Week 7 - Lecture 18 (Respiratory Physiology)

Question 1

Why is CO2 transport important?

Answer 1

CO2 transport allows for blood buffering

Question 2

What happens if blood [H+] rises?

Answer 2

H+ combines with HC03-

• A rise of [H+] means the blood is becoming more acidic (also called acidosis)
• triggering buffering system, increase respiration

Question 3

If blood [H+] rises, what compound would be the proton acceptor?

Answer 3

HC03- acts as proton acceptor

Question 4

What happens if blood [H+] drops?

Answer 4

H+ dissociates from H2CO3

• blood becomes less acidic and more alkaline
• Body slows breathing (hypoventilation) to retain more CO2 which combines with water to form carbonic acid to dissociates into H+

Question 5

what vessels have higher oxygen content?

Answer 5

In the pulmonary circuit the pulmonary veins have higher oxygen content and systemic arteries

Question 6

What vessels have higher carbon dioxide content?

Answer 6

• Pulmonary arteries
• Systemic veins?

Question 7

What causes carbon dioxide and oxygen to move in or out of the blood when the RBC is in the
pulmonary or systemic circuits?

Answer 7

• differences in partial pressures called diffusion
• Gases move from areas of higher partial pressure to areas of lower partial pressure

Question 8

Where does O2 diffuse into what?

Answer 8

Diffuses from blood into tissues

Question 9

Where does CO2 diffuse into what?

Answer 9

• Diffuses from tissues into blood

Question 10

When pCO2 is higher, pO2 is

Answer 10

Lower
- Cells produce CO2 as a waste product of metabolism and consume O2 for energy

Question 11

When pCO2 is higher, pH is

Answer 11

• ph is lower (more acidic)
• Carbon dioxide reacts with water in the blood to form carbonic acid (H2CO3), which dissociates into H+ ions

Question 13

When pH is higher, pO2 is

Answer 13

• Hemoglobin’s affinity for oxygen increases
  (Meaning oxygen binds more tightly to hemoglobin)
• pO2 (partial pressure of oxygen) reflects the amount of dissolved O2 in plasma, NOT HOW much is bound to hemoglobin

Question 14

when pCO2 is higher, HCO3- is

Answer 14

Higher

• CO2 combines with water to form carbonic acid, which dissociated into H+ and HCO3-

Question 15

Hemoglobins’ affinity for oxygen is directly related to how much oxygen is actually currently held by the hemoglobin. So, if hemoglobin has high oxygen saturation, hemoglobin’s affininty for oxygen is high. What do you think happens to hemoglobin’s affinity for oxygen after it moves through the systemic capillaries?

A) As the RBC moves through the systemic capillary, hemoglobin’s affinity for oxygen decreases.

B) As the RBC moves through the systemic capillary, hemoglobin’s affinity for oxygen increases.

C) As hemoglobin moves through the systemic capillary, hemoglobin’s affinity for oxygen stays the same.

Answer 15

A)

• When hemoglobin travels through the pulmonary capillary it moves into a very high oxygen environment causing it to have a high oxygen affinity and the opposite for systemic capillary.

Question 16

Think about the equation: HHb + O2 –> HbO2 + H+ when answering:

The lower hemoglobin’s affinity for oxygen, the more hemoglobin can prevent blood acidosis.

True or false?

Answer 16

True

• When affinity is high, hemoglobin binds oxygen tightly and does not release it
• When affinity is low, hemoglobin releases oxygen readily.
• When hemoglobin is release an oxygen molecule, it provides a binding site on the hemoglobin for an H+, acting a buffer and to prevent acidosis

Question 17

In the pulmonary capillaries:

A) oxygen combines with water to form bicarbonate ions and hydrogen ions

B) the blood leaving the pulmonary capillaries is more acidic than the blood entering

C) Carbon dioxide must detach from hemoglobin to allow oxygen to bind

D) Hydrogen ions combine with bicarbonate ions to form carbon dioxide and water

F) the lowest PO2 must be in red blood cell mitochondri

Answer 17

D)

B) is wrong since blood leaving

Question 18

Why is it acceptable to make CO2 in RBCs found in pulmonary capillary blood?

A) Because you can convert that CO2 back in to H+ & HCO3-

B) Because you can release CO2 into the alveoli and remove it from the body

Answer 18

B)

Question 19

Look at the equation in Model 2: Inside the RBC, what happens to carbonic anhydrase activity and bicarbonate production if H+ ion concentration rises?
A) Carbonic anhydrase makes more HCO3-

B) Carbonic anhydrase makes less HCO3-

Answer 19

B)

Question 20

According to Model 3, what does hemoglobin release when it binds O2?

A) H+
B) Cl-
C) HCO3-
D) H2O

Answer 20

A)