Respiratory Physiology Flashcards
1
Q
internal respiration consumes and produces what
A
consumes O2
produces CO2
2
Q
list the four steps of external respiration
A
ventilation
gas exchange between alveoli and blood
gas transport in blood
gas exchange at tissue level
3
Q
definine ventialtion
A
moving air between atmosphere and alveoli spaces
4
Q
define Boyle’s law
A
at any constant temp the pressure exerted by a gas varies inversely with the volume of the gas
as volume of a gas increases = pressure by gas decreases
5
Q
what must the intra-alevolar pressure become less than for air to flow into lungs
A
atmospheric pressure
6
Q
2 forces holding thoracic wall and lungs
A
intrapleural fluid cohesiveness
negative intrapleural pressure
7
Q
explain inspiration
A
active process
cause - contraction of inspiratory muscles
vl of throax increased vertically by contracting of diaphragm
phrenic nerve from cervical 3,4,5
external intercostal muscle contraction - lifts ribs + moves out sternum = bucket handle
increased lung size = intra-alveolar pressure fall air in larger volume (Boyle’s Law)
air enters down pressure gradient
8
Q
name major inspiratory muscle
A
diaphragm
9
Q
explain expiration
A
passive process relaxation of inspiratory muscles recoil of lungs = intra-alveolar pressure rises more molecules smaller volume (Boyle's) air leaves down pressure gradient
10
Q
explain pneumothorax
A
air in pleural space (abolishes transmural pressure gradient)
11
Q
causes of pneumothorax
A
SPONTANEOUS
TRAUMATIC
IATROGENIC
12
Q
pneumothorax can lead to
A
lung collapse
13
Q
small pneumothorax can be
A
symptomatic
14
Q
pneumothorax symptoms
A
SOB
chest pain
15
Q
physical signs of pneumothorax
A
hyper resonant percussion ote
decreased/absent breath sounds
16
Q
what causes lungs to recoli during expiration
A
elastic connective tissue
alveolar surface tension
17
Q
explain alveolar surface tension
A
H2O molecules attraction at liquid air interface
produces force = resists lung stretching
alveoli lined H2O alone = tension too strong = alveoli collapse
18
Q
what does surfactant reduce
A
alveolar surface tension
19
Q
Law of LaPlace - alveolli
A
smaller alveoli = higher tendency to collapse
20
Q
importance of surfactant
A
lowers surface tension of smaller alveoli more
prevents alveoli collapsing + emptying air contents into large alveoli
21
Q
Laplace’s Law calculation
A
P=2T/r
P=inward directed collapsing pressures
T=surface tension
r=radius of bubble
22
Q
Respiratory Distress Syndrome in New Born
A
fetal lungs unable synthesize lungs until late pregnancy
premature - lack of pulmonary surfactant
= respiratory distress syndrome of new born
= very strenuous inspiratory effects overcome high surface tension
23
Q
explain alveolar interdependence
A
alveolus starts to collapse surrounding alveoli = stretched = recoil = expand forces in collapsing alveoli = open it
24
Q
list forces keeping alveoli open
A
transmural pressure gradient
pulmonary surfactant
alveolar interdependence
25
forces promoting alveolar collapse
elasticity of stretched lung of connective tissue
| alveolar surface tension
26
list the major inspiratory msucles
diaphragm and external intercostal muscles
27
list the accessory muscles of inspiration
sternocleidomastoid
scalenus
pectoral
28
list the muscles of active expiration
abdominal muscles
| internal intercostal muscles
29
define tidal volume
vl air entering or leaving lungs single breath
30
define inspiratory reserve volume
extra vl of air that can be maximally inspired over and above typical resting tidal volume
31
define expiratory reserve volume
extra vl of air that can be actively expired by maximal contraction beyond normal vl of air after resting tidal volume
32
define residual volume
min vl of air remaining in lungs even after max expiration
33
define inspiratory capacity
max vl of air that can be inspired at end of normal quiet expriation
34
define functional residual volime
vl of air in lungs at end of normal passive expiration
35
define vital capacity
max vl of air moved out during a single breath following max inspiration
36
define total lung capacity
total vl air lungs can hold
37
explain total lung capacity
```
max vl air lungs can hold
vital capacity + residual vl
residual cannot be measure by spirometry
hence TLC not measured by spirometry
loss of elastic recoli = residual vl increases
```
38
FVC =
max vl forcibly expelled from lungs following max insirtaion
39
FEV1 =
forced expiratory volume in 1 second
40
FEV1/FVC ratio =
proportion of FVX expired in 1st second
(FEV1/FVC) x100
Normally >70%
diagnosis of obstructive + restrictive lung disease
41
Obstructive Lung Disease FEV1/FVC =
<70%
42
Restrictive Lung Disease FEV1/FVC =
>70%
43
Primary determinant of airway reiststance =
radius of conducting airway
44
parasympathetic =
bronchoconstriction
45
sympathetic =
bronchodilation
46
dynamic airway compression in normal people
no problem
increase in airway pressure
increases driving pressure between alveolus and airway
47
dynamic airway compression during active expiration in patients with airway obstruction
driving pressure
fall in airway pressure
airway compression by rising pleura pressure
diseased airway - more likely to collapse
worse - decreased elastic recoli of lungs
48
Peak Flow Meter
```
peak flow rate estimate
assesses airway function
useful - obstructive lung disease
short sharp blow
best of 3 attempts
varies age and height
```
49
define pulmonary compliance
effort lungs has to go to stretching or distending lungs
| less compliant = more work
50
causes of decreased pulmonary compliance
```
pulmonary fibrosis
pulmonary oedema
lung collapse
pneumonia
absence of surfactant
```
51
result of decreased pulmonary compliance
greater change in pressure required
SOC esp on exertion
restrictive pattern of lung vl
52
cause of increased pulmonary compliance
elastic recoil of lungs = lost
emphysema
age
dynamic airway obstruction
53
work of breathing increased when...
pulmonary compliance decreased
airway resistance increased
elastic recoil decreased
need for increased ventilation
54
calculate pulmonary ventilation
tidal volume x respiratory rate
55
why is alveolar ventilation less ham pulmonary ventilation
presence of anatomical dead space
56
calculate alveolar ventilation
(tidal volume - dead space) x respiratory rate
57
define pulmonary ventilation
vl air breathed in and out per minute
58
define alveolar ventilation
vl air exchanged between atmosphere + alveoli per minute
59
because of dead space it is more advantageous to
increase depth of breathing
60
transfer of gases between body and atmosphere depend on
ventilation
| perfusion
61
define ventilation
rate at which gas is passing through lungs
62
define perfusion
rate at which blood is passing through lungs
63
ventilated alveoli which are not adequately perfused with blood are considered as
alveolar dead space
64
alveolar dead space in health people
very small + little importance
65
disease on alveolar dead space
increased significantly
66
accumulation of CO2 in alveoli as a result of increased perfusion =
decreased airway resistance = increases airflow
67
increased alveolar O2 concentration as a result of increased ventilation =
pulmonary vasodilation = increases blood flow
68
areas in which perfusion = grater than ventilation
```
CO2 increases in area
dilation of local airways
airflow increases
O2 decreases in area
constriction of local blood vessels
blood flow decreases
```
69
areas in which ventilation = greater than perdusion
```
CO2 decrease in area
constriction of local airways
airflow decreases
O2 increases in area
dilation of local blood vessels
blood flow increases
```
70
effect of O2 on pulmonary arterioles
```
decreased = vasoconstriction
increased = vasodilation
```
71
effect of O2 on systemic arterioles
```
decreased = vasodilation
increased = vasoconstriction
```
72
factors influencing rate of gas exchnage
partial pressure gradient of O2 and CO2
diffusion coefficient for O2 and CO2
surface area of alveolar membrane
thickness of alveolar membrane
73
explain Dalton's Law of Partial Pressures
Total pressures exerted by a gaseous mixture = sum of partial pressures of each individual component in gas mixture
74
partial pressure of gas =
pressure that 1 gas in a mixture of gases would exert if it were the only gas present in the whole volume occupied by the mix at a a given temp
75
alveolar gas calculation =
```
PAO2 = PiO2 - (PaCO2/0.8)
PAO2 = partial pressure of O2 in alveolar air
PiO2 = partial pressure of O2 in inspired air
PaCO2 = partial pressure of CO2 in arterial blood
0.8 = respiratory exchange ratio
```
76
describe partial pressure gradient
gases move from higher to lower partial pressure
77
define diffusion coefficient
solubility of gas in membrane
78
compare diffusion coefficient for CO2 compared to O2
CO2 = x20 O2
79
big gradient between PAO2 and PaO2 indicates
problems with gas exchange in lungs
| right to eft heart shunt
80
explain Fick's Law of diffusion
amount of gas that moves across a sheet of tissue in unit time is proportional to the area of the sheet but inversely proportional to its thickness
81
what does pulmonary circulation recieve
entire cardiac output
82
respiratory tree pathway
trachea - bronchi - bronchioles - terminal bronchioles - respiratory bronchioles - alveolar ducts - alveolar sacs
83
what are allveoli
```
thin walled inflatable sacs
function in gas exchange
single layer of flattened type 1 alveolar cells
```
84
what circles alveolus
pulmonary capillaries
85
list 4 factors influencing rate of gas transfer across alveolar membrane
partial pressure gradient of O2 and O2
diffusion coefficient
surface area of alveolar membrane
thickness of alveolar membrane
86
causes of decrease in surface area of alveolar membrane
emphysema
lung collapse
pneumonectomy
87
O2 picked up by blood in lungs -
transported in blood to tissues for cellular use
88
CO2 produced at tissues -
transported in blood to lungs for removal from body
89
Henry's Law
O2 amount dissolved in blood = proportional to partial pressure
90
O2 is present in the blood in 2 forms
bound to haemoglobin
| physically dissolved
91
features of haemoglobin
Hb molecules contain 4 haem groups
each haem binds reversible to 1 O2 molecule
fully saturated when all Hb present = max load of O2
92
primary factor determining percentage saturation of haem with O2
Po2
93
calculate oxygen delivery index
```
DO2l = CaO2 x Cl
VO2I = oxygen delivery index (ml/min/meter^2)
CaO2 = Oxygen content of arterial blood (ml/L)
Cl= cardiac index (L/min/meter^2)
```
94
what is O2 delivery to the tissues a function of
O2 content of arterial blood
| cardiac output
95
calculate O2 content of arterial blood (Ca)2)
```
CaO2 = 1.34 x (Hb) x SaO2
SaO2 = % saturated with O2 = determined by PO2
```
96
causes of impaired O2 delivery to tissues
```
respiratory distress (decrease arterial PO2 = decrease Hb saturation with O2 and O2 blood content)
heart failure (decreased cardiac output)
anaemia (decreased Hb conc = decreased )2 content in blood)
```
97
what does partial pressure of inspired O2 depend on
total pressure
| proportion of O2 in gas mic
98
O2 binding of haem
binding O2 to Hb increases affinity
co-operativity
sigmoid
flattens = all sites occupied
99
co-operativity
binding of 1 O2 to Hb increases affinity of Hb for O2
100
Bohr Effect
| shift to right
increase Pco2
increase H+
increase temp
increase 2,3 biphosphoglycerate
101
features of foetal haemoglobin
HbF
2 alpha subunits
2 gamma subunits
interacts less with 2,3 biphosphoglycerate = higher affinity for 02 = shifted to left
allows O2 mother to baby even if PO2 = low
102
features of myoglobin
```
present in skeletal and cardia muscles
1 haem per myoglobin
no cooperative binding
dissociation curve = hyperbolic
presence in blood = muscle damage
```
103
transporting CO2 in blood
solution
bicarbonate
carbamino compounds
104
where does carbonic anhydrase occur
red blood cells
105
describe carbamino compounds
CO2 + terminal amine groups
globulin of haemoglobin
rapid even without enzyme
reduced Hb = bind more CO2 than HbO2
106
explain haldane effect
removing 02 from Hb = increases ability of Hb to pick up CO2 and CO2 generated H+
107
what does the rhythm refer to
inspiration followed by expiration
108
fairly normal ventilation if
section above medulla
109
ventilation ceases if
section below medulla
110
medulla is a
major rhythm generator
111
explain Pre-Botzinger complex
network of nerves
pacemaker activity
upper end of medullary reps centre
112
rise to inspiration
```
rhythm generated = pre-botzinger complex
excites dorsal resp group neurones
fires in bursts
firing - contraction of inspiratory muscles
firing stops = passive expiration
```
113
when does active expiration
during hyperventilation
114
describe active expiration
increased firing of dorsal neurones= excited 2nd group
ventral respiratory group neurones
excite intercostal abdominals etc
forceful expiration
115
rhythm generated in medulla can be modified by?
neurones in the pons
116
what happens in absence of pneumotaxic centre
APNEUSIS
| breathing = prolonged inspiratory gasps with expiration
117
respiratory centres = influenced by stimuli received from
```
higher brain centres
stretch receptors
Juxtapulmonary receptors
Joint receptors
Barorecptors
Central chemoreceptors
Peripheral chemoreceptors (high altitudues)
```
118
causes of hypoxia at high altitudes
decreased partial pressure of inspired O2
119
acute response of hypoxia
hyperventilation
| increased cardiac output
120
symptoms of acute mountain sickness
```
headache
fatigue
nausea
tachycardia
dizziness
sleep disturbance
exhaustion
shortness of breath
unconsciousness
```
121
chronic adaptation to high altitude hypoxia
```
increased RBC
increased 2,3 BPG produced within RBC
increased capillary number
increased mitochondria number
kidneys conserve energy
```
122
arterial Pco2 as chemical factor
weak stimulation - peripheral
| strong stimulation - central
123
arterial Po2 as chemical factor
important if Po2 < 8KPA - peripheral
| severe hypoxia decreases resp centre - central
124
arterial H+ as chemical factor
stimulation - peripheral
| H+ cannot cross blood brain barrier - central
