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Physiology 208 > Respiratory System > Flashcards

Respiratory System Flashcards

1
Q

4 Primary Functions of Respiratory System

A
  1. exchange of gases btwn the atmosphere and blood
  2. homeostatic regulation of body pH
  3. protection from inhaled pathogens and irritating substances
  4. vocalization
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2
Q

Air Exchange Principles

A
  • occurs by bulk flow
    1. flow occurs from region of high pressure to low pressure
    2. muscular pump creates the pressure gradients
    3. resistance is primarily influenced by diameter of tubes that air flows through
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3
Q

Cellular Respiration

A
  • convert organic molecules to ATP

ex) Aerobic metabolism of glucose

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4
Q

External Respiration

A
  • the movement of gases between the environment and the cells within the body
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5
Q

4 Steps of External Respiration

A
  1. exchange I: atmosphere to lungs (ventilation)
  2. exchange II: lung to blood
  3. transport of gases in the blood
  4. exchange III: blood to cells
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6
Q

Structure Involved in Ventilation/Gas Exchange

A
  1. conducting system or airways
  2. alveoli
  3. bones and muscles of the thorax (chest cavity)
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7
Q

Lungs

A
  • composed of light spongy tissue
  • volume occupied mostly by air-filled spaces
  • right lung slightly larger
  • surrounded by pleural sac
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8
Q

Pleural Sac

A
  • double-walled, two layers

- visceral pleura and parietal pleura

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9
Q

Visceral Pleura

A
  • connected to the outside surface of the lungs
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10
Q

Parietal Pleura

A
  • connected to the inside surface of the thoracic cavity
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11
Q

Jobs of Pleural Sac

A
  1. creates moist slippery surface

2. holds lungs tight to thoracic wall

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12
Q

Airway Pathway

A
  1. air enters pharynx
  2. air flows through larynx
  3. air flows to trachea
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13
Q

Conducting Surface

A
  1. Trachea
  2. Primary Bronchi
  3. Smaller Bronchi
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14
Q

Exchange Surface

A
  1. Bronchioles

2. Alveoli

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15
Q

Velocity of Airflow

A
  • inversely proportional to total cross sectional area

V=Q/A

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16
Q

Important Role of Upper Airways and Bronchi

A
  1. Warming air to body temp
  2. Adding water vapour
  3. Filtering out foreign material
    - these are more efficient with nose breathing
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17
Q

Nasal Cavity

A
  • large surface area, rich blood supply and nasal hair

- shop of nasal airway causes particles to embed in mucus in back of pharynx and slide down esophagus

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18
Q

Air Filtration

A
  • filtered in trachea and bronchi

- contains cilia, goblet cells

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19
Q

Ciliated Cells

A
  • cilia move mucus layer toward the pharynx, removing trapped pathogens and particulate matter
  • move saline layer which pulls mucus layer
  • without saline, cilia would become embedded in thick mucus and unable to move
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20
Q

Goblet Cells

A
  • secretes mucus
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21
Q

Saline

A
  • produced by the epithelial cells

- overtop of saline is a layer of mucus

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22
Q

Mucus

A
  • contains immunoglobulins

- produced by goblet cells

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23
Q

Mucocilliary Escalator

A
  • epithelial cells contain cilia which push the mucus towards the pharynx
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24
Q

Cystic Fibrosis

A
  • autosomal recessive mutation in gene producing CFTR
  • reduced production of saline
  • mucus can’t be cleared properly, so bacteria can colonize in airways = reoccurring lung infections
  • also affects GI and pancreas
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25
Q

Alveoli

A
  • site of gas exchange
  • make up bulk of lung tissue
  • clustered at the ends of bronchioles
  • heavily vascularized (80-90% alveoli covered) and huge surface area
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26
Q

Exchange Surface of Alveoli

A
  • endothelium layer
  • fused basement membrane
  • surfactant
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27
Q

Type I Alveolar Cell

A
  • for gas exchange

- 95% surface area

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28
Q

Type II Alveolar Cell

A
  • surfactant cell

- synthesizes surfactant

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29
Q

Pulmonary Circulation

A
  • high-flow, low pressure
  • rate of blood flow through lungs is very high
  • *CO is equal in pulmonary and systemic circuit**
  • 25/8 vs 120/80 mmHg
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30
Q

Low Pressure of Pulmonary Circulation

A
  • due to low resistance (shorter length circuit, more distensible and larger total cross sectional area of arterioles)
  • low pressure means minimal filtration of fluid out of capillaries
  • lymphatics remove any fluid that does get filtered and keep diffusion distance to a minimum
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31
Q

Daltons Law

A
  • the total pressure exerted by a mixture of gases is the sum of the pressure exerted by each gas
  • also dependent on humidity of air
  • partial pressure
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32
Q

Air Flow

A
  • gases move down pressure gradients

- air moves by bulk flow: from a region of high pressure to low pressure

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33
Q

Inspiration Pressure Gradient

A
  • alveolar pressure lower than atmospheric pressure
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34
Q

Expiration Pressure Gradient

A
  • alveolar pressure higher than atmospheric pressure
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35
Q

Boyle’s Law

A
  • describes pressure-volume relationships
    P1V1=P2V2
  • helps explain how a change in lung volume results in a change in lung pressure driving the bulk flow of air
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36
Q

Compression

A

decrease volume

increase pressure

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37
Q

Decompression

A

increase volume

decrease pressure

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38
Q

Spirometer

A
  • measures lung volume changes during ventilation
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39
Q

Lung Volumes

A
  1. Tidal Volume
  2. Inspiratory Reserve Volume
  3. Expiratory Reserve Volume
  4. Residual Volume
    - don’t overlap
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40
Q

Tidal Volume (TV)

A

~500 ml

- total ventilation during rest represents the product of tidal volume and frequency of breaths

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41
Q

Total Pulmonary Ventilation

A

= TV x frequency of breaths

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42
Q

Inspiratory Reserve Volume (IRV)

A

~3000 ml

- the additional air that could still be inspired after quiet inspiration

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43
Q

Expiratory Reserve Volume (ERV)

A

~1100 ml

- at the end of quiet expiration, the volume of air that still remains within the lungs that can be expired

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44
Q

Residual Volume

A

~1200 ml

  • even with maximal expiratory effort air always remains in the lungs
  • can’t be measured with spirometer
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45
Q

2 Important Functions of the Residual Volume

A
  1. prevents airway collapse, after a collapse it takes an unusually large pressure to re-inflate it
  2. it allows continuous exchange of gases
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46
Q

Lung Capacities

A
  • made up of diff. combinations of the 4 primary volumes
    1. Total Lung Capacity
    2. Functional Residual Capacity
    3. Inspiratory Capacity
    4. Vital Capacity
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47
Q

Total Lung Capacity

A
  • the sum of all 4 volumes
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48
Q

Functional Residual Capacity

A
  • the capacity of air remaining in the lungs after quiet expiration, the sum of ERV and RV
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49
Q

Inspiratory Capacity

A
  • the sum of IRV and TV representing the maximal amount of air that one can inspire
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50
Q

Vital Capacity

A
  • the sum of IRV, TV, and ERV representing the maximal achievable tidal volume
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51
Q

Pulmonary Function Test

A
  • involves testing an individuals forced vital capacity (FVC) and comparing it to their Forced expired volume in one second (FEV1)
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52
Q

FEV1

A
  • is normally ~80% of vital capacity
  • below 80% indicative of obtrusive pulmonary disease (increased resistance)
  • low initial FVC indicative of restrictive pulmonary disease (decrease in lung compliance)
53
Q

Inspiration

A
  • occurs when alveolar pressure decreases
  • Boyle’s Law: increase in volume will cause a decrease in pressure
  • use inspiratory muscles (skeletal) to increase volume of alveoli –> decrease in pressure
54
Q

Main Inspiratory Muscle

A
  • diaphragm

- 60-75% of inspiratory volume change

55
Q

Movement of Rib Cage for Inspiration

A
  • accounts for 25-40% of inspiratory volume change
56
Q

Pump Handle Motion

A
  • motion caused by the external intercostals of upper ribs and scalene attached to sternum
57
Q

Bucket Handle Motion

A
  • motion caused by external intercostals in lower ribs
58
Q

Expiration

A
  • occurs when alveolar pressure increases
  • diaphragm relaxes
  • thoracic volume decreases
59
Q

Quiet Expiration

A
  • passive

- relaxation of inspiratory muscles (external intercostals and scalene muscles)

60
Q

Muscles of Forced Inspiration

A
  • additional accessory/secondary muscles become activated
    1. sternocleidomastoids
    2. neck and back muscle
    3. upper respiratory tract muscles
61
Q

Sternocleidomastoids

A
  • lift the sternum outward

- contributes to water pump handle effect

62
Q

Neck and Back Muscles

A
  • elevate pectoral girdle increasing thoracic volume and extend back
63
Q

Upper Respiratory Tract Muscles

A
  • decrease airway resistance

- internal muscle to help open airway

64
Q

Muscles of Forced Expiration

A
  • accessory muscles of forced expiration:
    1. abdominal muscles
    2. internal intercostals and triangular sterni
    3. neck and back muscles
65
Q

External Intercostal Muscles

A
  • inspiration
  • slope obliquely btwn ribs, forward and downward
  • attachment to lower rib is farther forward from axis of rotation so contraction raises lower rip more than it depresses upper rib
66
Q

Internal Intercostal Muscles

A
  • expiration
  • slope obliquely btwn ribs, backward and downward
  • depressing upper rib more than raising lower rib
67
Q

Pleural Sac

A
  • between lung and thoracic wall
  • keeps lungs from going into natural recoiled state
  • keeps thoracic cavity from natural outward recoil
68
Q

Intrapleural Pressure

A

~ -3

- negative pressure at all times because of tension Pleural Sac is under at all times

69
Q

Intrapleural Cavity

A
  • inspiratory muscles pull parietal layer away from visceral layer
  • increases volume of intrapleural cavity
  • negative pressure
70
Q

Decrease in Intrapleural Pressure

A
  • pulls alveoli open

- decreases alveolar pressure and air flows in

71
Q

When does Air Flow Stop?

A
  • when air pressure in alveoli begins to match atmospheric pressure
72
Q

Pneumothorax

A
  • collapsed lungs

- an interruption in intrapleural pressure

73
Q

Traumatic Pneumothorax

A
  • interruption in parietal pleura

- lung goes into natural recoil

74
Q

Spontaneous Pneumothorax

A
  • lung and visceral pleura ruptures

- ~70% due to COPD (emphysema)

75
Q

Lung Compliance

A
  • degree of lung expansion at any time is proportional to the change in pressure
76
Q

Compliance

A
  • “stretchability” of the lungs

- determines how much any given change in P expands the lungs

77
Q

Lung Elastance

A
  • elastic recoil
  • reciprocal of compliance
  • the ability to resist being deformed
78
Q

Compliance Equation

A

Compliance = ∆V/∆P

79
Q

Pulmonary Fibrosis

A
  • formation or development of excess fibrous connective tissue in lungs
  • ex. of decreased compliance
  • inhalation of pollutants (metals, asbestos, certain gases)
  • infections
  • idiopathic (age, genetic predisposition)
80
Q

Emphysema

A
  • proteolytic enzymes secreted by leukocytes (neutrophils) attack alveolar tissue
  • weakens alveoli walls creating airway resistance
  • alveoli merge: loss of capillaries and reduction surface area
  • loss of lung recoil
  • cause: smoking
81
Q

Surface Tension

A
  • a determinant of compliance
  • a major determinant of the lungs elastic recoil (air water interface of airways)
  • measure of the force acting to pull a liquid’s molecules together at air-water interface
82
Q

Laplace’s Equation

A
  • surface tension

P = 2T/r

83
Q

Relationship between Alveoli Radius and Pressure Needed

A
  • decrease radius = higher pressure needed
84
Q

Surfactant

A
  • surface active agent
  • helps overcome surface tension: interferes with intermolecular bond of water
  • detergent-like molecule secreted by Type II alveolar cells
  • ~90% phospholipids, 10% protein
  • amphipathic
85
Q

Jobs of Surfactant

A
  1. increased compliance

2. ensures alveoli of all size inflate

86
Q

Rapidly Expanding Alveolus

A
  • expands radius of 100µm to one of 150µm during inflation
  • greatly reduces surface density of surfactant
  • surface tension and elastic recoil rise, putting “brake” on expansion
87
Q

Slowly Expanding Alveolus

A
  • radius has only expanded from 100µm to 120µm

- surfactant is less diluted, putting less of a “brake” on expansion

88
Q

Infant Respiratory Distress Syndrome

A
  • in premature infants
  • developmental insufficiency of surfactant production and immaturity of lungs
  • prevalence decreases with gestational age
  • prevention: glucocorticoid injection
  • treatment: artificial surfactant, CPAP, intubate
89
Q

Poiseuille’s Equation

A
  • airway resistance
    R = 8nl / (pi)r^4
    F = ∆P * (pi)r^4 / 8nl
90
Q

Factors that Affect Airway Resistance

A
  1. length of the system
  2. viscosity of air
  3. diameter of airways
  4. upper airways
  5. bronchioles
91
Q

Airway Resistance: Length of the System

A
  • constant: not a factor
92
Q

Airway Resistance: Viscosity of Air

A
  • usually constant

- humidity and altitude may alter slightly

93
Q

Airway Resistance: Upper Airways

A
  • affected by physical obstruction

- mediated by mucus and other factors

94
Q

Airway Resistance: Bronchioles

A
  • affected by bronchoconstriction
  • -> mediated by parasympathetic neurons, histamine, leukotrienes
  • affected by bronchodilation
  • -> mediated by CO2, epinephrine, beta2-receptors
95
Q

90% of Airway Resistance Occurs in…

A
  • trachea and bronchi

- constant (smallest total cross-sectional area)

96
Q

Controls of Bronchoconstriction/Dilation

A
  • paracrine control
  • CO2 is the major determiner of diameter
  • histamine
  • parasympathetic nerves
97
Q

CO2 Control of Bronchoconstriction/Dilation

A
  • high levels = dilation

- low levels = constriction

98
Q

Histamine Control of Bronchoconstriction/Dilation

A
  • released from mast cells bronchoconstricts
99
Q

Parasympathetic Nerves Control of Bronchoconstriction/Dilation

A
  • innervate bronchiole smooth muscle

- activate PLC-IP3 pathway via M3 muscarinic receptor (constriction)

100
Q

Asthma

A
  • constricted bronchioles
  • infrequent attacks: beta2-adrenergic agonist
  • oppose bronchoconstriction
  • more frequent attacks:
  • weekly inhaled corticosteroid
101
Q

Efficiency of Breathing

A
  • determined by total pulmonary ventilation: the volume of air moved into and out of the lungs each minute
  • normal ventilation rate = 12-20 breaths/min
  • tidal volume = 500 ml
102
Q

Minute Ventilation

A
  • volume of air moved into and out of the lungs each minute
103
Q

Total Pulmonary Ventilation Equation

A

= ventilation rate x tidal volume (VT)

104
Q

Alveolar Ventilation Equation

A

= ventilation rate x (tidal volume - dead space)

105
Q

How much Air Leaves the Lungs?

A
  • 350 mL leaves the alveoli
  • stale air
  • 150 mL is still considered as “fresh air” and left in the lungs
106
Q

Normal Tidal Volume

A
  • 500 mL

- alveolar ventilation = 4200 mL/min

107
Q

Shallow Tidal Volume

A
  • 300 mL

- alveolar ventilation = 3000 mL/min

108
Q

Deep Tidal Volume

A
  • 750 mL

- alveolar ventilation = 4800 mL/min

109
Q

Maximal Voluntary Ventilation

A

= 125 - 175 L/min

110
Q

Gas Composition in the Alveoli

A
  • gas composition in the alveoli determines rate of O2 and CO2 diffusion between alveoli and capillaries
111
Q

Why does PO2 and PCO2 Remain Constant during Quiet Respiration

A
  • O2 entering = O2 uptake

- fresh air diluted upon entering the lungs

112
Q

Alteration in Ventilation Rate

A
  • independent of changes in the CV system will alter partial pressures of O2 and CO2
  • alters diffusion
113
Q

Perfusion

A
  • the passage of fluid through CV system or lymphatic system to an organ or tissue
  • refers to the delivery of blood to a capillary bed in tissue
114
Q

Ventilation and Alveolar Blood Flow Relationship

A
  • matched
  • blood flow must be high enough to pick up the available O2
  • wasted ventilation/perfusion
115
Q

Local Regional Control: Gravity

A
  • lungs have zone 1, 2, 3

- more negative intrapleural pressure due to gravity at apex

116
Q

Zone 1 in Lungs

A
  • perfusion is absent
117
Q

Zone 2 in Lungs

A
  • perfusion is sporadic
118
Q

Zone 3 in Lungs

A
  • perfusion is constant
119
Q

Gravity at Apex Means…

A
  • alveoli are partially open even and filled at rest

- don’t take much air during respiration

120
Q

Local Control of Ventilation and Perfusion

A
  • very little autonomic innervation of the pulmonary arterioles
  • pulmonary arterioles primarily influenced by decreasing O2 levels around them
  • bronchioles sensitive to CO2 levels
121
Q

Decreases in O2

A
  • causes constriction
  • opposite of CV system
  • presence of O2 sensitive K+ channels
122
Q

Increase in PCO2

A
  • bronchioles = dilate
  • pulmonary arteries = (constrict)*
  • systemic arteries = dilate
123
Q

Decrease in PCO2

A
  • bronchioles = constrict
  • pulmonary arteries = (dilate)
  • systemic arteries = constrict
124
Q

Increase in PO2

A
  • bronchioles = (constrict)
  • pulmonary arteries = (dilate)
  • systemic arteries = constrict
125
Q

Decrease in PO2

A
  • bronchioles = (dilate)
  • pulmonary arteries = constrict
  • systemic arteries = dilate
126
Q

What Happens when a Blood Clot is Present in Arteriole

A
  • blood clots prevent gas exchange
  • alveolar PO2: increase
  • alveolar PCO2: decrease
  • tissue PO2: increase
  • tissue PCO2: decrease
  • bronchiole smooth muscle constricts
127
Q

Local Control of Ventilation/Perfusion

A
  • gravity

- gas levels in tissues near bronchiole and arteriole smooth muscle

128
Q

Local Control: Gravity

A
  • causes similar regions of lungs to receive matching ventilation and perfusion
129
Q

Local Control: Gas Levels

A
  • bronchiole smooth muscle sensitive to CO2

- arteriole smooth muscle sensitive to decreases in O2

Physiology 208 (11 decks)

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