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A & P > obj 5 pt 2 > Flashcards

obj 5 pt 2 Flashcards

1
Q

what are the 2 phases of pulmonary ventilation?

A

inspiration
expiration

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2
Q

gases flow into lungs

A

inspiration

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3
Q

gases exit lungs

A

expiration

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4
Q

pressure exerted by air surrounding the body

A

atmospheric pressure

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5
Q

pressure in alveoli
fluctuates with breathing
always eventually equalizes with atmospheric pressure

A

intrapulmonary pressure

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6
Q

pressure in pleural cavity
fluctuates with breathing
always a negative pressure in order to keep lungs inflated

A

intrapleural pressure

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7
Q

difference between intrapulmonary and intrapleural pressures
determines the size of the lungs
if equal, causes lung collapse

A

transpulmonary pressure

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8
Q

consists of inspiration and expiration
mechanical process that depends on volume changes in thoracic cavity
volume changes lead to pressure changes
pressure changes lead to the flow of gases to equalize pressure
gases always move from an area of high pressure to an area of low pressure

A

pulmonary ventilation

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9
Q

active process involving inspiratory muscles (contraction of diaphragm and external intercostals)
As thoracic cavity volume increases, lungs are stretched as
they are pulled out with thoracic cage
Intrapulmonary pressure drops
Because of difference between atmospheric and
intrapulmonary pressure, air rushes into lungs until
intrapulmonary and atmospheric pressures are equalized

A

inspiration

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10
Q

what are the actions of the diaphragm?

A

when dome-shaped diaphragm contracts, moves inferiorly and flattens out; there is an increase in thoracic volume

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11
Q

what are the actions of the intercostal muscles?

A

when external intercostals contract, rib cage is lifted up and out
results in increase in thoracic volume

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12
Q

passive process
depends on lung elasticity more than muscle contraction
inspiratory muscles relax, thoracic cavity volume decreases, lungs recoil
volume decrease causes intrapulmonary pressure to increase so air flows out of lungs down its pressure gradient until intrapulmonary pressure is equal to atmospheric pressure

A

expiration

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13
Q

may modify normal respiration rhythm
most result from reflex action, although some are voluntary

A

non-respiratory air movements

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14
Q

what are the 3 factors that influence the ease of air passage and the amount of energy required for ventilation?

A

airway resistance
alveolar surface tension
lung compliance

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15
Q

major non-elastic source of resistance to gas flow
decreases air passage
causes breathing movements to become more strenuous
greatest resistance to airflow occurs in midsize bronchi
F(gas flow) = P/R

A

airway resistance

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16
Q

the attraction of liquid molecules to one another at gas-liquid interface

A

surface tension

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17
Q

tends to draw liquid molecules closer together and reduce contact with dissimilar gas molecules
resists any force that tends to increase surface area of liquid
tends to cause alveoli to shrink to smallest size- that is, collapse
surfactant, a fat-protein complex, prevents alveolar collapse

A

alveolar surface tension

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18
Q

measure of how much “stretch” the lung has

A

lung compliance

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19
Q

why is lung compliance normally high?

A

distensibility of lung tissue
surfactant, which decreases alveolar surface tension

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20
Q

how do we assess ventilation?

A
  • Several respiratory volumes can be used to assess
    respiratory status
  • Respiratory volumes can be combined to calculate
    respiratory capacities, which can give information on a
    person’s respiratory status
  • Respiratory volumes and capacities are usually abnormal in
    people with pulmonary disorders
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21
Q

amount of air moved into and out of lung with each breath
averages ~500ml

A

tidal volume

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22
Q

amount of air that can be inspired forcibly beyond the tidal volume (2100-3200ml)

A

inspiratory reserve volume

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23
Q

amount of air that can be forcibly expelled from lungs after a normal tidal expiration (1000-12000ml)

A

expiratory reserve volume

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24
Q

amount of air that always remains in lungs

A

residual volume

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25
Q

sum of tidal volume + inspiratory reserve volume

A

inspiratory capacity

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26
Q

sum of residual volume + expiratory reserve volume

A

functional residual capacity

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27
Q

sum of tidal volume + inspiratory reserve volume + expiratory reserve volume

A

vital capacity

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28
Q

sum of all lung volumes (TV + IRV + ERV +RV)

A

total lung capacity

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29
Q

what are the pulmonary functions tests can measure rate of gas movement?

A

forced vital capacity
forced expiratory volume

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30
Q

amount of gas forcibly expelled after taking deep breath

A

forced vital capacity

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31
Q

amount of gas expelled during specific time interval of FVC

A

forced expiratory volume

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32
Q

total amount of gas that flows into or out of respiratory tract in 1 min

A

minute ventilation

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33
Q

flow of gases into and out of alveoli during particular time

A

alveolar ventilation rate

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34
Q

occurs between lungs and blood as well as blood and tissues

A

gas exchange

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35
Q

diffusion of gases between blood and lungs

A

external respiration

36
Q

diffusion of gases between blood and tissues

A

internal respiration

37
Q

what are both external and internal respiration subject to?

A
  • Basic properties of gases
  • Composition of alveolar gas
38
Q

the total pressure of a mixture pf gases is the sum of the partial pressures of the individual components

A

Dalton’s law of partial pressures

39
Q

the pressure exerted by an individual gas in a mixture. is proportional to the percentage of that gas in the gas mixture

A

partial pressure

40
Q

PO2 is high
PCO2 is low
bcuz inspiration occurred

A

alveoli

41
Q

PO2 is low
PCO2 is high
blood just came from tissues

A

pulmonary capillaries

42
Q

PO2 is low
PCO2 is high
bcuz tissues using oxygen

A

tissues

43
Q

PO2 is high
PCO2 is low
because blood just came from lungs

A

tissue capillaries

44
Q
  • the relative concentration of gases (their partial
    pressures) does not change as the pressure and
    volume of the gas mixture changes
  • so air inhaled into the lungs will have the same
    relative concentration of gases as atmospheric air.
  • In the lungs, the relative concentration of gases
    determines the rate at which each gas will diffuse
    across the alveolar membranes
A

Dalton’s law

45
Q
  • predicts how gasses will dissolve in the alveoli and
    bloodstream during gas exchange.
  • The amount of oxygen that dissolves into the
    bloodstream is directly relational to the partial pressure
    of oxygen in alveolar air
A

Henry’s law

46
Q

what happens for gas mixtures in contact with liquid?

A
  • Each gas will dissolve in the liquid in proportion to its
    partial pressure
  • At equilibrium, partial pressures in two phases will be
    equal
47
Q

what does the amount of each gas that dissolves depend on?

A
  • Solubility: CO2 more soluble in water than O2
  • Temperature: at temp of liquid rises, solubility
    decreases
48
Q

what is the composition of alveolar gas?

A
  • Alveoli contain more CO2 and water vaporand less O2 than
    atmospheric air because:
  • Gas exchanges in lungs (O2 diffuse out of lungs and CO2
    diffuse into lung)
  • Humidification of air by conducting passages
  • Mixing of alveolar gas with each breath
  • Newly inspired air mixes with air that was left in
    passageways between breaths
49
Q

what is exchange of external respiration influenced by?

A
  • pressure gradients (Dalton’s Law) and gas solubilities
    (Henry’s Law)
  • Thickness and surface area of respiratory membrane
  • The thicker the membrane, the less diffusion; thinner
    the membrane, more diffusion. This affects the rate of
    gas exchange
50
Q

a steep partial pressure gradient for O2 exists between blood and lungs

A

partial pressure gradients and gas solubilities

51
Q

40 mm Hg

A

venous blood P02

52
Q

104mm Hg

A

alveolar P02

53
Q

what is the partial pressure gradient for CO2?

A

venous blood PCO2 = 45 mm Hg
alveolar PCO2 = 40mm Hg

54
Q
  • Gas movement occurs by diffusion
  • Rate of diffusion depends on the concentration of
    the gas and the barrier; especially the thickness
    of the respiratory membranes
  • Respiratory membranes are very thin
  • 0.5 to 1 m thick
  • Large total surface area of the alveoli is 40 the
    surface area of the skin
A

thickness and surface area of the respiratory membrane

55
Q

what are the 2 ways molecular O2 is carried in the blood?

A
  • dissolved in plasma
  • bound to hemoglobin (Hb) in RBCs
56
Q

hemoglobin-O2 combination

A

oxyhemoglobin

57
Q

hemoglobin that has released O2

A

deoxyhemoglobin

58
Q

all four heme groups carry O2

A

fully saturated

59
Q

when only one to three hemes carry O2

A

partially saturated

60
Q

what are the factors that influence hemoglobin saturation?

A
  • PO2
  • Other factors such as:
  • Temperature
  • Blood pH
  • PCO2
  • Concentration of BPG
61
Q

what is the influence of PO2 on hemoglobin saturation?

A

PO2 heavily influences binding and release of O2 with
hemoglobin

62
Q

what is the influence of PO2 on hemoglobin saturation in arterial blood?

A
  • Hgb is 98% saturated
  • Further increases in PO2 (as in deep breathing)
    produce minimal increases in O2 binding
63
Q

what is the influence of PO2 on hemoglobin saturation in venous blood?

A
  • Hgb is still 75% saturated
  • Venous reserve: oxygen remaining in venous blood
    that can still be used
64
Q

what are the 3 forms that CO2 is transported in blood?

A
  • dissolved in plasma as PCO2
  • bound to hemoglobin
  • Accumulating CO2 lowers blood pH
  • Depletion of CO2 in blood raises blood pH
65
Q

what is carbon dioxide transport?

A
  • Most carbon dioxide molecules entering the plasma quickly
    enter RBCs. The reactions that convert carbon dioxide to
    bicarbonate for transport mostly occur inside RBCs because
    they contain carbonic anhydrase, an enzyme that reversibly
    catalyzed the conversion of carbon dioxide and water to
    carbonic acid.
  • Hydrogen ions are released during the reaction bind to
    hemoglobin triggering the bohr effect. The carbon dioxide
    loading enhances oxygen release.
  • In systemic capillaries, after bicarbonate is created, it quickly
    diffuses from RBCs to plasma
  • This outpouring of bicarbonate from RBCs is balanced as
    chloride moves into RBCs from plasma (chloride shift)
  • In pulmonary capillaries, the process occurs in
    reverse
  • Bicarbonate moves into RBCs while Chloride
    moves out of RBCs back into plasma
  • Bicarbonate binds with H+ to form H2CO3
    (carbonic acid)
  • Carbonic acid is split by carbonic anhydrase into
    CO2 and H20
  • CO2 diffuses into alveoli
66
Q

helps blood resist changes in pH

A

carbonic acid-bicarbonate buffer system

67
Q

what are respiratory rhythms regulated by?

A

higher brain centers
chemoreceptors
other reflexes

68
Q

involve neurons in reticular formation of medulla and pons

A

neural controls

69
Q

clustered neurons in two areas of medulla

A

medullary respiratory centers

70
Q

sets normal respiratory rate and rhythm

A

ventral respiratory group

71
Q

assists VRG

A

dorsal respiratory group

72
Q
  • Neurons in this center influence and modify
    activity of Ventral Respiratory Group (VRG)
  • Act to smooth out transition between inspiration
    and expiration and vice versa
  • Transmit impulses to VRG that modify and fine-
    tune breathing rhythms during vocalization,
    sleep, exercise
A

pontine respiratory centers

73
Q

determined by how actively the respiratory center stimulates respiratory muscles

A

depth

74
Q

determined by how long center is active

A

rate

75
Q

what are respiratory centers affected by?

A
  • Chemical factors
  • Influence of higher brain centers
  • Pulmonary irritant reflexes
  • Inflation reflex
76
Q
  • Most important of all factors affecting depth and
    rate of inspiration
  • Changing levels of CO2, O2, and pH are most
    important
A

chemical factors

77
Q

located throughout brain stem

A

central chemoreceptors

78
Q

found in aortic arch and carotid arteries

A

peripheral chemoreceptors

79
Q
  • Most potent and most closely controlled
  • blood PCO2 levels rise (hypercapnia), its most
    powerful respiratory stimulant
  • Respiratory centers increase depth and rate
    of breathing, which act to lower blood PCO2,
    and pH rises to normal levels
  • If blood PCO2 levels decrease (hypocapnia),
    respiration becomes slow and shallow
A

influence of PCO2

80
Q
  • Peripheral chemoreceptors in aortic and carotid bodies
    sense arterial O2 levels
  • Declining PO2 normally has only slight effect on
    ventilation because of huge O2 reservoir bound to Hgb
  • Requires substantial drop in arterial PO2 (below
    60 mmHg) to stimulate increased ventilation
  • When excited, chemoreceptors cause respiratory
    centers to increase ventilation
A

influence of PO2

81
Q
  • pH can modify respiratory rate and rhythm
    even if CO2 and O2 levels are normal
  • Mediated by peripheral chemoreceptors
  • Decreased pH may reflect CO2 retention,
    accumulation of lactic acid, or excess ketone
    bodies
  • Respiratory system controls attempt to raise
    pH by increasing respiratory rate and depth
A

influence of arterial pH

82
Q

modify rate and depth of respiration

A

hypothalamic controls

83
Q

bypass medullary controls

A

cortical controls

84
Q
  • Receptors in bronchioles respond to irritants such
    as dust, accumulated mucus, or noxious fumes
  • Receptors communicate with respiratory
    centers via vagal nerve
  • Promote reflexive constriction of air passages
  • Same irritant triggers a cough in trachea or
    bronchi or a sneeze in nasal cavity
A

pulmonary irritant reflexes

85
Q
  • Stretch receptors in pleurae and airways are
    stimulated by lung inflation
  • Send inhibitory signals to medullary
    respiratory centers to end inhalation and
    allow expiration
  • May act as protective response more than as
    a normal regulatory mechanism
  • a reflex triggered to prevent over-inflation of
    the lung
A

hering-breuer reflex

A & P (21 decks)

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