Module 3 Section 1 (Intro to Respiratory Physiology)

Question 1

Describe the purpose of the respiratory system, and the 4 steps involved in external respiration.

Answer 1

External respiration involves all of the processes that bring O2 from the atmosphere into the body, the transport of O2 to the tissues, and the removal of CO2 from the tissues and its release back into the atmosphere.

The four steps are:
1) Ventilation: air is moved in and out of the lungs (breathing/ ventilation) and
moves air b/w the atmosphere and the air sacs (alveoli) in the lungs.
2) Exchange of O2 and CO2 b/w Air and Blood: the diffusion of O2 from the alveoli to the pulmonary capillaries and the movement of CO2 in the opposite direction.
3) Transport of O2 and CO2: the transport of O2 in the blood to the tissues and the movement of CO2 in the opposite direction.
4) Exchange of O2 and CO2 b/w Blood and Tissues: the exchange of O2 from the blood to the tissues and CO2 from the tissues into the blood via diffusion.

These steps of external respiration are what are considered to be the primary functions of the respiratory system.

Question 2

Describe the role of the respiratory muscles in both inspiration and expiration.

Answer 2

Muscles of Inspiration:

• The main inspiratory muscles = the diaphragm and the external intercostal muscles.
• During inspiration (breathing in), the diaphragm descends to enlarge the thoracic cavity.
• Contraction of the external intercostal muscles elevates the ribs to further enlarge the thoracic cavity.

Muscles of Expiration:

• These muscles are responsible for decr the V of the thoracic cavity. The main expiratory muscles are the internal intercostal muscles and the abdominal muscles.
• In healthy individuals, these muscles are generally inactive and only get recruited when there is an incr in ventilator demand as during exercise or during coughing, sneezing, and vomiting.

Question 3

Describe the purpose of the pleural space.

Answer 3

The lung is covered by the visceral pleura (membrane), and the inside wall of the thorax is lined by
the parietal pleura.

B/w these 2 membranes = the pleural space (small; around 2 mm) and is filled with pleural fluid.
- This fluid allows the membranes to rub against each other during breathing with reduced friction.

Question 4

What is internal respiration?

Answer 4

It’s a process:

• Oxygen (O2) is necessary for the production of ATP.
• This production of ATP creates CO2 that must be expelled from the cells.

Question 5

In addition to external respiration, the respiratory system plays many other key roles in the body.

Using what you have learned from previous Modules and from your own experience, try to identify a few of the other functions of the respiratory system. (5)

Answer 5

1) Enables speech by air passing over the vocal chords.
2) Defends against inhaled foreign matter.
3) The respiratory muscles play a role in parturition and defecation.
4) The lung acts as a blood reservoir to allow for rapid equalization of left and right cardiac outputs.
5) Helps to maintain the acid-base balance.

Question 6

The respiratory system can be divided into 3 anatomical parts. What are those parts?

Answer 6

The lungs, the chest wall, and the

pleural space.

Question 7

Discuss the anatomy of the lungs (which are split into the upper and lower tract).

Answer 7

The respiratory system consists of the airways and the alveoli.
- Airways = carry air b/w the atmosphere and the alveoli, where O2 and CO2 are exchanged.

The upper airway includes the nose, nasal cavities, pharynx (the common tube for respiration) and the digestive system.
- From the pharynx, air travels to the larynx (location of the vocal chords).

The lower airway begins with the trachea (divides into the left and right bronchi, each of which supplies a lung).

• The bronchi branch into progressively narrower airways = bronchioles.
• The smallest bronchioles = the respiratory bronchioles (their walls are so thin that some gas exchange can occur).
• At the end of the terminal bronchioles = the alveoli (the air sacs where the majority of gases are exchanged b/w air and blood).

Question 8

The branching airways of the lower tract are often described as the respiratory tree or tracheobronchial tree. Even though each branch gets smaller and smaller, the overall cross sectional area increases. Why is this important?

Answer 8

This is very important as it allows for the transition from convective flow (requires energy in the form of muscle contraction to maintain air flow), to diffusive flow (occurs passively to allow air to flow into the alveoli). The diffusive zone begins at the level of the respiratory bronchioles.

Question 9

True or false: the branching of the airways serves a similar function to the branching of the circulatory system.

Answer 9

True

Question 10

Discuss the anatomy of the chest wall.

Answer 10

The chest wall is basically anything else that contributes to respiration and it includes the thorax (chest) and the abdomen.
- It contains the muscles that are necessary in generating pressures that allow air flow.

The thoracic cavity contains the lungs and the heart and is protected by the rib
cage.

The intercostal muscles are found b/w the ribs and are divided into the inner intercostal muscles and the external intercostal muscles, which lie over the innermost intercostals.

The thoracic cavity and abdominal cavity are separated by the diaphragm, a large sheet of skeletal muscle.

Question 11

External respiration essentially accomplishes the movement of O2 containing air into the alveoli, such that O2 can be transported to the tissues by the circulatory system, and the removal of CO2 that has been transported to the lungs, from the alveoli. This process can be further broken up into 2 different processes. What are they?

Answer 11

1) The ability of the respiratory muscles to generate the necessary pressure gradient to move air through the airways (overcoming the resistance to flow) and to inflate the lungs.
2) The ability of O2 and CO2 to diffuse across the alveolar-capillary barrier.

Both of these can be explained by the equation: Pressure / Resistance = Flow (diffusion)

~Check vid on slide 10~

Question 12

Which of the following muscles play a role in
inspiration?
a) External intercostals, pectoralis, diaphragm
b) External intercostals, internal intercostals,
diaphragm
c) Internal intercostals, diaphragm
d) External intercostals, diaphragm

Answer 12

d) External intercostals, diaphragm

Question 13

Which of the following muscles play a role in
expiration?
a) External intercostals, diaphragm
b) Pectoralis muscle, diaphragm, latissimus
dorsi
c) Internal intercostals, internal obliques
d) Internal intercostals, internal obliques, diaphragm

Answer 13

d) Internal intercostals, internal obliques, diaphragm