Variations in Breathing Rate

Question 1

What is tidal volume?

Answer 1

The volume of air in each breath

Question 2

How do you calculate tidal volume?

Answer 2

Find the average difference in the volume of gas between each peak and each trough on the trace

Question 3

What is breathing rate?

Answer 3

How many breaths are taken in a minute

Question 4

How do you calculate breathing rate?

Answer 4

Count the number of peaks in the trace in a minute

Question 5

What is oxygen consumption?

Answer 5

The volume of oxygen used by the body

Question 6

How do you calculate oxygen consumption?

Answer 6

Find the change in the volume of gas on the trace using the first and last trough

Question 7

What is respiratory minute ventilation?

Answer 7

The volume of gas breathed in or out in a minute

Question 8

How do you calculate respiratory minute ventilation?

Answer 8

tidal volume x breathing rate

Question 9

Where are the ventilation centres located?

Answer 9

Medulla oblongata

Question 10

Name the two different ventilation centres.

Answer 10

1. Inspiratory Centre

2. Expiratory Centre

Question 11

What is the inspiratory centre’s role in breathing?

Answer 11

1. Sends impulses to the intercostal muscles and diaphragm to make them contract
2. This increases the volume of the lungs, decreasing pressure
3. Air enters the lungs due to the pressure difference
4. As lungs inflate, stretch receptors are stimulated which sends impulses to inhibit the action of the inspiratory centre. The expiratory centre is no longer inhibited

Question 12

What is the expiratory centre’s role in breathing?

Answer 12

1. Sends impulses to diaphragm and intercostal muscles causing them to relax
2. Lungs deflate and pressure inside lungs increases, forcing air out
3. Stretch receptors become inactive again which sends impulses to the inspiratory centre
4. Inspiratory no longer inhibited and cycle starts again

Question 13

How does exercise affect breathing rate?

Answer 13

1. Increases breathing rate
2. Increases breathing depth
3. Increases heart rate to deliver oxygen to muscles faster and remove more carbon dioxide

Question 14

How is breathing rate increased during exercise?

Answer 14

1. Level of CO2 in blood increases, decreasing blood pH
2. Chemoreceptors in medulla oblongata, aortic & carotid bodies detect change in blood pH
3. They send impulses to medulla oblongata, which sends more frequent impulses to intercostal muscles & diaphragm
4. This increases the rate and depth of breathing