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Physiology of Resp Flashcards

1
Q

what is ventilation/ external resp

A

the mechanical process of exchange of air in atmosphere and of alveoli in lungs

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2
Q

internal resp

A

biochemical reactions

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3
Q

describe inspiration

A

active process

contraction of respiratory muscles

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4
Q

describe expiration

A

passive process

relaxation of respiratory muscles

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5
Q

forces keeping alveoli open

A

surfactant
transmural pressure gradient
Alveolar interdependence

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6
Q

forces keeping alveoli closed

A

Elastic recoil of lungs and chest wall

Alveolar surface tension

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7
Q

what is transmural pressure?

describe the three pressures

A

sub-atmospheric pressure gradient in pleura- keeps alveoli open

atmospheric and intra-alveolar pressures are equal
intrapleural pressure is sub-atmospheric

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8
Q

major inspiratory muscles

A

Diaphragm and external intercostal muscles

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9
Q

accessory muscles of respiration

A

sternocleomastoid
scalenus
pectoral

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10
Q

muscles of active expiration

A

Abdominal muscles

internal intercostal muscle

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11
Q

What is a pneumothorax?

2 methods of how this can occur

A

A build up of air in the intra-pleural space, abolishing the TPG, causing the lung to collapse
Puncture to chest wall or hole in lung

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12
Q

Symptoms and Signs of pneumothorax

A

SOB, pleuritic chest pain
hyper-resonance, reduced chest expansion and chest sounds
small PX can be asymptomatic

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13
Q

Boyle’s Law

A

as the volume of a gas increases, the pressure exerted by that gas decreases

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14
Q

What happens during inspiration

A

Active process
Contraction of diaphragm- phrenic nerve C3,4,5 (increases volume vertically) and external intercostal muscles (increased volume A, P, L)
volume of thorax increases therefore intra-alveolar pressure decreases and air moves in

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15
Q

what happens during expiration

A

passive process
relaxation of diaphragm (dome- vertical volume decreases) and external intercostal muscles (A, P, L)
Elastic recoil of chest and lungs so decreased volume- increased pressure- air moves out

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16
Q

What causes alveolar surface tension

A

H2o molecules lining the alveoli interface

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17
Q
  • Cells that produce surfactant
  • Contents of surfactant
  • Function
A

Type II pneumocytes
lipids and proteins
Reduces alveolar surface tension, preventing collapse

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18
Q

Equation for alveolar pressure

A

P=2T/R

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19
Q

RDS in new born and its treatment

A

Premature baby, born without adequate surfactant, high surface tension, lung collapse
Steroids to mum before birth, synthetic surfactant

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20
Q

Alveolar interdependence

A

one alveoli starts to collapse, neighbouring alveoli stretch and recoil, exerting an expanding force to open the alveoli.

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21
Q

what lung volumes/capacities cannot be measured by spirometry

A

residual volume, functional residual capacity and TLC

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22
Q

tidal volume

A

volume of air entering or leaving lungs during a single breath 0.5L

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23
Q

IRV

A

Extra Volume of air that can be maximally inspired above TV 3.0L

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24
Q

ERV

A

Extra Volume of air that can be maximally expired by maximal contraction after normal TV 1.0L

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25
RV
Minimum volume of air remaining in lungs after maximal expiration 1.2L
26
inspiratory capacity (+equation)
IC= IRV+TV 3.5L | Maximum volume of air that can be inspired after normal quiet expiration
27
FRC
FRC=RV+ERV 2.2L | volume of air that remains in lungs after passive expiration
28
VC
VC= IRV+TV+ERV 4.5L | Maximum volume of air that can be expired in a single breath after maximal inspiration
29
TLC
TLC= RV+VC 5.7L Total volume of air that the lungs can hold
30
when would RV increase
loss of lung elasticity eg emphysema
31
FVC
maximum volume of air forcefully expired from lungs after maximal inspiration
32
FEV1
the volume of air expired in the 1st second of FVC
33
Normal FEV1/FVC ratio
>0.75
34
- Asthmatic FEV1/FVC ratio and why | - what type of lung disease is asthma
<0.75 normal FVC, reduced FEV1 asthma is an obstructive lung disease
35
- COPD FEV1/FVC ratio and why | - what type of lung disease is COPD
<0.7 FEV1 and FVC reduced COPD is an obstructive lung disease
36
Reversibility of Asthma and COPD with bronchodilator
Asthma shows reversibility with bronchodilator, COPD does not
37
FEV1/FVC of a) obstructive b) restrictive
Restrictive- normal ratio, (proportional reduction) | obstructive- reduced ratio
38
Equation for airway resistance
F= change in pressure/resistance
39
primary determinant of airway resistance
radius
40
effect of parasympathetics and sympathetics on airways
p- bronchoconstriction | s- bronchodilation
41
effect of dynamic airway compression
normal person- fine airway disease-makes active expiration more difficult as airway and alveoli are compressed obstruction causes fall in airway pressure made worse by reduced elasticity
42
what is peak flow meter used to measure what disease is it used in how is it used
measures peak flow rate asthma, COPD short sharp blow, Best of 3
43
lung compliance
measure of unit of change of lung volume per unit of TPG across lung wall the less compliant the lungs are, more work required to expand lungs
44
causes of reduced lung compliance, symptoms and what type of lung disease pattern?
pulmonary fibrosis, oedema, lung collapse, oedema, lack of surfactant SOB Restrictive lung disease
45
causes of increased lung compliance
Loss of elastic recoil due to aging, emphysema | ie hyperinflation of lungs
46
Fick's law
diffusion of gases across alveolar membrane increases with - increased SA - decreased thickness
47
what is Diffusion coefficient | compare DC of co2 and o2
solubility | co2 twenty times more soluble than o2
48
Daltons Law
the total pressure exerted by a gaseous mixture= sum of PP of each component in gas mixture
49
define ventilation and perfusion
rate at which air passes through lungs | rate at which blood passes through lungs
50
equation for pulmonary ventilation
PV=TV x RR
51
what is alveolar dead space
alveoli not adequately perfused with blood
52
what is alveolar dead space
ventilated alveoli which are not adequately perfused with blood
53
effect of increased/decreased o2 on pulmonary and systemic capillaries
increased 02 -pulmonary vasodilation, systemic vasoconstriction decreased o2- pulmonary vasoconstriction systemic vasodilation
54
four factors which influence rate of GA across alveoli
thickness SA diffusion coefficient of 02 PP of 02
55
four factors which influence rate of GA across alveoli
thickness SA diffusion coefficient of 02 and co2 PP of 02 and co2
56
partial pressure
the pressure that one gas in a mixture of gases would exert if it were the only gas in the whole volume occupied by the mixture of gas at a constant temperature
57
what would a large difference between pa02 and PAo2 indicate
problems with GE in lungs | left to right shunt
58
which factor of GE has the greatest influence
PP of o2 and co2
59
State Henry's Law
the amount of gas dissolved in a given type and volume of liquid at a constant temperature is proportional to the partial pressure of the gas in equilibrium with the liquid (increased PP of o2 will increase conc of o2 in blood)
60
two mechanisms of o2 transport in the blood and which carries the most o2?
- Haemoglobin (98.5%) | - dissolved (1.5%)
61
how any o2 molecules can each Hb carry?
4 02 (4 haem groups)
62
What is the primary factor which determines % saturation of Hb with o2
Po2
63
Structure of Hb
2 alpha chains 2 beta chains 4 haem groups (Fe2+)
64
factors which determine o2 delivery to tissues
- o2 content of arterial blood | - CO
65
Factors which determine arterial o2 content of blood
concentration and saturation of Hb
66
three diseases which impair o2 delivery to tissues
``` Anaemia (reduced Hb conc) heart failure (reduced CO) respiratory disease (reduced p02) ```
67
Relationship between altitude and PP O2
as altitude increases, PPO2 decreases
68
what does PP of inspired o2 depend on
atmospheric pressure and proportion of o2 gas (21%)
69
Alveolar gas equation
PAO2= Pio2- [paco2/0.8]
70
effect of binding of 1 o2 to Hb
increases affinity of Hb for o2
71
explain Bohr curve
sigmoid curve-flattens where all sites are occupied flat upper portions-moderate fall in pao2 wont affect o2 loading steep lower part- alot of o2 released at peripheries for small drop in pa02
72
What causes a right shift in Bohr curve and consequence
increased PaCo2, [H+], Temp, 2,3-bisphosphoglycerate occurs at tissues - increased release of 02
73
difference in structure between adult and foetal Hb
adults Hb- 2 beta units + 2 alpha units | foetal Hb- 2 beta units + 2 gamma units
74
why does foetal Hb have a higher affinity for 02 than adult Hb and effect of this on the o2-Hb dissociation curve?
- HbF has lower affinity for 2,3 Bisphosphoglycerate in RBC | - Curve for Hbf Shifted to left (compared to the right)
75
shape of myoglobin o2 dissociation curve | binding of o2 and myoglobin
Hyperbolic | 1:1 (1 haem group per myoglobin)
76
where is myoglobin present
cardiac and skeletal muscle
77
when is myoglobin released
-released at very low p02, short term storage of p2 in anaerobic conditions
78
Three ways in which Co2 is transported in blood and % of each
- solution (10%) - bicarbonate (60%) - carbamino compounds (30%)
79
what part of haemoglobin does co2 bind to
Globin
80
Equation of bicarbonate formation in the body and enzyme required where does this occur
H2O+CO2->H2CO3-> HCO3- + H+ Carbonic anhydrase occurs in RBC
81
Haw are carbamino compounds formed
Co2 combines with terminal amine group in blood proteins
82
State the Haldane effect
Removing oxygen from Hb increases ability of Hb to pick up co2 and co2 generated H+
83
how do Bohr effect and Haldane effect work together
o2 liberation and CO2 and CO2 generated H+ uptake at tissues
84
what is the major rhythm generator of respiration
medulla
85
in which neurons is the rhythm of breathing generated | and location
Pre-Botzinger complex | upper end of medullary respiration centre
86
contents of pons respiratory centre
pneumotaxic centre | apneuristic centre
87
contents of medullary respiratory centre
pre-Botzinger complex | dorsal and ventral respiratory groups
88
What neurons give rise to inspiration
dorsal respiratory group
89
what neurons cause forceful inspiration
ventral respiratory group
90
what would increased firing from dorsal neurons cause
activation of ventral respiratory group
91
what is the rhythm of breathing modified by
pons
92
``` function of the pneumotaxic centre what is it stimulated by ```
terminates inspiration | dorsal neurons firing
93
function of apneustic centre
excitation of inspiratory area of medulla prolonging inspiration
94
Hering Breur reflex
protects against over-inflation | pulmonary stretch receptors
95
Process of cough reflex
sharp intake of air closure of larynx contraction of abdominal muscle opening of larynx, expulsion of air
96
Function of chemoreceptor
sense blood gas tensions (especially C02)
97
peripheral chemoreceptors and their function
carotid bodies aortic bodies sense tension of o2,co2 and [H+] in blood
98
Location of central chemoreceptors and what they detect
located near the medulla detect changes in H+ of CSF co2 diffuses across BB barrier and makes H+
99
what is responsible for hypoxaemic drive and when is this stimulated
peripheral chemoreceptors, po2<8KPa
100
target SaO2 in patients with type II respiratory failure
88-92%
101
What is hypoxia at high altitudes caused by
decreased Pio2
102
acute response to hypoxia at high altitudes
hyperventilation and increased CO
103
symptoms of hypoxia at high altitude
tachycardia, tachypnoea, confusion, disturbed sleep, collapse, headache, fatigue, nausea, dizziness
104
chronic adaptions to high altitude hypoxia
``` increased: RBC (polycythaemia) 2,3 BPG in RBC (o2 offload) Increased capillaries increased mitochondria kidneys conserve acid (reduced pH) ```
105
Describe H+ drive of respiration
increased H+ detected by peripheral chemoreceptors causes hyperventilation to blow off co2 (as co2 can make H+)

Respiration (6 decks)

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