Week 7 - Respiration During Exercise (Part 3)

Question 1

What does Dalton’s Law State

Answer 1

the total pressure of a gas mixture is equal to the sum of the
pressure that each gas would exert independently

Question 2

Whats the partial pressure of inspired o2 and co2

Answer 2

Partial pressure is 159 and 0.3mmHg, respectively

Answer 3

Oxygenated inspired air is mixed in the lungs with
deoxygenated air returning from the venous blood

Question 4

Explain the steps of pulmonary circulation
(ON SHEET)

Answer 4

1. Pulmonary artery carries deoxygenated blood from the right ventricle to the lungs
2. Gas exchange between the alveoli and pulmonary capillaries occurs
3. Oxygenated blood is returned to the left atrium via the pulmonary vein
4. Oxygenated blood is pumped around the systemic circulation to the systemic cells

Question 5

What are the pressure measurements within the pulmonary circuit

Answer 5

Mean pulmonary artery pressure = 15 mmHg
Systemic arterial pressure = 100 mmHg

Question 6

Whats the result of the pulmonary circuit being thin walled with little smooth muscle

Answer 6

Accepts entire cardiac output
No redistribution of blood flow
Pulmonary vascular resistance decreases during exercise
due to recruitment and distension of pulmonary capillaries

Question 7

What is the ideal ventilation to blood flow ratio
(ON SHEET)

Answer 7

1
If ratio is >1 = underperfused
If ratio is <1 = overperfused

Question 8

How does gravity impact ventilation/blood flow ratio in the upright lung

Answer 8

blood flow increases
disproportionately more than ventilation
from the top to bottom of the lung

Question 9

During exercise how is ventilation/blood flow improved

Answer 9

Increased tidal volume
Increased pulmonary arterial pressure
In some cases V/Q worsens especially during heavy exercise

Question 10

How is oxygen carried in the blood

Answer 10

Oxygen is carried in the blood by 2 forms:
1. Dissolved (2%)
2. Combined with haemglobin (98%)

Question 11

What is Henry’s Law

Answer 11

Amount dissolved is proportional to partial pressure

Question 12

How does dissolved o2 follow Henry’s Law

Answer 12

The amount of O2 dissolved is 0.003 mL O2/100 mL blood/mmHg
At an arterial PO2 of 100 mmHg, this results in 0.003*100=0.3 mL O2/100 mL blood

Question 13

Whats the ratio between haemoglbin molecules transporting o2 molecules

Answer 13

1 haemoglobin molecule can transport 4 o2 molecules

Question 14

What is the amount of oxyhaemoglobin dependent on

Answer 14

Haemoglobin mass

Question 15

What is the Bohr effect

Answer 15

Exercise causes an increase in H+, CO2 and core body temperature, causing a rightward
shift in the oxyhaemoglobin dissociation curve
The Bohr effect facilitates unloading of o2 to active tissue

Question 16

What is myoglobin

Answer 16

An o2 binding protein found in skeletal muscle

Question 17

What is the role of myoglobin

Answer 17

It has a high o2 affinity and unloads at low po2
Shuttles o2 from muscle cell membrane to mitochondria for aerobic respiration
Provides intramuscular o2 storage

Question 18

How is carbon dioxide transported in blood

Answer 18

Co2 is carried in the blood in 3 forms:
1. Dissolved 10%
2. Bound to haemoglobin (20%)
3. Bicarbonate (70%)

Question 19

Is Co2 more soluble than o2

Answer 19

Co2 is 20x more solube than o2

Question 20

What is the chloride shift
(ON SHEET)

Answer 20

Hco3- leaves the cell and Cl- moves into the cell to maintain neutrality

Question 21

How is carboamino Hb created

Answer 21

H= binds to Hb for form HHb which binds to Co2 to create carboamino Hb

Question 22

Whats the effect in increased co2 production during exercise

Answer 22

CO2 production increase causes an increase in h+ and thus a decrease in arterial pH, which stimulates breathing via a feedback loop