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respiration > physiology 2/2 > Flashcards

physiology 2/2 Flashcards

1
Q

what circulation provides nutrients to the lungs & where from

A

the Bronchial circulation which is from the systemic circulation to supply smooth muscle, nerves and tissue

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2
Q

what is important about the pulmonary circulation

A

HIGH flow

LOW pressure

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3
Q

what is the O2 and CO2 concentration of the alveoli

A

PO2 = 100mmHg

PCO2 - 40mmHg

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4
Q

what is special about the alveoli gas pressures

A

they become the systemic arterial pressures

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5
Q

how do the gasses diffuse across the membrane

A

down the partial pressure gradient

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6
Q

what is the de oxygenated bloods gas pressure

A

PO2 = 40mmHg

PCO2 = 46mmHg

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7
Q

what is the oxygenated blood gas pressure

A

PO2 = 100mmHg

PCO2 = 40mmHg

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8
Q

what is the symbol V(with a squiggle on top)

A

mixed venous blood

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9
Q

how much blood passes through systemic/pulmonary circulation

A

5 litres

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10
Q

what are the 2 factors that tranaport across a membrane are proportional too

A
  • partial pressure gradient

- directly proportional to gas solubility

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11
Q

at what rate do CO2 and O2 move down their partial pressure gradients

A

CO2 = 200ml/min

O2 = 250ml/min

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12
Q

which gas has a grater partial pressure gradient why is it not bigger

A

Oxygen

CO2 is more soluble

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13
Q

why is the gap between alveoli and capillary so small

A

the alveoli and capillary have fused basement membranes

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14
Q

what are the 4 lung diseased related to gas exchange

A

emphysema
fibrotic lung disease
pulmonary oedema
asthma

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15
Q

what is the ideal ventilation-perfusion rate

A

ideally matching each other

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16
Q

what happens to blood flow and ventilation as you move up the lung - why

A

it decreases

FRC is bigger in alveoli so compresses capillaries

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17
Q

which declines at a faster rate with height

A

blood flow

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18
Q

what is the ventilation-blood flow rate at the bottom vs the apex

A

blood>ventilation

it then switches

ventilation>blood flow

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19
Q

what does the problem of ventilation>blood flow

A

alveolar dead space

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20
Q

what is the problem with blood flow>ventilation

A

shunt

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21
Q

how is shunt combated

A

vasoconstriction of the vessel adjacent to the alveoli with reduced ventilation

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22
Q

what is physiological dead space

A

alveolar dead space + anatomical dead space

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23
Q

how much O2 is dissolved in the plasma

A

3ml per litre of plasma

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24
Q

how much O2 is carried in the haemoglobin

A

197ml per litre

200ml /L in total plasma and Hb

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25
Q

what is arterial partial pressure of O2 referring too

A

its referring to the oxygen in solution this means you can have a normal PaO2 and have low haemoglobin saturation meaning you have low O2 concentration

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26
Q

what is the PaO2 value

what is this known as

A

100mmHg

aka oxygen tension

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27
Q

how much arterial O2 is needed and extracted by peripheral tissue at rest

A

250ml/min

this is only 25% of the arterial O2 created

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28
Q

what determines the saturation of haemoglobin

A

PaO2

the partial pressure of O2 in the blood

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29
Q

how many O2 molecules bind two 1 haemoglobin group

A

4

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30
Q

what is the reaction that is occurring when O2 binds to Haemoglobin

A

oxygenation (tinder shag)

NOT

oxidation (marriage)

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31
Q

what is the most prominent form of Haemoglobin in red blood cells

A

92% of haemoglobin is HbA

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32
Q

how long does Hb saturation take

A

normally 0.25s out of the 0.75 seconds of contact time

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33
Q

what role does Hb play at the alveoli

A

it binds to O2 in the plasma keeping the [atrial pressure gradient across the alveoli until the Hb and plasma are saturated

34
Q

in order of highest affinity what is the order of Hb

what does this mean

A

myoglobin

foetal Hb

normal HB

they require less partial pressure of oxygen

35
Q

what is the saturation of Hb when PaO2= 60mmHg

A

Hb saturation = 90%

36
Q

what is the normal venous PO2 , what is the Hb reserve saturation at this level

A

40mmHg

Hb saturation = 75%

37
Q

what is the definition of anaemia

A

any condition where the oxygen carrying capacity of the blood is compromised

38
Q

what are some causes of anaemia

A

Iron deficiency, haemorrhage, vitamin B12 deficiency

39
Q

what effect does pH have on Haemoglobins affinity for O2

A

alkalosis (7.6) increases O2 affinity

acidosis decreases affinity - exercise muscle releases lactic acid - lower affinity - releases more O2

40
Q

what is the pH of normal blood

A

pH 7.2 so slightly alkali

41
Q

what effect does temperature have on Haemoglobins affinity for O2

A

the higher the temperature the less the affinity for O2 as bond between Hb and O2 becomes denatured

AND VISE VERSA

42
Q

what effect dose an increase in PCO2 have

A

it decreases the affinity of O2 as the increased CO2 produces H+ ions which have the same effect as acidosis

AND VISE VERSA

43
Q

what is 2,3 - DPG

what effect dose it have on O2 affinity

A

it is a intermediate in glycolysis found in RBCs when there is inadequate O2 supply

added 2,3,DPG = less affinity for O2 meaning more is realised to the peripheral tissue when needed

44
Q

what is CO affinity to Hb in relation to O2

A

CO has a affinity of 250 times greater than O2

45
Q

what is the problem once CO is dissolved in the circulation

A

it disassociates from the Hb very slowly

46
Q

what are the symptoms of CO poisoning

A

CHERRY RED SKIN, Hypoxia and anaemia, nausea and headaches

47
Q

what is the respiration rate in someone who has Co poisoning

A

normal due to normal arterial CO2 levels

48
Q

what is the definition of hypoxia

A

inadequate supply of O2 to the tissues

49
Q

what are the 5 main types of hypoxia

A

Hypoxemic Hypoxia - most common - due to bad O2 diffusion at lungs

Anaemic Hypoxia - reduction in O2 carrying capacity

Stagnant Hypoxia - blood not reaching lungs and tissue

histotoxic hypoxia – poison prevents cells using O2 - CARBON MONOXIDE

metabolic hypoxia - O2 not enough for tissue

50
Q

what are the 3 forms of CO2 transport through the blood - what percentage?

A

dissolved in plasma (7%)

CO2 + Hb (23%)

CO2 + water to form carbonic acid - then disassociates to get H+ IONS (70%)

51
Q

what can the creation of carbonic acid by CO2 do

A

control the pH of the extracellular fluid

52
Q

how is normal pH maintained

A

because ALL CO2 produced is eliminated in expelled air

53
Q

what does hypoventilation cause

A

CO2 retention leading to more [H+ ] and respiratory acidosis

54
Q

what does hyperventilation cause

A

blowing off more C)2 leading to decreased [H+] and respiratory alkalosis

55
Q

what muscle type/muscles are stimulated during ventilation

A

skeletal muscles, diaphragm and intercostal muscles

56
Q

what nerves are stimulated during ventilation

A

phrenic nerves and intercostal nerves

57
Q

where is the origin of the phrenic nerve

A

C3,4,5 keep the diaphragm alive

58
Q

where is ventilation controlled

A

in the respiratory centres

59
Q

where are the respiratory centres

A

in the pons and medulla

60
Q

what is the respiratory system modulated by (4)

A

Emotion - via limbic system (brain)

Voluntary over-ride

Mechano-sensory input (from thorax)

chemical input into CHEMORECEPTORS

61
Q

what is the role of the respiratory centres

A

set an autonomic rhythm of breathing and adjust in response to stimuli (CO2, pH …)

62
Q

what are the two types of chemo receptors

A

peripheral and central

63
Q

what is the role of peripheral chemoreceptors

A

carotid and aortic bodies

respond to plasma [H+] (INDIRECT) and PO2

secondary ventilatory drive

64
Q

what is the role of central chemoreceptors

A

in the medulla

respond directly to [H+] in the CSF which directly reflects (PCO2)

PRIMARY ventilatory drive

65
Q

what is the name for raised PCO2

A

Hypercapnia

66
Q

what can/cannot cross the blood-brain barrier

A

CAN - gas and some nutrients

CANNOT - ions

67
Q

how do central chemoreceptors respond to [H+] if ions cannot cross the blood-brain barrier

A

CO2 is able to diffuse through the barrier into the CSF where it forms carbonic then bicarbonate ant H+ ions

these then interact with the central chemoreceptors on the medulla

68
Q

what is hypoxic drive

A

what patients with COPD develop due to chronically elevated levels of PCO2

use secondary ventilatory drive (PO2)

69
Q

when do the peripheral chemoreceptors activate

A

when a significant change in arterial PO2 (PaO2 so in plasma) is recorded

70
Q

what overrides voluntary control of ventilation (i.e. holding breath and voluntary hypoventilation)

A

cant override involuntary stimuli - to get rid of PaCO2

or by a increase in PaO2 (hypoventilation - takes longer)

71
Q

when is respiration inhibited - why

A

during swallowing to avoid aspiration of food or fluid

72
Q

what happens after swallowing

A

a expiration occurs to get small particles (that might have got past the epiglottis) out

73
Q

what do opioids to the respiratory centre

A

suppress it and death occurs due to respiratory failure

74
Q

what dose nitric oxide (NO) do to the respiratory system

A

suppresses the peripheral chemoreceptors to PaO2 - DANGEROUS in HYPOXIC DRIVE (don’t give hypoxic drive)

75
Q

what happens when you get a decrease in PCO2

A

mild bronchial constriction

76
Q

what happens when you get a increase in alveolar PO2

A

pulmonary vasodilation

77
Q

what is O2 solubility in water - why is this important

A

0.03ml/L/mmHg

as we have 3ml of O2 in the plasma it that gives a pressure of 100mmHg

78
Q

what is the major factor that determines haemoglobin saturation

A

the partial pressure of oxygen in arterial blood

79
Q

what is the O2 reserve capacity at normal Venous PO2

A

75%

at PO2 = 40mmHg

80
Q

where fires the signals to the respiratory muscles

A

DRG (DORSAL respiratory group of neurons)

VRG (ventral respiratory group of neurons)

81
Q

what causes a raise in H+

A

a raise in PCO2 = hypercapnia

82
Q

what crosses the blood brain barrier

A

CO2 - which is then converted in to H+

respiration (17 decks)

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