O2 and CO2 transport

Question 1

Alveolar PO2 and PCO2

Answer 1

PO2 - 100 mmHg
PCO2 - 40 mmHg

Question 2

Arterial PO2 and PCO2

Answer 2

PO2 - 100 mmHg
PCO2 - 40 mmHg

Question 3

Venous PO2 and PCO2

Answer 3

PO2 - 40 mmHg
PCO2 - 46 mmHg

Question 4

Two ways oxygen is carried in the blood

Answer 4

• dissolved in blood plasma (1.5%)
• bound to hemoglobin inside erythrocytes (98.5%)

Question 5

Why does Carbon Monoxide poisoning occur?

Answer 5

• binds to heme group better than O2 and is permanently bound to it

Question 6

How is Carbon Dioxide carried in the blood (3 ways)

Answer 6

• dissolved in the plasma (7%)
• bound to blood proteins including hemoglobin (23%)
• as bicarbonate (70%)

Question 7

How is homeostasis maintained (in regards to PO2 and PCO2)

Answer 7

• peripheral chemoreceptors in the carotid artery and aortic arch (sense PO2, PCO2, and pH) and central chemoreceptors in the brainstem (medulla) (senses only pH [H+] )
• send APs back to respiratory centre in medulla

Question 8

Why is ventilation increased during exercise? Explain the ventilation response.

Answer 8

• increase in metabolic activity
• increased PCO2 and decreased PO2
• chemoreceptors sense this and send APs to medulla
• APs sent to increase respiratory rate
• faster and deeper breaths = increase in PO2 to normal and decrease in PCO2 to normal

Question 9

Explain the Bohr effect

Answer 9

• Hb affinity changes
• graph shifts right
• occurs when increase in PCO2 (more acidic /higher temp)