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HLSC 128 - Human Physiology II > Chapter 13 - The Respiratory System > Flashcards

Chapter 13 - The Respiratory System Flashcards

1
Q

Respiratory System Function(s) - Respiration

A

-gas exchange: supply O2 and eliminate CO2

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2
Q

External Respiration

A

-entire sequence of events in the exchange of O2 and CO2 between external environment and body cells

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3
Q

Steps on External Respiration

A
  1. Breathing (ventilation): movement of air in and out of the lungs between atmosphere and alveoli, regulated according to bodily need for O2 uptake or CO2 removal
  2. O2 diffusion: O2 diffuses from alveoli into the blood within pulmonary capillaries (CO2 moves in the opposite direction)
  3. Transport: blood transports O2 from the lungs to tissues and CO2 moves in the opposite direction
  4. Tissue Exchange: O2 and CO2 exchanged between blood and tissues by diffusion across systemic capillaries
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4
Q

Non-respiratory Respiratory System Functions

A

-water loss
-heat elimination
-enhancing venous return
-maintain acid-base balance
-vocalization
-defence against foreign matter
-removes substances through pulmonary circulation
-smell
-pressure needed during child birth and defecation
-blood reservoir

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5
Q

Lungs

A

-two lungs
-divided into several lobes, each supplied by a bronchi
-occupy most of the thoracic cavity
-highly branched airways
-alveoli
-pulmonary blood vessels
-elastic connective tissue

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6
Q

Pharynx

A

-airway/throat
-common passageway for respiratory and digestive systems

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7
Q

Trachea

A

-windpipe

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8
Q

Larynx

A

-voice box

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9
Q

Role of Skeletal Muscles in the Airway

A

-change the diameter of the larynx and pharynx to prevent aspiration of food into the lungs
-vocalization
-resistance to airflow

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10
Q

Bronchioles

A

-have no cartilage to hold them open
-walls have smooth muscle innervated by ANS
-sensitive to hormones and local chemicals

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11
Q

Alveoli

A

-air sacs
-clustered at the ends of terminal bronchioles
-have no muscles to inflate or deflate them (this would interfere with diffusion)
-changes in volume result from dimensional changes in the thoracic cavity (diaphragm, intercostal muscles, abdominal muscles)

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12
Q

Airways

A

-carry air between atmosphere and alveoli
-begin at nasal passage (nose), pharynx, larynx, trachea (also divides into esophagus)

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13
Q

Preventing Food From Entering Airways

A

-epiglottis
-skeletal muscle, reflex mechanism closes trachea during swallowing
-esophagus stays closed except during swallowing
-this function originates in the brain stem

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14
Q

Vocal Folds

A

-two bands of elastic tissue
-lie across larynx opening
-vibrate to produce sounds as air passes them
-also prevent food aspiration

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15
Q

Cartilage Rings

A

-line trachea and larger bronchioles to ensure airways always remain open

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16
Q

Where does the transition from convection to diffusion occur?

A

-starts at the respiratory bronchioles

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17
Q

Convection

A

-requires energy
-produced by muscles that generate flow

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18
Q

Convection Zone

A

-made up of trachea and larger bronchi
-rigid, non-muscular tubes
-cartilage rings prevent collapse
-no gas exchange occurs here

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19
Q

Diffusion

A

-doesn’t require energy

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20
Q

Diffusion Zone

A

-bronchioles
-no cartilage to hold them open
-smooth muscle (ANS) control diameter

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21
Q

Type I Alveolar Cells

A

-alveolar walls
-single layer of flattened cells

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22
Q

Type II Alveolar Cells

A

-secrete pulmonary surfactant

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23
Q

Alveolar Macrophages

A

-guard lumen
-start as a monocyte
-use phagocytosis to guard and clean areas

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24
Q

What mechanisms ensure diffusion is rapid and complete?

A

-walls of alveoli are only one cell thick
-interstitial space between alveoli and capillaries is super thin
-alveolar surface are is very large

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25
Q

Pores of Kohn and Collateral Ventilation

A

-gaps between adjacent alveoli that permit airflow between adjoining alveoli (collateral ventilation)
-allow fresh air to enter when terminal conducting airway is blocked due to disease

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26
Q

Chest Wall

A

-formed by 12 pairs of ribs
-sternum (ribs 1-7) protects anteriorly
-thoracic vertebrae protect posteriorly
-ribs protect lungs and heart

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27
Q

Intercostal Muscles

A

-muscles in the rib cage
-generate pressure that causes airflow

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28
Q

Muscles of Inspiration

A

-external intercostals (contracting)
-diaphragm (flat)
-sternocleidomastoid
-scalenes
-parasternal intercostals

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29
Q

Diaphragm

A

-large sheet of skeletal muscle
-major inspiratory muscle
-forms the floor of the thoracic cavity (separates from abdominal cavity)
-penetrated by esophagus and blood vessels
-innervated by phrenic nerves
-responsible for 75% of volume change at rest
-relaxed/exhale = dome shape
-contracted/inhale = flat

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30
Q

Muscles of Expiration

A

-internal intercostals
-external abdominal oblique
-internal abdominal oblique
-transverse abdominis
-rectus abdominus

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31
Q

External Intercostal Muscles

A

-innervated by intercostal nerve
-lift the rib cage up and out
-enlarge thoracic cavity
-aid in inspiration

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32
Q

Internal Intercostals

A

-used during exhalation

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33
Q

Expiratory Muscles During Activity

A

-most of the muscles are inactive during rest or in healthy individuals
-activated during activity when ventilation demands increase
-also during coughing, sneezing, vomiting
-**generate higher pressures than inspiratory muscles

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34
Q

Pleural Sac (serosal membrane)

A

-double walled
-closed sac
-separated each lung from thoracic wall
-prevents friction
-secrete fluid
-allows organs to move past each other

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35
Q

Visceral Pleura

A

-cover the lung and other internal structures

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36
Q

Parietal Pleura

A

-lines the inside wall of the thorax

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37
Q

Pleural Cavity

A

-lines the space between the visceral and parietal pleura
-contains fluid

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38
Q

Intrapleural Fluid

A

-lubricates the surfaces of the two membranes
-secreted by pleural surfaces

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39
Q

Pressure Gradient

A

-what airflow depends on
-flow = ΔP/R
-used to overcome elastic stiffness of the respiratory system
-for flow to occur, the pressure in the alveoli must be less than the pressure at the mouth (expiration is vice versa)

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40
Q

ΔP

A

-equal to atmospheric pressure - alveolar pressure

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41
Q

4 Pressure Considerations

A
  1. 𝑃ʙ - Barometric (Atmospheric) Pressure
  2. 𝑃𝙰 - Alveolar Pressure
  3. 𝑃𝘱𝑙 - Pleural Pressure
  4. 𝑃𝑡𝘱 - Transpulmonary Pressure (Lung recoil), inside pressure - outside pressure
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42
Q

Pressure Relationships

A

-respiratory pressures and atmospheric pressures are always relative to each other

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43
Q

Pressure Measurement Units

A

-mmHg (diffusion)
-cmH₂O (bulk flow)
-atm (atmospheres)

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44
Q

Pressure at Sea Level

A

-760 mmHg
-1 atm
-1034 cmH₂O

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45
Q

Pressure at High Altitudes

A

-pressure is less than at sea level
-ie. in the rocky mountains

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46
Q

Atmospheric (Barometric) Pressure

A

-the pressure exerted by the weight of the air in the atmosphere on objects on Earth’s surface
-diminishes with increasing altitude

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47
Q

Alveolar Pressure

A

-aka intrapulmonary pressure
-pressure within the alveoli

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48
Q

Pleural Pressure

A

-aka intrapleural pressure
-the pressure outside the lungs but within the thoracic cavity (pleural space)

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49
Q

Transpulmonary Pressure Difference

A

-aka transmural pressure difference
-the pressure gradient across a structure
-equal to the inside pressure - outside pressure or the alveolar pressure - pleural pressure

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50
Q

Elastic Recoil of the Lungs

A

-a property of lungs that keep the lungs and ribcage together
-how readily the lungs rebound after being stretched
-returns lungs to pre-inspiratory volume
-the thoracic wall is more rigid but recoils outward

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51
Q

Elastic Recoil Depends on:

A
  1. Elastic Connective Tissue - stretchability
  2. Alveolar Surface Tension (70%) - the thin liquid film that lines each alveoli
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52
Q

Alveolar Surface Tension

A

-alveoli are lined by water
-water molecules on the surface are highly attracted to each other vs in the air (water vapour)
-the unequal attraction, polarity, provides surface tension
-the liquid layer resists expansion of the alveolus
-greater the surface tension, the less compliant the lungs
-shrinks alveoli, leads to recoil

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53
Q

Sub-atmospheric Pressure

A

-a property of the pleural sac
-means the pressure in the lungs is always lower than the atmosphere

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54
Q

Collapse Alveoli

A

-the smaller the alveoli, the greater the surface tension = collapse
-beacuse… collapsing pressure = 2xSurface Tension/Alveolar Radius

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55
Q

2 Factors that Oppose Alveolar Collapse:

A
  1. Pulmonary Surfactant
  2. Alveolar Interdependence
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56
Q

Pulmonary Surfactant

A

-mixture of phospholipids and proteins
-reduces surface tension (the cohesive force between water molecules)
-deep breathing increases secretion by stretching Type II Alveolar Cells
-increases compliance, thus reducing the work of the lungs
-reduces recoil pressure of smaller alveoli (means small and large can work together)

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57
Q

Pulmonary Surfactant and Babies

A

-premature babies have difficulty breathing due to lack of surfactant
-little surfactant allows alveoli to collapse and then have to re-inflate every time (energy drain)
-surfactant not usually made till last 2 months in utero
-solutions: give mother steroids, put baby on ventilator, artificial surfactant

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58
Q

Alveolar Interdependence

A

-contributes to alveolar stability
-alveoli are connected to each other by connective tissue
-if one starts to collapse, the others recoil to resist stretch
-this exerts an expanding force on the collapsing one
-like “tug of war”

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59
Q

Forces that Keep Alveoli Open

A

-positive transmural pressure
-pulmonary surfactant
-alveolar interdependence

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60
Q

Forces Promoting Alveolar Collapse

A

-elasticity of stretched connective tissue
-alveolar surface tension

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61
Q

Pneumothorax

A

-demonstrates elastic recoil property of lungs and the importance of pleural pressure to keep lungs inflated
-can result from puncture wound
-contact w/ atmosphere = no pressure difference (𝑃𝙰 and 𝑃𝘱𝑙 = 𝑃ʙ)
-no air flow in/out
-air enters pleural space
-thoracic wall springs outward
-results in a collapsed lung to its un-stretched size (elastic recoil!)

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62
Q

Which pressure needs to change to allow air flow?

A

-alveolar, specifically pleural pressure must change it by activating muscles to change lung volume
-barometric remains constant

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63
Q

Alveolar Pressure Equation

A

alveolar pressure = lung recoil pressure (aka transpulmonary pressure) + pleural pressure

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64
Q

Activating Inspiratory Muscles _______ Pleural Pressure

A

decreases

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65
Q

Activating Expiratory Muscles _______ Pleural Pressure

A

increases

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66
Q

When does alveolar pressure equal atmospheric pressure?

A

-before inspiration
-this results in no air flow in/out of the lungs

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67
Q

Boyle’s Law

A

-v=1/p or v1p1=v2p2
-as pleural pressure decreases, thoracic cavity enlarges (increases lung volume), and the alveolar pressure drops due to decompression
-the number of molecules doesn’t change, they are just more/less compressed
-at a constant temperature

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68
Q

If alveolar pressure is less than atmospheric pressure, air ____ the lungs.

A

enters

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69
Q

If alveolar pressure is greater than atmospheric pressure, air ____ the lungs.

A

exits

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70
Q

How does lung volume change?

A

-by contracting muscles
-intercostals
-diaphragm

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71
Q

Relaxing Inspiratory Muscles

A

-is the onset of expiration
-**not necessary for the expiratory muscles to be activated for expiration
-ability to expand thorax is decreased
-pleural pressure is less negative
-alveolar pressure is positive

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72
Q

Deeper Inspirations

A

-contract diaphragm and external intercostals more forcefully
-recruiting the inactive accessory inspiratory muscles
-increase volume of thoracic cavity

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73
Q

Before Inspiration

A

-alveolar and atmospheric pressure are equal
-no flow

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74
Q

Inspiration

A

-pleural pressure decreases (due to muscle contraction)
-alveolar pressure decreases (due to decompression)
-air flows inward

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75
Q

End of Inspiration

A

-inspiratory muscle contraction decreases
-lung recoil pressure is equal to pleural pressure
-alveolar pressure equals atm. pressure
-flow stops

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76
Q

Expiration

A

-no inspiratory muscle contraction
-lung recoil pressure is greater than pleural pressure
-alveolar pressure is positive
-air flows out

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77
Q

Forced (active) Expiration

A

-seen during exercise
-empties lungs more rapidly
-sometimes more completely
-inspiratory muscles relaxed
-alveolar elastic recoil
-abdominal expiratory muscles used
-internal intercostals

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78
Q

Airway Resistance (R)

A

-determined by airway radius
-controlled by autonomic nervous system
-smooth muscle in walls

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79
Q

Bronchoconstriction

A

-parasympathetic activity
-at rest, when ventilatory demands are low
-smooth muscles contract
-resistance increased
-ACh from nerve endings

80
Q

Bronchodilation

A

-sympathetic nervous system
-during activity
-smooth muscles relax
-decreased resistance
-norepinephrine from nerve endings
-epinephrine (hormone)

81
Q

Pathological Bronchoconstriction Factors

A

-allergic reaction
-histamine
-physical blockage (mucus)
-edema of the walls
-airway collapse

82
Q

Local Chemical Bronchoconstriction

A

-decreased CO2 concentration

83
Q

Local Chemical Bronchodilation

A

-increased CO2 concentration

84
Q

Disease States and Breathing

A

-flow can be restricted
-muscles work harder to breathe
-greater pressure difference needed to keep flow constant
-expiration is more difficult than inspiration = wheezing

85
Q

Asthma

A

-usually episodic and triggered by air, dust, temp, etc.
-smooth muscle spasm = constriction
-airway walls thickened from inflammation or histamine induced edema
-increased mucus secretions
-can lead to infection

86
Q

Chronic Obstructive Pulmonary Disease (COPD)

A

-chronic - never goes away
-damages airways
-usually results from smoking, asbestos, coal dust
-not due to smooth muscle contraction
-can be chronic bronchitis or emphysema

87
Q

Chronic Bronchitis (COPD)

A

-long term
-inflammation of smaller airways
-airway lining is thickened by mucus
-coughing won’t remove mucus and leads to bacterial infections

88
Q

Emphysema (COPD)

A

-collapse of smaller airways
-breakdown of alveolar walls, decreasing the volume to surface area ratio making gas exchange less efficient
-trypsin (enzyme) contributes to breakdown (from macrophages in alveoli)

89
Q

Spirometer

A

-used to measure lung volume
-air-filled drum floating in a water-filled chamber

90
Q

Adult Male Max Lung Volume

A

5.7L

91
Q

Adult Female Max Lung Volume

A

4.2L

92
Q

Lung Volume at Rest

A

-2.2L
-about half full even after expiration

93
Q

Why do the lungs not completely empty?

A

-alveoli continue gas exchange

94
Q

Lung Capacity

A

-the sum of two or more lung volumes

95
Q

Why can’t you measure total lung volume with a spirometer?

A

-you can’t completely empty the lungs

96
Q

*Tidal Volume (TV)

A

-volume of air entering or leaving lungs
-during a single breath
~500mL

97
Q

Inspiratory Capacity (IRV)

A

-extra volume of air maximally inspired over the typical resting tidal volume
~3000mL

98
Q

Inspiratory Capacity (IC)

A

-maximum volume of air that can be inspired at the end of a normal expiration
-IC=IRV+IV
~3500mL

99
Q

Expiratory Reserve Volume (ERV)

A

-extra volume of air that is actively expired by maximal contraction
-beyond normal volume of air
-after resting tidal volume
~1000mL

100
Q

*Residual Volume (RV)

A

-minimum volume of air remaining in the lungs
-even after maximal expiration
~1200mL

101
Q

Functional Residual Capacity (FRC)

A

-volume of air in the lungs at the end of normal passive expiration
-FRC=ERV+RV
~2200mL

102
Q

*Vital Capacity (VC)

A

-maximum volume of air that can be moved out during a single breath
-following maximal inspiration
-VC=IRV+TV+ERV
~4500mL

103
Q

*Total Lung Capacity (TLC)

A

-maximum volume of air that the lungs can hold
-TLC=VC+RV
~5700mL

104
Q

Forced Expiratory Volume (in 1 second) (FEV₁)

A

-volume of air that can be expired during the first second of inspiration

105
Q

Obstructive Lung Disease

A

-respiratory dysfunction that yields abnormal spirometry results
-increased airway resistance
-FEV₁ less than 80%

106
Q

Restrictive Lung Disease

A

-respiratory dysfunction that yields abnormal spirometry results
-normal airway resistance
-reduced vital capacity

107
Q

Impaired Respiratory Movements

A

-lung tissue abnormalities
-pleura
-chest wall
-neuromuscular machinery

108
Q

Other Respiratory Dysfunctions

A

-diffusion of O2 and CO2
-mechanical failure = reduced ventilation
-inadequate pulmonary blood flow
-poor matching of air and blood = inefficient gas exchange

109
Q

Pulmonary Ventilation

A

-minute ventilation
-the volume of air breathed in and out in one minute
-pulmonary ventilation (mL/min) = tidal volume (mL/breath) x respiratory rate (breaths/min)

110
Q

Alveolar Ventilation

A

-more important than pulmonary ventilation
-the volume of air exchanged between the atmosphere and alveoli per minute

111
Q

Why is alveolar ventilation less than pulmonary ventilation?

A

-anatomic dead space
-the volume of air in conducting airways that is useless for exchange
~150mL

112
Q

Alveolar Ventilation Equation

A

alveolar ventilation = (tidal volume - dead space) x respiratory rate

113
Q

Quiet breathing requires __% of total energy

A

3

114
Q

Situations Where Work of Breathing is INCREASED

A

-need for increased ventilation (ie. exercise)
-decreased pulmonary compliance
-airway resistance decreased (ie. COPD)
-elastic recoil is decreased (ie. emphysema)

115
Q

Gas Exchange

A

-the simple diffusion of O2 and CO2 down partial pressure gradients (not conc. gradients)

116
Q

Where does gas exchange occur?

A

-pulmonary capillaries in the lungs
-systemic tissue capillaries in vital organs and tissues

117
Q

When does gas exchange pause?

A

-when partial pressures are equilibrated

118
Q

How much gases diffuse depends on:

A
  1. partial pressure gradient
  2. resistance to diffusion
119
Q

Resistance to diffusion depends on:

A
  1. surface area of membrane
  2. membrane thickness (distance)
  3. diffusibility of the gas (constant so it doesn’t matter)
120
Q

Partial Pressure

A

-total pressure x fractional composition of the gas
-ie. 760 mmHg x 0.79 (for N2)

121
Q

Why is alveolar PO2 100 mmHg and not 160 mmHg?

A

-due to the addition of water vapour in airways (47 mmHg)

122
Q

Effect of water vapour in airways (alveolar air)

A

-dilutes all gases by 47 mmHg

123
Q

Typical dry air contains ___% N2 and ___% O2

A

79; 21

124
Q

Total Atmospheric Pressure at sea level ____mmHg

A

760
(the sum of the pressures exerted by N2 and O2)

125
Q

Alveolar O2 = _____ mmHg

A

100

126
Q

Partial Pressure Gradients of O2 and CO2: In Lungs

A

-O₂ diffuses from alveoli to pulmonary capillaries
-CO₂ diffuses from pulmonary capillaries to alveoli
-blood leaves the lungs high in O₂ and low in CO₂

127
Q

Partial Pressure Gradients of O2 and CO2: In Tissues

A

-O₂ diffuses from capillaries to tissue cells
-CO₂ diffuses from tissue cells to capillaries
-blood leaves the tissues low in O₂ and high in CO₂

128
Q

Why doesn’t all blood O₂ get diffused into the tissue capillaries?

A

-mixed venous oxygen content
-a reserve that is immediately available when oxygen demands increase

129
Q

Why doesn’t all blood CO₂ get diffused into the alveoli?

A

-plays a role in acid-base balance
-generates carbonic acid
-stimulates respiration

130
Q

Why does CO₂ require a smaller pressure gradient to diffuse?

A

-it is 20x more soluble than oxygen

131
Q

As membrane thickness _______, gas exchange ______.

A

increases; decreases
-found in pulmonary edema, fibrosis, and pneumonia

132
Q

As surface area ______, diffusion ________.

A

increases; increases

133
Q

As the partial pressure gradient ______, diffusion ______.

A

increases, increases
-major factor

134
Q

Frick’s Law of Diffusion

A

-the rate of diffusion depends on the surface area and thickness of the membrane

135
Q

Blood spends ~_.__ seconds in a capillary

A

-0.75
-0.25 for equilibrium
-enough time for gas equilibration
-0.4 sec blood transit time (exercise)

136
Q

___% of oxygen is physically dissolved in blood

A

1.5

137
Q

___% of oxygen is bound to hemoglobin

A

98.5

138
Q

__-__% of CO₂ is physically dissolved in blood

A

5-10

139
Q

__-__% of CO₂ is bound to hemoglobin

A

5-10

140
Q

__-__% of CO₂ travels as bicarbonate (HCO₃⁻) in blood

A

80-90

141
Q

Hemoglobin Equation

A

-Hb + O₂ ⇆ HbO₂
-deoxyhemoglobin ⇆ oxyhemoglobin
- alveoli to blood→
- ←blood to tissues

142
Q

Oxygen bound to hemoglobin _____ contribute to the 𝑃𝑜₂ of the blood

A

does not

143
Q

Each hemoglobin molecule can carry up to ___ oxygen molecules

A

4

144
Q

What is Hb sats?

A

how much O₂ is attached to Hb

145
Q

What does Hb saturation depend on?

A

𝑃𝑜₂

146
Q

Hb sat ~__% when blood leaves the lungs

A

98

147
Q

Hb sat ~__% when blood leaves the tissues

A

75

148
Q

% Hb sat is ____ where the partial pressure of O₂ is _____ (lungs)

A

high; high

149
Q

% Hb sat is _____ where the partial pressure of O₂ is _____ (tissue cells)

A

low; low

150
Q

Oxygen Hb Dissociation Curve

A

-not a linear relationship
-shows the relationship between blood 𝑃𝑜₂ and % Hb
-sigmoid shaped curve

151
Q

Plateau Phase

A

-where the partial pressure of oxygen is high (lungs), only small % Hb sat increase
-shows a good margin of safety
-Hb almost completely saturated

152
Q

Steep Phase

A

-at the systemic capillaries
-Hb unloading O₂ into the tissue cells

153
Q

Bohr Effect

A

-CO₂ and lactic acid produced H+ (more acidic pH) that changes the Hb shape and reduce its O₂ affinity
-lower Hb %
-more O₂ is released at a given PO₂ level

154
Q

The Bohr Effect shifts the Hb sat curve to the _____

A

right

155
Q

Factors that increase O₂ unloading

A

-increased CO₂
-increased H+
-increased temperature

156
Q

Haldane Effect

A

-increase in PO₂ leads to less CO₂ bound to Hb
-this increases the capacity for Hb to carry CO₂ in it’s deoxygenated state

157
Q

Temperature on % Hb

A

-shifts curve to the right
-more O₂ unloading

158
Q

2,3-biphosphoglycerate (BPG) on % Hb

A

-a factor inside the RBCs
-produced during RBC metabolism
-reduces Hb O₂ affinity
-shifts curve to the right

159
Q

3 Ways CO₂ Travels

A
  1. dissolved
  2. Hb bound
  3. as bicarbonate
160
Q

Bicarbonate ion (HCO₃⁻)

A

-CO₂ combines with H₂O to form carbonic acid (H₂CO₃)
-facilitated by carbonic anhydrase in the RBC cytoplasm
-carbonic acid dissociated into H+ ions and HCO₃⁻
-CO₂ + H₂O (carbonic anhydrase→) H₂CO₃ → H+ + HCO₃⁻

161
Q

CO₂ binds with the ____ part of hemoglobin

A

globin

162
Q

O₂ binds with the ____ part of hemoglobin

A

heme

163
Q

________ hemoglobin has a greater affinity for CO₂

A

reduced (deoxyhemoglobin)

164
Q

Chloride Shift

A

-in tissues (does the opposite in alveoli)
-the exchange of Cl- (into RBC) for HCO₃⁻ (out of RBC)
-the HCO₃⁻ out makes an electrical gradient for Cl- to flow in

165
Q

Apnea

A

-cessation of breathing

166
Q

Asphyxia

A

-oxygen starvation of tissues
-accompanied by CO₂ rise

167
Q

Cyanosis

A

-blueness of skin resulting from insufficiently oxygenated blood in arteries

168
Q

Dyspnea

A

-difficult or laboured breathing

169
Q

Eupnea

A

-normal breathing

170
Q

*Hypercapnia

A

-excess CO₂ in arterial blood
-caused by hypoventilation or lung disease
-acidosis

171
Q

Hyperpnea

A

-increased pulmonary ventilation to match metabolic demands

172
Q

Hyperventilation

A

-increased pulmonary ventilation in excess of metabolic requirements
-alkalosis
-anxiety attack, fever, aspirin poisoning

173
Q

*Hypocapnia

A

-below normal PCO₂ in arterial blood
-alkalosis
-brought about by hyperventilation

174
Q

Hypoventilation

A

-underventilation
-related to metabolic requirements
-acidosis

175
Q

Hypoxaemia

A

-below normal PO₂ in arterial blood

176
Q

*Hypoxia

A

-insufficient O₂ at the cellular level

177
Q

*Anaemic Hypoxia

A

-reduced O₂ carrying capacity of the blood
-despite normal PO₂ levels
-reduced RBC, Hb
-CO poisioning

178
Q

*Circulatory Hypoxia

A

-inadequate oxygenated blood delivered to tissues
-heart attack
-circulatory shock

179
Q

*Histotoxic Hypoxia

A

-inability of cells to use available O₂
-cyanide poisoning (blocked ETC)

180
Q

*Hypoxic Hypoxia

A

-low arterial PO₂
-inadequate Hb sat
-respiratory malfunction
-low environmental O₂ (altitude, suffocation)

181
Q

*Hyperoxia

A

-above normal arterial PO₂
-only when breathing supplemental O₂
-can damage brain or eyes

182
Q

Dorsal Respiratory Group (DRG)

A
  • in the Medullary Respiratory Centre
    -mostly inspiratory neurons that penetrate inspiratory muscles
    -firing = inspiration
    -cease firing = expiration
183
Q

Ventral Respiratory Group (VRG)

A

-in the Medullary Respiratory Centre
-inspiratory and expiratory neurons
-mostly inactive during regular breathing
-activate when increased ventilation is required

184
Q

pre-Bötzinger Complex

A

-pacemaker like neurons near the VRG
-generate respiratory rhythm

185
Q

Pneumotaxic Centre

A

-sends impulses to the DRG to switch off inspiratory neurons
-dominant over apneustic

186
Q

Apneustic Centre

A

-prevents inspiratory neurons from being switched off
-extra boost for inspiratory drive

187
Q

PO₂ - Controlling Ventilation

A

-peripheral detection (not sensitive)
-Carotid Chemoreceptors: activated in an emergency (PO₂ below 60 mmHg)
-depresses central chemoreceptors when less than 60 mmHg

188
Q

A ______ in PO₂ will activate chemoreceptors

A

-decrease

189
Q

PCO₂ - Controlling ventilation

A

-central detection
-Carotid receptors: weakly stimulates, sensitizes to hypoxia
-Central receptor: strongly stimulates (~70% of increased ventilation)

190
Q

The dominant control of ventilation

A

-an increase in PCO₂ to stimulate the central chemoreceptors

191
Q

Increased Arterial H+ - Controlling ventilation

A

-pH; usually from non-respiratory sources
-carotid: important in acid-base balance
-central: does not affect (can’t cross BBB)

192
Q

Carotid Bodies

A

-peripheral chemoreceptor
-lies further north up the aorta, in the carotid sinus

193
Q

Aortic Bodies

A

-peripheral chemoreceptor
-lies on the aortic arch

194
Q

An ______ in PCO₂ will stimulate chemoreceptors

A

increase

195
Q

Which mechanism is the most important regulator in ventilation?

A

PCO₂

HLSC 128 - Human Physiology II (11 decks)

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