Respiratory System Lecture 5

Question 1

What happens to Hemoglobin with an increased/decreased partial pressure of oxygen?

Answer 1

Increasing partial pressure oxygen:
- More oxygen binds to Hb (increasing Hb-O2 saturation (Hb Sat); loading).

Decreasing partial pressure oxygen:
- Less oxygen binds Hb (decreasing Hb-O2 saturation; unloading).

Question 2

When do we want High Hb Saturation?
When do we want Low Hb Saturation?

Answer 2

Sometimes we want high Hb saturation (loading for gas transport).

Sometimes we want low Hb saturation (unloading for gas exchange).

Question 3

What are the Resting levels of Oxygen Partial Pressure leaving the Tissues? Leaving the Lungs?

Answer 3

Leaving tissues in systemic veins – returning to heart – to lungs
- 40 mmHg – 78% saturation.

Leave lungs – returning to heart – pump out into systemic arteries
- 100 mmHg – ~100% saturation.

22% difference – oxygen added from alveoli to blood (oxygenated).

Question 4

Oxygen Saturation Curve

Answer 4

Not a linear relationship; “S” shaped.

Question 5

Plateau Portion (PP):
(4)

Answer 5

Plateau portion (PP):
- Decrease in oxygen
- little effect on saturation
- PO2 100 mmHg to 80 mmHg;
- Hb Sat 100 % to 98 %
- Provides a safety margin for decreasing oxygen.

Question 6

Steep portion (SP):
(4)

Answer 6

Steep portion (SP):
- Decrease in oxygen
- large decrease in saturation
- PO2 40 mmHg to 20 mmHg;
- Hb Sat 78 % to 38 %

Question 7

How is Hemoglobin Saturation affected during Exercise Conditions?

Answer 7

Under resting conditions, oxygen leaving the lungs and returning to the heart has a high partial pressure of approximately 100 mmHg), and hemoglobin is nearly fully saturated (around 100%).

During exercise, the body’s oxygen demand increases, and there’s still enough time in the lungs to ensure that the blood leaving the lungs retains a high partial pressure of oxygen (close to 100 mmHg) and remains nearly fully saturated (around 100%). This is possible because of the plateau portion of the oxygen-hemoglobin saturation curve.

Question 8

What is the Hemoglobin Saturation after internal respiration during exercise?

Answer 8

After internal respiration – leaving tissues in
systemic veins - returning to heart – to lungs
– 20 mmHg – 38% saturation.

Further down the steep portion of the curve from resting:
- 40 mmHg – 78% saturation makes a significant difference

Exercise conditions
- 78% vs. 38% difference in venous blood after internal respiration.

Question 9

Right Shift of Saturation Curve:
(Purple) (4)

Answer 9

Right shift (purple): [High Acidity, Temp, CO2]
- decreased affinity
- increased unloading
- lower Hb Sat
- more oxygen for gas exchange

Question 10

Left Shift of Saturation Curve:
(Green) (4)

Answer 10

Left shift (green): [Decreased Acidity, Temp, CO2]
- increased affinity
- decreased unloading
- greater Hb Sat
- less oxygen for gas exchange

Question 11

Bohr effect on Saturation Curve
4 major points

Answer 11

1. Active Muscles and High CO2 and H+ Levels:
   During physical activity, in active muscles, metabolism is heightened, resulting in an increased production of CO2 and H+ ions. This can lead to a decrease in blood pH, making the blood slightly more acidic.
2. Right Shift of the Oxygen-Hemoglobin Dissociation Curve:
   The Bohr effect causes the oxygen-hemoglobin dissociation curve to shift to the right. Hemoglobin now has a reduced affinity for oxygen.
3. Oxygen Unloading:
   As a result, when oxygenated blood flows through the active muscles with high CO2 and H+ levels, hemoglobin readily releases oxygen. This is essential because active tissues need oxygen to support their increased metabolism, and the Bohr effect facilitates this release.
4. Hemoglobin’s Role in Gas Transport: Hemoglobin, having released oxygen, is now available to bind with CO2 and H+ for gas transport to removal areas. This includes transporting CO2 to the lungs for exhalation (external respiration) and transporting excess H+ ions to the kidneys for urinary excretion, helping to regulate the body’s pH balance.

Question 12

all the same

Answer 12

acidity increase
hydrogen ion concentration increase
lower pH

Question 13

Factors affecting Saturation Curve:

Answer 13

Rightward Shift:
- increase in H+ ion, decrease in pH
- increase in CO2
- increase in temperature

Leftward Shift
- decrease in H+ ion, increase in pH
- decrease in CO2
- decrease in tempertaure

Question 14

What happens to CARBON DIOXIDE during Gas Transport? (3)

Answer 14

• 7% CO2 dissolved in plasma and inside erythrocyte (can dissolve more CO2 in blood than oxygen).
• 23% CO2 binds Hb as carbaminohemoglobin (HbCO2) inside the erythrocyte.
• 70% CO2 converted to bicarbonate inside erythrocyte; moves outside erythrocyte (accompanying chloride shift) and is dissolved in plasma. (during expiration)

Question 15

What is the effect of CARBON MONOXIDE on Gas Transport?

Answer 15

Binds heme portion of Hb to form HbCO (carboxyhemoglobin).

Extremely high affinity for binding sites on Hb - 210 times that of O2 – CO and O2 competing for Hb binding sites.

Results:
Reduces O2 binding Hb in external respiration (limits oxygen being transported and delivered to tissues).

Shape change in Hb when binds CO making it harder for any bound O2 to let go (interfering with unloading / gas exchange)

Question 16

Carbon Monoxide:

Answer 16

• Colorless, odourless gas.
• Common cause of sickness and death, both intentional and accidental.