module 11 mechanics of breathing Flashcards

1
Q

4 mechanics of breathing

A

airway resistance
lung compliance
opposing lung forces (elastic recoil vs chest wall expansion)
work of breathing

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2
Q

lungs and recoil

A

lungs have natural recoil tendency

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3
Q

chest wall prefers expansion

A

inspiration

  • chest wall muscles contract elevating ribs, diaphragm moves down
    expiration:
  • lung deflates passively d/t recoil and relaxation of diaphragm
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4
Q

lung during heavy breathing (exercise)

A

elastic forces not strong enough to cause rapid expiration

  • abd. muscles contract pushing up
  • > compression of lungs
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5
Q

muscles of inspiration

A

Major:

  • intercostal muscles
  • diaphragm
  • recuts abdominis
    accessory: when major are tired
  • serratus posterior superior
  • sternocleidomastoid
  • scalenus muscles
  • intercostal muscles
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6
Q

airway resistance

A

resistance = driving pressure/rate of airflow
influence by radius and pattern of gas flow
- resistance inc. as radius dec.
– radius dec. from trachea to terminal bronchioles

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7
Q

pattern of gas flow

A

turbulent flow
- bronchospasm
laminar
transitional

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8
Q

turbulent flow

A

nasal cavity -> large bronchi

- inc. friction and resistance

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9
Q

laminar

A

small airways

smooth flow

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10
Q

transitional flow (mixed)

A

large airway bifurcations

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11
Q

newborns and resistance

A

increased until about 5 y/o

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12
Q

lung compliance

A

compliance = change in volume/ change in pressure
- lung expandability and ease of lung inflation
2 factors
- chest wall expandability
- lung expandability

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13
Q

peds and compliance

A

increased in neonates and peds < 3.5 yrs

- chest wall flexibility

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14
Q

elderly and compliance

A

dec compliance

  • chest wall rigidity
  • dec. motility of ribs
  • partial contraction of inspiratory muscles
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15
Q

disease processes affecting compliance

A
  • > stiffer lungs
  • pneumonia
  • pulmonary edema
  • atelectasis
  • ARDS
  • pulmonary fibrosis
  • obesity
  • abd. distention
  • pregnancy
  • kyphosoliosis
  • abd. surgery
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16
Q

abnormal inc. in lung compliance w/ loss of elastic recoil

A

-> WOB d/t inc. effort to exhale

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17
Q

functional components of respiratory system

A

neurochemical control of ventilation
mechanics of breathing
gas transport
control of pulmonary circulation

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18
Q

neurochemical control

A
neural control: respiratory center
- medulla oblongata
- pons 
Chemoreceptors: 
- central
- peripheral 
Baroreceptors
Proprioceptors 
Environmental factors
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19
Q

Stimulation to breathe

A

inc in arterial CO2

20
Q

respiratory center

A

efferent nerve impulses form brain -> diaphragm via phrenic nerve -> muscular contraction -> inhalation

21
Q

medullary center

A

dorsal respiratory group:
- stimulate inspiratory muscles: intercostal and diaphragm
- ramp signal: generated in increasing fashion. begin slowly and inc. for 2 seconds -> inspiration
abruptly stop for 3 seconds -> expiration

22
Q

upper pons

A

pneumotaxic center

  • influence rate of respirations
  • ends inspiration by inhibiting ramp
23
Q

lower pons

A

apneustic center

  • pattern of respiration
  • provide extra driving force for inspiratory neurons
  • > prolonged inspiration
24
Q

sensory inputs

A
central chemoreceptors
peripheral chemoreceptors
Hering-Breuer stretch receptors
proprioceptors
baroreceptors 
environmental sensations
25
central chemoreceptors
change in CO2 and pH | - increase
26
peripheral chemoreceptors
aortic arch and carotid | sense dec. in arterial O2
27
hering-breuer reflex
alveolar septa, bronchi, and bronchioles - inflation of lungs -> vagus nerve stimulation to medulla -> inhibition of inspiration - affects rate and duration - primarily seen in neonates at and high tidal vol. (>1500mL) - prevents overinflation
28
proprioceptors
muscles and tendons | - body movement -> respiratory rate and depth to maintain O2
29
baroreceptors
aortic arch and carotid - sense change in BP - - inc. BP -> dec. respiration - - dec. BP -> inc. respiration
30
environmental sensations
``` cold shower pain airway irritation stress smoking infection fever exercise ```
31
Distribution of blood flow in lungs
affected by body position and exercise - upright: blood flow dec. in upper regions of lungs (apices) compared to bases - supine: blood to posterior is inc. more than anterior affects of gravity
32
Perfusion: pulmonary blood flow
pulmonary circulation is a low pressure system and distribution of blood flow is uneven - zone 1 - zone 2 - zone 3
33
Zone 1
upper regions of lungs minimal blood flow r/t enlarged alveolar sacs -> pressure > capillary pressure -> capillary collapse - no gas exchange
34
Zone 2
middle region of lungs pulmonary artery pressure > pressure in alveoli during systole, but may fall below during diastole - intermittent perfusion
35
zone 3
bases of lungs pulmonary arterial pressure > venous pressure > alveoli pressure -> capillary vessels distended, dec. vascular resistance
36
O2 requires high pressure gradient to diffuse
PO2 in alveoli: 104 | PO2 in capillaries: 40
37
affinity of hemoglobin for O2 and shifting of curve
normal curve: normal affinity of hgb for O2 left shift: inc. affinity of hgb for O2 - helps loading of O2 in lungs, decreased release to tissues right shift: dec. affinity of hgb for O2 - aids in release of O2 to tissues
38
factors shifting curve to left
increased affinity for O2 - dec. H+, inc. pH - dec. PCO2 - dec. temp - hypothyroidism - carboxyhemoglobin
39
factors shifting curve to right
decreased affinity for O2 - inc. H+, dec. pH - inc. PCO2 - inc. temp - hyperthyroidism - anemia - chronic hypoxemia - - high altitude, congenital heart disease
40
alveoli hypoxic vasoconstriction
alveolar hypoxia -> vasoconstriction r/t no diffusion at that alveoli, body sends blood elsewhere chronic alveolar hypoxia -> chronic vasoconstriction -> chronic pulmonary HTN
41
carbon dioxide diffusion and transport
dissolved in plasma (5-10%) bicarbonate (60-70%) carbamino compound on hgb (20-30%)
42
respiratory membrane
what CO2 and O2 pass through for diffusion - surfactant - alveolar membrane - interstitial fluid - capillary membrane - plasma - RBC
43
O2 concentration in alveoli and partial pressure controlled by
rate of absorption in blood | rate of entry of new O2 into lungs
44
diffusion capacity impairment
alveolar thickening or capillary membrane - pneumonia - pulmonary edema - interstitial lung disease dec. surface area - emphysema inc. physical activity - dec. time of RBC in capillary
45
factors that determine ability to diffuse
surface area of alveoli and capillaries integrity of capillary and alveolar membranes available hemoglobin solubility of gas diffusion coefficient of the gas differences in partial pressure (concentration)
46
O2 transport mechanisms
dissolved in plasma ( 0.3mL O2/ 100mL blood) bound to Hgb - once at area of low O2 partial pressure hgb releases O2