Respiration I

Question 1

What is the primary function of the respiratory system?

Answer 1

The primary function is gas exchange; inhalation of O2 and expiration of CO2 produced by the body tissues.

Question 2

Describe sequence of structures through which air flows from inhalation to gas exchange.

Answer 2

Nasal turbinates -> pharynx -> larynx -> trachea -> bronchi -> alveoli

Question 3

What is the function of nasal turbinates?.

Answer 3

They filter out big dust particles that must have gotten inhaled.

Question 4

The right main bronchus divides into […] and the left main bronchus divides into […]

Answer 4

3 lobar bronchi, 2 lobar bronchi

Question 5

The smallest airways without alveoli are called […]

Answer 5

terminal bronchioles

Question 6

How are the lungs inflated?

Answer 6

This is done by the respiratory muscles (diaphragm, intercostal muscles). Your brain tells your respiratory muscles to contract. The pleural space, between the rib cage (thoracic cage) and the lungs, links the respiratory muscles and the lungs.

Question 7

What is the difference between the conducting zone and the respiratory zone in the airways? What structure delimits them?

Answer 7

The purpose of the conducting zone is just to transport air, while you only get gas exchange in the respiratory zone. Everything after the terminal bronchioles is part of the respiratory zone.

Question 8

Name 4 structures in the conducting zone and 3 in the respiratory zone of the airway.

Answer 8

Conducting zone: trachea, bronchi, bronchioles, terminal bronchioles
Respiratory zone: repsiratory bronchioles, aveolar ducts, alveolar sacs

Question 9

What are the pleural surfaces? State the two types and the body parts they’re associated with.

Answer 9

Parietal pleura = attack to the thoracic cage interior
Visceral pleura = enclose the lungs

Question 10

The pressure in the pleural space is […]

Answer 10

negative

Question 11

Explain how the pleural space works to link the abdominal muscles to the lungs.

Answer 11

Your brain tells you to enlarge the size of the ribcage, and because of that pleural fluid coupling, it creates suction that pulls the lungs open, increasing lung volume.

Question 12

The physiological unit of the lungs is called the […]

Answer 12

actinus

Question 13

How does the outside of the bronchi differ from the outside of the bronchioles?

Answer 13

The outside of the bronchi is lined with cartilage plaques. The outside of the bronchioles is lined with smooth muscle

Question 14

What are the 4 main functions of the conducting airways?

Answer 14

1. Defense against bacterial infection and foreign particles. The epithelial glands in the bronchi secrete mucous that lines the respiratory passages down to the bronchioles. Cilia in the bronchi sweep the mucous up into the pharynx. This is called the mucociliary defense system.
2. Warm and moisten inhaled air
3. Sound and speech and produced by the movement of air passing over the vocal cords
4. Regulation of air flow: smooth muscle around the airways may contract or relax to alter resistance to air flow.

Question 15

What is the main function of the respiratory zone?

Answer 15

The respiratory zone is the site of gas exchange between the air in the alveoli and the blood in the pulmonary capillaries. Each alveolus may be associated with as much as 1000 capillaries.

Question 16

How many circulations do the lungs have? Explain its/their function.

Answer 16

The lungs have 2 circulations: the pulmonary circulation and the bronchial circulation.
- Pulmonary: brings deoxygenated blood to the lungs and back into the left heart
- Bronchial: supplies oxygenated blood from the systemic circulation to the tracheobronchial tree, allowing the airways to get oxygenated.

Question 17

Describe the setup of the bronchial circulation.

Answer 17

Bronchial arteries supply the airways with oxygenated blood. There are no bronchial veins, however. The tiny amount of deoxygenated blood just gets mixed into the oxygenated blood travelling in the pulmonary vein back to the heart.

Question 18

What are the 3 alveolar cell types?

Answer 18

1. Epithelial type 1 and 2 cells
2. Endothelial cells
3. Alveolar macrophages

Question 19

What is the function of epithelial type 1 and 2 cells?

Answer 19

Little is known about epithelial type 1 cells. Type 2 cells produce pulmonary surfactant, a subtance that decreases the surface tension of the alveoli.

Question 20

What is the function of alveolar endothelial cells?

Answer 20

They constitute the walls of the pulmonary capillaries

Question 21

What is the function of the alveolar macrophages?

Answer 21

They remove foreign particles that may have escaped the mucociliary defense system of the airways and found their way into the alveoli

Question 22

What is the formula for pressure due to surface tension? State the variables.

Answer 22

P = 4T/R

Where P = pressure
T = surface tension
R = radius (of circular formation)

Question 23

Where is surface tension a concern? Explain why.

Answer 23

Surface tension is a concern in the alveoli, where, due to their round shape, surface tension can cause pressure that pushes air out. Since air gets pushed out at different pressures depending on the size of the alveolus, this creates an unstable system. This is why the type 2 cells produce surfactant.

Question 24

What are the 2 principle roles of pulmonary surfactant?

Answer 24

1. Prevents the pressure inside the small alveoli from exceeding that of the large alveoli
2. Reducing overall surface tension so that we can breathe, allowing us to inflate our lungs.

Question 25

What are the 2 types of respiratory muscles?

Answer 25

Inspiratory and expiratory

Question 26

Name the principle muscles of inspiration. State their function.

Answer 26

• External intercostals - elevate ribs
• Parasternal intercartilaginous muscles - elevate ribs
• Diaphragm - decreases longitudinal dimension of chest, elevates lower ribs.

Question 27

Name the accessory muscles of inspiration. State their function.

Answer 27

• Sternocleidomastoid - elevates sternum
• Scalenus - elevates and fixes upper ribs

Question 28

Name the muscles of expiration involved in quiet breathing and active breathing and their function.

Answer 28

Quiet breathing: expiration results from passive recoil of lungs

Active breathing:
- Internal intercostals (except parasternal intercartilaginous muscles) - depress ribs
- Abdominal muscles - depress lower ribs, compress abdominal contents
- Rectus abdominis
- External oblique
- Internal oblique
- Transversus abdominis

Question 29

What is the main inspiratory muscle?

Answer 29

The diaphragm

Question 30

The diaphragm is innervated by […]

Answer 30

The phrenic nerves from cervical segments 3, 4, and 5

Question 31

What is the purpose of accessory inspiratory muscles?

Answer 31

Their main contribution occurs during high levels of ventilation. Contraction of these muscles is also apparent during severe asthma and other disorders that obstruct the movements of air into the lungs.