Respi physio pt 1/3

Question 1

What’s the role of the respiratory system?

Answer 1

Hint: CfG Say Smell

Question 2

(anat note) What is the functional division of the respiratory system?

Answer 2

Conducting portion vs
Respiratory portion

Question 3

Explain the physiological mechanism of (quiet) inspiration and expiration.

Question 4

Explain the physiological mechanism of FORCED inspiration and expiration.

Question 5

Gas exchange of alveoli:
1. Who/what
- what subst exchanged?
- Gex barrier made of?
- what is the partial p.a of air in terms of O2 and CO2:
(i) entering cap at arteriolar end
(ii) leaving cap at venule
(iii) entering alveolar space from atmosphere

2. When?
3. How?
   - what are the 3 components affecting Gex (Hint: think of/ construct an eqn)
   - what are the factors affecting these 3 components, thus = factors affecting Gex?

Question 6

Ventilation:
- Define.

• What are the 4 factors affecting ventilation? (Hint: CORD)
• Define and explain these acronyms related to ventilation:
  (i) TV
  (ii) IRV
  (iii) ERV
  (iv) RV
  (v) VC

Question 7

Eqns associated with ventilation:

• Minute ventilation?
• Alveolar ventilation?
• What are the units for ventilation?

Question 8

Define:
(i) Anatomical dead space
(ii) Physiologic dead space

Question 9

Gas tpt in blood:
- Outline how O2 is tpted in blood

• What are 3 factors affecting Hb in RBC’s affinity for O2? (hint: PT bd)

Answer 9

• 1% as dissolved O2 in blood plasma (exerts partial p.a. in blood) - PaO2
  99% as Hb-O2 (bound to Hb in RBCs)
• 3 factors:
  (i) pH
  (ii) temp
  (iii) 2,3-BPG/2,3-DPG

Question 10

Gas tpt in blood:
- Outline how CO2 is tpted in blood (write out the eqn for guidance!)

• Why must CO2 be converted to HCO3- in cells for tpt and not more dissolved CO2?

Answer 10

• 7% as dissolved CO2 in blood plasma;
  23% as Hb-CO2 (carbamino-Hb) in RBCs
  70% as HCO3- in blood plasma (note that the CO2 + H2O –> … conversion eqn takes place in RBCs tho, then H+, HCO3- tpted out)
• keep PaCO2 of blood less than that of tissues (pdc CO2 during metab processes like respiration) so that CO2 can diffuse down conc gradient and get removed from tissues via blood.

Question 11

Eqn linking PCO2 and alveolar venti (L/min)?

Question 12

What does PaO2 and PaCO2 mean?

Answer 12

partial pressure exerted by DISSOLVED gases in blood plasma.

Question 13

What are the red flag readings of PaO2 and PaCO2 in body?

Answer 13

PaO2 < 60mmHg (hypoxemia! wld probs give rise to/ alr have hypoxia of tissues!)

PaCO2 > 45mmHg (respi acidosis)

Question 14

What’s the difference between PaO2 and SpO2/SaO2 readings? (in terms of way they’re obtained)

Question 14

O2 dissoc curve:

Define SpO2 (aka % Hb-O2).

Draw out and explain the O2 dissociation curve with impt values!

And which is more accurate?

Answer 14

note:
from 60-100mmHg PaO2, decrease in PaO2 in blood decreases SpO2 slightly.
@ pO2 = 100mmHg –> SpO2 97.5%
@ pO2 = 60mmHg –> SpO2 90%

once PaO2 reaches and falls below 60mmHg PaO2, consequential decrease in SpO2 is rapid.
@ pO2 = 50mmHg –> SpO2 80%
@ pO2 = 40mmHg –> SpO2 70%