MSAP Physiology Respiratory System

Question 1

Gauge scale vs Absolute Scale

Answer 1

Ex. °F °C

O° C= Point at which water freezes (arbitrary) (doesn’t mean anything in energy terms)

100°C= Point at which water boils Relativistic information (arbitrary scale)

0°K= no heat or movement associated with it

Kelvin is the better scale to use (absolute temperature scale) 0

Degrees Farenheight: how cold he could make water before it froze 100 Degrees F: temperature underneath his armpit (arbitrarily driven) Kelvin: 0°C= 273K

Question 2

Gauge scale pulmonary physiology

Answer 2

mmHg, cmH2O (pressures) (P)

Atmospheric = 0

Gauge scale starts at zero

+ cmH2O (positive pressure) = higher atmospheric pressure

-cmH20 (negative pressure) = lower atmospheric pressure

Question 3

What happens when you punch a balloon?

Answer 3

The hand is enveloped by the balloon

Something similar happens to the lungs

Lungs are surrounded by pleural membrane full of fluid

plural fluid allows lungs to inflate and have layers of pleural membrane rub against each other without damage

Question 4

Viseral Pleura

Answer 4

covers the outside of the lung

Question 5

Parietal Pleura

Answer 5

Covers the inside of the chest wall

Question 6

Static Conditions in the Lung

Answer 6

Pleural space pressure = (-)ve at static conditions

Lungs are trying to collapse inwards and thorax is trying to push outwards; expansionist force is generated which decreases the pressure

Alveolar pressure= 0

Transmular pressure (pressure across the alveolar wall)= Pressure alveolar-Pressure pleural membrane= 0-(-5)=+5

Question 7

How does pleural pressure, alveolar pressure, airflow and lung volume change during Inspiration?

Answer 7

As the thorax expands (recruited muscles to expand the thorax) the pleural pressure decreases even further; Pp= more (-)ve

Alveolar pressure= O

Transmular pressure=PA-PP=0-(-10)= +10 à this causes the alveolar walls to move outwards

Pressure inside alveolar drops and now there is a slight negative pressure inside; Barometric (atmospheric) pressure is still zero.

Pressure differential causes gases to start filling the lungs.

Question 8

How does pleural pressure, alveolar pressure, airflow and lung volume change during expiration?

Answer 8

Relax muscles–> thorax decreases in volume–> increase pleural pressure–> decrease transmular pressure which makes the pressure inside the alveolar (+)-ve –>pressure differential allows air to go outwards into the atmosphere

Question 9

Sequence of events for one breathing cycle

Answer 9

Expiration:

All driven by contraction of diaphragm muscle –> increase in thoracic volume–> drop in pleural pressure–> increase in transmeural pressure across the alveoli–> expansion of the alveoli –> drop in alveoli pressure–> pressure differential between alveolar pressure and atmospheric pressure allows for gas to start filling the lungs –> as gas continues to fill the lungs pressures then equilibrate–> flow will slow down and stop–> flow leaves–> lung volume declines–> back to normal lung volume

Question 10

Movement related to atmospheric and alveolar pressures during the breathing cycle

Answer 10

Expiration

Elastic force cause alveolar to contract and causes positive pressure inside alveolar which moves air back into the atmosphere; once PA and PB have equilibrated then flow is stopped movement related to

Question 11

Compliance

Answer 11

Change in volume per given change in pressure (think of a balloon)

As the mechanical properties of the lungs change, the compliance changes

Question 12

What causes a drop in compliance

Answer 12

Clinically Lung Fibrosis; extra collagen gives us very stiff lungs that make them difficult to inflate; large pressure needed for small changes in volume

Question 13

What causes high compliance?

Answer 13

High Compliance= little resistance to changes in volume

Clinically: Emphysema; the walls of the aveoli are eaten away by protease activity; lungs becomes like plastic bag (easy to inflate, but there is very tough low elasticity alveoli )

Question 14

What is spirometry? What is a weakness of the system?

Answer 14

Main method through which we measure certain parameters of lung function

Weakness: have to be able to exhale that air to measure it

Question 15

Spirometry: What is tidal volume?

Answer 15

Measure difference between shallow breaths

How much you breath in a average cycle (usually 500ml) ;how much we breath in and out during FRC

Question 16

Spirometry: Total Lung Capactity

Answer 16

Breathing in as much as possible

Question 17

Spirometry:Residual volume

Answer 17

Still 2L of gas in the lungs after we exhale fully

Question 18

Important Clinical Parameters

Answer 18

4 main parameters to predict lung volume: Need to know height of pt, age,

sex, race

Question 19

Spirometry: FRC

Answer 19

Function residual capactiy = rest volume of lungs

Question 20

Spirometry: Vital Lung Cpacity

Answer 20

Vital lung capacity= total lung capacity- rest volume of lungs

• maximum dynamic volume (as much as you can breath in or out)
• Forced vital capacity (when pt is asked to force air out of lung) ; name reflects the method that the patient was asked to do

Question 21

What is the VC in a normal pt?

Answer 21

80% VC from TLC is FEV1= In one second you should be able to get 80% of the vital capacity out of the lungs

Question 22

What are the steps of spirometry?

Answer 22

Volume/Time spirometry; amount of air the pt can breath over time

Ask pt to go to total lung capacity (breathing in as much as possible) and then forcefully exhale for as long as possible

Measuring the volume that the pt exhales from total lung capacity over time

Question 23

Spirometric abnormalities with restrictive lung diseases

Answer 23

Pt with Restrictive Lung Disease (low lung volumes):

Abnormalities: Dampening of entire curve so that FVC is low and FEV1 is low; both parameters lower than predicted, but FEV1 to FVC ratio is normal (80%)

Clinically: Lung Fibrosis (difficult to fill mechanically tight lungs)

Question 24

Spirometric abnormalities with obstructive lung diseases

Answer 24

Pt with Obstructive Lung Disease (Problem with rate at which air can flow in and out of the lung):

Abnormalities: FVC is normal but FEV1 is very low and FEV1:FVC ratio is <<80%

Clinically: Asthma, COPD

Question 25

Partial Pressure

Answer 25

**_Partial Pressure:_** In a mixture of gases, each gas has a partial pressure which is the hypothetical pressure of that gas if it alone occupied the volume of the mixture at the same temperature

Question 26

Dalton's Law

Answer 26

**_Daltons Law:_** The total pressure of a mixture of gasses is equal to the sum of the partial pressures of the individual gases in the mixture

Question 27

Fraction of inspired oxygen

Answer 27

the assumed percentage of oxygen concentration participating in gas exchange

Question 28

Partial pressures in alveolar during constant ventilation

Answer 28

P02: 100mmHg PCO2: 40 mmHg Steady state values

Question 29

Partial Pressures in arterial blood system

Answer 29

P02: 100mgHg PCO2: 40mmHg

Question 30

Partial pressures in venous blood system

Answer 30

PO2: 40mmHg PCO2: 45mmHg

Question 31

Partial pressure gradient for O2 deliver into and out of hte body

Answer 31

Partial pressure gradient for O2 delivery into the body= 100mmHg (alveolar)- 40mmg(venous)= 60mmHg Partial pressure gradient for CO2 delivery out of the body= 40(alveolar)-45(venous)= -5mmHg

Question 32

Fick's Law Correlation

Answer 32

- Flux of gases, driving pressure (partial pressure), SA (lung is approximately the size of a tennis court), and thickness (minimized diffusion thickness by decreasing the distance between the alveolus and the blood) We have evolved to maximize flux Enhance the delivery of oxygen by increasing the rate of ventilation; opposite if you slow the rate of ventilation

Question 33

Pulmonary Edema

Answer 33

Increases the distance between the alveolus and the blood

Question 34

Fibrosis

Answer 34

increases the thickness of the diffusing difference

Question 35

Driving Partial Pressure of O₂

Answer 35

Partial pressure of O2 in the systemic venous is about 40mmHg and in the alveolus is about 100mmHg; gives a DeltaPO2 (driving partial pressure) = 60mmHg

Question 36

Capillary Reserve Time

Answer 36

It only takes 0.25 seconds for blood to get fully equilibrated with alveolus (fully oxygenated so…… Q: Why is full resting transit time 0.75 seconds? Answer: When cardiac output increase the velocity flow increases and so the transit time lessens; blood is still able to get fully oxygenated even if it spends less than 0.75 seconds in contact with alveolus

Question 37

Darcy's Law

Answer 37

Q= ΔP/R ; driving pressure over resistance

Question 38

What is the normal flow throughout the pulmonary circulation?

Answer 38

Q= flow= 5L/min (has to be continuous and constant throughout cardiac output)

Question 39

What is the driving pressure and resistance in the pulmonary system?

Answer 39

ΔP in pulmonary: 20 mmHg Resistance in pulmonary: 4 (low so we can maintain constant flow with minimal pressure driving it) (tissue is delicate and if pressure is too high we will cause pulmonary edema)

Question 40

What is the driving pressure and resistance in the systemic system?

Answer 40

ΔP in systemic: 100 mmHg Resistance in systemic: 20

Question 41

Why is the lung a good place to modify blood?

Answer 41

The lung is the only organ that receives almost all of the cardiac output

Question 42

Factors that affect diffusion of gas between the alveolus and the pulmonary capillary

Answer 42

Flux of gases, driving pressure (partial pressure), SA (lung is approximately the size of a tennis court), and thickness (minimized diffusion thickness by decreasing the distance between the alveolus and the blood)

Question 43

What is the oxygen content of plasma?

Answer 43

0 xygen is not very soluble O2 solubility: is 0.003ml per deciliter of blood per mmHg PAO2: 100mmHg…….0.3 ml dl-1

Question 44

What is the oxygen consumption rate?

Answer 44

Oxygen consumption: 200ml/min

Question 45

Why do we need Hb? why can we rely on the dissolved oxygen in our plasma?

Answer 45

Cannot rely on dissolved oxygen content in plasma; does not supply needs; that is why we need hemoglobin! Vast majority of blood carried in hemoglobin

Question 46

What is the oxygen contect of Hb?

Answer 46

20.4 ml dl-1

Question 47

What is the percent hemoglobin saturation of arterial blood?

Answer 47

Arterial blood: High saturation (96-98%), O2 content (21 ml dl-1) As we increase the partial pressure of O2 we increase the amount of binding sites occupied and increase the oxygen content of blood

Question 48

What is the percent hemoglobin saturation in venous blood?

Answer 48

Venous blood: Low saturation; O2 content: About 16 ml dl-1

Question 49

How would a RT Bohr Shift change the affinity of oxygen for Hb?

Answer 49

Decrease in pH (acidification, increase temp, and increase in CO2; RT shift is so we can unload more oxygen: Blood comes out of lungs and into tissues--\> higher PP CO2 and lower pH--\> helps to drive the unloading of blood and give it to tissues that are metabolically active

Question 50

How would a LT Bohr Shift change the affinity of oxygen for Hb?

Answer 50

Alkalizations, drop in temperature, drop in CO2; Increase the affinity of Hb for O2 and O2 does not get unloaded; would reduce the supply of O2 to the tissues

Question 51

Peripheral Chemoreceptors

Answer 51

in carotid and aortic; When PO₂ is \<60 then there is an increase in ventilation. There is no direct sensor for CO2 CO2 can turn into H+ and HCO3-

Question 52

Central Chemoreceptors

Answer 52

Cerebral spinal fluid pH receptor CO_² easily crosses the blood brain barrier into the CSF; broken down to H+ and Bicarb H+ receptors in CSF measure CO₂ Rise in H+ in CSF= Increase in VA PCO₂= 40 mmHg CO2 usually drives the ventilation regulation in most individuals

Question 53

Respiratory acidosis (adding protons)

Answer 53

If you slow ventilation CO2 will increase; increased CO2= increased H+; causes acidosis

Question 54

Respiratory alkalosis (removing protons)

Answer 54

Increased ventilation CO2 decreases and so there are less H+ ions= alkalosis

Question 55

Respiratory Acid-Base Compensations

Answer 55

HEY THIS IS KIND OF COOL: The protons produced from the carbonate anhydrase reaction binds to Hb and helps O2 unload from Hb; cause the dissociation of O2 from Hb If CO2 is high from high metabolic demand then there is a lot of H+--\> what is going to help? More oxygen; See the feedback? CO2 essentially regulates itself almost (feedback) High metabolic demand--\>High CO2--\> lots of H+--\> H+ binds to Hb and delivers oxygen where it is needed (the site of high metabolic demand) - Bicarb rapidly taken out of cell and into the plasma ( CO2 in plasma) so that intracellular levels are low and the the conversion of CO2 to bicarp and protons can occur quickly and efficiently - Did not need carrier protein for CO2; partial pressure of CO2 goes up the actual content of CO2 will continue to go up (does not happen with Oxygen because sites are saturated on carrier proteins)

Question 56

Henry’s Law

Answer 56

Amount of gas concentration in solution is equal to the partial pressure of that gas multiplied by the solubility of the gas

Question 57

Carbonate Anhydrase

Answer 57

CO2+H2O--\> H+ + HCO3-; largely controls blood pH

Question 58

CO₂ in the tissues

Answer 58

Vast majority converted to bicarbonate ion (HCO3-) and is thought of as primary carrier of CO2 in blood

Question 59

CO₂ in the lungs

Answer 59

Bicarbonate is recombined with hydrogen ion to reform CO2 Alveolar partial pressure of CO2 low; drives CO2 in opposite direction keeps the partial pressure of CO2 in the blood cell very low favor H ions to dissociated from Hb recombine with bicarbonate to form CO2 and be released out through the lung

Question 60

Acidosis

Answer 60

If you slow ventilation CO2 will increase; increased CO2= increased H+;

Question 61

Alkalosis

Answer 61

Increased ventilation CO₂ decreases and so there are less H+ ions

Question 62

Clinical Correlation of Emphysema

Answer 62

- Imbalance in the protease/antiprotease activity in the lung - Anti-protease activity is greater than the protease activity (starts to break down alveolar walls and lose surface area for gas exchange) - Less tissue causes mechanical effect; lose the elasticity - Decrease SA for gas exchange; lose volume of gas flux (gas diffusion) - Decrease in CSA of vasculature (may cause problems in the RT side of the heart since there will be an increase in pressure) - RV has to work much harder to increase the flow into the lungs (increase in afterload) - Increases pressures in pulmonary pressure we increase filtration (causes pulmonary edema) - Increased compliance (shift to the left) - No elastic elements means that there is little elastic recoil which makes it difficult to exhale; easy inspiration, difficult exhalation (resembles a plastic bag (have to squeeze the bag) instead of a balloon) - Airways are easily collapsed with loss of alveolar wall leads in reduction in airway diameter (Obstructive)

Question 63

Respiratory Acidosis

Answer 63

Respiratory Acidosis Clinical situation: Pt is not ventilating sufficiently; CO2 increases; PCO2; move up buffer line to greater PCO2; acidic; slow ventilation you developed acidosis with bicarbonate excess

Question 64

Respiratory Alkilosis

Answer 64

Clinical Situation: Pt is ventilating too much; Lower PCO2; alkilinic and have a base deficit; lose bicarbonate and H+

Question 65

Metabolic Acidosis

Answer 65

Cardiac output is low and there is not enough O2 to tissues; anaerobic metabolism; produces many H+ Increase of H+, but CO2 stays the same; acidification, but will stay on the same PCO2 isopleth Excess protons produced by metabolic disorder protons are buffered by bicarbonate; lose bicarbonate and produces a deficit

Question 66

PT with COPD (respiratory acidosis). What kind of compensation would take them back to baseline? How do we get rid of the excess H+? Metabolic compensation which would takes you back to baseline pH (7.4pH) Excess protons. How do we get rid of them? Kidney increases protonic secretion and slows down bicarbonate excretion; keep bicarbonate and get rid of H+ which takes you back towards baseline

Question 67

Metabolic Alkilosis

Answer 67

Alkalinic and an excess of bicarbonate; lose protons (excess vomiting); CO2 remains normal