PaO2 drop on bipap?
    3 months ago
  • Calleigh
    When PO2 is high, which of the following is expected to occur?
    2 months ago
  • clorinda
    What are side effects of a low vienous po2?
    2 months ago
  • addison smith
    How does high po2 increase risk of ards?
    2 months ago
  • hazel
    How to decrease p02 levels on vent?
    2 months ago
  • Nuguse
    How long do you have to be anoxic to change po2?
    2 months ago
  • sanelma
    Why does a rise in pco2 cause a fall in po2?
    1 month ago
  • fiyori
    How to lower high pco2?
    1 month ago
  • ciaran mcintyre
    How to treat increased pco2 levels?
    30 days ago
  • bruto
    What can cause PO2 to be low?
    17 days ago
  • Robert Street
    Why does ventilatory response increase as pao2 approaches 60 mmhg?
    17 days ago
  • Licia
    How does body alter breathing when po2 levels are lower than normal?
    12 days ago
  • Lobelia
    Why do ventilation problems cause changes in arterial PO2 but not CO2?
    7 days ago
  • monica
    Why are pCO2 and pO2 elevated after supplemental oxygen?
    7 days ago
  • MHRET
    What are side effects of a low pao2 level?
    7 hours ago

Post a comment