Lecture 9 2/1/24 Flashcards

1
Q

Which processes are involved with delivering gases within the body?

A

-ventilation
-circulation
-perfusion
-diffusion

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2
Q

What is ventilation?

A

movement of gas into and out of the lung

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3
Q

What is minute ventilation?

A

total volume of air breathed per minute

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4
Q

What is tidal volume?

A

the volume of each breath

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5
Q

What is respiratory frequency?

A

the number of breaths per minute

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6
Q

What are the characteristics of pulmonary circulation?

A

-receives total output of right ventricle
-low pressure and low resistance
-involved in gas exchange

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7
Q

What is perfusion?

A

delivery of blood in capillaries surrounding the alveolar space in the lungs

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8
Q

What is a V/Q ratio?

A

comparison of ventilation to perfusion

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9
Q

What is diffusion?

A

flow of particles from a region of high pressure to a region of low pressure

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10
Q

Where does gas movement take place?

A

-within alveoli: air to air
-across alveoli into blood: air to liquid
-from blood into tissues: liquid to tissues

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11
Q

What are the general characteristics of conducting airways?

A

-conduits to get air to alveoli
-no gas exchange occurs

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12
Q

Which spaces comprise anatomic dead space?

A

-nasal cavity
-pharynx
-larynx
-trachea
-bronchi
-bronchioles

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13
Q

What are the characteristics of alveolar dead space?

A

-caused by poor perfusion of alveoli
-prevents gas exchange
-blood flow is disrupted/absent while alveolus is ventilated

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14
Q

What is physiologic dead space?

A

alveolar dead space + anatomic dead space

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15
Q

Why is it important to minimize the amount of plastic tubing when ventilating a patient?

A

decrease the amount of dead space contributed by the tubing

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16
Q

What is the importance of calculating the tidal volume minus the dead space volume?

A

it represents the actual volume of gas available for gas exchange

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17
Q

What are the characteristics of minute ventilation?

A

-amount of fresh gas entering lungs per minute
-estimated by resp. rate x tidal vol. in simplest form

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18
Q

What is alveolar ventilation?

A

amount of fresh gas reaching the alveoli per minute

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19
Q

How can alveolar ventilation be increased?

A

-increase tidal volume
-increase respiratory rate

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20
Q

Why is it possible to measure alveolar ventilation?

A

-no gas exchange occurs in the anatomic dead space, thus all CO2 must come from alveolar gas
-measuring CO2 in clinic can provide a measure of alveolar ventilation

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21
Q

What are the characteristics of the dead space/tidal volume ratio?

A

-identifies the fraction of each breath that ventilates dead space
-can change with disease and exercise
-changes tend to reflect alveolar/physiologic dead space changes

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22
Q

What is the purpose of dead space?

A

-warming and moistening of air
-particle clearance

23
Q

What are the general steps of inhalation?

A

-resp. muscles contract
-thorax expands
-lung stretches
-neg. pressure forces air into lungs

24
Q

What are the general steps of expiration?

A

-resp. muscles relax
-thoracic volume decreases
-lung compresses
-increased pressure forces air out of lungs

25
Q

What are the characteristics of exhalation?

A

-does not require muscular effort in normal animals at rest
-can be assisted by muscle contraction during exercise or due to disease

26
Q

Why are horses unique in terms of exhalation?

A

they have an activate phase of contraction when normal and at rest

27
Q

What are the characteristics of the diaphragm?

A

-most important inspiratory muscle
-innervated by phrenic nerve
-contraction pulls diaphragm caudally to expand thoracic cavity

28
Q

What is the main function of external intercostal contraction?

A

pull ribs rostral and outward to expand thoracic cavity volume

29
Q

What is the main function of the abductor muscles?

A

prevent collapse of the nares/upper airways during inspiration

30
Q

How does the pressure in the alveolar space differ based on the phase of respiration?

A

-pos. pressure for expiration
-neg. pressure for inspiration

31
Q

What is the resting pressure of the pleural space?

A

-4 cmH2O

32
Q

What happens as the lungs deflate and fall away from the chest wall?

A

generates negative pressure

33
Q

What is the inspiratory pressure of the intrapleural space?

A

-8 cmH2O

34
Q

What are the characteristics of transpulmonary pressure?

A

-difference between pressures within the airways and the pleural pressures
-driving force behind expanding and contracting lungs

35
Q

What is distensibility?

A

the ability of the lung to stretch

36
Q

What is elasticity?

A

the capability of a strained body to recover its size and shape after deformation

37
Q

What is compliance?

A

change in the dimension of a structure for a change in applied force

38
Q

What is the relationship between compliance and elasticity?

A

compliance is the inverse of elasticity

39
Q

What is residual volume?

A

air that remains in the lung after it is exposed to atmospheric pressure

40
Q

What is functional residual capacity?

A

air left in the lung at the end of normal expiration

41
Q

What is total lung capacity?

A

maximum amount of air that can be in the lungs

42
Q

What are the limiting factors of total lung capacity?

A

-collagen in pleural surface
-rib cage

43
Q

What is surface tension?

A

elastic tendency of a fluid surface to acquire the least surface area possible

44
Q

Why is surface tension important in the alveolus?

A

-water molecules have tendency to go towards alveolar membrane
-makes water layer in alveolus thinner, favoring collapse

45
Q

Which alveoli are more likely to collapse due to surface tension?

A

those with a smaller radius

46
Q

What are the characteristics of surfactant?

A

-produced by type II pneumocytes
-has hydrophilic and hydrophobic ends
-opposes natural attraction between the water molecules
-reduces surface tension

47
Q

Why is surfactant important to the alveolus?

A

-promotes alveolar stability
-increases lung compliance (makes inflation of lungs easier)

48
Q

What determines lower airway resistance?

A

-length
-radius

49
Q

How does inspiration impact airway resistance?

A

-increased radius
-decreased resistance

50
Q

How does contraction of bronchial smooth muscle impact airway resistance?

A

-decreased radius
-increased resistance

51
Q

Which breath function is more exaggerated during resp. distress?

A

expiration

52
Q

Which portion of the nervous system stimulates airway muscle contraction?

A

parasympathetic system

53
Q

Which type of receptor mediates airway dilation?

A

beta-2 adrenergic receptor