Gas Transport (Respiratory System)

Question 1

How is oxygen transported

Answer 1

98.5% bound to hemoglobin, 1.5% is gas dissolved in plasma

Question 2

Describe hemoglobin.

Answer 2

Four protein (globin) portions; Each has a heme group, bind one O2 to an iron atom

Question 3

What happens after the first heme group binds with O2?

Answer 3

Hemoglobin changes shape in a way the facilitates uptake of the following O2

Question 4

What three forms is carbon dioxide transported in blood in?

Answer 4

gas (5%), carbonic acid (90%), carbamino compounds (5%)

Question 5

What enzyme catalyzes the carbonic acid reaction?

Answer 5

Occurs rapidly in RBC, catalyzed by enzyme carbonic anhydrase.

Question 6

What are the relative amounts of CO2 exchanged from the blood to alveolar air?

Answer 6

Carbonic acid - 70%, Carbamino compounds - 23%
Gas - 7%

Question 7

Describe the chloride-bicarbonate exchanger.

Answer 7

Pumps out most of the HCO3- out of the RBC in exchange for Cl- from the blood plasma.

Question 8

Describe alveolar gas exchange.

Answer 8

As hemoglobin loads oxygen its affinity for H+ declines. H+ dissociates from the hemoglobin & binds with bicarbonate ion transported from the plasma into the RBCs. Chloride ions are transported back out of the RBC.

Question 9

How does ambient Po2 adjust the rate of oxygen unloading?

Answer 9

-active tissue has lower PO2, O2 is released from Hb

Question 10

How does ambient pH adjust the rate of oxygen unloading?

Answer 10

-active tissue has higher CO2, lowers pH of blood, promotes O2 unloading

Question 11

How does temperatue adjust the rate of oxygen unloading?

Answer 11

Active tissue has higher temperature, promotes O2 unloading

Question 12

How does bisphopholglycerate (BPG) adjust the rate of oxygen unloading?

Answer 12

• RBCs produce BPC, which binds to Hb, O2 is unloaded
• high body temp, thyroxine, growth hormone, testosterone, and epinephrine all raise BPG and promotes o2 unloading.

Question 13

What is hypocapnia?

Answer 13

To little hydrogen ions; low Po2 (normal 37 to 43 mm Hg), most common cause of alkalosis (ph > 7.45)

Question 14

What is hypercapnia?

Answer 14

To many hydrogen ions; high Po2 (normal 37 to 43 mm Hg), most common cause of acidosis (ph < 7.45)

Question 15

What is hyperventilation?

Answer 15

A corrective homeostatic response to acidosis; H+ (product) is consumed and the ph rises and ideally returns blood to normal

Question 16

What is hypoventilation?

Answer 16

A corrective homeostatic response to alkalosis; H+ (product) is produces and the ph lowers and ideally returns blood to normal

Question 17

What is hypoxic drive?

Answer 17

Respiration driven more by low Po2 that by co2 or pH - can occur in pneumonia, high elevation

Question 18

What is hypoxia?

Answer 18

Deficiency of oxygen or the inability to use oxygen; consequence of respiratory diseases.

Question 19

What is hypoxemic hypoxia?

Answer 19

State of low arterial Po2; usually due to inadequate pulmonary gas exchange

Question 20

What is ischemic hypoxia?

Answer 20

Inadequate circulation of blood.

Question 21

How does oxygen toxicity develop?

Answer 21

Whe pure o2 is breathed at 2.5 atm or greater. Damages nervous tissue.