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Respiratory Medicine Exam I > Respiratory Physiology Review > Flashcards

Respiratory Physiology Review Flashcards

1
Q

During inspiration, intrapleural pressure at the base of the lungs _______ and lungs are pulled into expanded position

A

Decreases

[pressure in the airway becomes slightly negative and air flows in]

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2
Q

Expiration is a passive process during normal quiet breathing, so no muscles are required to contract to decrease intrathoracic volume. However, some contraction of the inspiratory muscles occurs in the early part of expiration, why is this?

A

To exert braking action on recoil forces and slow expiration

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3
Q

Measurement of air that can still be breathed in after normal inspiration

A

Inspiratory reserve volume

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4
Q

Measurement of air that moves into lung with each quiet inspiration, typically 500 mL

A

Tidal volume

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5
Q

Measurement of air that can still be breathed out after normal expiration

A

Expiratory reserve volume

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6
Q

Measurement of air in lung after maximal expiration; cannot be measured on spirometry

A

Residual volume

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7
Q

How is inspiratory capacity calculated?

A

IRV + TV

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8
Q

Volume of gas in lungs after normal expiration which includes residual volume

A

Functional residual capacity

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9
Q

How is functional residual capacity calculated?

A

RV + ERV

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10
Q

What pulmonary capacity represents the balancing point between elastic recoil of the lungs and recoil of the chest wall?

A

Functional residual capacity

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11
Q

What pulmonary capacity represents the maximum amount of gas that can be expired after a maximal inspiration?

A

Vital capacity

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12
Q

What is FEV1?

A

Fraction of vital capacity expired during the first second of a forced expiration

FEV1/FVC ratio is a useful tool in recognizing classes of airway disease

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13
Q

How is vital capacity calculated?

A

TV + IRV + ERV

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14
Q

The total lung capacity is the volume of gas present in lungs after a maximal inspiration. How is total lung capacity calculated?

A

IRV + TV + ERV + RV

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15
Q

Largest amount of air that can be expired after a maximal inspiratory effort; measured clinically as an index of pulmonary function

A

Forced vital capacity

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16
Q

Compare/contrast anatomic and physiologic (total) dead space

A

Anatomic dead space = respiratory system volume exclusive of alveoli (air not available for gas exchange)

Physiologic dead space = volume of gas not equilibrating with the blood (i.e., wasted ventilation)

In healthy individuals, the two values are identical. In some disease states, no exchange may take place between the gas in some of the alveoli and some may be over-ventilated. Physiologic dead space can increase in response to diseases affecting air exchange in the respiratory zone

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17
Q

_______ represents the change in lung volume for a change in pressure; it is inversely proportional to wall stiffness

A

Compliance

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18
Q

High compliance means that the lung is easier to fill. What conditions increase compliance?

A

Emphysema
Normal aging
Surfactant

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19
Q

Lower compliance means the lung is harder to fill. What conditions decrease compliance?

A

Pulmonary fibrosis
Pneumonia
Pulmonary edema

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20
Q

The same volume of blood goes through the right and left heart every minute, so why is the pressure lower on the right?

A

Due to lower resistance to blood flow

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21
Q

What effect does a decrease in PaO2 have on pulmonary circulation?

A

A decrease in PaO2 causes hypoxic vasoconstriction that shifts blood away from poorly ventilated regions of the lung to well-ventilated regions

22
Q

There is extensive autonomic innervation of the pulmonary vessels. Stimulation of cervical sympathetic ganglia _____ pulmonary blood flow by as much as 30%

A

Reduces

23
Q

Describe alveolar barrier

A

Very thin - consisting of capillaries, type I and type II epithelial cells, and alveolar macrophages

Thin barrier makes it ideal for gas diffusion/exchange!

24
Q

______ is a complex mix of lecithins, the most important of which is dipalmitoylphosphatidylcholine

A

Surfactant

25
Q

Role of surfactant in respiratory system

A

Decreases alveolar surface tension
Prevents alveolar collapse
Decreases lung recoil
Increases compliance

26
Q

Differentiate type I vs. type II epithelial cells

A

Type I cells form structure of alveoli

Type II cells produce surfactant

27
Q

Differentiate T vs. R state of Hb

A

T = taut — deoxygenated form, found in tissues. Low affinity for O2 promotes its release to tissues

R = relaxed — oxygenated form, found in respiratory areas. High affinity for O2

28
Q

CO2 is transported in what 3 forms?

A

HCO3- (90%)

Carbaminohemoglobin aka HbCO2 (5%) — note CO2 binding favors taut form (O2 unloaded)

Dissolved CO2 (5%)

29
Q

In the lungs, oxygenation of Hb promotes dissociation of H+. This shifts equilibrium toward CO2 formation so that CO2 is released from RBCs. This is known as the _____ effect

A

Haldane

30
Q

Increased H+ from peripheral tissue metabolism shifts curve to the right, unloading O2. This is known as the _____ effect

A

Bohr

31
Q

What generates the respiratory rhythm?

A

Synaptically coupled pacemaker cells in the pre-botzinger complex (located on either side of the medulla)

32
Q

Which chemoreceptors, peripheral or central, are more sensitive to O2 and H+ in terms of regulating breathing?

A

Peripheral — located in carotid and aortic bodies as well as collections of cells in medulla

[central chemoreceptors are less sensitive to O2 and H+ in arterial blood]

33
Q

Describe slowly-adapting stretch receptors in terms of whether or not they are myelinated, location, and stimuli that they respond to

A

Myelinated

Located among airway smooth muscle cells

Stimulated by lung inflation or hyperinflation

34
Q

Slowly adapting stretch receptors are stimulated by lung inflation or hyperinflation. What are some responses of these receptors?

A

Shortening of inspiration produced by vagal afferent activity

Hering-Breuer inflation reflex = increase in duration of expiration produced by steady lung inflation

Hering-Breuer deflation reflex = decrease in the duration of expiration produced by marked deflation of lung

35
Q

Describe rapidly-adapting stretch receptors in terms of whether or not they are myelinated, location, and stimuli that they respond to

A

Myelinated

Located among airway epithelial cells

Stimulated by exogenous and endogenous substances (e.g., histamine, prostaglandins)

36
Q

Rapidly-adapting stretch receptors are stimulated by exogenous and endogenous substances (e.g., histamine, prostaglandins). What are some responses of these receptors?

A

When activated in trachea —> cough, bronchoconstriction, mucus secretion

When activated in lung —> hyperpnea

37
Q

Describe J receptors in terms of whether or not they are myelinated, location, and stimuli that they respond to

A

Unmyelinated

Located close to blood vessels (J stands for juxtacapillary)

Stimulated by lung hyperinflation, exogenous or endogenous substances (e.g., capsaicin, bradykinin, serotonin)

38
Q

J receptors may be stimulated by lung hyperinflation, exogenous, or endogenous substances. What are some responses?

A

Pulmonary chemoreflex = apnea followed by rapid breathing, bradycardia, and hypotension

Coronary chemoreflex (Bezold-Jarisch reflex) = unknown role, but occurs in states of pulmonary congestion or embolization in which it is produced by endogenously released substances

39
Q

How is acid-base homeostasis maintained by the respiratory system in metabolic acidosis?

A

Respiratory stimulation (Kussmaul breathing) = hyperventilation —> decreased alveolar PCO2 and compensatory fall in blood H+ concentration

40
Q

How is acid-base homeostasis maintained by the respiratory system in metabolic alkalosis?

A

Ventilation is depressed and arterial PCO2 rises, raising the H+ concentration toward normal

41
Q

What are some physiologic adjustments made in states of chronic hypoxia (classic example is high altitude adjustment)

A

Chronic increase in ventilation

Increase in EPO with subsequent increase in Hct and Hb

Increased 2,3 BPG (binds Hb so that it releases more O2)

Increase in cellular mitochondria

Increase in renal excretion of HCO3 to compensate for respiratory alkalosis

42
Q

Physiologic responses to hypercapnea

A

Initially stimulates respiration

Retention of larger amounts produces confusion, diminished sensory acuity, and eventually coma with respiratory depression and death. In pts with these symptoms, PCO2 is markedly elevated and severe respiratory acidosis is present. Large amounts of HCO3 are excreted, but more is reabsorbed - raising the plasma HCO3 and partially compensating for the acidosis

43
Q

How does hypocapnea occur, and what is the resultant change of chronic hypocapnea on cerebral blood flow?

A

Hypocapnea is the result of hyperventilation

With chronic hyperventilation, cerebral blood flow may be reduced 30% or more because of direct constrictor effects of hypocapnea on cerebral vasculature

44
Q

T/F: the conducting zone of the airways are considered to be physiologic dead space

A

False; the conducting airway represents anatomic dead space

45
Q

T/F: FEV1/FVC is reduced in a patient who has a restrictive pulmonary disease

A

False — it is increased in a pt with restrictive disease. It is reduced in a pt with obstructive disease

46
Q

T/F: the intrapleural pressure is 0 cm H2O at the end of a normal expiration

A

False; intrapleural pressure is negative at the end of normal expiration

47
Q

T/F: surfactant reduces the surface tension in small alveoli, preventing their collapse into the larger alveoli

A

True

48
Q

T/F: an increase in body temp will result in a decrease in the afinity of Hb for oxygen

A

True

49
Q

T/F: an increase in CO2 levels is associated with respiratory alkalosis

A

False; a decrease in CO2 levels is associated with respiratory alkalosis. An increase in CO2 = respiratory acidosis

50
Q

T/F: respiratory compensation for a metabolic acid/base disturbance takes days or weeks to become complete

A

False; respiratory compensation mechanisms are FAST

51
Q

T/F: the peripheral chemoreceptors are sensitive to changes in PaO2, PaCO2, and pHa

A

True

52
Q

T/F: rapidly-adapting pulmonary stretch receptors trigger cough in response to various irritants

A

True

Respiratory Medicine Exam I (9 decks)

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