Unit 4- Respiratory Phys. Flashcards

1
Q

VC

A

vital capacity (4,500 ml) - maximum amount of air a person can exhale after taking the deepest breath possible

VC = TV + ERV + IRV
= tidal volume + expiratory reserve vol. + inspiratory reserve volume

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2
Q

TLC

A

Total Lung Capacity 5,700 ml) -

TLC = VC + RV
= vital capacity + residual volume

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3
Q

TV

A

Tidal Volume (500 ml) - amount of air that enters lungs during a normal, quiet inspiration.

TV = VC - (IRV + ERV)
= vital capacity - (inspiratory reserve vol + expiratory reserve vol)

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4
Q

RV

A

Residual Volume (1,200 ml) - even after a forceful expiration, some air remains in the lungs. Prevents lungs from collapsing.

RV = FRC - ERV
= functional residual capacity - expiratory reserve vol

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5
Q

Dead space

A

About 150 ml - air entering the respiratory tract that fails to reach the alveoli. Air remains in trachea, bronchi & bronchioles where gas exchange cannot take place.

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6
Q

How is Carbon Dioxide transported in the body?

A

~60% as bicarbonate ion (HCO3-) in the plasma
~30% as bound to the protein portion of Hb in RBC (cabaminohemoglobin, HbCo2)
~10% dissolved in plasma

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7
Q

What is the OD Curve?

A
  • oxygen dissociation (sigmoid) curve

- shows the relationship between Po2 and % Hb saturation

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8
Q

What is the significance of the Plateau Portion of the OD curve?

A
  • Top part of the curve (on the right)
  • Where the P02 is high (lungs)
  • Even with a 40% decrease in P02, O2 content of blood is only slightly reduced (from 97.5% to 90%)
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9
Q

What is the significance of the Steep Portion of the OD curve?

A
  • left side of curve

- only a small drop in blood PO2 can make large amounts of O2 available to active tissues

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10
Q

A right shift of the OD curve indicates higher oxygen……

A

unloading (reduced affinity)

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11
Q

carbonic anhydrase

A
  • causes C02 to combine with H20 to make bicarbonate ions w/in red blood cells
  • in this version is how 60% of C02 travels in RBC
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12
Q

Chloride Shift

A
  • Diffusion of bicarbonate ions (HCO3-) out of RBC into plasma & Cl- ions into the RBC
  • important to keep the charge of the cell stable
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13
Q

Haldane Effect

A
  • Deoxygenated Hb has a greater affinity to CO2 than oxygenated Hb
  • overall effect:
    1. O2 unloading in tissues causes CO2 loading to Hb
    2. O2 loading in lungs causes CO2 unloading from Hb
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14
Q

hypoxia

A

insufficient oxygen at cellular level

  • hypoxic hypoxia: due to a low Po2 in arterial blood
  • anemic hypoxia: due to reducted O2-carrying capacity in blood
  • stagnant hypoxia: inadequate oxygen delivered to tissues
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15
Q

hyperoxia

A

an above-normal partial pressure of Po2

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16
Q

hypercapnia

A

an excess of CO2 in blood caused by hypoventilation

17
Q

hypocapnia

A

below-normal level of CO2 in the blood due to hyperventilation

18
Q

respiratory acidosis

A

decrease in pH due to increased H+ produced when CO2 accumulates b/c of hypoventilation

19
Q

What are the PHYSICAL factors influencing ventilation?

A
  1. Airway resistance: relationship between Flow, pressure & resistance
  2. Elastic behavior of lungs: compliance (expand) & elastic recoil
  3. Alveolar surface tension: influences elastic behavior of lungs
20
Q

compliance

A
  • ability to stretch; ease with which lungs can be expanded
  • determined by (1) distensibility of lung tissue _ thoracic cage, and (2) surface tension of alveoli
  • High compliance = stretches easily
  • Low compliance = requires more force
21
Q

elastic recoil

A
  • returning to its resting volume when stretching force is released
  • surface tension of alveolar fluid draws alveoli to their smallest possible size
  • ELASTANCE: measure of how readily the lungs rebound after being stretched.
22
Q

Neural control of respiration

A
  1. Medullary respiratory centers

2. Pons respiratory centers

23
Q

Medullary Respiratory center

A
  1. dorsal respiratory group (DRG)

2. ventral respiratory group (VRG)

24
Q

Dorsal Respiratory group (DRG)

A
  • Part of Medullary Respiratory center

- Excites inspiratory muscles

25
Ventral respiratory group (VRG)
- Part of Medullary Respiratory center | - Active when ventilation demands increase
26
Pre-Botzinger complex
- Neurons show pacemaker activity: sends signals to DRG
27
Pontine respiratory group (PRG) [aka Pons Respiratory centers]
Has greater influence on respiration than the medulla 1. pneumotaxic center 2. apneustic center
28
pneumotaxic center
sends impulses to DRG that help "switch off" inspiratory neurons, limiting the duration of inspiration
29
apneustic center
prevents inspiratory neurons from being switched off
30
Hering-Breuer (inflation) reflex
- triggered to prevent overinflation of lungs | - pulmonary stretch receptors
31
Where are the peripheral chemoreceptors located and what do they do?
- Located in the carotid & aortic bodies - respond to low levels of Po2 - used only in dire situations; as will only respond when Po2 goes below 60 mmHg - stimulate the medullary centers - increase ventilation
32
Where are the central chemoreceptors located & what do they do?
- in the brain (medullary center) - sensitive to CO2-induced H+ concentration in the brain ECF that bathes them. - increased H+ increases ventilation
33
What 3 pressures are involved in ventilation?
1. atmospheric 2. intra-alveolar 3. intra-plueral pressure