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Respiratory > Respiratory physiology - ventilation and perfusion > Flashcards

Respiratory physiology - ventilation and perfusion Flashcards

1
Q

Does there have to be a pressure gradient for air to be drawn into the lungs

A

yes

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2
Q

how is respiratory Air flow determined

A

by the pressure difference between the mouth and the alveoli ( in the lungs)
has to be a difference either increase p1 or decrease p2

flow results from either an upstream rise ( positive pressure breathing) or a downstream fall in pressure ( negative pressure breathing)

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3
Q

what is positive pressure breathing

A

increase P1 at the mouth - creating positive pressure in relation to the lungs therefore forcing air in

assisted breathing

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4
Q

what is negative pressure breathing

A

Decrease P2 relative to the atmosphere so you create gradient drawing air in

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5
Q

what is normal ATM

A

750mmHg

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6
Q

when you increase the pressure inside the lungs to create gradient and force air out
what is happening

A

expiration

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7
Q

Pip

A

inter pleural pressure ( intrathoracic pressure)

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8
Q

Palv

A

Alveolar pressure - pressure inside the alveoli

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9
Q

Ptp

A

transpulmoanry pressure (Palv-Pip=Ptp)

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10
Q

Patm

A

atmospheric pressure - pressure around us

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11
Q

what happens in the mechanism of inspiration

A

inspiratory muscles contract
diaphragm goes flat
ribs up and out increasing thoracic cavity size

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12
Q

what process
alveolar vol increase
Palv decrease
difference in pressure between alveolar and atm

inspriaotry muscles contract sp Pip more negative so increase difference

A

Inspiration

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13
Q

what happens in the mechanism of expiration

what happens to Ptp

A

inspiratory muscles relax , chest wall decreases and goes down so the space between the two membranes decrease so Pip less negative so decrease ptp

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14
Q

what to fibres are used in expiration in elastic recoils

A

elastin - twice its size

collagen fibres - 2/3 and retain

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15
Q

As we know outer alveoli are affected by the change in inter pleural pressure - this in turn effects the next alveoli along the chain until it reaches the inner depth - what is this called

A

alveolar interdependence

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16
Q

In a pneumothorax the pleural seal is broken - what does this mean

A

negative pressure cannot be generated as ventilation is ineffective , lung collapses - alveoli recoil layers can’t hold

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17
Q

Resistance

A

resistance of respiratory tract to airflow during inspiration and expiration( predominantly expiration)

Affected by diameter of airways

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18
Q

compliance

A

Measure of ability of the lungs to stretch and expand ( distensibility of elastic tissue)

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19
Q

what is an obstructive disorder

A

increasing resistance going from a large entry point to small entry point - reduced diameter

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20
Q

what is a restrictive disease

A

when the ability of expansion s reduced such as fibrosis as thicker lung tissue so have a lower compliance

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21
Q

what is the conduction zone

A

conducts air breathed in that is filtered warmed and moistened by the lungs

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22
Q

if radius is reduced by half what would the resistance be - knowing that r^4

A

16

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23
Q

is resistance predominately an expiratory problem

A

yes

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24
Q

what happens in emphysema

A

Destruction of the alveolar walls → large air spaces that are not cleared of air on exhalation ( air trapping)
Reduced elastic fibres as a result of destruction which then leads to a reduced elastic recoil
Characteristic “barrel chest”
Decreased gas exchange leads to reduced oxygen diffusion so reduced oxygen levels in the blood - blood vessels also destroyed with destruction of alveolar walls
Even mild exercise can cause breathlessness

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25
Q

what can cause emphysema

A

farmers lungs

consistent exposure of irritants - smoke, dust chemicals and irritants and that roofs

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26
Q

what causes the genetic version of emphysema

A

alpha 1 antitrypsin deficiency

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27
Q

Principle Causes of COPD

A

emphysema and chronic bronchitis

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28
Q

what cells secrete surfactant

A

type 2 alveolar cells - lipoprotein

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29
Q

what does surfactant do

A

Lowers surface tension
- increases compliance
- less forces trying to bring the alveoli in making breathing easier
Improves work of breathing

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30
Q

ventilation of alveoli is

A

4-6L/min

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31
Q

pulmonary blood flow of alveoli

A

Co= 4-6L/min
Hr - beats per min
SV is volume of blood ejected duringg each ventricular contraction
CO- amount of blood pumped through circulatory system in one minute

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32
Q

where is the greater ventilation and perfusion occur

A

at the bottom of the lung

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33
Q

does regional V/Q vary and does it have a high impact on gas exchange

A

yes and no

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34
Q

what is it called when no ventilation can reach area but pulmonary arterial blood can

A

shunt

breathe in something

35
Q

when a pulmonary embolism occurs ( travels from somewhere else) and gets lodged you still have ventilation but no perfusion what is this called

A

alveolar dead space

36
Q

Stages involved in supply of oxygen and removal of carbon dioxide

A

Ventilation - gas exchange between atmosphere and alveoli
External respiration - oxygen and carbon dioxide transfer between alveoli and blood
Internal respiration - oxygen and carbon dioxide transfer between blood and tissue
Gas transport - oxygen and carbon dioxide carried in blood between alveoli and tissues
Cellular respiration - oxygen utilization and carbon dioxide production by tissues

37
Q

what is external respiration

A

oxygen and Co2 transfer occurs between alveoli and the blood

38
Q

what is internal respiration

A

oxygen and CO2 transfer is between the blood and the tissues

39
Q

In the upper division of the respiratory tree tidal flow is generated by what 1-16 ( conducting airways)

A

respiratory muscles

40
Q

in alveoli where respiratory exchange occurs and lower division of the respiratory tree 17-32 how is air moved

A

passive diffusion driven by partial pressure gradients

41
Q

daltons law

A

how gases move down their conc gradient by diffusion

42
Q

henrys law

A

how the solubility of a gas relates to its diffusion

43
Q

in daltons law gases move from a higher partial pressure to a lower partial pressure
ATM 750mmHg
PO2 is 157mmHg
where does this occur

A

between alveoli and capillaries
then later on between blood and tissue cells

also atmosphere and lungs

44
Q

partial pressure in solution =

A

partial pressure in gas phase

45
Q

in external respiration - deoxygenated blood goes to oxygenated blood and the diffusion of gas is an independent process
Alveolar air is P02 105mmHg
PCO2 = 40mmHg
what is the partial pressure of oxygen and carbon dioxide in deoxygenated blood coming towards alveoli

A 
PO2 = 40mmHg 
PCO2 = 45mmHg
46
Q

in internal respiration exchange occurs between systemic capillaries and tissue cells - Oxygen-deoxy
As we know oxygenated blood is PO2=100mmHg
PCO2 = 40mmHg
coming from the alveoli
what is its levels in tissue cells

A

PO2=40mmHg

PCO2 = 45mmHg

47
Q

solubility of oxygen in plasma is low only 1.5% what carries oxygen to form Hb-O2

A

oxyhemoglobin

48
Q

How do we measure the partial pressure of oxygen

A

measure the oxygen dissolved in plasma - not carried by Hb

49
Q

Hb is a globin protein made of 4 polypeptides - 2 alpha and 2 beta - it has 4 haemolytic groups which has a porphyrin ring what ion is at the centre attached by 2 bonds ( 1st bond joins with oxygen molecule )

A

Fe2+

binding is reversible

50
Q

when fully saturated how many oxygen molecule does Hb carry

A

4

51
Q

on a O2 -Hb saturation curve which - Indicates that the saturation of Hb depends on the PO2
High PO2 → high saturation of HB from oxyhB
Low PO2 → low saturation of Hb ( Hb + O2)
this sigmoidal curve shows that the initial binding is difficult due to finding it but after a conformational change the next 2 can join - why is binding of the last oxygen so hard

A

full saturation is hard as oxygen has to find the last group

52
Q

how much oxygen can 1g of Hb hold

A

1.34ml

53
Q

At level of pulmonary capillaries what is the level of the partial pressure of O2

A

02 high partial pressur e of oxygen - most bound to HB

54
Q

At level of peripheral capillaries Is partial pressure of O2 low or high and why is this beneficial to the tissue?

A

partial pressure of oxygen is low, saturation of Hb flals rapidly - beneficial for tissue as allows cells to tke up unload O2

55
Q

in tissues that need more O2 the local environment moves the Hb-O2 curve to the right aidning unloading of O2

true or false

A

true

56
Q

what two products increase as a result of tissue metabolism

A

lactic acid and carbon dioxide

57
Q

carbonic acid is the product of water and carbon dioxide

produces what

A

proton and HCO3-

decerases O2 carrying capacity

58
Q

what side does the curve shift to in Bohr effect as tissue environment

A

right

so Hb is less saturated and gives up oxygen more easily

59
Q

what side does the Bohr effect curve shift in the lungs and why

A

left

Hb can more easily bind to molecules of oxygen so more saturated - low Co2 conc environment

60
Q

In the foetus at the level of the umbilical vein which way does the Hb-O2 curve shift and why

A

Up and to the left

oxygen saturation in the placenta is very low compared to maternal blood
Fetus has more Hb than adult and fatal Hb has a higher affinity for oxygen

61
Q

How Is fatal blood more adapted to get oxygen

A

higher affinity for oxygen

More Hb than adult

62
Q

in anaemia what happens to the saturation( PO2 ) and content of the blood

A

the saturation is not affected so the Hb present will still be effectively saturated

content of Hb in blood is halved

63
Q

what does PO2 measure

A

dissolved oxygen

64
Q

Co2 is 25x more soluble than O2 in plasma - but still needs transport systems
Carried in 3 forms

A

Dissolved in plasma
Bicarbonate -generated in RBC
Carbamino compounds - generated in RBC

as Co2 content increases the PCO2 increases

65
Q

In RBC water and CO2 form bicarbonate and move out the cell to maintain electrochemical balance
how do chloride ions move into the cell and HCO3- out

A

chloride shift

buffer effect

66
Q

what is the purpose of the chloride shift

A

exchange of ions that takes place in RBC in order to ensure that no build up of electric change takes place during gas exchange

67
Q

Co2 can also bind to amino groups to from carbamino compound to take up more Co2 from the tissues
what is produced from both this and bicarbonate process that needs to be buffered

A

protons

68
Q

what is the Haldane effect

A

the lower the amount of oxyHb the higher capacity of blood to carry Co2

69
Q

In peripheral tissues Hb give up O2 so increases affinity for CO2 increases so has a greater Co2 carriage
However in the lungs Hb binds to O2 so affinity for Co2 decreases so allows removal of it from blood as Hb given up CO2

true or false

A

true

70
Q

frequency of ventilation is controlled by rthymic activity of autonomic neurones in respiratory centre found where

A

medulla

71
Q

what nerves are involved

A

phrenic and intercostal nerves

72
Q

central chemoreceptors respond to PCO2and mechanoreceptors in muscles and joints all stimulate respiration in response to exercise.
what to peripheral chemoreceptors and baroreceptors do

what cranial nerves control motor autonomic function of peripheral chemoreceptors

A

Baroreceptors stimulate respiration in response to hypotension

Peripheral chemoreceptors ( in aortic and carotid bodies) respond to decreased PO2 , metabolic acidosis

9,10

73
Q

CO2 is the main controller of ventilation - how does this work

A

central chemoreceptors respond to this. The higher the partial pressure of CO2 in blood the more acidic CSF becomes ( BBB) driving up ventilation lowing the partial pressure

74
Q

dependent variable

A

the effect - the one you are measuring

on Y axis

75
Q

independent variable

A

the one you change

76
Q

Hyperventilation leads to lower levels of CO2 also called ?

A

Hypocapnia

77
Q

Hypoventilation increases level of Co2 also called what

A

Hypercapnia

78
Q

pleural reflection

A

where the pleura changes direction

79
Q

visceral pleura( around lungs) is continuation of parietal pleura true or false

A

true

80
Q

medial mediastinum contains the heart true or false

A

true

81
Q

function of intercostal muscles

A

hold ribs in place and assist In inspiration

82
Q

An 8 year old boy comes into the GP with his mother. His mother explains that he gets SOB quite often and sometimes when he breathes out he makes a strange sound.
What is the most likely dx?

A

asthma

obstructive
wheeze

tests vital-graph and peak flow

83
Q
  1. You’re on ward and a really educated patient comes in and tells you that he has an alpha 1 anti trypsin deficiency. What on earth does this mean?
  2. He’s got an autoimmune condition
  3. Gas exchange can’t take place in the alveoli
  4. He has a neurotransmitter problem
  5. He is suffering from hyperinflation of the lungs
  6. He will have peripheral neuropathy
A

4
Alpha 1 antitrypsin usually stops elastin in the lungs being broken down by proteases.

Therefore a deficiency means elastin is broken down and so lungs can’t inflate and come down and stuff –hyperinflation!

Respiratory (22 decks)

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