Respiratory Adaptations Flashcards
Low oxygen available to tissues
Hypoxia
Total absence of oxygen being delivered to tissues
Anoxia
Low oxygen in the blood
Hypoxemia
Hypoxic Hypoxia
PaO2 is BELOW normal
What can cause Hypoxic Hypoxia?
Decreased PAO2 or the blood is unable to equilibriate fully with the alveolar air
Anemic Hypoxia
Oxygen carrying capacity of the blood is reduced
What can cause Anemic Hypoxia?
Carbon Monoxide
- It binds better to Hb, and oxygen will not be able to bind to be carried to the tissues
Circulatory Hypoxia
Heart cannot pump blood to tissue so the tissue is not receiving sufficient oxygen
What can cause Circulatory Hypoxia?
Sickle Cell Anemia
- The cell shape impedes circulation
Histotoxic Hypoxia
Cells in the tissues are poisoned and unable to use the oxygen that is correctly delivered to them
What can cause Histotoxic Hypoxia?
Cyanide
Normally, describe how the central chemoreceptors increase respiration rate
- CO2 diffuses into CSF
- CSF converts to H+ and Bicarbonate
- H+ activates central chemoreceptors to increase firing rate to pre-botzinger complex
= Increased ventilation rate
Hypocapnia
Reduced Carbon Dioxide in the blood
When low oxygen stimulates the peripheral chemoreceptors to increase ventilation, what decreases?
PaCO2!! – BAD for central chemoreceptors!
With hyperventilation caused by low oxygen, oxygen is increased and carbon dioxide is further DECREASED. Why is this bad?
H+ and thus, CO2 is needed in the CSF to activate the central chemoreceptors to drive our need to breathe!
What will compensate for decreased CO2 to maintain the drive to breathe?
Cells in the choroid plexus!
What do cells in the choroid plexus do in the case of hypocapnia?
Selectively pump out more H+ into the CSF so the CSF is back to normal pH even in the presence of low CO2
What enzyme do the cells of the choroid plexus contain?
Carbonic Anhydrase