Respiration Under Unusual Conditions

Question 1

How does pp of O2 and CO2 and ventilation change when undergoing increasingly strenuous exercise?

Answer 1

start - no change to pps, increased ventilation (anticipation)
mild/moderate - no change to pps, increased ventilation to a plateau
strenuous - changes in pps, increased ventilation

Question 2

Cause of increased ventilation at the start of exercise

Answer 2

neural mechanism anticipating extra demand through detection by proprioceptors

Question 3

Cause of increased ventilation during moderate exercise

Answer 3

remove excess CO2 produced by active cells and increase O2 taken in due to increased demand, in order to maintain equilibrium of pp in the blood
chemical control by central chemoreceptors maintain the pp levels

Question 4

Cause of increased ventilation during strenuous exercise

Answer 4

high body temperature and metabolic production of acid
hyperventilation = reduced pCO2 (and increased O2)
maintain acid-base balance

Question 5

Stages of cardiovascular adaptations to exercise

Answer 5

1. activation of SNS
2. myocardial contractile force, cardiac acceleration, peripheral vasoconstriction
3. compresses blood vessels, blood translocated from peripheral vessels into heart and lungs to aid in increased blood flow and cardiac output

Question 6

Hypoxia

Answer 6

at high altitude
inadequate delivery of O2 to body tissues
(due to low pressure)

Question 7

Adaptations to high altitude - acute exposure

Answer 7

acute hypoxia detected by peripheral chemoreceptors, try to increase ventilation
increasing ventilation = reduction in ppCO2, leading to alkalinic CSF

Question 8

Problem of adaption to acute exposure to high altitude

Answer 8

increase ventilation: die from alkalosis

keep ventilation the same: die from hypoxia

Question 9

Solution for alkalosis

Answer 9

alkalinic CSF = increased HCO3-
choroid plexus cells export HCO3- from CSF to correct pH
hypoxic drive reinstated and ventilation increases further

Question 10

Adaptions to chronic exposure to high altitude

Answer 10

hours: breathing controlled around lower ppCO2, increased ventilation from hypoxic drive
days: alkalinity of blood corrected by increased excretion of HCO3- in urine

Question 11

Haematology adaptation to chronic exposure to high altitude

Answer 11

O2 carrying capacity of blood is increased with:

2,3 DPG and polycythaemia

Question 12

Effects on the body upon return from high altitude

Answer 12

left upper quadrant pain due to enlargement of the spleen (splenomegaly), as it breaks down excess RBCs
cardiac output is increased and directed to vital organs
systemic acid-base imbalance corrected

Question 13

Respiratory consequences of diving (descent)

Answer 13

increased pressure causes increased N2 dissolved in blood - nitrogen narcosis ‘rapture of the deep’
symptoms: euphoria, drowsiness, weakness, clumsiness, unconsciousness

Question 14

Respiratory consequences of diving (ascent)

Answer 14

decreasing pressure causes already dissolved N2 to form gas bubbles leading to decompression sickness - ‘the bends’
symptoms: excruciating pain, fatigue

Question 15

Acute consequences of space flight

Answer 15

motion sickness with nausea and vomiting

Question 16

Chronic consequences of space flight

Answer 16

decreased blood volume, cardiac output, red blood cell mass and muscle strength
loss of Ca2+ and PO4 3- from bones - favour osteoclasts

Question 17

Effects on the body upon return from space

Answer 17

orthostatic hypotension - cardiovascular system not used to responding to gravity
symptoms: dizziness, fainting

Question 18

Cause of orthostatic hypotension

Answer 18

baroreceptor reflexes are down-regulated due to lack of use in space