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From Flashcardlet > PHYSIOL [D] > Flashcards

PHYSIOL [D] Flashcards

0
Q

define respiration

A

process of burning of glucose for energy (cellular level)

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1
Q

define “breathing”:

A

process of getting gas in and out of your lungs

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2
Q

via what process do cells and tissues(cells) get nutrients?

A

diffusion

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3
Q

what is “Fick’s” law?

A

that gas moves from high -> low concentration

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4
Q

what does Fick’s law depend on?

A
  • gradient (ΔC)
  • permeability of membrane (P)
  • area (A)
  • molecular weight (MW)
  • distance (D)
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5
Q

what is the equation for Fick’s law?

A

ΔC x P x A
net rate of diffusion = —————-
MW x D

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6
Q

problem with multi-cellular organism & nutrient diffusion?

A

cells in the middle(further away) too far from air, just diffusion process alone not sufficient

…solution? transfer system!

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7
Q

how long does it take for one RBS to go through your circulation?

A

1 minute

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8
Q

how many branches are there in the conducting airways?

A

28

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9
Q

within conducting pathways where does exchange actually occur?

A

end of branches in the alveolus

no exchange occurs along pathways - this is “dead” space

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10
Q

what part of the respiratory tract are reinforced with cartilage?

A

trachea

bronchi

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11
Q

what are the non-respiratory functions of the respiratory system?

A
  • enhances venous return(cardiac suction pump)
  • contributes to normal acid-base balance(CO2)
  • enables vocalisations
  • defends against inhaled foreign matter
  • excretes some drugs(ethanol, anaestetics)
  • route for water and heat eliminations
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12
Q

partial pressure:

A

in a mix of gases each component behaves separately

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13
Q

how do you calculate the partial pressure of one component of gas?

A

conc.(%) of that gas x total pressure

eg. AIR! oxygen = 21% nitrogen = 79%
total pressure @ sea level = 760mmHg
partial pressure of O2 = 0.21 x 760 = 150mmHg

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14
Q

how would the % composition change at everest?

A

% stays the same!

partial pressure is what changes

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15
Q

how to calculate transmural pressure across lung wall?

A

intra-alveolar pressure - intra-pleural pressure

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16
Q

how to calculate transmural pressure across thoracic wall?

A

atmospheric pressure - intra-pleural pressure

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17
Q

what is the intra-alveolar pressure @ rest?

A

760mmHg same as atmospheric!

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18
Q

what is the intra-pleural pressure?

A

slightly lower! 756mmHg

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19
Q

what nerve innervates the diaphragm?

A

phrenic nerve

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20
Q

what nerve innervates the external intercostal muscles?

A

intercostal nerve

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21
Q

what is enlargement of thoracic cavity during quiet respiration due to?

A

75% enlargement is due to contraction and flattening of the diaphragm

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22
Q

describe effects of thoracic expansion on pressures in lung:

A

decreases intra-pleural pressure (down to 754)

  • > lungs drawn into area of low pressure
  • > increase volume
  • > decrease in intra-alveolar pressure
  • > below atmospheric pressure => air enters lungs due to pressure differences
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23
Q

contraction of external intercostal muscles?

A

“bucket handle” elevation of ribs

=> increases side to side dimension of thoracic cavity

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24
Q

steps in onset of expiration?

A

1) relaxation of diaphragm & muscles of chest wall, elastic recoil of alveoli, decrease in size
2) intra-pleural and alveolar pressure increases
3) above atmospheric => air driven out

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25
Q

how can forced expiration occur?

A

contraction of expiratory muscles
what muscles?
skeletal muscles in abdominal wall and internal intercostal muscles

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26
Q

negative pressure ventilator?

A

atmospheric pressure reduced

=> inspiration

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27
Q

positive pressure ventilator?

A

air pumped in and out of trachea directly

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28
Q

major determination of resistance in respiratory tract?

A
  • radius of conducting airways
  • autonomic NS controls smooth muscle in walls of bronchioles
  • > changing radii
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29
Q

diseases with increased resistance?

A

chronic obstructive pulmonary disease

asthma -> obstruction of airways

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30
Q

define compliance:

A

effort required to stretch or distend the lungs
=> high compliance
=> lung stretches further

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31
Q

what tends to COLLAPSE alveolus?

A

surface tension of water

and elasticity of membranes

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32
Q

why don’t alveoli collapse?

A

1) properties of surfactant (diagram 3 sperm pushing out to every one water pushing in)
reduces tension more as area decreases molecules are more crowded
2) alveolar inter-dependence “supports” individual alveoli

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33
Q

normal volume of quiet breathing cycle?

A

500ml inspired and expired

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34
Q

define Tidal Volume:

A

the air entering or leaving the lungs in a single breath

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35
Q

define inspiratory reserve volume?

A

extra air that can be maximally inspired over the typical resting TV

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36
Q

define inspiratory capacity?

A

max volume of air that can be inspired at the end of a normal quiet expiration

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37
Q

define expiratory reserve volume?

A

extra volume of air that can be actively expired by maximal contraction beyond the normal volume of air after a tidal volume

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38
Q

define vital capacity?

A

max volume of air that can be expired following a max inspiration

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39
Q

what is max and min volume of lungs?

A

lungs not completely emptied
max = 5,700ml
min = 1,200ml

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40
Q

normal volume of dead space?

A

150ml - will remain in dead space

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41
Q

volume/proportion of old/new air to reach alveoli each breath?

A

500ml total
350ml fresh air
150ml old air from dead space(left over from preceding expiration)

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42
Q

how is pulmonary ventilation calculated?

A

PV = TV x RR

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43
Q

how is alveolar volume calculated?

A

AV = (TV - DS) x RR

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44
Q

what is the PO2 in atmosphere?

A

21% x 760mmHg = 160mmHg

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45
Q

what is the PO2 in airways?

A

21% x (760 - 47) = 150mmHg

this is minus the water vapour pressure

46
Q

what is the PO2 in alveoli?

A

around 100

PAO2 balance between addition from ventilation and removal by diffusion

47
Q

At peak volume describe alveolar and atmospheric pressures:

A

alveolar pressure = atmospheric pressure

48
Q

what does the bohr effect do to the O2 supply

A

increases the O2 supply to tissues

49
Q

what is hyperventilation?

A

breathing too much!

-> blows off too much CO2, CO2 stimulates body to breath more

50
Q

what happens to PAO2 and PACO2 during hyperventilation?

A 
PAO2 = increases
PACO2 = decreases (breath out more CO2 than take in)
51
Q

what is the role of surfactant?

A

acts as detergent that reduces surface tension in the alveoli

52
Q

what is the PAO2 and PACO2 composition of health air?

A 
PAO2 = 100mmHg
PACO2 = 40mmHg
53
Q

how is the PAO2 of a person with anaemia(with reduced haem by 25%) affected?

A

PAO2 is normal, partial pressure not effected

O2 carrying capacity of blood will be reduced by about 25%

54
Q

PO2 & PCO2 in atmosphere?

A 
PO2 = 160
PCO2 = 0.03
55
Q

PO2 & PCO2 in alveoli:

A 
PO2 = 100
PCO2 = 40
56
Q

what is the O2 and CO2 partial pressure gradient in the circulatory system?

A 
O2 = 100-40 = 60
CO2 = 40-46 = 6
57
Q

what is the amount of oxygen dissolved in plasma proportional to?

A

partial pressure

58
Q

in dissolved form how much oxygen does normal arterial blood contain?

A

0.3ml O2/100ml

so 0.3%

59
Q

how much O2 does 1g of Hb combine with?

A

1g Hg -> 1.39ml O2

60
Q

how many g of Hg per 100ml of blood?

A

15g per 100ml

61
Q

what is O2 capacity of normal blood?

A

15g(Hg per 100ml) x 1.39ml(O2 per g Hg) = 20.8ml O2/100ml blood

therefore 20.8%

62
Q

what factors promote unloading of O2?

A

increase in CO2 from tissue
increase in acidity
higher temperature

63
Q

what does the bohr effect do to the dissociation curve?

A

shifts curve to the right

64
Q

difference between Hg affinity to CO and O2?

A

affinity of Hb for CO is 240 times its affinity of O2

65
Q

what happens to the blood of someone who moves to high altitude for a few months?

A

chronic hypoxia -> erythropoietin release

= more blood cells

66
Q

what is the blood content of an anaemic subject who has low [Hb] at sea level?

A
  • normal PAO2
  • normal Hb saturation (97.5%)
  • decreased total O2 content
67
Q

how is CO2 transported in blood(include percent):

A

physically dissolved: 10
bound to hemoglobin: 30
as bicarbonate (HCO3-): 60

68
Q

what is the bicarbonate formula?

A

H+ + HCO3- <–> CO2 + H2O

increase in H+ increase in acidity
increase in

69
Q

how does the plasma membrane of the erythrocyte facilitate diffusion of bicarbonate ions and chloride ions?

A

by the chloride shift passively facilitates diffusion

70
Q

what us Hypercapnia?

A

excess of CO2 in the blood caused by hypoventilation

71
Q

what is Hypocapnia?

A

below normal arterial level of CO2 in the blood, due to hyperventilation

72
Q

what is Hyperpnea?

A

increased need for oxygen delivery and CO2 elimination during exercise

73
Q

what provides rhythmic activity to breathing?

A

motor nerves innervating diaphragm

and external intercostal muscles

74
Q

location of motorneurons innervating diaphragm?

A

in spinal cord receiving descending input from medulla

75
Q

what are the neurons in medulla that connects to phrenic nerve?

A

DRG neurons - drive inspiration by firing

- drive expiration by not firing

76
Q

where does the rhythm of breathing come from?

A

Boltzinger complex

77
Q

role of higher control center in breathing?

A

pons

act to produce smooth coordinated breathing

78
Q

what occurs if higher breathing control centers eg. pons are damaged?

A

breathing occurs in gasping pattern - rhythm fucks up

79
Q

how are blood gas PCO2 and PO2 monitored?

A

2 receptor systems

1) peripheral chemoreceptors
2) central chemoreceptors

80
Q

where are the peripheral chemoreceptors located?

A

carotid bodies and aortic arch

81
Q

where are the central chemoreceptors located?

A

in the medulla

82
Q

what are peripheral chemoreceptors sensitive to and why?

A

PCO2 - “life-savers” NOT PO2
as there is a large safety margin for O2 binding to Hb
small drop would not be noticeable

83
Q

what are the central chemoreceptors sensitive to?

A

depressed by severe lack of oxygen

VERY sensitive to to PCO2

84
Q

what is the relationship between partial pressure of CO2 in alveoli(PAO2) and ventilation?

A

inversely proportional

so if persons breathing is suppressed PAO2 will rise in precise relation to the depression of their ventilation

85
Q

what are central chemoreceptors actually sensing?

A

actually sensing pH change

H+ + HCO3- <–> CO2 + H2O

SENSING THE H+ ACIDITY LEVELS

86
Q

what do peripheral chemoreceptors do?

A

respond to pH(H+ concentration) of blood

regulate acid-base balance by altering amount of CO2 “blown off”

87
Q

why does ventilation increase during exercise??

A

temperature?
reflexes from body movements?
adrenaline response?
input from higher brain centres? motor cortex?

88
Q

why is it vital to maintain clean lungs?

A

blood is only a micron away from alveoli => most lung diseases are result of breakdown/by-pass of lung defences

89
Q

where do inhaled particles end up?

A
  1. deposited in respiratory tract => disease process begins
  2. exhaled in next breath
  3. large particles lodged in nose
  4. smaller particles that make it through the nose/mouth settle out in small-diameter bronchioles => trapped by mucus lining
90
Q

what is the main factor affecting movement of smallest particles?

A

diffusion, may carry them into the alveoli

91
Q

why isn’t rate of air flow affecting movement of smallest particles?

A

rate of airflow decreases as gas moves closer to alveoli

92
Q

after what part of the respiratory tract does the cross sectional area dramatically decrease?

A

terminal bronchioles

93
Q

what is sneezing caused by?

A

irritation of mechanoreceptors in nasal mucosa

94
Q

steps in sneezing reflex?

A
  1. deep inspiration
  2. glottis closed, expiratory muscles contract forcefully against closed glottis
  3. open -> pressure(intra-thoracic) forces air out
95
Q

what is coughing caused by?

A

presence of foreign particle or liquid in larynx

96
Q

steps in coughing reflex?

A
  1. forced expiration against closed glottis, collapse of medium airways, sides touch - mucus meniscus stretches across airways
  2. as you cough, mucus and other particles are blown towards mouth
97
Q

what drugs suppress the cough reflex?

A

alcohol @ blood conc. 0.08%

narcotics eg. codeine & morhine => increase risk of vom in intoxicated people

98
Q

what are some non-neural defence mechanisms?

A

muco-cilary system

thickness of mucus film in healthy humans = 5-10 um thick

99
Q

how much mucus do healthy people secrete every day?

A

7-21ml/day

100
Q

what does secreted mucus bind?

A

large quantities of water
forms stringy fibres
elastic recoil

101
Q

what are the 2 layers of broncial mucosa?

A
  1. sticky layer

2. fluid layer (containing beating cilia)

102
Q

difference between beating cilia in airway tubes and nasal?

A 
airway = beat "UPWARDS"
nasal = beat "backwards" towards pharynx
103
Q

how often is bronchial mucosa cleared?

A

every 24 hours

104
Q

how often is nasal mucosa cleared?

A

every 10-15 mins

105
Q

why is clearing of mucosa important?

A

as inflammation of mucosa may kill cilia

106
Q

what is chronic bronchitis?

A

number of cilia greatly reduced

rate of mucus production greatly increased => overloading of muco-cilary “escalator => risk of pneumonia

107
Q

describe cellular defense:

A

lungs = macrophages and leukocytes

engulf particulate matter and carry it to the muco-cilary excalator for removal from lungs

108
Q

what happens when one particular part of the lungs decreases ventilation?

A
  • > decrease of alveolar O2
  • > vasoconstriction (reduce blood flow to that part of lung and redirects flow to parts that work better)
  • > increase CO2 relaxes bronchioles attempt to increase circulation
109
Q

describe distribution of blood flow in lung:

A 
APEX = low blood flow 
BASE = high blood flow

why? gravitational - this can change with posture & exercise

110
Q

describe ventilation in lung?

A

more ventilation lower and less ventilation in the upper area

as top cannot stretch as much…think of slinky diagram

111
Q

what would save your life when oxygen is low?

A

peripheral receptors

112
Q

what would be the effect on the dissociation curve on everast?

A

same shape, stops at around 50 PO2

113
Q

changes in partial pressure gradients in circulation?

A

PO2: 100 -> 40
PCO2: 40 -> 46

From Flashcardlet (34 decks)

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