BIOL 0800 Reading- Chapter 13 Flashcards Preview

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Flashcards in BIOL 0800 Reading- Chapter 13 Deck (113):
1

Every minute, approximately how much air and blood flows through the lungs/pulmonary capillaries?

4L air, 5L blood

2

What is the structure of the pulmonary system after the larynx?

Trachea, into two bronchi, into two bronchioles, into terminal bronchioles, into respiratory bronchioles, into alveolar ducts, into alveolar sacs: alveoli show up in respiratory bronchioles and increase in alveolar ducts and alveolar sacs

3

What is the conducting zone?

From the top of the trachea to the beginning of the respiratory bronchioles; contains to alveoli and no gas exchange

4

What is the respiratory zone?

From the respiratory bronchioles downwards; contains alveoli and gas exchange

5

What are type I alveolar cells?

One-cell thick, flat layer of epithelial cells lining the air-facing surfaces of alveolar walls

6

What are type II alveolar cells?

Interspersed between type I cells; thicker, specialized: produce surfactant

7

What is inside the alveolar wall?

Capillaries and a very small interstitial space: interstitial fluid and loose mesh of connective tissue

8

What are intercostal muscles?

Muscles that run between ribs

9

What is the pleural sac?

Completely closed sac that encloses each lung, made of thin sheet of cells called pleura

10

What is the difference between visceral and parietal pleura?

Internal surface touching the lung, and external surface touching the thoracic cavity interior

11

What is intrapleural fluid?

Fluid between the visceral and parietal pleura

12

What is the equation for bulk flow?

F = deltaP/R

13

In the equation for bulk flow, what is delta P?

Alveolar pressure (Palv) minus atmospheric pressure (Patm)

14

What happens when Palv is less than Patm?

Negative flow, or inspiration

15

What happens when Palv is greater than Patm?

Positive flow, or expiration

16

What is Boyle's law?

PV = PV

17

Lung volume depends on what two factors?

Transpulmonary pressure and lung stretchability

18

What is transpulmonary pressure?

The difference in pressure between the inside and outside of the lung; Palv minus Pip (intrapleural)

19

What are the formulas for transmural pressure on the lungs and on the chest cavity?

On the lungs is Palv - Pip, and on the chest cavity is Pip - Patm

20

How does transmural pressure affect inspiration/expiration?

Transmural pressure increases for inspiration (decreases Pip relative to Palv), and uses elastic recoil to drive passive expiration

21

When there is no airflow, why is Pip negative?

Because there is always a positive transmural pressure, so Palv > Pip, but Palv = 0

22

What forces cause intrapleural pressure to be zero when there is no airflow?

Elastic recoil of the lungs and the chest cavity causes the lungs to shrink and thoracic cavity to expand: pulls the pleural walls apart and decreases pressure

23

What is the crucial factor in keeping the lungs partially expanded between breaths?

The negative (subatmospheric) intrapleural pressure

24

What causes the diaphragm to contract?

Activation of the phrenic nerves

25

How does inspiration occur?

Thorax expands, Pip becomes subatmospheric, transpulmonary pressure increases, lungs expand, Palv becomes subatmospheric, air flows into alveoli

26

How does expiration occur?

Diaphragm and chest wall recoil inward; Pip returns to normal value, transpulmonary pressure decreases, elastic recoil overcomes transpulmonary pressure, and lungs passively recoil

27

What is lung compliance?

The magnitude of the change in lung volume produced by a given change in transpulmonary pressure

28

What is the formula for lung compliance?

Delta V/delta Ptp

29

What are two major determinants of lung compliance?

Stretchability of lung tissues, and surface tension on alveoli

30

What is surfactant for?

Reduces cohesive forces between water molecules on the alveolar surface: lowers the surface tension and increases lung compliance

31

What is the law of Laplace?

P = 2T/r

32

Why do alveoli of different sizes exist?

Because of Laplace's law: if the radius is smaller, then the surfactant is denser and surface tension is less, which allows for a higher pressure to prevent the small alveolus from condensing into larger ones

33

How does transpulmonary pressure affect resistance?

Increase in transpulmonary pressure increases airway radius, and airway resistance is decreased (inspiration)

34

What is lateral traction?

When the elastic connective-tissue fibers around the alveolar tissue help pull the airways open when the lungs pull on them.

35

How does epinephrine affect airway resistance?

Relaxes airway smooth muscle through beta-adrenergic receptors

36

What substance contracts airways to increase airway resistance?

Leukotriene, an eicosanoid

37

What is the tidal volume?

The volume of air taken in during a single expiration; usually the same volume as is expired

38

What is the inspiratory reserve volume (IRV)?

The maximal amount of air that can be increased above TV

39

What is functional reserve capacity (FRC)?

The amount of air left in the lungs after a normal tidal expiration: ERV + RV

40

What is expiratory reserve volume (ERV)?

The maximal amount of air that can be expired below TV

41

What is residual volume?

The amount of air remaining in the lungs after maximum expiration

42

What is the function of residual volume?

Keeps alveoli inflates between breaths, mixes with fresh air on next inspiration

43

What is the vital capacity (VC)?

The maximum amount of air you can exhale after a maximum inspiration; ERV + TV + IRV

44

What is inspiratory capacity (IC)?

Maximum amount of air that can be inhaled after a normal tidal expiration; RV + ERV

45

What is minute ventilation?

Total ventilation per minute: TB x RR (respiratory rate)

46

What is the approximate minute ventilation of a normal person?

6 L: (0.5 TV)(12 breaths each minute)

47

What is anatomical dead space?

The space within the airways that doesn't permit gas exchange

48

How do you calculate how much fresh air enters the lungs?

TV - deadspace = fresh air volume

49

What is alveolar ventilation?

The total volume of fresh air entering the alveoli per minute: = (TV - deadspace)(respiratory rate)

50

Why is breathing depth more important than breathing frequency to increase alveolar ventilation?

Because you still need to overcome dead space

51

What is alveolar dead space?

The volume of air that isn't used for gas exchange because alveoli have little or no blood supply; small in normal lungs

52

What is physiological dead space?

The sum of anatomical and alveolar dead space

53

What is the respiratory quotient?

The ratio of CO2 produced to O2 consumed; approximately 0.8

54

What is Dalton's law?

The sum of all the partial pressures of gases is the total pressure, since the pressures of different gases don't depend on each other

55

What is Henry's law?

The amount of gas dissolved in a liquid will be directly proportional to the partial pressure of the gas with which the liquid is in equilibrium; partial pressures at equilibrium of a gas in liquid and gas phases is identical

56

What are normal alveolar gas pressures?

105 for oxygen, 40 of CO2

57

Why are air pressures of O2 and CO2 different from alveolar pressures?

Because of diffusion in the pulmonary capillaries

58

What are three factors that determine the precise value of alveolar PO2?

PO2 of atmospheric air (decreased causes decrease); rate of alveolar ventilation (decreased causes decrease); rate of oxygen consumption (increased causes decrease) assuming only one factor changes at a time

59

What is hypoventilation?

When alveolar ventilation can't keep up with CO2 production: increase in PCO2

60

What is hyperventilation?

When alveolar ventilation is too great for CO2 production; decrease in PCO2

61

What is the major disease-induced cause of inadequate oxygen movement between alveoli and pulmonary capillary beds?

Ventilation-perfusion inequality

62

What is the major effect of ventilation-perfusion inequality?

To lower the PO2 of systemic arterial blood

63

Why is the PO2 of blood in circulation normally about 5 mmHg less than that of average alveolar air?

Because gravity causes a different blood flow distribution in the lung, which contributes to ventilation-perfusion inequality, which reduces PO2

64

What is shunt?

Blood flow to an area without ventilation

65

What is the main homeostatic mechanism to avoid ventilation-perfusion inequality for low ventilation and low perfusion?

When there is low alveolar PO2 (due to decrease in ventilation), the vessel vasoconstricts and directs blood elsewhere to properly ventilated areas; of when there is low alveolar PCO2, the bronchioles constrict and direct airflow elsewhere

66

What is hemoglobin?

Four subunits made of one polypeptide and one heme each (a globin and four heme groups); heme groups contain iron for cooperative binding to oxygen

67

What is percent hemoglobin saturation?

(O2 bound to Hb) / (maximal capacity of Hb to bind to O2) x 100

68

What factors determine the % Hb saturation?

Blood PO2

69

What is the oxyhemoglobin dissociation curve?

The experimentally determined quantitative relationship between blood PO2 and the combination of oxygen with hemoglobin; sigmoid because of cooperative binding

70

What is the approximate shape/range of the oxyhemo dissoc curve?

Steep slope from 10-60 mmHg, plateaus at 70-100 mmHg PO2; **at a PO2 of 60 mmHg, 90% hemoglobin saturation

71

What is the biological significance of the plateau in the oxyhemo dissoc curve?

Safety net! Even if atmospheric PO2 decreased from 100 to 60 mmHg, total hemoglobin saturation would only decrease by 10% or so

72

What is the biological significance of the steep slope of the oxyhemo dissoc curve?

Allows for easy unloading of oxygen: small PO2 changes can lead to a big decrease in hemoglobin saturation

73

How does temperature affect the OHD curve?

Increased temperature shifts the curve right: makes it more difficult to unload oxygen

74

How does acidity affect the OHD curve?

Increased acidity (lower pH) shifts the curve right: makes it more difficult to unload oxygen

75

How does DPG concentration affect the OHD curve?

Increased DPG concentration shifts curve right: makes it more difficult to unload oxygen

76

How does PCO2 affect the OHD curve?

Increased PCO2 increases H+ concentration, which increases acidity: shifts curve right: lowers affinity of Hb for O2

77

How do CO2 and H+ affect hemoglobin's affinity for oxygen?

Allosterically modulate the globin

78

How does DPG affect Hb's affinity for oxygen?

DPG = released during glycolysis (only respiration for RBCs, so lots of DPG in RBCs); allosterically modulates Hb

79

Which is more soluble in water, CO2 or O2? Why is this important?

CO2: blood carries more dissolved CO2 than dissolved O2

80

How is CO2 transported in the blood?

Some by dissolving, some by binding with Hb to form carbaminohemoglobin, and most converted to bicarbonate and hydrogen ions by carbonic anhydrase

81

What is carbaminohemoglobin?

When CO2 binds to Hb (deoxyhemoglobin, which has a higher affinity for CO2 than for O2, than does HbO2)

82

Why is it important that the chloride-bicarbonate exchange removes HCO3- from the RBC?

So that the reaction still favors dissociation of bicarbonate

83

Why is venous blood slightly more acidic than arterial blood?

Because dissociation of bicarbonate produces H+, which binds to deoxyhemoglobin, but there's still some left: decreases the pH (more acidic)

84

What is associated with hypo/hyperventilation, respiratory acidosis or alkalosis?

Acidosis associated with hypoventilation, alkalosis associated with hyperventilation

85

What initiates nerves impulses to the respiratory skeletal muscles?

Medulla oblongata activity: in medullary respiratory center

86

What are the two components of the medullary respiratory center?

The dorsal and ventral respiratory groups (DRG and VRG)

87

What is the DRG?

Primarily fire during inspiration; input to spinal motor neurons that activate inspiratory muscles: diaphragm and inspiratory intercostal muscles

88

What is the nerve that innervates the diaphragm?

Phrenic nerve

89

What is the VRG?

Rhythm generator: pacemaker cells and complex neural network that sets basal respiratory rate; respiratory rhythm generator located in the pre-Botzinger complex in the upper VRG; nerves in lower half that fire for inspiration AND expiration

90

What is the upper half of the VRG?

Rhythm generator in the pre-Botzinger complex; pacemaker cells; inspiratory neurons (input from DRG inspiratory neurons, from respiratory rhythm generator; output to inspiratory motor neurons)

91

What is the lower half of the VRG?

Expiratory neurons: important for large increases in ventilation like in exercise: active expiration through contraction

92

How is medullary inspiratory nerve activity modulated?

By the pons: apneustic center in lower pons, pneumotaxic center in uppon pons

93

What is the apneustic center?

In the lower pons: modulates medullary inspiratory activity, inhibitory to end inspiration

94

What is the pneumotaxic center?

In the upper pons: modulates apneustic center; smooths transition between inspiration/expiration

95

What are pulmonary stretch receptors for?

Cutting off inspiration: activated by large lung inflation: afferent nerve fibers send action potentials to inhibit medullary inspiratory neuron activity

96

What is the Hering-Breuer reflex?

When afferent nerve fibers from stretch receptors send action potentials to the brain to inhibit medullary inspiratory behavior and end inspiration; BUT only under conditions of large TV like during exercise

97

What are peripheral chemoreceptors for respiration?

Located in neck by common carotid arteries and in thorax on aortic arch: carotid bodies and aortic bodies (distinct from carotid and aortic baroreceptors); stimulated by decrease in arterial PO2 or increase in H+; provide excitatory input to medullary respiratory systems

98

What are the central chemoreceptors for respiration?

Located in medulla oblongata; provide excitatory input to medullary respiratory systems; stimulated by increase in H+

99

Why do changes in PCO2 trigger ventilation control reflex?

Mostly through increases or decreases in H+ concentration, which is detected by the central chemoreceptors and dealt with accordingly

100

Which chemoreceptors respond to H+ concentration changes, peripheral or central?

Peripheral for metabolic acidosis/alkalosis (not caused by CO2 changes), and central for respiratory acidosis/alkalosis (caused by CO2 changes)

101

How does H+ concentration affect chemoreceptor activity?

Increase in H+ increases chemoreceptor activation of medullary respiratory neurons, which increases respiration

102

What is associated with hyper/hypoventilation, metabolic alkalosis or acidosis?

Metabolic acidosis triggers hyperventilation (reduces arterial PCO2, so H+ back to normal); metabolic alkalosis triggers hypoventilation (increases arterial PCO2, so H+ back to normal)

103

Why doesn't arterial PCO2 increase during exercise?

Because arterial PCO2 depends on alveolar PCO2, and alveolar PCO2 depends on ratio of CO2 production to alveolar ventilation: ventilation increase proportionally with CO2 production during exercise, so no increase in alveolar PCO2

104

What is the limiting factor in strenuous exercise, ventilation or cardiac output?

CO: ventilation can increase enough to maintain PO2

105

Why is lactic acid partially responsible for hyperventilation during exercise?

Because it increases blood H+ concentration, which triggers the peripheral chemoreceptors to innervate the medullary inspiratory neurons to increase ventilation

106

How do J receptors act as a protective respiratory reflex?

In capillary walls/interstitium: stimulated by increase in lung interstitial pressure cased by fluid collection: rapid breathing, dry cough

107

What are the four kinds of hypoxia?

Hypoxic hypoxia (hypoxemia); anemic hypoxia (CO hypoxia); ischemic hypoxia; histotoxic hypoxia

108

What is hypoxic hypoxia?

Hypoxemia: arterial PO2 reduced

109

What is anemic hypoxia?

CO hypoxia; arterial PO2 normal but total oxygen content of blood is reduced because of inadequate numbers of RBCs, deficient Hb, or CO poisoning

110

What is ischemic hypoxia?

Blood flow to tissues is too low

111

What is histotoxic hypoxia?

Normal quantity of oxygen to tissues, but cell can't use it properly because of toxic agent interference

112

What is hypercapnea?

Increased retention of CO2 that leads to increased arterial PCO2

113

Why does ventilation-perfusion inequality affect O2 more than CO2?

Because of the oxyhemo dissoc curve: increasing ventilation doesn't really increase PO2 because of the curve, so PO2 remains low (hypoxia); but CO2 is linear: poor ventilation does increase PCO2, but then increased ventilation brings it right back down again