the challenge of extreme environments

Question 2

what are the two challenges of altitude?

Answer 2

1. hypoxia
2. cold weather

Question 3

how does atmospheric pressue drop at increased altitude?

Answer 3

• reduction in the weight of the air above

Question 4

what is erythrocytosis

Answer 4

when an individual has a higher production of RBCs

Question 5

what is arterial hypoxaemia?

Answer 5

lower PaO2 in the blood

Question 6

why are adaptations in populations living at high altitude not the same?

Answer 6

• the populations have evolved in isolation from one another

Question 7

what are the two main genes associateed with adaption and survival in high altitudes?

Answer 7

• HIFs
• ACE

Question 8

what is HIF (3)

Answer 8

• Hypoxia-inducible transcription factor
• plays a crucial role in body’s response to low O2 levels
• triggers erythropoietin production

Question 9

what do the different variants of HIF dictate and how? (2)

Answer 9

• dictates the amount of erythropoietin production
• more stable HIF variants are degraded slower, so produce more erythropoietin

Question 10

what is the ACE geneotype for endurance and power

Answer 10

endurance = II (insertion)
power = DD (deletion)

Question 11

what ACE genotype is associated with reduced risk from envrionmental hypoxia?

Answer 11

II

Question 12

what is the characteristic of all deserts?

Answer 12

• little rain
• extremes of temperature (cold and hot)

Question 13

what occurs if the body temperature goes outside its vital thermoregulatory range (2)

Answer 13

• denaturing of enzymes occur (can freeze)
• changes the rate of chemical reactions in the body

Question 14

what is the vital thermoregulatory range? (2)

Answer 14

• the range of ambient temperatures within which the human body can maintain a stable core temperature
• without needing to expend energy for thermoregulation

Question 15

what is non-shivering thermogenesis (2)

Answer 15

• a metabolic process by which the body gnerates heat without the need for shivering muscle contractions
• involves uncoupling of mitochondrial respiration from ATP synthesis in brown adipose tissue to produce heat

Question 16

what are the factors affecing thermoregulatory ability? (5)

Answer 16

• gender
• age
• body shape/compositon
• clothing
• training status

Question 17

the overexpression of what gene helps protect against microgravity-induced cardiac remodelling?

Answer 17

• CKIP-1

Question 18

what are the two main challenges of underwater activities?

Answer 18

• presure increase with depth
• inability to respire

Question 19

why is reduced peripheral circulation involved in the diving reflex?

Answer 19

• vasoconstriction causes redistribution of blood away from extremities and towards vital organs

Question 20

why does splanchnic contraction occur in the diving reflex? (3)

Answer 20

• spleen contraction releases additional RBCs into circulation
• enhances the oxygen-carrying capacity and oxygen delivery to tissues
• helps sustain aerobic metabolism during underwater activites

Question 21

what triggers the diving reflex? (2)

Answer 21

• facial immersion in cold water
• breath-holding (apnoea)

Question 22

what extreme environment poses the most challenges to homeostasis, and what are these challenges (5)?

Answer 22

space:
* hypoxia
* pressure
* fluid balance
* temperature
* radiation