Ventilation and Control of Breathing Part 2

Question 1

Dalton’s Law

Answer 1

Each gas in a mixture exerts its own pressure as if there were no other gases present

Question 2

Normal atmospheric pressure value

Answer 2

760 mmHg

Question 3

Henry’s Law

Answer 3

Quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its liposolubility
Oxygen has a lower solubility than CO2

Question 4

Oxygen content (CaO2) definition

Answer 4

Amount of O2 bound to Hb plus the O2 dissolved in plasma

Question 5

How is oxygen transported

Answer 5

1. 5% dissolved in plasma

98. 5% on Hb

Question 6

What is the % saturation of Hb in deoxygenated blood (at rest)

Answer 6

75%

Question 7

4 factors affecting oxygen affinity to Hb

Answer 7

Acidity
Partial pressure of CO2
Temperature
Biphosphoglycerate (BPG)

Question 8

What causes a right shift?

Answer 8

Decreased affinity of Hb for O2
Low pH
High blood PCO2
High temperature
Added BPG
Ex: exercise

Question 9

What causes a left shift?

Answer 9

Increased affinity of Hb for O2
High blood pH
Low blood PCO2
Low temperature
No BPG
Ex: hyperventilation

Question 10

Chloride shift

Answer 10

When HCO3- goes out of the cell into the plasma, a Cl- must enter the cell to maintain electrical balance
Vice versa as well

Question 11

2 respiratory centers

Answer 11

Medullary

Pontine

Question 12

2 areas in the Pontine respiratory cener

Answer 12

Pneumotaxic area

Apneustic area

Question 13

3 groups/complexes in the medullary respiratory center

Answer 13

Ventral resp group
Dorsal resp group
Pre-Botzinger complex (pacemakers)

Question 14

What do
1. DRG
2. VRG
control

Answer 14

1. Mostly inspiratory neurons with quiet breathing

2. Involved in forceful breathing (inspiratory and expiratory)

Question 15

Apneustic center

Answer 15

Part of pontine RC
Sends stimulatory discharge to inspiratory neurons
Removal of it, and respiratory becomes shallow and irregular

Question 16

Pneumotaxic center

Answer 16

Part of pontine RC
Major role is regulation of resp volume and rate
Controls cessation of insp signal from DRG
Hypoactivation of this center causes prolonged deep inspiration with limited brief expiration
Hyperactivation = shallow inspiration

Question 17

Central chemosensitive area

Answer 17

The direct stimulant is H+ ions
Only CO2 can cross the BBB though
H+ concentration depends on PaCO2
Not directly responsive to PaCO2 or PaO2

Question 18

Peripheral chemoreceptors

Answer 18

In direct contact with arterial blood
Afferent neurons project to medullary respiratory control centers
Respond mostly to changes in PO2 or pH (a little PCO2)

Question 19

What does PO2 have to drop to in order to affect ventilation?

Answer 19

60 mmHg
Due to activation of peripheral chemoreceptors
Protective factor of O2 curve