Respiratory System at Rest

Question 1

Inspiration at rest (4 things)

Answer 1

• Active process
• External intercostal muscles contract
• by doing so this causes the rib cage to rise.
• At the same the diaphragm lowers, contracts and flattens.

Question 2

Inspiration during exercise (6 steps)

Answer 2

1. External intercostal and diaphragm muscles contract harder.

Additional muscles also contract and they are:

• Sternocleidomastoid
• Scalenes
• Pectoralis minor

2. This causes the ribcage to move upwards and outwards and the diaphragm to flatten even more
3. Increasing the volume of the thoracic cavity even more
4. As the volume of the thoracic cavity increases, the lung pressure decreases to below atmospheric pressure
5. Air moves down the trachea into the lungs as it flows down a pressure gradient
6. Inspiration is an active process - it requires energy.

Question 3

Expiration at rest (4 things)

Answer 3

• passive activity
• external intercostal muscles relax
• the rib cage moves downwards and inwards (moves back to original position),
• the diaphragm relaxes into its resting dome shape.

Question 4

Expiration during exercise (4 things)

Answer 4

• active process
• the internal intercostal muscles are used
• the abdominals are used
• the abdominals pull the ribcage down at a faster rate as well as with more force.

Question 5

Summary of muscles used during rest and exercise

Answer 5

Inspiration:

• Rest - Contraction of external intercostal muscles and diaphragm
• Exercise - Contraction of external intercostal muscles, diaphragm, sternocleidomastoid, scalenes and pectoralis minor

Expiration:

• Rest - Relaxation of external intercostal muscles and diaphragm
• Exercise - Contraction of internal intercostal muscles and abdominals

Question 6

Breathing rate at rest (definition and adult approximate value)

Answer 6

• The number of inspirations or expirations (breaths) per minute
• The approximate value of this for an adult is 12-15 breaths a minute

Question 7

Tidal volume at rest

Definition?
Approximate value for an adult?
Varies on which factors? (6)

What is dead space?

Answer 7

• Volume of air inspired or expired per breath
• The approximate value of this for an adult is 500ml.

However this can vary depending on the following factors:

• Size of lungs
• Size of thoracic cavity
• Age
• Gender
• Fitness
• Respiratory conditions

Dead space - Only 350 out of 500ml reaches the alveoli for gaseous exchange with the remaining 150ml remaining in the airways.

Question 8

Minute ventilation at rest (definition and formula)

Answer 8

• Volume of air inspired or expired per minute

Minute ventilation (VE) = frequency (f) x Tidal volume (TV)

Question 9

Why would the trained athlete have a lower VE at rest?

Answer 9

• They may be lower than a trained athlete because their gaseous exchange is more efficient.
• This means that they are can meet the demands for O2 more efficiently at rest.

Question 10

Lung Volumes and Capacities

The process of inspiration and expiration causes volume of air to enter and leave the lungs. These volumes of air vary depending upon:(4)

Answer 10

• Size of individual
• Height
• Health
• Sex