Respiratory System DYK Questions

Question 1

Can you name and briefly describe the function of key structures in the lower respiratory system?

Answer 1

• Larynx - sound production (glottis) and preventing food from entering trachea (epiglottis)
  - Trachea - airflow to alveoli
  - Bronchus - airflow to alveoli
  - Bronchioles - airflow to alveoli
  Alveoli - gas exchange

Question 2

Can you name and briefly describe the function of key structures in the upper respiratory system?

Answer 2

UPPER RESPIRATORY TRACT
- Nose, nasal cavity, sinuses, pharynx
- Functions
○ Filter, warm, and humidify incoming air to protect surfaces of lower respiratory system
Reabsorb heat and water from outgoing air

Question 3

What are the characteristics that make alveoli well suited to gas exchange?

Answer 3

Alveolar sac?
Alveolus
Smooth muscle
Capillaries

Question 4

What cells line the exposed surfaces of the respiratory system and what is the role of each?

Answer 4

Cell type depends on location and function
- Pseudostratified ciliated columnar epithelium
○ Protection and mucus removal
- Mucus (goblet) cells
○ Mucus secretion - protects surface
- Stratified squamous epithelium
Protects from abrasion, shared space with digestive tract

Question 5

How does the respiratory system defend itself against pathogens and particles?

Answer 5

Mucous escalator
○ Particles and pathogens in inhaled air can damage the gas exchange surfaces in the alveoli
Alveolar macrophages
○ Phagocytes
Innate immune response against foreign particles and pathogens in alveoli

Question 6

What is the definition of respiratory rate?

Answer 6

Number of breaths per minute (12-18 breaths during quiet breathing)

Question 7

What is the definition of tidal volume?

Answer 7

• Amount of air you move into or out of your lungs during a single respiratory cycle
  § Single inhalation or exhalation - 500ml during quiet breathing

Question 8

What is the definition of total lung capacity?

Answer 8

• Total volume of your lungs (~6000 ml for males and 4200 ml for females)
  Can be divided into a series of volumes and capacities

Question 9

What is the definition of vital capacity?

Answer 9

Maximum amount of air that you can move into or out of your lungs in a single respiratory cycle

Question 10

What is the definition of functional residual capacity?

Answer 10

Amount of air that remains in your lungs after completing a quiet breathing cycle

Question 11

What is the definition of residual capacity?

Answer 11

Amount of air that remains in your lungs even after maximal exhalation

Question 12

What is internal and external respiration and how does O2 and CO2 diffuse between the air and blood and between blood and tissues?

Answer 12

◊ Occurs via diffusion
◊ Partial pressure of O2 and CO2 in alveolar air and alveolar capillaries determines the directions of movement of O2 and CO2 across blood air barrier
- O2 moves from air to blood
- CO2 moves from blood to air

	- O2 moves from blood to tissues CO2 moves from tissues to blood

Question 13

What is the role of the partial pressure of O2 and CO2 in this process?

Answer 13

Partial pressure of O2 and CO2 in alveolar air and alveolar capillaries determines the directions of movement of O2 and CO2

Question 14

Can you describe the processes involved in local regulation of gas transport and alveolar function?

Answer 14

◊ Alveolar blood flow (perfusion)
- Eg. Blood in alveolar capillaries is directed towards pulmonary lobules that have high partial pressure of O2
- How? Constriction of alveolar capillaries that have a low local partial pressure of O2
◊ Alveolar airflow (ventilation)
- Eg. Airflow is directed to pulmonary lobules with a high partial pressure of CO2
How? Smooth muscle in the bronchioles is sensitive to the partial pressure of CO2

Question 15

Can you describe how the nervous system controls the depth and rate of respiration and how sensory information can trigger changes in respiratory rate

Answer 15

◊ Respiratory centres
○ Medulla oblongata
§ Respiratory rhythmicity centres
□ Set respiratory rate
○ Pons
§ Apneustic and Pneumotaxic centres
□ Adjust output of respiratory rhythmicity centres and depth of respiration in response to sensory stimuli or input from other brain centres
○ Cerebral cortex, limbic system and hypothalamus
§ Higher centres
□ Adjust activity in the Pneumotaxic centre

◊ Sensory receptors in the lung respond to  
	○ Mechanical (stretch) stimuli
		§ Eg. Stretch receptors

◊ Chemical stimuli
	§ Eg. Irritant receptors
◊ Sensory receptors in the brain stem respond to chemical stimuli
	□ Chemical chemoreceptors
◊ Sensory receptors in the aortic and carotid bodies respond to chemical stimuli Peripheral chemoreceptors