Respiratory Adaptations Flashcards
What are the four forms of hypoxia?
- hypoxic hypoxia
- anemic hypoxia
- circulatory hypoxia
- histotoxic hypoxia
What is hypoxic hypoxia?
-low arterial P of oxygen
- maybe alveolar P of oxygen is low (ex: high altitude)
- maybe bc of lung disease (ex: emphysema)
What is anemic hypoxia?
- oxygen-carrying capacity of the blood is reduced
- ex: anemia, carbon monoxide poisoning
What is circulatory hypoxia?
- heart can’t pump blood to the tissue
- ex: arteries to the tissue have been blocked by clots
What is histotoxic hypoxia?
- tissue is unable to use the oxygen
- ex: cyanide poisoning
What is the initial effect of hypocapnia on hydrogen ions and the pH in blood, and the pH in CSF?
- hydrogen ions decrease
- pH of blood increases
- pH of CSF increases
How does the body compensate for hypocapnia?
-carbonic anhydrase in the choroid plexus uses water to convert the little amt of carbon dioxide available into hydrogen ions and bicarbonate; hydrogen ions are selectively pumped into the CSF and bicarbonate is sent to the blood
How does hypoxia lead to hypocapnia?
- peripheral receptors detect the hypoxia and send signals to increase RR
- increased RR causes the body to get rid of carbon dioxide faster than it produces the waste product
How does the lack of hydrogen ions and increased pH of CSF affect the body in a state of hypocapnia?
-the decreased hydrogen ions signal the central chemoreceptors to decrease RR
Why does the body compensate and normalize the pH of the CSF in chronix hypoxia?
-normalizing the CSF pH dampens the signal of the low carbon dioxide that would normally be sent to the chemoreceptors to decrease RR; thus peripheral receptors’ signals prevail to maintain an increased RR in an effort to maintain oxygen levels
What happens to the pH of the CSF in chronic hypercapnia?
pH of CSF becomes acidic
What happens to the respiratory control centers of the brain when lung disease has advanced so far that the body is in both a hypoxic and hypercapnic state?
-the respiratory control centers are receiving lots of stimuli to increase RR
Do neurons respond well in acidic conditions?
No
How does the body compensate for chronic hypercapnia?
-carbonic anhydrase in the choroid plexus uses water to convert carbon dioxide into hydrogen ions and bicarbonate; bicarbonate is selectively pumped into the CSF to normalize the pH
What are the effects of increased barometric pressure on the amt of gases in our bodies?
they increase
What are the effects of oxygen toxicity in our bodies?
-production of superoxide anion and hydrogen peroxide, at a rate higher than enzymes can clear them
What are the effects of increased dissolved nitrogen in our bodies?
increased nitrogen has similar effects to alcohol on the CNS
-“rapture of the deep”
What causes an air embolism?
- compressed air in the lungs expands as barometric P decreases
- if P decreases too quickly w/ closed glottis, air escapes into the pulmonary vv. and may rupture them
What does decreased barometric pressure due to the level of oxygen at equilibrium b/w alveolar P of oxygen and arterial P of oxygen?
the oxygen level at equilibrium decreases, causing hypoxic hypoxia
How does the choroid plexus aid the body in acclimatizing to decreased altitude?
- choroid plexus pumps more hydrogen ions back into the CSF to bring the pH back down
- this overrides the effect of hypocapnia on the body that results from increased RR due to hypoxia at altitude
How does the kidney aid the body in acclimatizing to decreased altitude?
increased release of erythropoietin that stimulates bone marrow to produce more RBC
How do mitochondria aid the body in acclimatizing to decreased altitude?
increase in size and number
What are three pathologies associated with decreased barometric pressure?
altitude sickness (d/t change in cerebral circulation)
pulmonary edema
pulmonary HTN (d/t hypoxic vasoconstriction)
What are the effects of high levels of nitrogen in the body?
- excess nitrogen exerts an effect on the CNS that is similar to alcohol
- Nitrogen Narcosis (“Rapture of the Deep”)
What happens to excess nitrogen in the body of divers who ascend from the deep too quickly?
-excess nitrogen converts from the dissolved state to the gaseous state while it’s still in the blood
- The Bends (aka Decompression Sickness)
- pain, paresthesia, paralysis, itching
What is oxygen toxicity?
-accumulation of excess oxygen creates superoxide anion and hydrogen peroxide faster than enzymes can clear it from the body
What are the symptoms of oxygen toxicity?
-sore throat, coughing, muscle twitching, tinnitus, dizziness, convulsions, death
What are the effects of too much oxygen on infants?
- bronchopulmonary dysplasia = abnormal lung growth
- retrolental fibroplasia = abnormal capillary growth d/t disrupted oxygen gradient (aka retinopathy of prematurity)
