L17 - Respiration 4

Question 1

What is the hemoglobin saturation at a partial pressure of 100 mm Hg in the lungs?

Answer 1

around 98% saturation

Question 2

What is the hemoglobin saturation at a partial pressure of 40 mm Hg in the lungs?

Answer 2

around 75% saturation

Question 3

How much lower is hemoglobin saturation in peripheral tissues during exercise? Why is hemoglobin saturation lower?

Answer 3

significantly lower
around 40-50% saturation
because more oxygen is being utilised by the tissues resulting in a lower pO2

Question 4

What are common factors that change hemoglobin’s affinity for O2?

Answer 4

pH, temperature and partial pressure of CO2

Question 5

How does pH affect hemoglobin affinity?

Answer 5

increase in pH results in curve shifting to the left = tighter O2 binding and vice versa

Question 6

How does temperature affect hemoglobin affinity?

Answer 6

increase in temperature results in curve shifting to the right = weaker O2 binding and vice versa

Question 7

How does partial pressure of CO2 affect hemoglobin affinity?

Answer 7

increase in partial pressure of CO2 results in curve shifting to the right = weaker O2 binding and vice versa

Question 8

Why does hemoglobin dissociation curve shift back to original position in the lungs?

Answer 8

homeostasis is maintained in the lungs and all values for pH, pCO2 and temp should be at their normal physiological levels

Question 9

How is 2,3-DPG made?

Answer 9

intermediate of the glycolysis pathway (anaerobic metabolism)

Question 10

What happens when there is low O2?

Answer 10

increase in 2,3-DPG

Question 11

What are the three main ways in which CO2 is transported in the body?

Answer 11

dissolved CO2 in blood = 7%
bound to Hb = 23%
HCO3- in plasma = 70%

Question 12

Under normal resting conditions at sea level, which of the following would control ventilation? (plasma O2 levels / plasma CO2 levels / plasma O2 + CO2 levels)

Answer 12

plasma CO2 levels

Question 13

How is plasma pCO2 regulated?

Answer 13

increase in plasma CO2 in CSF and arteries -> stimulation of central and peripheral chemoreceptors which trigger an increase in ventilation = decrease in plasma CO2 -> negative feedback

Question 14

What do central chemoreceptors do? Where are they located?

Answer 14

monitor CO2 in CSF

in the medulla

Question 15

What do peripheral chemoreceptors do? Where are they located?

Answer 15

sense changes in pO2, pH and pCO2

located in carotid and aortic arteries

Question 16

Are peripheral chemoreceptors as sensitive as central chemoreceptors?

Answer 16

no

Question 17

How does altitude affect atmospheric pressure and proportion of gas molecules?

Answer 17

atmospheric pressure decreases

proportion of gas molecules remains the same

Question 18

At high altitude what will happen to plasma pO2 levels, plasma CO2 levels and ventilation rate?

Answer 18

plasma pO2 levels would decrease, plasma CO2 levels would decrease and ventilation would increase

Question 19

At high altitude, plasma pH woud (increase / decrease / not change)

Answer 19

increase

Question 20

Why does plasma pO2 decrease at high altitude?

Answer 20

due to increase in pO2 in air and alveoli

hypoxia at tissues

Question 21

Why does ventilation increase at high altitude?

Answer 21

due to decrease in plasma pO2 to below 60 mm Hg

Question 22

Why does pCO2 decrease at high altitude?

Answer 22

due to increase in ventilation

Question 23

Why does plasma pH increase at high altitude?

Answer 23

due to decrease in pCO2

Question 24

What are factors that contribute to acclimatization to high altitude?

Answer 24

red blood cell production increases
number of capillaries within tissues increases
nitric oxide increases
cells use O2 more efficiently via an increase in mitochondrial enzymes

Question 25

What are factors which limit exercise?

Answer 25

muscles need to obtain and use large amount of oxygen
cardiovascular system may reach its maximum
pulmonary system not limiting (unless highly trained)

Question 26

Why do muscles which need to obtain and use large amount of oxygen limit exercise?

Answer 26

may be limited by oxygen availability via local blood flow and number of mitochondria