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Physiology > Respiratory Physiology Lecture 1 > Flashcards

Respiratory Physiology Lecture 1 Flashcards

1
Q

What is the difference between ventilation and respiration?

A

Ventilation refers to the entire process of breathing in and out

Respiration is strictly the events involved in gas exchange

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2
Q

What is the difference between external respiration and internal respiration?

A

External respiration: exchange of O2 and CO2 between the atmosphere and body tissues

Internal respiration: use of O2 in generation of ATP by ox-phos; CO2 is the waste product

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3
Q

What are some of the nonrespiratory functions of the respiratory system? (7)

A
  1. Filters thrombi (clots) and emboli (fat or air) from the blood
  2. Metabolism (AngI -> AngII; produces surfactant)
  3. Shock absorber for the heart & enhances venous return
  4. Alter blood pH
  5. Route for water loss and heat elimination
  6. Blood reservoir (10% of total blood volume)
  7. Provide airflow for speech, singing, and other vocalizations
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4
Q

What is the purpose of cartilaginous rings and plates along the trachea and bronchi?

A

Prevent collapse of airway during pressure changes, coughing (increased pressure), etc

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5
Q

If bronchioles contain no cartilage, what physical characteristics keep them open to allow for gas exchange? (2)

A

Lung tissue parenchyma

Elasticity

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6
Q

How is airway diameter regulated? (2)

A

Smooth muscle innervation (ANS)

Circulating hormones and local chemicals

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7
Q

What are the components of the conducting zone? Why is it considered “anatomical dead space”?

A

Trachea & first 16 generations of airways

No alveoli, so no gas exchange

~150 mL

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8
Q

What are the components of the respiratory zone?

A

Last 7 generations of airways (only a few mm long)

~300 milion alveoli

~3 L

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9
Q

What are the functions of the conducting zone? (3)

A

Distribution of air evenly to deeper parts of the lungs

Warms (37 ℃), humidifies, and filters air

Defense (mucociliary escalator; macrophages)

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10
Q

What is the total surface area of alveoli?

A

60-80 m2

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11
Q

What are the functions of Type I and Type II alveolar cells?

A

Type I: simple squamous epithelia that allow for gas exchange

Type II: secrete surfactant

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12
Q

What is the function of Pores of Kohn?

A

Permit airflow between adjacent alveoli and connect one alveolus to the next (collateral ventilation)

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13
Q

What are the components of lung tissue parenchyma (4)? Which components contain smooth muscle?

A

airways (SM)

alveoli

blood vessels (SM)

elastic connective tissue

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14
Q

Describe the pleural sac.

A

Double-walled, closed sac:

Visceral wall covers surface of the lung

Parietal wall interacts with the inside of the thoracic cavity

Secretes intrapleural fluid (~1.5 mL) to lubricate pleural surfaces to adhere together

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15
Q

Define atmospheric (barometric) pressure (PB).

A

Pressure exerted by the weight of the air in the atmosphere

~760 mm Hg at sea level

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16
Q

Define intrapulmonary (alveolar) pressure (PA).

A

Pressure inside the alveoli

~760 mm Hg (or 0 mm Hg)

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17
Q

Define intrapleural pressure (PIP).

A

Pressure in the pleural fluid; normally less than intrapulmonary pressure

~756 mm Hg (-4 mm Hg)

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18
Q

Define transmural pressure (PT). Formula?

A

Pressure difference across the wall

(transpulmonary = across the lung wall)

PT= PA - PIP

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19
Q

Neither the thoracic wall nor lungs are in their “natural positions.” Which directions do each of these structures tend to pull?

A

Stretched lungs tend to recoil in

Compressed thoracic wall tends to recoil out

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20
Q

What two forces keep the lung and chest from pulling away from each other?

A

Transmural pressure gradient

Intrapleural fluid cohesiveness

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21
Q

PIP tends to be ______ during quiet breathing and deep inspiration. PIP tends to be ______ during forced expiration.

A

Negative; positive

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22
Q

Explain what happens during a pneumothorax (4).

A

Air enters the pleural space

PIP equilibrates with PB

Transpulmonary pressure gradient is lost and IPF alone cannot hold lungs and wall

Lungs and thorax separate and assume their “natural positions”

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23
Q

Define atelectasis

A

Collapse of alveoli

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24
Q

What do the following primary symbols denote?

P

V

F

Q

C

A

Physical quantities:

P = pressure, tension or partial pressure of a gas

V = volume of a gas

F = fractional concentration of a gas

Q = Volume of blood

C = content

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25
Q

What do the following secondary symbols denote?

A

a

B

D

E

I

ip

v

A

Location of the gas:

A = alveolar

a = arterial

B = barometric

D = dead space

E = expiratory

I = inspiratory

ip = pleural

v = venous

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26
Q

What does “•” denote?

A

Rate

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27
Q

Define pleurisy.

A

Inflammation of the pleural sac

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28
Q

What must occur in order to alter lung volume (3)

A

Respiratory muscles must change the size of the thoracic cavity

Overcome tissue elastance

Overcome surface tension within alveoli

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29
Q

If air flows down a pressure gradient, which direction is air flowing when PA < PB?

A

Air enters the lungs

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30
Q

If air flows down a pressure gradient, which direction is air flowing when PA > PB?

A

Air exits the lungs

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31
Q

Define Boyle’s Law. What is the equation for it?

A

The pressure and volume of a gas are inversely related.

As volume increases, pressure exerted by gas decreases proportionally

P1 * V1 = P2 * V2

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32
Q

How much pressure is needed to create airflow? Why is this?

A

1 mm Hg

Resistance in the airway is low, so 1 mm Hg is sufficient to create airflow

33
Q

Describe the pressure changes during inspiration.

A

Before inspiration:

PA = PB

Diaphragm contracts:

PA drops –> fresh air flows in until pressures equalize

PIP drops –> increased transpulmonary pressure gradient

34
Q

How much does the diaphragm move during normal inspiration vs forced inspiration?

A

Normal: 1 cm

Forced: 10 cm

35
Q

What nerve innervates the diaphragm? How does it contract?

A

Phrenic nerve

Increases thoracic cavity by descending downward

36
Q

What nerves innervate the external intercostal muscles? How do they contract?

A

Intercostal nerves

Elevate ribs and thus sternum upward and forward (“bucket-handle” fashion)

37
Q

What are the accessory muscles recruited during forced inspiration (2)? What are their functions?

A

Scalene muscles: elevate the first two ribs

Sternocleidomastoid: raises the sternum

38
Q

What are the steps of expiration? (4)

A

Inspiratory muscles relax

Lungs recoil due to elastic properties

Pleural & alveolar pressures rise (PA = 761 mm Hg)

Gas flows passively out of the lungs due to elastic recoil

39
Q

What muscles are involved in forced (active) expiration (“2”)? What pressure change occurs with contraction of these muscles?

A

Internal intercostals

Abdominal muscles (Transverse abdominis, external abdominal oblique, internal abdominal oblique)

Increases PA

40
Q

What are some factors that make it difficult to expand the lungs and breathe in? (4)

A

Scar tissue

Reduced surfactant

Excess mucus

Fluid

41
Q

What are the differences between laminar and turbulent flow?

A

Laminar:

Air flows in the same direction, parallel to walls, low flow rates, gas in center travels more rapidly

Turbulent:

As airflow increases, air moves more irregularly; creates resistance to flow which requires higher pressures

42
Q

Renolds Number determines ______. What is the equation to calculate it?

A

Gas flow patterns

Re = (2rvd) / n

r = radius

v = velocity

d = density

n = viscosity

43
Q

Laminar flow becomes turbulent when Reynold’s number_____

A

> 2000

44
Q

Under what conditions is turbulence most likely to occur?

A

Average velocity is high and radius is large

Ex: in the trachea, large diameter (3 cm) and gas flow (1 L/sec)

*gas flow in larger airways is turbulent*

45
Q

Which type of flow can be heard with a stethoscope (breath sounds) and which type cannot?

A

Laminar: silent

Turbulent: induce vibrations on the airway walls

46
Q

Ohm’s law equation

A

F = ΔP/R

F = flow rate

ΔP = pressure difference

R = resistance

47
Q

Poiseuille’s Law for resistance (for laminar air flow) equation. What is the biggest determinant for resistance?

A

R = (8 * L * η) / (π * r4)

R = resistance to flow in a tube

L = length of tube

η = viscosity of the fluid

π = 3.14

r = radius of the tube (biggest determinant)

48
Q

The smaller the airway, the ______ the resistance

A

greater

49
Q

Which of the following has the highest resistance to airflow? Explain:

Large airways (trachea and large bronchi)

Medium-sized bronchi

Small airways (terminal bronchioles and alveoli)

A

Large airways: has turbulent flow, but radius is too large

Medium-sized bronchi: tubes in series (R1 + R2….) have greater resistance than tubes in parallel (1/R1 + 1/R2….)

Small airways: small radius, but vast cross-sectional area, so they contribute little to resistance

50
Q

What are some factors that affect resistance? (4)

A

Lung volume (diameter of airways)

Bronchial smooth muscle

Gas density

Forced expiration

51
Q

What physiologic factors can cause bronchoconstriction? (2)

A

Neural control (PNS): acetylcholine acts on muscarinic receptors during quiet relaxed situations when demand is not high

Local control: when CO2 is low

52
Q

What major physiological factors can cause bronchodilation? (2)

A

Hormones: Epi and nEpi when demand is high (β2 adrenergic agonists); ex: albuterol

Local control: high CO2

53
Q

What is the equal pressure point (EPP)?

A

During forced expiration, where Pairway = PIP

*If PIP > Pairway, airway will collapse

54
Q

Where does EPP occur normally in healthy lungs? Why?

A

Where cartilage is

Prevents closure of the airway

55
Q

Using the provided diagram, describe what pathological changes happen in the lungs in someone with emphysema.

A

Loss of alveoli and thus elastic recoil; lowers PA further during forced expiration

EPP occurs closer to the alveoli where the cartilage cannot prevent airway collapse

56
Q

EPP is influenced by lung elastic recoil. Describe the changes in elastic recoil of someone with emphysema and what it ultimately leads to.

A

Healthy: Recoil -> increases PA -> EPP established in larger airways; collapse is minimal

Emphysema: low recoil -> decreased PA -> EPP established in small airways; easily compressed

57
Q

What is chronic obstructive pulmonary disease?

A

COPD

Umbrella term used to describe chronic lung diseases that cause limitations in lung airflow (increased resistance)

58
Q

What are the two main forms of COPD and how are they different from each other?

A

Chronic bronchitis (bottom): airway walls become thickened & inflamed; airways become clogged with mucus

Emphysema (top): alveolar walls are destroyed; alveoli lose their ability to recoil

59
Q

What does spirometry measure?

A

Pulmonary function test; measures lung volumes and capacities

60
Q

Describe tidal volume (VT)

A

Volume of air entering or leaving lungs during a single breath

~500 mL

61
Q

Describe inspiratory reserve volume (IRV)

A

Extra volume of air that can be maximally inspired over and above the typical resting tidal volume

~3100 mL

62
Q

Describe expiratory reserve volume (ERV)

A

Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume

~1200 mL

63
Q

Describe inspiratory capacity (IC). How can it be calculated?

A

Maximum volume of air that can be inspired at the end of a normal quiet expiration (IC = IRV +VT)

~3600 mL

64
Q

Describe residual volume (RV)

A

Minimal volume of air remaining in the lungs after maximal expiration

~1200 mL

65
Q

Describe functional residual capacity (FRC). How can it be calculated?

A

Volume of air in lungs at the end of normal passive expiration (FRC = ERV +RV)

~2400 mL

66
Q

Describe vital capacity (VC). How can it be calculated?

A

Maximum volume of air that can be moved out during a single breath following maximal inspiration (VC = IRV + VT + ERV)

~4800 mL

67
Q

Describe total lung capacity (TLC). How can it be calculated?

A

Maximum volume of air that the lungs can hold (TLC = VC + RV)

~6000 mL

68
Q

Label the following components of the volume-time curve:

Residual volume (RV), Expiratory reserve volume (ERV), Vital capacity (VC), Total lung capacity (TLC), Tidal volume (VT), Inspiratory reserve volume (IRV), Functional residual capacity (FRC), and Inspiratory capacity (IC)

A
69
Q

Spirometry cannot provide any information about a patient’s RV, FRC, nor TLC. What techniques must be performed in order to measure them? (2)

A

gas dilution

body plethysmography

70
Q

How do the lung volumes change in someone with an obstructive lung disorder? What factors cause this?

A

Increased RV, FRC, and TLC (static lung volumes)

Slow flow rates, hyperinflation, decreased recoil

Ex: COPD

71
Q

How do the lung volumes change in someone with a restrictive lung disorder? What factors cause this?

A

Decreased TLC due to decreased VC, RV, FRC, and VT

Increased recoil, decreased volume

Ex: pulmonary fibrosis, scoliosis, ALS

72
Q

What is FEV1?

A

Forced expiratory volume in 1 second

73
Q

FEV1/FVC measures what?

A

proportion of FVC expired in 1st second of expiration

74
Q

What is compliance? How is it calculated?

A

How easily the lung can be stretched (distensibility)

C = ΔV/ΔP

75
Q

Is compliance greater at the apex or base of the lungs? Why?

A

Base

Gravity causes weight of lungs to pull down on alveoli

76
Q

A lung that is more distensible has ____ elastic recoil

A

less

(the two are inversely related)

77
Q

What two factors determine elastic behavior of the lungs?

A

Elastin & collagen fibers (1/3 of total force)

Alveolar surface tension (2/3 of total force)

78
Q

Surfactant is secreted by Type II alveolar cells. What is this surfactant called and what is its function?

A

Dipalmitoyl phosphatidylcholine (DPPC)

Reduce surface tension in alveoli, thus increase compliance

79
Q

DPPC/Sphingomyelin (L/S) ratio in amiotic fluid indicates lung maturity. In a ratio of 2:1 indicates ______ and a ratio <2:1 indicates _____.

A

mature enough lungs to survive outside of the womb

immature lungs that can develop into breathing problems

Physiology (11 decks)

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