Respi physio pt 2/3

Question 1

note: can write/ draw out answers for better memorisation!

Question 2

How is ventilation (rate and depth) regulated?

Answer 2

Chemoreceptors

Question 3

What are the 2 locations of chemoreceptors involved in regulation of ventilation and what do they each sense?

Outline the homeostatic arcs from stimulus -> action.

Question 4

Where is the respi centre located and what 2 structures does it involve?

What are each of the structures’ roles in regulating ventilation?

Question 5

Will changes in blood pH (via changes in [H+]) activate respi centre too?

Answer 5

(note: instead, pH [H+] will be sensed by peripheral chemoreceptors! - central chemoreceptors only sense CO2 -via [H+]!)

Question 6

Why is CO2 the main/ more potent regulator of respiration > O2?

Question 7

What do these terms mean:
(i) Hypoxaemia
(ii) Hypoxia
(iii) Hypercapnia/ Hypercarbia
(iv) Dyspnea

Question 8

What happens to ventilatory drive in chronic elevated PCO2 (eg. in COPD patients) vs acutely elevated PCO2?

Question 9

What are the 4 main challenges to ventilation? (CORD)

same answers as “What are the factors affecting the work of breathing?”

Answer 9

within medulla - respi centre:
D: venti Depression

within lung:
C: Compliance of lung

within airways:
O: airway Obstruction
R: airway Resistance

Question 10

Define compliance.

What are the 3 factors affecting compliance of lungs.
(Hint: Locational
- Lungs (level)
- within alveolar INTERSTITIUM
- within alveolar AIR SACS

What is the MAJOR determinant of compliance in alveoli/thus lungs?

Answer 10

(note: Impt that lung is compliant because decreased compliance = increase work of breathing + challenge to proper ventilation)!

Question 11

How is surface tension generated in alveoli?

Effect of surface tension on compliance of alveoli and effect on smaller alveoli (think in terms of volume and p.a. for the latter)

Question 12

Where is surfactant made?

Composition of surfactant?

Role of surfactant?

Question 13

Name 2 causes of airway resistance.

Answer 13

• bronchoconstriction (smooth muscles! - symp and psym-mediated mainly)
• increased mucus accum

Question 14

Name 3 causes of airway obstruction.

Question 15

What are some causes of (acute) depression of respiratory control centres in brain?

Outline the positive feedback-like process in CNS (and why hypercapnic drive doesn’t work here) –> causing CO2 narcosis even.

Question 16

(note: Effective respiration = ventilation + Gex)

ventilation = movement of air into alveoli for a chance at Gex

breathing = mechanical mvmt of changing vol.s of air in lungs
respiration = Gex takes place during ventilation

Answer 16

(altho note: Respi rate is the same as breathing rate in clinical terms! so tachypnea = high RR)

Question 17

Name the 2 challenges in Gas Exchange. (Hint: EV)

Explain the first challenge. (E) and what medical prob it could give rise to.

Question 18

Explain V/Q mismatch (the 2nd challenge of Gex).
- V/Q principles
- V/Q ratio

Answer 18

Tip:
think of:
- ‘DEAD’ as no blood; ‘shunt’ as no air