Unit 6: Respiration and Gas Exchange

Question 1

Describe Pulmonary ventilation, external respiration, internal respiration and cellular respiration

Answer 1

Pulmonary: nose/mouth and lung
External: lungs and the blood
Internal: blood and the cells
Cellular: cells and aerobic metabolism

Question 2

The body’s supply of oxygen is dependent on:

Answer 2

Concentration
Pressure

Question 3

Name percentage of gases in air

Answer 3

O2: 20.93%
N2: 79.04%
CO2: 0.03%

Question 4

What is the partial pressure of O2 and the mixture of gases in PP

Answer 4

At sea level atm: 760 mmHg

21% of 760 = 159 02
79% of 760 = 600 N2
0.035% of 760 = 0.2 mmHg CO2

Question 5

What two factors govern gas exchange

Answer 5

Solubility of gas in fluid
partial pressure difference

Question 6

T or F: if pressure is 400 in lungs and 300 in alveoli, O2 will move from alveoli to lungs

Answer 6

F, pressure moves from high to low

Question 7

Name PO2 at different point in the body:
Air
Alveolar
Arterial
Mean capillary
Myoglobin

Answer 7

Air: 159 mmHg
Alveolar: 103 mmHg
Arterial: 98 mmHg
Mean capillary: 40 mmHg
Myoglobin: 2-3 mmHg

Question 8

Name the PO2 in the blood at sea level

Answer 8

PAO2 = 104 mm Hg alveolar O2

PaO2 = 100 mm Hg arterial O2

PvO2 = 40 mm Hg venous O2

PaCO2 = 40 mm Hg arterial CO2

PvCO2 = 45 mm Hg venous CO2

Question 9

T or F: Partial pressure plays a key role in loading and loading of O2

Answer 9

True

Question 10

Since the pressure of O2 and CO2 stays at equilibrium when switching from pulmonary to systemic (or vice versa) at rest, what happens during exercise

Answer 10

• RBC velocity only goes up by about 50%
• With increasing intensity pulmonary capillaries increase blood flow which slows pulmonary blood flow velocity

Question 11

How does gas transfer within tissues work during exercise

Answer 11

• O2 and CO2 diffuse rapidly as their pressure gradients widen
• Alveolar ventilation keeps up to metabolic demands to keep alveolar gas composition remarkably constant
• Stability in alveolar gas concentrations persists even during strenuous activity that increases O2 consumption and CO2 output 25 times the values at rest

Question 12

How is O2 transported in the blood

Answer 12

In physical solution dissolved in blood

in loose combination w Hb (iron protein molec in RBC)

Question 13

c

Answer 13

[Hb]
SaO2
PaO2

O2 content (ml O2 / 100ml blood) = [Hb] (g/dl) x SaO2 (%) x 1.34 mlO2/g Hb + (0.003 x PO2)

Question 14

What are the 3 different way to express O2 content in the blood

Answer 14

• Oxygen content (CaO2)…measured in ml O2 / 100 ml blood
• Partial pressure (PaO2)…measured in mm Hg
• Haemoglobin saturation with oxygen (SaO2)…measured in

Question 15

• What would happen to oxygen content in anemia?
• What would happen to oxygen content in pulmonary disease where SaO2 can decrease to 90%

Answer 15

In anemia O2 content would decrease due to decrease in RBC

O2 content would also decrease if SaO2 decreases to 90%. Reduced SaO2 indicates lower % of Hb saturated with O2

Question 16

How does COVID-19 affect Respiration

Answer 16

• Causes pulmonary dysfunction due to arterial hypoxemia leading to acute respiratory distress
• COVID patients reported SaO2 between 69-75%
• increasing Hb is vital

Question 17

What happens to pulmonary, internal and external respiration during exercise

Answer 17

1