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Systems Phys 2022 > Respiratory I > Flashcards

Respiratory I Flashcards

1
Q

The dance of respiratory physiology:

A

blood and oxygen coming together

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2
Q

Function of respiration

A

All events involved in gas exchange

gas exchange between external environment and body → obtain O2 and eliminate CO2

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3
Q

Define: Acidotic

A

can’t get rid of CO2

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4
Q

General Organization of the respiratory system

A
  • an air pump for alveolar ventilation → get air in and out
  • a surface for gas exchange → alveoli are exquisitely evolved for efficient gas
  • A mechanism to carry oxygen and carbon dioxide in the blood
  • a circulatory system
  • a mechanism for locally regulating the distribution of air and blood flow
  • a mechanism for centrally regulating ventilation → the brain
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5
Q

External Respiration

A

The exchange of O2 and CO2 between the atmosphere and body tissues

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6
Q

Internal Respiration

A

Use of O2 in mitochondria to generate ATP by ox-phos

CO2 is waste product

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7
Q

Main purpose of Ventilation

A

to maintain optimal composition of alveolar gas

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8
Q

Define: alveolus

A

a buffer compartment between atmosphere and capillary blood

O2 constantly removed by blood

CO2 continuously added from blood

O2 replenished and CO2 removed by ventilation

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9
Q

What are the two phases of ventilaiton?

A

inspiration and expiration

they provide a stable alveolar environment

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10
Q

Non-respiratory Functions of Respiratory System

A
  • Filter → catches thrombi (clots) and emboli (fat or air)
  • metabolic organ → converts Ang I to Ang II, produces surfactant
  • Shock-absorber for the heat and enhances venous return
  • Alter the pH of blood → blow off CO2
  • Route for water loss and heat elimination
  • Blood reservoir → 10% of blood volume in pulmonary circulation
  • Provide airflow → enables speech, singing, and other vocalizations
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11
Q

Respiratory consists of…

A

Airways → leading into lungs

Lungs

Structures in thorax → producing movement air through airways

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12
Q

Respiratory Airways: Tubes

A

carry air between the atmosphere and alveoli

Nasal passages (nose/mouth)

Pharynx

Trachea (windpipe) → air to lungs

Larynx (voice box) → folds vibrate to make sound

Right and Left bronchi

Bronchioles → alveoli (air sacs) clustered at ends of terminal bronchioles

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13
Q

Respiratory Airways: Trachea and Primary Bronchi

A
  • Rings of cartilage prevent collapse during
    • negative and positive pressure changes
    • a cough (⇡ pressure)
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14
Q

Respiratory Airways: Lobar and Segmental Bronchi

A

Secondary and Tertiary bronchi

small plates of cartilage

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15
Q

Respiratory Airways: Bronchioles

A
  • No cartilage
    • Parenchyma (lung functional tissue) and lung elasticity keep them open
  • Airway diameter regulated by
    • smooth muscle innervation (ANS)
    • circulating hormones and local chemicals
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16
Q

Define: Conducting Zone

A
  • Trachea + first 16 generations of airways
  • no alveoli
  • no blood gas barrier
  • no gas exchange (between blood and lungs)
  • anatomic dead space
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17
Q

Define: Respiratory Zone (3L)

A
  • last 7 generations of airways
  • the site of gas exchange
  • 300 million alveoli
  • where the blood-gas barrier is
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18
Q

3 important functions of the Conducting Zone

A
  • Distributes air evenly to deeper parts of lungs
  • warms and humidifiers until inspired air is → 37o, saturated with water vapor
  • defense → moving staircase of mucus (secreted by goblet cells, cilia push out)
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19
Q

Respiratory Zone: Alveoli

A
  • Large Surface area
  • Thin walled → one layer of flattened Type I alveolar cells (93% of wall)
  • Total blood-gas barrier is 2 cells across
    • alveolar epithelium, interstitial fluid, capillary endothelium
  • Type II alveolar cells secrete surfactant
  • Alveolar macrophages guard lumen → secrete trypsin
  • Pores of Kohn permit airflow between adjacent alveoli (collateral ventilation)
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20
Q

Lungs: Apex

A

superior tip of the lungs

just deep to clavicle

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21
Q

Lungs: Base

A

Concave inferior surface resting on diaphragm

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22
Q

Lung Tissue consists of:

A

airways

alveoli

blood vessels

elastic connective tissue

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23
Q

Thorax: Thoracic Cage

A
  • Ribs and spine
  • Chest wall
  • Diaphragm
  • sealed cavity with 3 membranous bags
    • 1 pericardial sac contains the heart
    • 2 pleural sacs, each containing 1 lung
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24
Q

Thorax: Thoracic Cage: Ribs and Spine

A

12 pairs of curved ribs

sternum

thoracic vertebrae

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25
Q

Thorax: Thoracic Cage: Chest wall

A

muscles in chest cavity

internal and external intercostal muscles connect the 12 rib pairs

sternocleidomastoids and scalenes connect the head and neck to the first 2 ribs

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26
Q

Thorax: Thoracic Cage: Diaphragm

A

dome-shaped skeletal muscle

separates thoracic cavity from the abdominal cavity

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27
Q

Pleural Sac

A
  • separates each lung from the thoracic wall
  • double walled closed sac
    • visceral covers surface of lung
    • parietal on inside of thorax
  • Space within sac contains
    • intrapleural fluid (1.5 mL)
    • secreted by surfaces of the pleura
    • lubricates pleural surfaces
    • causes pleural surfaces to adhere together (lung and thorax)
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28
Q

Cohesive forces of intrapleural space: Horizontal

A

intrapleural fluid creates a slippery surface allowing lungs to slide against thoracic wall

pleural fluid = a lubricant

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29
Q

Cohesive forces of intrapleural space: Vertically

A

when chest expands → lungs are compelled to follow

Pleural Fluid = lungs and chest expand as a single unit

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30
Q

Define: Atmospheric (barometric) pressure

A

subject to gravity

pressure exerted by the weight of the air in the atmosphere (760 mm Hg at sea level)

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31
Q

Define: Intrapulmonary (alveolar) pressure

A

pressure inside the alveoli

when compared to atmospheric pressure it is 0 (B/C they are the same)

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32
Q

Define: Intrapleural pressure

A

pressure in pleural fluid; normally < intraalveolar pressure

normally less than what is in lungs

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33
Q

Transmural pressure

A

pressure difference across the lungs

transpulmonary = across lung wall; Palveolar - Pintrapleural

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34
Q

Transmural pressure gradient

A

important reason lungs follow chest

makes it easier to expand

pushes alveoli out as pressure goes down the gradient

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35
Q

Stretched lungs

A

tendency to pull in

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36
Q

Compressed thoracic wall

A

tends to pull out

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37
Q

____ helps keep the lung and chest from pulling away from each other except to the slightest degree

A

transmural pressure gradient and intrapleural fluid’s cohesiveness

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38
Q

The ever-so slight expansion of the pleural cavity…

A

creates a vacuum because fluid cannot expand to fill the slightly larger volume

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39
Q

Pip tends to be…

A

negative during quiet breathing

more negative during deep inspiration

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40
Q

When is Pip positive?

A

during forced expiration → blowing out

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41
Q

Define: Pneumothorax

A

air in chest

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42
Q

Symptoms of Pneumothorax

A

shortness of breath

fatigue

increased HR

chest pain

blue lips/fingers

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43
Q

What causes a pneumothorax?

A

opening in the chest wall → air enters pleural space → Pip equilibrates with PB → transplum pressure gradient is lost → lungs and thorax separate and assume their natural positions

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44
Q

P

A

Pressure, tension, or Partial Pressure of gas

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45
Q

V

A

volume of gas

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46
Q

F

A

functional concentration of a gas

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47
Q

Q

A

volume of blood

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48
Q

Cohesive forces of intrapleural space:C

A

content

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49
Q

A

A

alveolar

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50
Q

a

A

arterial

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51
Q

B

A

barometric

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52
Q

D

A

dead space

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53
Q

E

A

expiratory

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54
Q

I

A

inspiratory

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55
Q

ip

A

pleural

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56
Q

v

A

venous

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57
Q

O2

A

oxygen

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58
Q

CO2

A

carbon dixoide

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59
Q

N2

A

nitrgrogen n

60
Q

.

A

denotes a rate → VeCO2 → volume of CO2 in expired and as you rotate

61
Q

To alter lung volumes we need…

A
  • Respiratory muscles to change size of thoracic cavity
  • overcome tissue elastance
  • overcome surface tension within alveoli
62
Q

Air flows…

A

down a pressure gradient

from higher to lower

63
Q

PA < PB…

A

air enters lungs

64
Q

PA > PB…

A

air exits lungs

65
Q

Intra-alveolar pressure can be altered by…

A

changing the volume of the lungs

66
Q

Boyle’s Law

A

the pressure and volume of a gas are inversely related

P1V1 = P2V2

½ volume → double pressure

double volume → ½ pressure

67
Q

as the volume increases, pressure exerted by gas…

A

decreases proportionately

68
Q

How does Boyle’s Law work in us?

A
  • as the lungs expand in volume, pressure goes down
    • expand chest wall → ⇡ volume → ⇣ pressure → air flows in
  • as the lungs shrink in volume, pressure goes up
    • expiration → ⇣ volume → ⇡ pressure → air flows out
69
Q

___ change the volume of the thoracic cavity

70
Q

Inspiration

A

the active phase of the breathing cycle

71
Q

Before Inspiration

A

Respiratory muscles relaxed

no air is flowing → PA = PB

72
Q

During inspiration

A
  • motor impulses from brainstem activate muscle contraction
  • thoracic cavity expands → PA and Pip to drop
73
Q

Inspiration: Drop in PA

A

Fresh air to flow in until pressures are equalized

74
Q

Inspiration: Drop in Pip

A

⇡ transpulmonary pressure gradient

needed to overcome increased elastic recoil force of stretched lungs

75
Q

Diaphragm

A

sheet of skeletal muscle forms the floor of the thoracic cavity

major muscle of inspiratory effort (75%)

Normal inspiration: Diaphragm moves 1 cm

Forced inspiration: Diaphragm can move 10 cm

76
Q

When diaphragm is relaxed:

A

dome shape protrudes upward into thorax

77
Q

When diaphragm is contracted:

A

innervated by phrenic nerve

it increases thoracic cavity by descending downward

ribs forward

78
Q

Muscles of inspiration: External intercostal muscles

A

responsible for 25% of inspiratory effort

lie on top of internal intercostal

activated by intercostal nerves

contraction: elevate ribs an thus sternum → upward and forward ie. “bucket-handle” fashion

79
Q

Movements of the rib cage

A

help increase dimensions of thoracic cavity

pump handle movement

bucket handle movement

80
Q

Muscles of Inspiration: Accessory Muscles

A

assist with forces inspiration → eg. exercise

Scalene Muscles → elevate the first 2 ribs

Sternocleidomastoid Muscle → raises the sternum

both cause even greater drops in PA and Pip

81
Q

What is a good indication of respiratory distress?

A

using neck muscles to breath

82
Q

The act of inhaling is ___-pressure ventilation

83
Q

A ventilator would be ___-pressure ventilation

Why?

A

positive because machine forces air into you

84
Q

Expiration

A

The passive phase of breathing cycle

85
Q

During expiration

A

inspiratory muscles relax

lungs recoil due to elastic properties

pleural and alveolar pressures rise → PA = 761 mmHg

gas flows passively out of lung due to elastic recoil

86
Q

Muscles of Active Expiration

A

abdominal and internal intercostals

87
Q

Muscles of Active Expiration: To empty more completely,

A
  • need to ⇡ PA even more
    • need more force than accomplished by simple relaxation
    • exercise and disease states such as asthma
88
Q

Contraction of abdominal wall and internal intercostals…

A

⇡ intra-abdominal pressure

89
Q

Abnormal lung function

A
  • Unable to expand
    • hard to increase volume, difficult to decrease pressure and breathe in
  • unable contract lung
    • hard to decrease volume, difficult to increase pressure and breathe out
90
Q

Reasons you may be unable to expand lungs

A

Scar tissue

reduced surfactant

mucus

fluid

91
Q

Reasons you may be unable to contract (expire) lungs

92
Q

2 major patterns of gas flow

A

Laminar

Turbulent

flow changes: laminar to turbulent when Reynolds # >200

93
Q

Laminar gas flow

A

air flows in the same direction

parallel to walls

low flow rates → requires less pressure to flow

gas in center travels most rapidly

94
Q

Turbulent gas flow

A

As air flow rate increases → air moves irregularly → creates resistance to flow which requires higher pressures

95
Q

Reynolds number determines Gas Flow pattern

A

Re = 2rvd/n

r = radius, v = average velocity, d = density, n = viscosity

96
Q

Turbulence most likely to occur when:

A

Average velocity is high and radius is large

Trachea: large diameter (3 cm) and gas flow: 1L/sec

gas flow in larger airways (nose, mouth, trachea, bronchi) is turbulent

97
Q

Ohm’s Law

A

F = ΔP/R

F = flow rate, ΔP = pressure difference, R = resistance of airway

high pressure difference = fast flow

98
Q

Poiseuille’s Law for Resistance

A

R = ( 8*L*n) / (π * r4)

R = resistance, L = length of tube, n = viscosity of fluid

π = 3.14, r = radius of tube to the fourth power

99
Q

The smaller the airway, the __ the resistance

100
Q

In Poiseuille’s Law, reducing r by 50% will have what effect on R?

A

it will increase R 16-fold

101
Q

How does lung volume affect resistance?

A

the larger the lung volume the lower the resistance

diameter of airways change with lung volume

airways supported by radial traction of surrounding lung CT

as lung expands, it pulls open airways

as lung volume decreases, smaller airways may be compressed at low lung volumes → ⇡ R

102
Q

How does bronchial smooth muscle tone affect resistance?

A

contraction of airways ⇡ R

bronchoconstriction → ⇣ radius, ⇡ resistance to airflow

bronchodilation → ⇡ radius, ⇣ resistance to airflow

103
Q

Factors producing bronchoconstriction and decreasing airflow

A
  • Pathological: allergy-induced spasm of airways
  • Physical blockage: mucus, airway collapse
  • *neural control: PNS - during quiet relaxed situations, demand not high
    • Ach on M receptors
  • *local control: low CO2
104
Q

Factors producing bronchodilation and increasing airflow

A
  • Pathological: none
  • Neural (minimal effect): SNS
  • *Hormonal: EPI when demand high
    • Beta-2 adrenergic agonists (cause dilation)
  • *Local control: high CO2
105
Q

How does Gas density affect resistance?

A

Elevated gas density (deep sea diving) ⇡ R

for every 10 m you go down, you ⇡ 1 atm

106
Q

How does forced expiration affect resistance?

A

airway compression ⇡ resistance significantly

Pip is positive

PA = Pip + Pelastic recoil

as elastic recoil decreases, PA decreases

exhaling air loses pressure as it hits R

107
Q

Equal Pressure Point (EPP)

A

the point when Pairway = Pip

If Pip > than Pairway , collapse of the airway can occur

occurs in larger airways

in healthy lungs, the EPP occurs normally where cartilage is present and prevents closure of the airway

influenced by lung elastic recoil

108
Q

Forced expiration: Emphysema

A

the 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

109
Q

EPP: Healthy lungs

A

Recoil → ⇡ PA → EPP established in larger airways; collapse is minimal

110
Q

EPP: emphysema

A

Low recoil → ⇣PA → EPP established in small airways; easily compressed

111
Q

Chronic Obstructive Pulmonary Disease (COPD)

A
  • umbrella term used to describe chronic lung diseases that cause limitations in lung airflow → ⇡ R
  • when R ⇡s, larger pressure gradient needed to maintain normal flow rate
  • Two main forms:
    • chronic bronchitis
    • emphysema
112
Q

COPD causes the following changes

A
  • Chronic bronchitis
    • alveolar walls are destroyed
    • alveoli lose their ability to recoil
  • Emphysema
    • airways walls become thickened and inflames
    • airways become clogged with mucus
113
Q

Pulmonary Function Tests (PFT)

A

a series of tests that evaluate how well lungs are working

used to diagnose, stage, and monitor pulmonary diseases

114
Q

Types of PFTs

A

Spirometry → 1st test performed → screening test

Formal lung volume measurement

diffusing capacity for CO → assess diffusion barrie and Hb

Arterial Blood gases

115
Q

PFT: Spirometry

A
  • Lung volumes and capacities
    • determine the amount (volume) of air someone can move in and out compared to normal population
  • Flow/Volume loops
    • determine speed (flow) → how fast can air escape
116
Q

Spirometry: Lung Volumes and Capacities

A
  • Anatomic measurements that vary with age (⇣ capacity with age) , weight (larger the weight, ⇣ capacity), height (⇡ capacity with taller height), sex (men have higher capacity than women), and race
    • can be altered by disease/trauma
  • seated subject breaths into closed system
    • old: an air filled drum floating in water filled chamber
    • New: Pneumotachometer
117
Q

Define: Tidal Volume (VT)

A

Volume of air entering or leaving lungs during a single breath

avg value = 500 mL

118
Q

Define: Inspiratory Reserve Volume (IRV)

A

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

119
Q

Define: 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

120
Q

Define: Inspiratory Capacity

A

maximum volume of air that can be inspired at the end of a normal quiet expiration

IC = IRV + VT

121
Q

Define: Residual Volume (RV)

A

minimum volume of air remaining in the lungs even after a maximal expiration

122
Q

Define: Functional Residual Capacity (FRC)

A

volume of air in lungs at the end of normal passive expiration

resting equilibrium point

FRC = ERV + RV

123
Q

Define: Vital Capacity (VC)

A

maximum volume of air that can be moved out during a single breath following a maximal inspiration

VC = IRV + VT + ERV

avg value = 4800 mL

124
Q

Define: Total Lung Capacity (TLC)

A

Maximum volume of air that the lungs can hold

TLC = VC = RV

avg value = 6000 mL

125
Q

How is lung function divided?

A
  • into 4 volumes that give 4 capacities
    • IRV = 3.1 L
    • VT = 0.5 L
    • ERV = 1.2 L
    • RV = 1.2 L
  • TLC = IRV + VT + ERV + RV = 6.0 L
  • IC = IRV + VT = 3.6 L
  • VC = IRV + VT + ERV = 4.8 L
  • FRC = ERV + RV = 2.4 L
126
Q

Determination of RV, FRC, TLC

A

spirometry measures the amount of air entering and leaving the lungs but cannot provide info about absolute lung volumes

need to use things like gas dilution and body plethysmography

127
Q

Obstructive Respiratory Dysfunction ⇡⇣

A

⇣ capacity to get air out

⇡ RV ( > 120% predicted)

⇡ static lung volumes: RV, FRC, TLC

slow flow rates; hyperinflation; ⇣ recoil

characteristic of COPD

128
Q

Restrictive Respiratory Dysfunction

A

⇣ capacity to get air in

⇣ TLC ( < 80% predicted)

⇣ static lung volumes: RV, FRC, VT, VC

⇡ recoil, ⇣ volume

129
Q

Important measurements from spirogram

A

FVC: forced vital capacity; the volume of air forcibly blown out after full inspiration → volume of air drops in the lungs

FEV1: forced expiratory volume in 1 sec

FEV1/FVC: proportion of FVC expired in 1st second of expiration

130
Q

What does FEV1/FVC of a spirogram tell you?

A

if the issue is obstructive or restrictive

< 80% = obstructive

> 80% = restrictive

131
Q

How well a lung inflates or deflates with a change in transpulmonary pressure depends on its..

A

elastic properties → once stretched it recoils to its unstretched position

132
Q

Compliance

A

how easily the lung is stretched (distensibility)

ΔV/ ΔP → Δ in lung volume resulting from a Δ in distending pressure (transmural pressure gradient)

133
Q

High compliance

A

large change in V for a given change in P

easy to stretch

low lung volume

stretches further for a given ⇡ in pressure

134
Q

Example of Disease that can cause a highly compliant lung

A

Emphysema → disappearing lung tissue → easy to inflate → larger increases in volume for a given change in pressure → low elastic recoil :

135
Q

Low compliance

A

small change in V for a given change in P

hard to stretch

high lung volume

a large transmural pressure gradient is needed to expand lungs

136
Q

Example of a Disease that results in low compliance of lungs

A

Pulmonary fibrosis → collagen deposition in response to injury → more work required → smaller increases in volume for a given change in pressure → “stiff lung” → lacks stretchability

137
Q

Which part of the lung is more compliant: the base or the apex?

A

the base

compliance of the base > apex

a greater portion of tidal volume goes to the base, resulting in greater ventilation

the base is relatively compressed but expands better due to smaller resting volume

138
Q

What effect does gravity have on lungs?

A

gravity causes weight of lung to pull down on alveoli → results in alveoli in apex to be more expanded → Pip is more negative allowing for greater initial expansion

lower compliance in distended alveoli

139
Q

Compliance of lungs changes with….

A

loss or gain of connective tissue

140
Q

Lung Properties: Elastic Recoil

A
  • Distensibility and elastic recoil are inversely related
    • lung that is easily inflates has less elastic recoil
    • lung that is hard to inflate has high elastic recoil
  • elastic recoil is directly related to lung stiffness
    • the stiffer the lung, the greater the recoil → coiled spring
141
Q

How do changes in lung compliance affect lung volume and FRC?

A

Normal: balanced

Obstructive: emphysema: FRC ⇡: chest elastic recoil wins

Restrictive: Fibrosis: FRC ⇣ → lung elastic recoil wins

142
Q

Elastic Behavior of the Lungs depends on…

A
  • elastin and collagen fibers
    • smoking destroys CT (⇡ compliance)
  • *Alveolar surface tension
    • ⅔ of total elastic force in lung is due to surface tension due to inspiration
    • thin liquid film lines each alveolus → produces as inwardly directed force (collapsing force) → resists being stretched
143
Q

Surfactant

A

in alveoli fluid and reduces surface tension

increases compliance

gets in between water molecules and breaks up cohesiveness making it easier for lungs to expand

secreted by Type II alveolar cells

144
Q

___ is required to overcome elastic recoil and surface tension in lungs

145
Q

___ is used to determine work of breathing

A

oxygen consumption

how much oxygen do we have to take in to use to make ATP → tells what work is for breathing

146
Q

Oxygen consumption

A

O2 cost of quiet breathing: 5% of total oxygen consumption

Heavy exercise increases O2 cost to 20%

147
Q

High O2 cost when…

A

compliance is decreased → more work required to expand lungs

airway resistance is increased → more work to achieve pressure gradients to overcome resistance

elastic recoil is decreased → passive expiration inadequate (need abs)

Systems Phys 2022 (25 decks)

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