Respiratory Adaptations

Question 1

What are the four forms of hypoxia?

Answer 1

• hypoxic hypoxia
• anemic hypoxia
• circulatory hypoxia
• histotoxic hypoxia

Question 2

What is hypoxic hypoxia?

Answer 2

-low arterial P of oxygen

• maybe alveolar P of oxygen is low (ex: high altitude)
• maybe bc of lung disease (ex: emphysema)

Question 3

What is anemic hypoxia?

Answer 3

• oxygen-carrying capacity of the blood is reduced

- ex: anemia, carbon monoxide poisoning

Question 4

What is circulatory hypoxia?

Answer 4

• heart can’t pump blood to the tissue

- ex: arteries to the tissue have been blocked by clots

Question 5

What is histotoxic hypoxia?

Answer 5

• tissue is unable to use the oxygen

- ex: cyanide poisoning

Question 6

What is the initial effect of hypocapnia on hydrogen ions and the pH in blood, and the pH in CSF?

Answer 6

• hydrogen ions decrease
• pH of blood increases
• pH of CSF increases

Question 7

How does the body compensate for hypocapnia?

Answer 7

-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

Question 8

How does hypoxia lead to hypocapnia?

Answer 8

• 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

Question 9

How does the lack of hydrogen ions and increased pH of CSF affect the body in a state of hypocapnia?

Answer 9

-the decreased hydrogen ions signal the central chemoreceptors to decrease RR

Question 10

Why does the body compensate and normalize the pH of the CSF in chronix hypoxia?

Answer 10

-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

Question 11

What happens to the pH of the CSF in chronic hypercapnia?

Answer 11

pH of CSF becomes acidic

Question 12

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?

Answer 12

-the respiratory control centers are receiving lots of stimuli to increase RR

Question 13

Do neurons respond well in acidic conditions?

Answer 13

No

Question 14

How does the body compensate for chronic hypercapnia?

Answer 14

-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

Question 15

What are the effects of increased barometric pressure on the amt of gases in our bodies?

Answer 15

they increase

Question 16

What are the effects of oxygen toxicity in our bodies?

Answer 16

-production of superoxide anion and hydrogen peroxide, at a rate higher than enzymes can clear them

Question 17

What are the effects of increased dissolved nitrogen in our bodies?

Answer 17

increased nitrogen has similar effects to alcohol on the CNS

-“rapture of the deep”

Question 18

What causes an air embolism?

Answer 18

• 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

Question 19

What does decreased barometric pressure due to the level of oxygen at equilibrium b/w alveolar P of oxygen and arterial P of oxygen?

Answer 19

the oxygen level at equilibrium decreases, causing hypoxic hypoxia

Question 20

How does the choroid plexus aid the body in acclimatizing to decreased altitude?

Answer 20

• 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

Question 21

How does the kidney aid the body in acclimatizing to decreased altitude?

Answer 21

increased release of erythropoietin that stimulates bone marrow to produce more RBC

Question 22

How do mitochondria aid the body in acclimatizing to decreased altitude?

Answer 22

increase in size and number

Question 23

What are three pathologies associated with decreased barometric pressure?

Answer 23

altitude sickness (d/t change in cerebral circulation)

pulmonary edema

pulmonary HTN (d/t hypoxic vasoconstriction)

Question 24

What are the effects of high levels of nitrogen in the body?

Answer 24

• excess nitrogen exerts an effect on the CNS that is similar to alcohol
• Nitrogen Narcosis (“Rapture of the Deep”)

Question 25

What happens to excess nitrogen in the body of divers who ascend from the deep too quickly?

Answer 25

-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

Question 26

What is oxygen toxicity?

Answer 26

-accumulation of excess oxygen creates superoxide anion and hydrogen peroxide faster than enzymes can clear it from the body

Question 27

What are the symptoms of oxygen toxicity?

Answer 27

-sore throat, coughing, muscle twitching, tinnitus, dizziness, convulsions, death

Question 28

What are the effects of too much oxygen on infants?

Answer 28

• bronchopulmonary dysplasia = abnormal lung growth

- retrolental fibroplasia = abnormal capillary growth d/t disrupted oxygen gradient (aka retinopathy of prematurity)