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Flashcards in Gas Exchange Deck (41):
1

alteration in gas exchange, definition

decrease in the exchange of O2 and CO2 between the blood and the lungs to meet cell's oxygen needs- results in imbalance between O2 supply and demand = cellular ischemia and necrosis

2

alveoli

the functional unit of gas exchange

3

right bronchi nota bene

straighter, wider, more likely site of aspiration

4

ventilation

moving gases through respiratory tract, moving air between atmosphere and alveoli- efficiency requires a V/Q match -- ventilation (V) = alveoli that have air-- perfusion (Q) = blood supply to alveolus

5

diffusion

gas exchange between alveoli and blood

6

perfusion

transport of O2 and CO2 in blood/body fluids to/from cells

7

room air O2 %

21%

8

1L nasal canula O2 %

24%

9

respiratory center in brain

medulla, pons - involuntary control- controls rate, depth, rhythm

10

central chemoreceptors of respiration

CO2 (major controller), pH

11

peripheral chemoreceptors of respiration

responds to changes in blood O2: pO2 <70

12

hypoxia

inadequate oxygen at cellular level

13

anoxia

absence of oxygen

14

hypoxemia

deficient oxygenation of the blood

15

hypercapnia

increased concentration of CO2 in the blood

16

hypocapnia

decreased concentration of CO2 in the blood

17

O2 in blood (x2)

bound to hemoglobin: 97%free gas dissolved in plasma: 3%

18

SaO2 + measurement method

saturation of O2 in arterial bloodmeasured by ABG (invasive!)

19

SpO2 + measurement method

saturation of peripheral O2measured by pulse oximetry (non-invasive!)expected reading: >= 95%

20

PaO2 + measurement method

partial pressure of oxygen in arterial blood (dissolved in plasma!) measured by ABGexpected reading: 80-100 mmHg (with supplement > 100)

21

oxygen saturation: hemoglobin

each has 4 heme groups (binding to O2) --> all or nothing affinity for O2% is of ALL heme, not of ONE heme

22

pulse oximetry results affected by

P: oor peripheral perfusion s/t cold or hypotensionE: demaL: ow cardiac outputV: asoconstrictionC: arbon monoxide poisoningalso technique/environment: shivering, high intensity lighting, dark nail polish, cold room, dirty sensor

23

carbon dioxide in blood (x3)

1. dissolved in plasma (7%) PaCO2 = 35 to 45 mm Hg2. combined with water as carbonic acid (70%)H2O + CO2 = H2CO3 = H+ + HCO3-3. coupled with hemoglobin in RBC (23%)

24

*tidal volume

volume of air inspired/expired with each normal breath500 ml

25

*inspiratory volume

extra volume that can be inspired over and above tidal volume 3000 ml*key for incentive spirometry!*

26

expiratory reserve

extra volume that can be expired from forceful expiration at end of tidal expiration1100 ml

27

ventilation: what affects work of breathing?

increased muscular work itself leads to increased O2 demand- compliance- diameter of bronchi (airway resistance)- elastic recoil of lungs- alveoli surface tension (surfactant)- chest wall (bellows!)

28

compliance

ease with which lungs expand

29

factors effecting rate of diffusion (x3)

1. pressure difference/concentration gradient2. distance (thickness of membrane)3. surface area (for gas exchange)

30

factors effecting perfusion (x3)

blood flow, right? so...- movement of blood around alveoli- cardiac output- vessel patency, lumen size (vasoconstriction)

31

perfusion labs

significant for understanding quality of bloodRBC, Hgb, HCT/PCValso know about anemia or blood loss

32

* RBC typical

5 million/uL

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* Hemoglobin (hgb) typical

15 g/dL

34

*Hematocrit (HCT/PCV) typical

45%

35

V/Q mismatch: V without Q

ventilation without perfusion- shock or PE- wasted air (air in alveoli, no blood flow)

36

V/Q mismatch: Q without V

perfusion without ventilation- change in ventilation volume: shallow- atelectasis, pneumonia, airway obstructionlungs compensate by pulmonary hypoxic vasoconstriction

37

*pulmonary hypoxic vasoconstriction

redirection of blood flow around collapsed alveoli- response to V/Q match (Q no V)

38

factors affecting cell respiration

- O2 consumption (related to cell BMR)- each organ/tissue = oxygen % according to need- availability/amount of O2 in blood - perfusion to cells- diffusion into cells (ex: edema increases distance for O2 to travel -> hypoxia)

39

*increase in basal metabolic rate (BMR)... + causes

increases consumption of oxygen- agitation- fever & shivering- infection, sepsis, wound healing, burns- ADL, ambulation- stress- hyperthyroidism- seizures- increase work: tachypnea, tachycardia

40

*hypoxia s/s

*DECREASED MENTAL ACTIVITY OFTEN FIRST*- anxiety, restlessness, confusion, irritability, apprehension, headache, impaired judgment, decreased concentration/LOCtachypnea, increased depth, dyspnea, adventitious soundstachycardia, dysrhythmiafatigue of skeletal or cardiac musclescyanosis LATE SIGNischemia and death of cells, tissues, organs

41

respiratory pathogens spread

> 5 feet

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