Respiratory Physiology: The Respiratory Cycle Flashcards Preview

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Flashcards in Respiratory Physiology: The Respiratory Cycle Deck (67):
1

Abbreviations:
Q (or Q with a dot over it)

Blood flow

2

Abbreviations:
V=?

Volume of gas

3

Abbreviations:
V with a dot over it (Vdot)=?

Airflow or volume per unit time

4

Abbreviations:
F=?

-Fractional concentration of gas (again you specify which gas)
-No units
-Example FO2=partial pressure of oxygen
(100% Oxygen = 1.0, 21% = .21)

5

Modifiers:
A=?

-Alveolar gas
-Conventional use: PAO2

6

Modifiers:
a?

-Arterial gas
-Conventional use: PaO2

7

Modifiers:
v?

venous blood

8

Modifiers:
E?

-Expired gas
-Can indicate that the volume in question was measured during expiration

9

Modifiers:
I?

-Inspired gas
-FIO2: Fraction of inspired oxygen

10

Muscles of Inspiration
-The diaphragm-Innervated by?

The phrenic nerve-C3,4,5 keeps the diaphragm alive

11

Muscles of Inspiration
-The diaphragm-What happens when it contracts?

-When the diaphragm contracts, it flattens or moves down into the abdomen
-As a result, the volume in the thorax is increased

12

Muscles of inspiration
-External Intercostal Muscles-Location? Which way do they run?

-The External intercostal muscles are located in between the ribs
-They slope down and forward-"Hands in pockets"

13

Muscles of inspiration
-External Intercostal Muscles-What happens when they contract?

-When the external intercostal muscles contract, they raise the ribs
-As a result, the anteroposterior diameter of the thorax is increased
-the "bucket handle motion"

14

Muscles of inspiration
-Additional muscles that participate in inspiration under certain circumstances (e.g. exercise)

-Scalene
-Sternomastoids
-Some muscles in head and neck

15

Muscles of inspiration
-Additional muscles that participate in inspiration under certain circumstances (e.g. exercise)
-Scalene-function?

Raise 1st and 2nd ribs

16

Muscles of inspiration
-Additional muscles that participate in inspiration under certain circumstances (e.g. exercise)
-Sternomastoids-function?

Raise sternum

17

Events in inspiration
-Step 1?

-Contraction of the inspiratory muscles
-Increase in thoracic volume

NOTE: Under normal conditions, the lungs and the muscles/ribs are NOT physically connected to one another

18

Events in Inspiration
-Pleurae

-Parietal pleura (outer layer) and visceral pleura (inner layer) with fluid/surfactant in between
-Fluid effectively connects the pleurae together

19

Intrapleural pressure
-Pressure generated from?
-How does this pressure compare to atmospheric pressure?

-Because of their anatomy and physical characteristics, the lungs and the chest wall are constantly trying to pull away from each other (even at rest)
-Intrapleural pressure is less than atmospheric pressure

20

Conventions in respiratory physiology
-Talks about units and such

-Because the pressures we are dealing with are relatively small, they are measured in cm H2O (not mmHg)
-We also normalize atmospheric pressure to 0cm H2O (so a barometric pressure of 760 mmHg = 0 cmH2O)
-If you are in a place with a different barometric pressure, it is still 0 cmH2O

21

Value of intrapleural pressure at rest?

-5 cmH2O

22

Events in inspiration
-As the thorax volume increases, what happens to intrapleural pressure?

-As the thorax volume increases, the intrapleural pressure will DECREASE to about -8 cmH2O

23

Events in inspiration
-Because of the coupling of the lungs and chest wall?

The lungs will expand as the thorax expands

24

Events in inspiration
-As the lungs increase in size, what happens to alveolar pressure (pressure within the alveoli)?

-As the lungs increase in size, alveolar pressure DECREASES

25

How do alveolar pressure and atmospheric pressure compare at rest?

They are both 0 cmH2O

26

-What happens to alveolar pressure during a normal inspiration?
-What causes this change?

-During a normal inspiration, alveolar pressure will go decrease to -1 cmH2O
-This change is caused by the increase in alveolar size

27

Which way does air flow when alveolar pressure drops below atmospheric pressure?

Air flows INTO the lungs (inhale) when alveolar pressure is LESS than atmospheric pressure

28

The Respiratory Cycle
-Typical graph shows changes in?

-A typical graph shows the change in volume, the alveolar pressure, the intrapleural pressure, and the airflow
-By convention, inspiratory volume is down (don't worry about why)

29

The Respiratory Cycle
-As inspiration proceeds, what happens to intrapleural pressure?
-Graphs!

As intrapleural pressure proceeds, intrapleural pressure will reach its lowest point at the end of inspiration (in a normal breath, about -8 cmH2O)

30

The Respiratory Cycle
-As inspiration proceeds-what happens to airflow into the lungs as alveolar pressure returns back to 0 cmH2O?

Airflow into the lungs will DECREASE

31

The Respiratory Cycle
-As inspiration proceeds-Tidal volume?
-Tidal volume in a typical breath?

-The amount of air inhaled in a given breath
-Abbreviated VsubT
-In a typical breath, tidal volume = 500mL

32

Expiratory muscles
-3 groups?

-Abdominal muscles
-Internal intercostals
-Accessory muscles of expiration

33

Expiratory muscles
-Abdominal muscles-action?

Push into the abdomen to displace the diaphragm upwards

34

Expiratory muscles
-Internal Intercostals
-orientation relative to external intercostals?
-action?

-Oriented at (more or less) a right angle to the external intercostals
-Decrease the AP diameter of the thorax

35

Expiratory muscles
-Accessory muscles of expiration-IMPORTANT:
-In a normal breath, we don't have to use these muscles because?

-In a normal breath, we don't have to use these muscles because expiration is PASSIVE
-The lungs "want" to be smaller (like a balloon)

36

Events in expiration
-As the inspiratory muscles relax, what happens to the volume of the thorax?
-What happens to the diaphragm and rib cage?

-As the inspiratory muscles relax, the volume of the thorax decreases
-The diaphragm and rib cage return to their starting positions

37

Events in Expiration
-As the volume decreases, what happens to intrapleural pressure?

As the volume decreases, the intrapleural pressure returns to its starting point-increases (-8)-->(-5)

38

Events in Expiration
-What happens to alveolar pressure? What is this cause by? When does it reach its peak and what is the normal value for this peak?

-Alveolar pressure INCREASES in expiration due to action of the rib cage
-Reaches a peak of about +1 cmH2O at mid-expiration

39

The respiratory cycle-Expiration
-There is now a pressure gradient that forces?

Air out of the lungs-Volume in lungs decreases

40

As expiration proceeds and the volume of air in the lungs decreases, what happens to alveolar pressure?

-Alveolar pressure begins to go back to 0
-Eventually, all the air that entered during inspiration is exhaled

41

Be able to draw the respiratory cycle
-Include magnitude (Y axis)

DRAW OUT

42

Compare and contrast intrapleural and alveolar pressures
-Intrapleural pressure at rest?

-5 cmH2O

43

What happens to intrapleual pressure with inspiration?

Intrapleural pressure becomes more negative with inspiration

44

Intrapleural pressure-when does it reach its peak negative value?

End-inspiration

45

What happens to intrapleural pressure in normal expiration?

Stays negative

46

When does intrapleural pressure reach its peak positive value?

End-expiration

47

Compare and contrast intrapleural and alveolar pressures
-Alveolar pressure at rest?

0 cmH2O at rest

48

What happens to alveolar pressure with inspiration?

Becomes negative

49

When does alveolar pressure reach its peak negative value?

MID-inspiration

50

What happens to alveolar pressure in ANY type (normal or otherwise) of expiration?

Becomes positive

51

When does alveolar pressure reach its peak positive value?

MID-expiration

52

WHY?
-Does the intrapleural pressure not return to resting value until the end of the respiratory cycle?
-Can also approach from standpoint of alveolar pressure-Why did the alveolar pressure return to 0 at the end of each phase?

kw efkje s

53

Ventilation
-minute ventilation
-definition?
-how is it calulated?

-How much air is inhaled every minute
-V(dot)=tidal volume x frequency

54

Alveolar ventilation

-How much air ACTUALLY gets to the alveoli
-The first 16 generations of airway don't have any alveoli-considered anatomic dead space

55

Anatomic dead space-definition?

Volume of air that remains in the conducting airways

56

Abbreviations:
P=?

-Partial pressure of a gas-you must specify which gas you are referring to
-Units are mmHg
-Examples-PO2, PCO2

57

Anatomic dead space

-Dead space-blood can't get oxygen there
-Anatomic-were not designed to exchange oxygen

58

The anatomic dead space of a patient can be estimated by knowing the patients weight
-If a patient weighs 150 lbs how much dead space do they have?

150 mL of dead space

59

Minute Alveolar Ventilation
How is it calculated?

Subtracting the anatomic dead space volume from the tidal volume
Valv=tidal volume-dead space volume
V(dot)ALV= Valv x f

60

Minute alveolar ventilation
-example-150 lb person who breathes in 500 mL with each breath

Valv=Tidal volume-dead space volume
Valv=500-150
Valv=350

61

Alveolar ventilation=?

tidal volume - dead space volume

62

Minute ventilation=?

Tidal volume x breathing rate

63

Minute alveolar ventilation=?

VALV x breathing rate

64

Minute alveolar ventilation
-example-150 lb person who breathes in 500 mL with each breath-->Valv=350 mL of every breath gets to alveoli
-Minute alveolar ventilation-Patient is breathing 12 breaths per minute V(dot)ALV=?

350 x 12 =4200 mL/min

65

alveolar ventilation

VT-Vdeadspace

66

Minute ventilation

VT x f

67

Minute alveolar ventlation

Valv x f