Final Review Important Concepts - Breathing mechanics.

Question 1

What is Respiration?

Answer 1

Respiration is the exchange of gas between the lungs and the atmosphere (external), and between tissues and the blood (internal). For this section we are concerned with external respiration.

Question 2

What is Breathing?

What are the phases of breathing?

What are the two types of breathing?

Answer 2

Breathing is caused by muscle action that changes the pressure gradient between the lungs and the atmosphere.

There are two phases of the breath: inspiration (inhalation) and expiration (exhalation). Breathing can be quiet or forced, depending on the activity one is undertaking. Quiet breathing is what you do while resting, sitting, or sleeping. Forced breathing is what you do during activities like singing, sneezing, coughing or exercising.

Question 3

Are the follow active or passive processes?

A) Quiet Inspiration

B) Quiet Respiration

C) Forced Inspiration

D) Forced Expiration

Answer 3

A) Quiet inspiration is an active process, which means it takes working muscles for it to occur.

B) Quiet expiration is a passive process, which means it requires no muscle action.

C) Forced inspiration is an active process that accompanies an increased need for air volume.

D) Forced expiration, unlike quiet expiration, is an active process.

Question 4

Describe Quiet Inspiration:

Active/passive?

Muscles?

Voluntary/involuntary?

Answer 4

Quiet inspiration is an active process, which means it takes working muscles for it to occur.

The diaphragm is the main muscle of breathing.

It is an involuntary skeletal muscle that contracts and flattens, creating a space in the intrathoracic area around the lungs.

At the same time the external intercostals elevate the rib cage. Because of these muscles working, the volume around the lungs increases while the pressure around the lungs decreases (Boyle’s Law, 1662). This causes a pressure differential between the outside of the body and the inside of the lungs with the pressure now greater outside, allowing air to flow in.

Question 5

Describe Quiet Expiration:

Active/Passive?

Muscles?

Voluntary/Involuntary?

Answer 5

Quiet expiration is a passive process, which means it requires no muscle action. During quiet breathing, the diaphragm relaxes and expiration results from a passive recoil of the lungs and ribcage.

Question 6

Describe Forced Inspiration:

Active/Passive?

Muscles?

Voluntary/Involuntary?

Answer 6

Forced inspiration is an active process that accompanies an increased need for air volume.

In addition to contraction of the diaphragm, the sternocleidomastoid lifts the sternum while the scalenes and pectoralis minor lift the ribcage, further increasing intrathoracic space so that the lungs can draw in a larger volume of air.

Question 7

Describe Forced Expiration:

Active/Passive?

Muscles?

Voluntary/Involuntary?

Answer 7

Forced expiration, unlike quiet expiration, is an active process.

In order to get air in at a faster rate when required, it must get out more quickly.

To accomplish this, the internal intercostals depress the ribcage while the abdominal muscles compress, pushing up on the diaphragm and forcing air out at a faster rate.

Question 8

What muscles are active during the phases of respiration? (quiet inspiration, quiet expiration, forced inspiration, and forced expiration?)

Answer 8

SUMMARY OF MUSCLES OF THE RESPIRATORY APPARATUS

Quite Inspiration

• diaphragm
• external intercostals

Quiet Expiration

• passive process – no muscles involved

Forced Inspiration

• sternocleidomastoid
• scalenes
• pectoralis minor

Forced Expiration

• internal intercostals
• abdominal muscles