Physiology Ii : Respiratory System 2 : Chapter 13 : (Test 1)

Front 1

Airway resistance influences what?

Back 1

Influences rate of airflow.

Front 2

Give the eqn for Flow Rate.

Back 2

F = ^P / R

F = flow rate

^P = pressure gradient

R = resistance (influences rate of airflow in and out)

(F and ^P are directly proportional)

(F and R are inversely proportional)

Front 3

What leads to increased airflow?

Back 3

Increased difference between atmospheric and intra-alveolar pressures (^P).

(remember F and ^P are directly proportional)

Front 4

What leads to decreased airflow?

Back 4

Increased resistance (R).

(F and R are inversely proportional)

Front 5

What is a major determinant of airway resistance?

Back 5

RADIUS of conducting airways. (R ~ 1/r^4)

R = airway resistance

r = radius

note, r is to the 4th power so any small change in radius has a big impact on airflow.

Front 6

What controls the contraction of smooth muscle in walls of bronchioles?

Back 6

Autonomic nervous system controls contraction of smooth muscle in walls of bronchioles.

Front 7

List three aspects of how the ANS controls the contraction of smooth muscle in walls of bronchioles.

Back 7

1. ANS can change conducting airway radii

2. Sympathetic stimulation and epinephrine: bronchodilation (related to asthma)

3. Parasympathetic stimulation (at rest) : bronchoconstriction (...demand for airflow is low)

Front 8

COPD stands for what?

Back 8

Chronic Obstructive Pulmonary Disorder

Front 9

What does COPD to airway resistance?

Back 9

There is increased airway resistance with copd.

Front 10

COPD is essentially what?

Back 10

Group of 2 chronic diseases.

1. Chronic Bronchitis

2. Asthma Emphysema

Front 11

What two properties allow the lungs to behave like balloons?

Back 11

Stretching and recessing is due to:

1. Elastic Recoil

2. Compliance

Front 12

What is elastic recoil?

Back 12

How readily the lungs rebound if stretched. This allows the lungs to return to preinspiratory volume when inspiratory muscles relax at end of inspiration.

Front 13

What is compliance?

Back 13

The effort required to stretch (distend) the lungs. How much effort does it take.

Front 14

Compliance is analogous to what?

Back 14

Analagous to the effort required to blow up a balloon. A thin balloon is more compliant than a thick balloon.

Front 15

A highly compliant lung does what?

Back 15

A highly-compliant lung stretches further for a given increase in P than less compliant lung.

Front 16

What happens to compliance in fibrotic lungs?

Back 16

There is decreased lung compliance in fibrotic lungs.

Front 17

Pulmonary elastic behavior depends upon what 2 things?

Back 17

(structural elements)

1. Pulmonary elastic connective tissue

2. Alveolar surface tension

Front 18

What is Pulmonary Elastic Connective Tissue?

Back 18

Lots of elastin fibers arranged to enhance elasticity.

Front 19

What is Alveolar Surface Tension?

Back 19

Tension determined by thin liquid film lining each alveolus. This film allows alveolus to resist expansion. Film also squeezes alveolus, producing recoil. Coating of pulmonary surfactant prevents alveolus from collapsing from this surface tension.

Front 20

What is pulmonary surfactant?

Back 20

Mixture of proteins and lipids secreted by type II alveolar cells.

Front 21

Where is pulmonary surfactant found?

Back 21

Found between H2O molecules in fluid lining alveolus.

Front 22

What does pulmonary surfactant reduce? What is the benefit to this?

Back 22

Pulmonary surfactant reduces alveolar tension, with important benefits:

1. Increases pulmonary compliance, reducing work reqd to inflate lung

2. Reduces lungs tendency to recoil, so they do not readily collapse.

Front 23

The work of breathing normally requires how much energy expenditure?

Back 23

Normally reqs 3% of total energy expenditure.

Front 24

What 4 situations INCREASE the amount of work necessary to breath?

Back 24

1. Decreased pulmonary compliance : pulmonary fibrosis

2. Increased airway resistance : COPD

3. Decreased elastic recoil : Emphysema

4. Need for increased ventilation : exercise

Front 25

How much are is inspired and expired during each quiet breathing cycle?

Back 25

~500 ml

Front 26

Do the lungs completely empty after each expiration?

Back 26

Lungs do not completely empty after each expiration.

Front 27

What is the total lung capacity at max inflation?

Back 27

5,700 mL

Front 28

What is the variation in lung volume with normal, quiet breathing?

Back 28

Volume of lungs at end of normal inspiration = ave 2700 mL

Volume of lungs at end of normal expiration = ave 2200 mL

Front 29

What is the minimum lung volume (residual volume) at maximum deflation?

Back 29

1200 mL

Front 30

What is tidal volume?

Back 30

The difference between end-expiratory and end-inspiratory volume. So it is the air entering or leaving lungs in a single breath.

Ave = 500 mL

(2700 - 2200 mL)

Front 31

How are lung volumes and capacities measured?

Back 31

Measured using spirometers.

Front 32

What is pulmonary ventilation aka? What is it?

Back 32

Pulmonary ventilation = Minute ventilation.

Volume of air breathed in and out in one minute.

Front 33

What is the respiratory rate?

Back 33

Number of breaths / minute

Front 34

What is the eqn for pulmonary ventilation?

Back 34

Pulmonary ventilation = Tidal volume (mL / breath) X Respiratory rate (breaths / min)

Front 35

What is the avg value of pulmonary ventilation?

Back 35

6000 mL (6 L)

Because: 500 mL/breath X 12 breaths/min = 6000 mL

Front 36

What is anatomic dead space?

Back 36

Not all inspired air reaches alveoli, where gas exchange can occur, some in conducting airways.

Front 37

Alveolar ventilation is ? ? pulmonary ventilation because of anatomic dead space.

Back 37

Alveolar ventilation is less than pulmonary ventilation because of anatomic dead space.

Front 38

What is the eqn for alveolar ventilation?

Back 38

Alveolar ventilation =
((tidal volume - dead space volume) / breath) X respiratory rate

Front 39

What is the avg alveolar ventilation?

Back 39

Avg alveolar ventilation = (500 mL - 150 mL)/breath X 12 breaths/min = 4200 mL/min

So dead space is about 150 mL.

Front 40

What patterns can affect alveolar ventilation? Explain.

Back 40

Breathing patterns (eg. deep and slow) can affect alveolar ventilation.

Rest, quiet : alveolar ventilation ~ 4200 mL/min

Deep, slow breaths (increased TV, decreased respiratory rate): alveolar vent ~ 5250 mL/min

Front 41

Alveolar dead space exist but is usually what?

Back 41

Alveolar dead space is usually small.

Front 42

The resistance of individual alveoli can be what?

Back 42

The resistance of individual alveoli can be adjusted independently.

Front 43

Local controls on the resistance of individual alveoli act on what?

Back 43

Local controls act on the SMOOTH MUSCLE of the airways.

Front 44

How do local controls act on smooth muscle of the airways?

Back 44

(opposite effects)

1. Accumulation of CO2 in alveoli : decreases airway resistance by causing airway supplying alveoli to relax

2. Decreased CO2 has opposite effects : increased contraction of airways supplying alveoli, reduced airflow

Front 45

Concerning local controls on resistance what should match?

Back 45

Ventilation and perfusion should match.

Front 46

List 4 stages for the transfer of gases.

Back 46

1. Breathing movements (muscles) : supplies air to respiratory surface

2. Diffusion of O2 and CO2 across respiratory epithelium (alveoli)

3. Transport of gases (blood)

4. Diffusion of O2 and CO2 across capillary walls between blood and tissue cells.

Front 47

What is the key to gas exchange?

Back 47

Partial pressure gradients

Front 48

O2 and CO2 exchange at pulmonary and tissue capillaries via what?

Back 48

O2 and CO2 exchange at pulmonary and tissue capillaries via SIMPLE DIFFUSION.

Front 49

Air is basically what?

Back 49

A mixture of gases.

Front 50

What does the partial pressure of each gas in the air depend on? Explain using Nitrogen as an example.

Back 50

The partial pressure of each gas depends on its percentage in total atmospheric pressure (760 mmHg).

For example, air is 79% nitrogen. Nitrogen partial pressure: 0.79 X 760 = 600.4 mmHg.

O2: 21% in air; 0.21 X 760 = 160 mmHg.

Front 51

What is a partial pressure gradient?

Back 51

Two partial pressures for a gas in different regions of the body.

Front 52

Describe the partial pressure of oxygen (Po2) as it relates to oxygen and carbon dioxide exchange in the lungs.

Back 52

Partial Pressure of Oxygen (Po2) =

Greater in alveoli (100 mm Hg) verses in blood of pulmonary capillaries (40 mm Hg).

O2 diffuses from alveoli into capillaries.

Front 53

Describe the partial pressure of carbon dioxide (Pco2) as it relates to oxygen and carbond dioxide exchange in the lungs.

Back 53

Partial pressure of carbon dioxide (Pco2):

Greater in blood of pulmonary capillaries (46 mm Hg) verses in alveoli (40 mm Hg).

CO2 diffues into alveoli from capillaries.

Front 54

Describe the partial pressure of O2 as it relates to oxygen and carbon dioxide exchange in tissue cells.

Back 54

Partial pressure of oxygen (Po2):

Greater in blood (100 mm Hg) verses in tissue cells (40 mm Hg0.

O2 diffuses from blood into tissue cells.

Front 55

Describe the partial pressure of carbon dioxide as it relates to oxygen and carbon dioxide exchange in the tissue cells?

Back 55

Partial pressure of carbon dioxide (Pco2):

Greater in tissue cells (46 mm Hg) verse in blood (40 mm Hg).

CO2 diffuses into blood from tissue cells.

Front 56

What is the O2 partial pressure gradient from ALVEOLI to BLOOD?
(so across pulmonary capillaries)

Back 56

60 mm Hg (100-->40). So O2 enters blood.

Front 57

What is the CO2 partial pressure gradient from BLOOD to ALVEOLI?
(so across pulmonary capillaries)

Back 57

6 mm Hg (46-->40). So CO2 released from blood to alveoli.

Front 58

What is the O2 partial pressure gradient from BLOOD to TISSUE CELLS?
(so across systemic capillaries)

Back 58

60 mm Hg (100-->40). So O2 enters tissue cells.

Front 59

What is the CO2 partial pressure gradient from TISSUE CELLS to BLOOD?
(so across systemic capillaries)

Back 59

6 mm Hg (46-->40). So CO2 released from tissue cells to blood.

Front 60

How does surface area affect the rate of gas transfer?

Back 60

Increased SA leads to an increased rate of gas exchange.

The alveoli collectively have a tremendous surface area.

Increased pulmonary blood pressure, from an increased cardiac output, increases SA.

Front 61

How does 'distance' affect the rate of gas transfer?

Back 61

Thin walls lead rapid gas exchange.

The alveolar and pulmonary capillary walls are thin.

Front 62

What conditions might thicken the areas for gas exchange?

Back 62

1. Pulmonary edema

2. Pulmonary fibrosis

3. Pneumonia

(all thicken the areas for gas exchange)

Front 63

How does the gas diffusion coefficient (fick's law) affect the rate of gas transfer?

Back 63

Exchange is directly proportional to diffusion coefficient for a gas.

The coefficient for CO2 is 20X that of O2 (so CO2 is more soluble). This is why it is only 6 mm Hg (compared to 60 of O2)