Pulmonary Physiology

Question 1

Describe respiration and ventilation?

Answer 1

respiration refers to the movement of “respiratory gas molecules across a cell membrane” and ventialtion referes to “the exchange of air between the lungs and atmosphere” (Darovic, 1995).

Question 2

How does negative intrathoracic pressure affect venous blood flow?

Answer 2

It creates a vacuum which facilitates and increases venous return to the heart (Darovic). In reverse, positive pressure ventilation decreases venous blood flow to the heart.

Question 3

About what quantity of inhaled air remains in the anatomical dead space?

Answer 3

1ml/lb of bodyweight. IBW because once adulthood is reached, the size of the respiratory system does not change

Question 4

In a healthy person, what is the dead space (VDanat) to tidal volume (Vt) ratio?

Answer 4

0. 3 or about 1:3

ex: 500ml Vt = 350ml exchanged and 150ml in deadspace

Question 5

Describe the relationship between Vt and f?

Answer 5

As f increases Vt usually decreases.

Question 6

Describe the relationship between dead space and f?

Answer 6

As f increases dead space increases because is stays constant in the face of decreasing Vt, even though Ve may stay the same. p.21

Question 7

Describe alveolar ventilation versus Ve.

Answer 7

Ve is the absolute volume inspired over one minute (Vt x f) Alveolar minute ventilation is the absolute Ve minus dead space ventilation. p21

Question 8

How does tube length impact flow resistance?

Answer 8

Resistance increases with tube length

Question 9

How does airway diameter impact resitance?

Answer 9

As airway diameter decreases, resistance increases. If bronchoconstriction deceases airway diameter by HALF, it increases resistance 16 fold.

Question 10

Compare the efficacy of diffusion between 02 and CO2?

Answer 10

CO2 diffuses across the A/C membrane 20 times easier than O2. Making a hypercarbia from a diffusion issues very unlikely.

Question 11

What is the pressure or weight of one atmosphere?

Answer 11

760 mm/Hg AT SEA LEVEL

Question 12

What is the partial pressure of O2 in atmospheric air?

Answer 12

21 % of 760 mm/Hg = 159 mm/Hg

Question 13

What volume of fresh, inspired air reaches the alveoli with one breath?

Answer 13

350ml

Question 14

What is the partial pressure of O2 in venous blood?

Answer 14

40 mmHg

Question 15

What is the partial pressure of O2 in the alveoli?

Answer 15

104 mmHg

Question 16

What is the partial pressure of alveolar CO2?

Answer 16

40mmHg

Question 17

What is the PvCO2 and value?

Answer 17

The partial pressure of CO2 in mixed venous blood and is about 47 mmHg.

Question 18

How does the law of diffusion work?

Answer 18

Gases move from an area of higher concentration to lower concentration across a membrane.

Question 19

What component of diffusion is lacking when alveolar dead space is present?

Answer 19

blood flow to the A/C unit. Causes “wasted ventilation”.

Question 20

What is a silent unit?

Answer 20

An A/C unit that has neither pulmonary blood flow or ventilation.

Question 21

What volume of O2 is dissolved in plasma?

Answer 21

about 0.3 ml per 100ml

Question 22

What percent of O2 is dissolved in plasma?

Answer 22

About 2%

Question 23

Why is the volume of O2 dissolved in plasma important?

Answer 23

Because the O2 must first dissolve in plasma before it can bind to Hgb.

Question 24

How many mls of O2 can a fully saturated Hgb carry?

Answer 24

1.36 ml

Question 25

How does body temperature affect Hgb affinity?

Answer 25

^ temp, > affinity

Question 26

Two factors that can increase 2,3 DPG levels?

Answer 26

banked blood transfusion (1st 24 hours) and sepsis

pregnancy

Question 27

Describe the relationship between pH and O2 affinity of Hgb?

Answer 27

The move in the same direction. As pH drops, so does binding causing a right shift. As pH increases , affinity increases, causing a Left shift.

Question 28

How does alkalosis affect the OHDC?

Answer 28

Causes a left shift and increased binding.

Question 29

How does a rightward shift of the OHDC affect the PO2?

Answer 29

It will be greater for a given SO2

Question 30

What is the CaO2?

Answer 30

The bloods oxygen content in ml’s expressed as a “volume percent” (vol%)

Question 31

What is a normal CaO2 range?

Answer 31

17 to 20 ml per 100ml, or 17-20 vol%