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Engelking Phys Review > Section3.Respiratory Physiology > Flashcards

Section3.Respiratory Physiology Flashcards

1
Q

What is the approximate normal oxygen tension (PO2) of fetal umbilical venous blood leaving the placenta?

A

30 mmHg

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2
Q

What are the reasons for low oxygen tension to the fetus?

A
  1. distance between maternal and fetal blood is almost 10 times the distance across alveolar membranes of the lung
    2.the total surface area of the mature placenta is many times less than the area of the pulmonary membranes
  2. both maternal and fetal arteriovenous shunts prevent blood on both sides from being fully exposed to placental membranes for gas exchange
  3. the placenta itself consumes 10 to 30% of the oxygen supply
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3
Q

Regarding the number and dimensions of alveoli in the adult lung compared to the neonatal lung :

A

following birth there is normally an increase in both the number and diameter of lung alveoli

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4
Q

The law of laplace tells us:

A

THe pressure exerted by teh surface tension of a bubble in a liquid is:
P= 2T/ r
T=surface tension
r=bubble radius

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5
Q

Production of pulmonary surfactant is stimulated by:

A

catecholamines
glucocorticoids

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6
Q

Function of pulmonary surfactant?

A

reduces surface tension of wate rin proportion to its concentration at teh surface

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7
Q

The respiratory act of moving gas in and/or out of the lungs is fundamentally:

A

a neural and voluntary neuromuscular function

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8
Q

Define eupnea

A

normal, quiet respiratory that occurs at rest and is ordinarily carried out without the organism being aware of it

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9
Q

Define tidal volume

A

volume of air that enters and leaves the lung at each natural respiratory effort at rest or in other states

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10
Q

Define inspiratory reserve volume

A

volume of air that can be taken in by a maximal inspiratory effort over and above the inspired tidal air

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11
Q

Define expiratory reserve volume

A

volume of air that can be expelled by the most powerful additional expiratory effort after the tidal air is allowed to escape naturally

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12
Q

Define vital capacity

A

sum of tidal air and inspiraotry and expiratory reserves

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13
Q

Define residual volume

A

volume of air remaining within the lungs after the strongest possible expiration

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14
Q

Define total lung capcity

A

the sum of vital capacity and residual air

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15
Q

Define inspiratory capacity

A

the voluem ofa ir that can be inspirared from the end-expiraotry level

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16
Q

Respiratory minute volume

A

product of tidal volume and frequency of respiration per minute

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17
Q

What factors make up airway resistance?

A

diameter and length of respiratory airways
-nature of gas breathed
-factors affecting the viscosity and density of the gas
turbulence factors assoc with high velocities of gas movement

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18
Q

The energy cost of breathing during modest to heavy exercise is normally about what percentage of the total energy work rate of the animal?

A

3%

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19
Q

Approximately what percentage of normal tidal volume is dead space air?

A

30%

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20
Q

What is the normal transit time for a red blood cell through a pulmonary capillary bed (at rest), and how soon does the hemoglobin contained within it become oxygenated?

A

<1 second
0.25seconds

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21
Q

The diffuse capacity of CO2 in bodily fluids is how many times greater than that for O2?

A

20 times greater

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22
Q

What is normal ventilation/perfusion ratio throughout the long (top to bottom)?

A

Top: High V/P ratio

Bottom: Low V/P ratio

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23
Q

What is the normal venous admixture, including the components of true anatomic shunt and the influence of disproportionate alveolar ventilation and blood flow, is approximately:

A

2% of cardiac output

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24
Q

What percentage of oxygen is transported from lungs to tissues is normally carried in chemical combination with erythrocytic hemoglobin?

A

97%

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25
Q

What remaining percentage of oxygen, not carried by erythrocytic hemoglobin, is carried in what form?

A

3% carried in dissolved state in water of plasma and cells

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26
Q

What is carboxy-hemoglobin?

A

carbon monoxide combined with hemoglobin

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27
Q

What is carbaminohemoglobin?

A

CO2 in combination with hemoglobin

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28
Q

What percentage of CO2 is transported as carbaminohemoglobin?

A

20%– majority is transported as BICARB

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29
Q

What is the average intracellular PO2?

A

23 mmHg
range: 5 to 40 mmHg

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30
Q

What is the average intracellular PCO2?

A

46 mm Hg

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31
Q

Hemoglobin molecule normally combines with oxygen in the ratio of about

A

1.34 ml O2/gm Hgb

32
Q

What is the Haldane effect (left-shift of oxyhemoglobin dissoc curve)

A

as blood passes through pulmonary capillaries, CO2 diffuses from blood to alveoli, thus reducing blood PCO2 and H concentration

33
Q

What effect occurs (opposite of the Haldane effect), when blood reaches tissue capillaries?

A

Bohr effect: CO2 entering blood from tissue shifts the oxyhemoglobin dissociation curve to the right, which displaces O2 from Hgb, thereby delivering O2 to tissues at a higher rate

34
Q

Which electrolyte normally exits erythrocytes of tissue capillary beds?

A

HCO3

I**exchange for Cl- (chloride shift)

35
Q

What cellular components are adult RBCs missing?

A

nucleus
mitochondria
lysosomes
endoplasmic reticulum
Golgi apparatus

36
Q

Hemoglobin from red blood cells are broken down into what products?

A

globin, heme and iron

37
Q

Erythrocytes that have defective glucose-6-phosphate dehydrogenase (G-6-PD), would:

A

be susceptible to oxidative stress

38
Q

Oxygen can be toxic to the body if its converted to substances known collectively as

A

superoxides

39
Q

What is a copper containing enzyme that is present in all aerobic tissues as well as erythrocytes?

A

Superoxide dismutase

40
Q

Erythrocyte methemoglobin reductase utilizes

A

NADH, thus regenerating NAD for continued glycolysis
**generated during anaerobic glycolysis

41
Q

Methemoglobin is

A

an inactive form of hemoglobin (Hb) in which the iron is oxidized form the ferrous (Fe++) to ferric (Fe+++) state by superoxides (O2-)

42
Q

erythrocytic 2,3-bisphosphoglycerate (or 2,3 DPG) formation by a mutase enzyme in erythrocytes occurs via

A

Rapoport shunt

43
Q

What is the most important function of 2,3 DPG?

A

to combine with Hb, causing a decrease in its affinity for oxygen and a displacement of the oxy-Hb dissociation curve to the right
**effectively unloads O2 from Hb, allowing it to diffuse into tissues where it is needed

44
Q

Activity of which enzyme is directly proportional to the aging of erythrocytes?

A

Hexokinase
**lose their capacity to oxidize glucose

45
Q

What are normal breakdown production of hemoglobin?

A

carbon monoxide
iron
amino acids (from break down of globin)
biliverdin

46
Q

The diaphragm is innerved by

A

phrenic nerves from cervical segments 3, 4, 5

47
Q

Which muscle (or muscles) is/are the most important for expiration during mild exercise?

A

Abdominal wall muscles

48
Q

What are things that increase/decrease lung compliance?

A

reduced: inc pulmonary venous pressure (lung engorged with blood), alveolar edema, lung remains unventilated for a long period of time, fibrosis
INC compliance: old age and emphysema

49
Q

What is the mechanical efficiency of normal respiration in air-breathing mammals (ie, resp work performed/unit O2 req for work, or O2 cost/liter of gas moved) is approximately what percentage?

A

8%

50
Q

In normal exercise, the cost of breathing is what percentage of total energy expended by the animal?

A

3%

51
Q

Where is the voluntary neural system for respiratory control located?

A

cerebral cortex
autonomic system is located in the medulla an dpons

52
Q

Motor fibers to inspiratory muscles are

A

normally inhibited, while those to expiratory mm are active (and vice versa)

53
Q

Since nerve fibers mediating inspiration converge on phrenic motor neurons, breathing stops:

A

when the spinal cord is transected above the origin of the phrenic nerves

54
Q

What is the pre-Bottzinger complex of neurons?

A

a group of medullary pacemaker neurons in the brain stem that produces rhythmic discharge in phrenic motor neurons of inspiration
**generator neurons that control respiratory rhythm

55
Q

The pneumotaxic center plays a role in

A

switching between inspiration and expiration

56
Q

What occurs when vagal nerves are cu tin anesthetized animals, what occurs?

A

there are prolonged inspiratory spasms that resemble breath holding (apneusis)

57
Q

Where is the apneustic center located?

A

-in the pons
-when stimulated can exert an excitatory effect upon inspiration

58
Q

Affective stages such as rage and fear can affect breathing. Reasons for this are that:

A

other parts of the brain besides the medulla and pons can alter the pattern of breathing

59
Q

Glomus cells in the carotid are sensitive to

A

dec PaO2, INC paCO2 and acidemia (INC H) and hemorrhage

60
Q

Medullary chemoreceptors response direct to

A

the presence of H (mediate hyperventilation produced by INC paCO2)

61
Q

Which of the following has the greatest difficult crossing the blood-brain-barrier (BBB)?
HCO3, H, CO2, O2, H20

A

H

62
Q

Which acid/base disturbance has the greatest effect on stimulating respiratory drive through medullary chemoreceptors?

A

acute respiratory acidosis

63
Q

Metabolic acid/base disturbances generally evoke same/opposite changes in the pH of CSF and blood, while respiratory disturbances bring about same/opposite changes?

A

Metabolic acid/base disturbances generally evoke opposite changes in the pH of CSF and blood,

while respiratory disturbances bring about same (parallel) changes

64
Q

When a resting animal falls asleep, what changes in respiration?

A

alveolar ventilation decreases
arterial PO2 falls
PaCO2, HCO3, H INC

65
Q

Give examples of substances that cause bronchial constriction?

A

acetylcholine
histamine
leukotrienes
sulfur dioxide

66
Q

Type II alveolar epithelial cells secrete

A

pulmonary surfactent

67
Q

Mucous in the respiratory passages is produced by:

A

goblet cells
small submucosal glands

68
Q

Cilia of the respiratory tract beat continually in what direction?

A

cilia stroke upward toward the pharynx

in the nose stroke downward

69
Q

List protective mechanisms of the pulmonary tract?

A

-secretory IgA from nasal mucosa and upper airways
-secretory IgG from the lower airways
-cytotoxic lymphs and macros in the interstitium and bronchus associated lymphoid tissue
-alveolar macros

70
Q

Angiotensin II is activated where?

A

by ACE in the lungs

71
Q

In the resting state, blood normally becomes fully oxygenated during transit through which fraction of the pulmonary capillary bed?

A

the First 1/3 of the pulmonary capillary bed

72
Q

What is the primary cause of muscle fatigue during exercise?

A

proton H accumulation

73
Q

What is the effect of the increase in protons (H), affect the function of skeletal muscle function?

A
  1. lowers the Vmax of phosphofructokinase, a key affect the function of skeletal muscle in a number of ways
  2. it reduces the release of Ca from the sarcoplasmic reticulum, as well ass the activity of myosin ATPase
  3. it detrimentally affects the conformation of contractile proteins
74
Q

define apnea

A

absence of breathing

75
Q

The Hering Breuer reflex produces apnea in response to

A

large lung inflations and facilitates expiration

**weak in adults, strong in newborns

76
Q

Describe Cheyne-stokes breathing

A

respiration characterized by respiratory efforts that are first weak, but become successively stronger until definite hyperpnea is present
**breathing then gradually diminishes ot hte point of apnea

Engelking Phys Review (5 decks)

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