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Kinesiology > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

Functions of respiratory system

A 
Gas exchange 
Acid-base balance 
Thermoregulation
Immune function 
Vocalization 
Enhances venous return
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2
Q

Air passages

A 
Mouth/nose 
Pharynx 
Larynx 
Trachea 
Bronchi
Bronchioles 
Alveoli
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3
Q

Bronchioles

A

Bronchoconstrict or dilate
Control air flow
Smooth muscle

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4
Q

Alveoli

A 
Site of gas exchange 
Thin walled 
Large surface area (75m2)
Contain fine elastic fibres 
Pores of kohn connect adjacent alveoli (helps equalize air pressure)
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5
Q

Types of alveolar cells

A

Type 1 = make up the wall
Type 2 = secrete surfactant (decreases surface tension)
Macrophages = immune function

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6
Q

Respiration

A

Ventilation
External respiration (gas exchange between alveoli and blood)
Gas transport
Internal respiration (gas exchange between blood and tissues)

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7
Q

Mechanics of breathing

A

2 phases = inspiration (gases flow into the lungs), expiration (gases exit the lungs)
Dependant on pressure differences

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8
Q

Pressure relationships in the thoracic cavity

A

Atmospheric (air) pressure (Patm) = 70 mm Hg at sea level

Respiratory pressures are relative to Patm = alveolar and pleural pressures

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9
Q

Respiratory mechanics

A 
Pressures = 
Atmospheric (air)
Intra-alveolar (in alveoli)
Intra-pleural (pleural space)
Transpulmonary (difference)
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10
Q

Pulmonary ventilation

A

Mechanical processes depends on volume changes in the thoracic cavity
Volume changes = pressure changes
Pressure changes = gases flow to equalize pressure

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11
Q

Boyle’s law

A

Pressure exerted by a gas varies inversely with volume of gas
Volume increases, pressure decreases (vice versa)

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12
Q

Quiet inspiration

A 
Inspiratory muscles contract (diaphragm and external intercostals) 
Thoracic volume increases (lungs stretch)
Intrapulmonary decreases (air flows into the lungs down its pressure gradient until Ppul = Patm)
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13
Q

Forced inspiration

A 
Recruit scalenus and sternocleidomastoid 
Greater increase in thoracic volume 
Larger decrease in thoracic pressure 
Larger pressure gradient 
More air flow in
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14
Q

Quiet expiration

A 
Passive process 
Inspiratory muscles relax 
Thoracic cavity volume decreases 
Elastic lungs recoil 
Increase in alveolar pressure 
Air flows out of lungs
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15
Q

Forced expiration

A 
Recruit abdominals and internal intercostals 
Larger decrease in thoracic volume 
Larger increase in thoracic pressure 
Larger gradient 
More air flow out
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16
Q

Physical factors influencing pulmonary ventilation

A 
4 factors = 
Airway resistance 
Alveolar surface tension
Lung compliance 
Elastic recoil
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17
Q

Airway resistance

A

Relationship between flow (F), pressure (P), and resistance (R)
F = 🔺P/R
Radius of bronchioles is the biggest determinant
Pressure gradient between atmosphere and alveoli

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18
Q

Asthma

A

Severe constriction or obstruction of bronchioles (prevents ventilation)
Epinephrine dilates bronchioles and reduces air resistance

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19
Q

Alveolar surface tension

A

Surface tension

Surfactant

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20
Q

Surface tension

A

Attracts liquid molecules to one another at a gas-liquid interface
Resists any force that tends to increase surface area of liquid

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21
Q

Surfactant

A

Detergent-like lipid and protein complex produced by type 2 alveolar cells
Decreases surface tension of alveolar fluid (discourages alveolar collapse)
Premature infants = decreased amount of surfactant, respiratory distress

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22
Q

Lung compliance

A

Expanding of the lungs = change in lung volume with a given change in pressure
Relates to effort required to distend the lungs

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23
Q

Lung compliance normally high due to

A

Distensibility of the lung tissue (connective tissue)

Alveolar surface surfactant

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24
Q

Lung compliance diminished by

A

Non elastic scar tissue (fibrosis)
Reduced production of surfactant
Decreased flexibility of thoracic cage (eg-paralysis of respiratory muscles)

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25
Q

Elastic recoil

A

How the lungs rebound after being stretched (help lungs return to their pre-inspiratory volume)
Depends on = connective tissue in lungs (elastic/collagen), alveolar surface tension (reduces tendency of alveoli to recoil)

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26
Q

Respiratory volumes

A

Used to asses a persons respiratory status

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27
Q

Lung volume and capacities (tidal volume)

A

Volume of air entering or leaving lungs during a single breath
Average value = 500ml

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28
Q

Lung volumes and capacities (inspiratory reserve volume)

A

Extra volume of air that can be maximally inspired over and above the typical resting tidal volume
Average volume = 3000ml

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29
Q

Lung volumes and capacities (inspiratory capacity)

A

Maximum volume of air that can be inspired at the end of a normal quiet expiration (IC = IRV + IV)
Average volume = 3500ml

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30
Q

Lung volumes and capacities (expiratory reserve volume)

A

Extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a resting tidal volume
Average volume = 1000ml

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31
Q

Lung volumes and capacities (residual volume)

A

Maximum volume of air remaining in the lungs even after a maximal expiration
Average volume = 1200ml

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32
Q

Lung volumes and capacities (functional residual capacity)

A

Volume of air in lungs at end of normal passive expiration
(FRC = ERV + RV)
Average volume = 2200ml

33
Q

Lung volumes and capacities (vital capacity)

A

Maximum volume of air that can be moved out during a single breath following a maximal inspiration (VC = IRV + TV + ERV)
Average volume = 4500ml

34
Q

Lung volumes and capacities (total lung capacities)

A

Maximum volume of air that the lungs can hold (TLC = VC + RV)
Average volume = 5700ml

35
Q

Dead space

A

Inspired air that doesn’t contribute to exchange
Anatomical dead space = volume of air passageways (~150ml)
Alveolar dead space = alveoli with no gas exchange due to collapse or obstruction

36
Q

Pulmonary function tests

A

Minute ventilation = total amount of gas flow into or out of the respiratory tract in one minute
Forced vital capacity (FVC) = gas forcibly expelled after taking a breath
Forced expiratory volume (FEV) = the amount of gas expelled during specific time intervals of FVC

37
Q

Obstructive disease

A 
High compliance 
Low recoil 
Easy to breathe in
Hard to breathe out 
Less “fresh air” each breath
Eg = emphysema, asthma
38
Q

Restrictive disease

A 
Low compliance 
High recoil 
Hard to breathe in 
Easy to breathe out 
Hard to hold air in long enough for gas exchange 
Eg = fibrosis
39
Q

Non respiratory air movements

A 
Most result from reflex action 
Cough
Sneeze 
Crying 
Laughing 
Hiccups 
Yawn
40
Q

Gas exchange

A 
Exchange oxygen and carbon dioxide between the alveolar air and blood and tissues 
External respiration (alveoli to blood)
Internal respiration (blood to tissue) 
Need a concentration (partial pressure) gradient, gas will move from higher partial pressure to lower partial pressure
41
Q

Dalton’s law

A

Partial pressure of each gas is directly proportional to its % in the mixture

42
Q

Dalton’s law (Partial pressures)

A

Fraction of a gas in an atmosphere x the atmospheric pressure (or barometric pressure)
O2 = 21%
N2 = 79%
Co2 and others = <1%

43
Q

Dalton’s law (gas exchange)

A

If atmospheric pressure at sea level is 760mmHg then:
Partial pressure of O2 = 0.21 x 760 = 160mmHg in dry air
Partial pressure of N2 = 0.79 x 760 = 600mmHg in dry air
Since 0.03% of air is Co2 partial pressure = 0.23mmHg in dry air

44
Q

Fraction of O2, Co2, and N2 is the same in air…

A

At any altitude

Partial pressure of O2 is different at different locations because atmospheric pressure is different

45
Q

Composition of alveolar gas

A

Alveoli contain more Co2 and water vapour than atmospheric air due to = gas exchanges in lungs, humidification of air, mixing of alveolar gas that occurs with each breath

46
Q

External respiration

A

Exchange of O2 and Co2 across respiratory membrane
Influenced by = partial pressure gradients, gas solubility, ventilation-perfusion coupling, structural characteristics of respiratory membrane

47
Q

Diffusion depends on

A

Concentration gradient
Diffusion distance
Solubility
Surface area (alveoli)

48
Q

Ficks law

A

Rate of diffusion = k x A x (P2-P1/D)
K = diffusion constant (depends on solubility of gas and temperature)
A = surface area available for exchange
D = distance (thickness of barrier to diffusion)
P2-P1 = difference in partial pressure of gas on either side of barrier to diffusion (partial pressure gradient for gas)

49
Q

Thickness and surface area of respiratory membrane

A

Respiratory membranes = 0.5-1 micrometers thick
Large total surface area (40x more than skin)
Thickness if lungs become waterlogged (edema) and has exchange decreases
Surface area decreases with emphysema (walls of adjacent alveoli break down)

50
Q

Partial pressure gradients

A

Partial pressure gradient for O2 in lungs is steep
Venous blood pO2 = 40mmHg
Alveolar pO2 = 104mmHg

51
Q

O2 partial pressures reach equilibrium

A

At 104mmHg in ~0.25 seconds

About 1/3 the time a red blood cell is in a pulmonary capillary

52
Q

Partial pressure gradients and gas solubilities

A

Partial pressure gradient for Co2 in the lungs is less steep
Venous blood pO2 = 45mmHg
Alveolar pCo2 = 40mmHg
But Co2 is 20x more soluble in plasma than oxygen
Co2 diffuses in equal amounts with oxygen

53
Q

Internal respiration

A

Capillary gas exchange in body tissues
Partial pressures and diffusion gradients are reversed compared to external respiration
pO2 in tissue is always lower than in systemic arterial blood
pO2 of venous blood is 40mmHg and pCo2 is 45mmHg

54
Q

Ventilation-perfusion coupling

A

Ventilation = amount of gas reaching alveoli
Perfusion = blood flow reaching alveoli
Ventilation and perfusion must be matched (coupled) for efficient gas exchange

55
Q

Ventilation-perfusion coupling (carbon dioxide and oxygen)

A

Carbon dioxide = bronchioles - increase causes bronchodilation, decrease causes bronchoconstriction
Oxygen = alveoli - increase causes vasodilation, decrease causes vascocontriction

56
Q

Oxygen transport in blood

A

Molecular oxygen is carried in the blood
1.5% dissolved in plasma
98.5% loosely bound to each Fe of hemoglobin (Hb) in RBCs
4 oxygen per hemoglobin

57
Q

Gas transport

A

Most oxygen in the blood is transported and bound to hemoglobin
Hb + O2 -> HbO2

58
Q

Rate of loading and unloading of oxygen is regulated by

A 
PO2
Temperature 
Blood pH
PCo2
Concentration of DPG
59
Q

Hypoxia

A 
Inadequate of oxygen delivery to tissues 
Due to =
Too few RBCs
Abnormal or too little hemoglobin 
Blocked circulation 
Metabolic poisons 
Pulmonary disease 
Carbon monoxide
60
Q

Carbon monoxide poisoning

A

Carbon monoxide has 200x the affinity for hemoglobin
Binds to hemoglobin and doesn’t let go
Blocks sites for oxygen

61
Q

Carbon dioxide transport

A

Transported in blood in 3 ways =
7-10% dissolved in plasma
20% bound to goo in of hemoglobin (carbaminohemoglobin)
70% transported as bicarbonate ions (HCO3-) in plasma

62
Q

Carbon dioxide combines with water to form

A 
Carbonic acid (H2CO3) which quickly dissociates 
CO2 + H2O  H2CO3  H+ + HCO3-
63
Q

Transport and exchange of CO2 (systemic capillaries)

A

HCO3- quickly diffuses from RBCs into the plasma

The chloride shift occurs = outrush of HCO3- from RBCs is balanced as Cl- moves in from plasma

64
Q

Transport and exchange of CO2 (pulmonary capillaries)

A

HCO3- moves into the RBCs and binds with H+ to form H2CO3
H2CO3 is split by carbonic anhydrase into CO2 and water
CO2 diffuses into alveoli

65
Q

Control of respiration

A

Involves neurons in the reticular formation of the medulla and pons
Respiratory centres in brain stem establish a rhythmic breathing pattern
Includes = medullary respiratory centre, Pre-Bötzinger complex, Pneumotaxic centre, apneustic centre, and hering-Breuer reflex

66
Q

Medullary respiratory centre

A

Dorsal respiratory group (DRG) = mostly inspiratory neurons
Ventral respiratory group (VRG) = inspiratory and expiratory neurons
Receive input from chemoreceptors

67
Q

Pre-Bötzinger complex

A

Widely believed to generate respiratory rhythm

68
Q

Pneumotaxic centre

A

Sends impulses to DRG that help “switch off” inspiratory neurons
Dominates over apneustic centre

69
Q

Apneustic centre

A

Prevents inspiratory neurons from being switched off

Provides extra boost to inspiratory drive

70
Q

Hering-Breuer reflex

A

Triggered to prevent over inflation of the lungs

Stretch receptors

71
Q

Central chemoreceptors

A

Medulla = sensitive to changes in increased H+ via increase CO2

72
Q

Peripheral chemoreceptors

A

Carotid bodies are located in the carotid sinus
Aortic bodies are located in the aortic arch
Responds to increased H, increased CO2, and decreased oxygen

73
Q

Depth and rate of breathing

A

Hyperventilation =
increased depth/rate of breathing
High removal of CO2
Causes CO2 levels to decline (hypocapnia) (loose “trigger” for inspiration, longer breath holds possible, may cause cerebral vasoconstriction and cerebral ischemia)

74
Q

Summary of chemical factors

A

Increased CO2 is the most powerful respiratory stimulant
If arterial PO2 < 60mmHg it becomes the major stimulus (eg-high altitudes)
Increase in arterial H+ (eg-lactic acid) also acts as a respiratory stimulant

75
Q

Influence of higher brain centres

A

Hypothalamus/limbic system = modify rate and depth of respiration (eg-breath holding that occurs in anger or gasping with pain)
Increased body temperature acts to increase respiratory rate
Cortical controls bypass medullary controls (eg-voluntary breath holding)

76
Q

Pulmonary irritant reflexes

A

Receptors in the bronchioles respond to irritants (promote reflexive constriction of air passages (allergies/asthma))
Receptors in the larger airways mediate the cough and sneeze reflexes

77
Q

Inflation reflex

A

Hering-Breuer reflex = stretch receptors in the pleurae and airways are stimulated by lung inflation (inhibitory signals to the medullary respiratory centres end inhalation and allow expiration to occur)
Acts more as a protective response than a normal regulatory mechanism

78
Q

Respiratory adjustments (exercise)

A

Increased CO2 production and O2 consumption (larger gradients for gas exchange)
Three neural factors increase ventilation as exercise begins =
Psychological = anticipation of exercise
Cortical activation of skeletal muscles and respiratory centres
Sensory feedback from muscles

Kinesiology (19 decks)

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