Year 1 resp. > Physiology > Flashcards

Physiology Flashcards

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1
Q

what is lung compliance

A
  • distensibility of lung

, ability to swell under pressure

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2
Q

increased lung compliance

A
  • less elastic fibres
  • less recoil
  • hard to expire
    e. g. COPD
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3
Q

decreased lung compliance

A
  • fibrosis/ scarring
  • more effort to expand
  • breathless
  • oedema, pneumothorax
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4
Q

inspiration overview

A

active process

air into lungs

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5
Q

Expiration overview

A

air out of lungs
passive/ active process
elastic recoil/ accessory muscles

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6
Q

Control of breathing + nerve origination

A

phrenic nerve

C3 - C5

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7
Q

Inspiration muscles

A

Diaphragm - contracts - inferiorly
External costal muscles
- out + up
bucket handle

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8
Q

passive expiration muscles

A

relaxation of diaphragm + elastic recoil

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9
Q

Active expiration muscles

A

abdominal wall + internal costal muscles

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10
Q

Process of inspiration

A
  • Phrenic nerve innervation
  • Diaphragm contracts
  • Decrease in pleural pressure
  • Lungs expand
  • Air in
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11
Q

Keeps lungs inflated

A 
Intra -pleuric cohesiveness 
- water in pleural space attracts each other 
Negative pressure 
- pleural space has -ve pressure 
pressure grad., keeps inflated
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12
Q

Pneumothorax

A

Air into pleural cavity
- increases pressure
No pressure gradient
- lung collapses

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13
Q

passive Expiration process

A 
- decreased phrenic nerve innervation
diaphragm relaxes 
increase in pleural pressure 
elastic recoil 
air out
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14
Q

Active respiration

A

diaphragm relaxes + internal costal muscles contract + abdominal wall contracts
- increased pleural pressure (become +ve)
forces air out lungs
- dynamic collapse

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15
Q

alveolar pressure = to

A

pleural pressure + elastic recoil pressure

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16
Q

Elastic recoil

A
  • elastic fibres in membrane

- decreases as less stretched

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17
Q

Dynamic Collapse

A

Positive pressure from active respiration
- Transmural pressure = -ve
- inward pressure on airway
exacerbated if decreased airway pressure
Causes a collapse
- Increases pressure behind collapse
- Airway re opened - pressure grad.

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18
Q

Emphysema + dynamic collapse

A

decreased elastic recoil (swollen alveoli)

  • decreased transmural pressure
  • airway more likely to collapse
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19
Q

Alveolar collapse

A 
inward pressure = 2x surface tension/ radius
- more likely in smaller alveoli 
- surfactant = amphipathic 
reduces tension via repulsion 
Alveolar independence 
- one alveoli collapses
rest = stretched, elastic recoil, open
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20
Q

Tidal Volume

A
  • normal expiration

0,5L

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21
Q

Vital Capacity

A
  • volume expired after max inspiration

4. 5 L

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22
Q

Inspiratory reserve volume

A
  • volume inspired after tidal volume

- 3L

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23
Q

expiratory reserve volume

A
  • volume exhaled after tidal volume

1L

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24
Q

residual volume

A
  • remaining air in lungs volume

1. 2L

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25
Total lung capacity
Vital capacity + residual volume | = 5.7L
26
Functional reserve capacity
total air left in lung after tidal volume | - 2.2L
27
Forced Vital Capacity
- volume of air forcibly exhaled after maximum inhalation
28
Forced expiratory volume 1
- max air expired 1 second after max inhalation
29
FEV1/FVC ratio + features of abnormalities
``` 70% = normal <70% = obstructive airway disease - can't expire (narrow lumen) 70% but low FVC + FEV1 = restrictive (cant inflate) ```
30
Physiological dead space
anatomical + functional dead space
31
Anatomical dead space
- recycled air/ not used air | e. g. airways
32
Functional dead space
- air not diffused | e. g. no blood supply
33
alveolar resp.
(tidal volume - dead space) x resp. rate
34
Diffusion - air -> blood
``` ideal 1:1 ratio - not likely, gravity apex < base lung - vasodilation perfusion/ diffusion limited ```
35
perfusion limited O2 uptake
- sub optimal conditions due to inadequate blood supply | determined by unbound gas (no partial pressure if bound)
36
diffusion limited O2 uptake
- dependent on a diffusion factor e.g. size of membrane
37
Dead Space
- air not available for perfusion | - anatomical/ functional
38
anatomical dead space
- air in airways | can't be perfused into blood
39
functional dead space
- insufficient blood supply | perfusion limited
40
4 factors effecting gas perfusion
- partial pressure of gas - Surface Area - Thickness of Membrane - Solubility in membrane
41
Features of O2 dissociation curve
- sigmoidal high O2 uptake at slightly low O2 conc. - keeps O2 sats high
42
Bohr effect
graph moves to right - increased dissociation of O2 in tissue + uptake in lung CO2, H+ conc., temp, 2,3 bisphosphoglycerate
43
Oxygen delivery index =
cardiac output x O2 arterial content
44
foetal haemoglobin
2 alpha, 2 gamma sub units higher affinity for O2 - picks up O2 from mother - less reactive to 2,3 bisphosphoglycerate
45
Myoglobin
in muscles carries 1 O2 short term relief of anaerobic conditions
46
Haldane effect
No O2 bound - globin has high affinity for CO2 O2 has greater affinity - displaces CO2 - CO2 removal, lungs
47
Reduce effects of dead space
Heavy deep breathing
48
Alveolar gas equation
Partial pressure O2 in air - (partial pressure CO2/0.8)
49
PO2 arterial + alveolar
small grad. = normal | large grad. = circulatory problem
50
Henrys law
Gas dissolved in liquid = proportional to partial pressure of gas
51
O2 arterial blood content
1.34 x haemoglobin conc. x 5 saturation
52
Oxygen delivery Index
Arterial O2 content x Cardiac Output
53
3 methods of CO2 transport
- plasma - bicarbonates - Carbamino Compounds
54
CO2 transport in plasma
Henrys law - proportional to partial pressure + solubility only unbound gas
55
Bicarbonates
In RBC carbonic anhydrase catalyses: CO2 + H2O H2CO3 H+ + HCO3- - bicarbonate exchanged for Cl- in RBC
56
Carbamino compounds
CO2 binds to globin | - doesn't affect partial pressure, bound CO2
57
Control Of respiration - 2 forms
neural | chemical
58
Neural control - rhythm
medulla Pre botzinger complex - innervates dorsal respiratory group neurones
59
Stimulation of inspiration
pre botzinger complex causes innervation of diaphragm via dorsal respiratory group neurones via phrenic nerve
60
Pneumotaxic centre function
- Inhibits dorsal respiratory group neurones, allows respiration activated by dorsal neurones - ve feedback
61
Apneustic centre function
Prolongs inspiration | - excites dorsal respiratory group neurones
62
Expiration
Pre botzinger complex inhibits dorsal respiratory centre innervation of phrenic nerve - relaxation
63
Active expiration
- ventral respiratory group neurones stimulated | innervation of internal intercostals + abdomen
64
Apneusis
Respiration - no pneumotaxic centre | long inspiration, short expiration
65
hering Breur reflex
Prevents hyper inflation | - inhibits inspiration
66
Chemical control of respiration mechanisms
Negative feedback of central + peripheral chemoreceptors
67
Location of central chemoreceptors
- surface of medulla
68
Main mechanism of resp. control
- H+ ion conc. in CSF via central chemoreceptors
69
Process of resp. control via central chemoreceptors
``` - CSF = impermeable to H+ + HCO3- ions very permeable to CO2 CO2 dissolves in H2O produces increased H+ ions low protein levels - low buffering ```
70
Peripheral control of respiration
senses PaO2, PaCO2 + Pa H+
71
Peripheral control - changes in Pa CO2
``` Hypercapnia - High CO2 increase ventilation expel more CO2 Hypocapnia - acidaemia - decreases ventilation decreases CO2 expelled prevents alkalaemia - process ineffective in severe chronic COPD ```
72
Peripheral chemoreceptor control of PaO2
Detects very low O2 levels Hypoxaemia very low PaO2 - increase ventilation
73
Mechanism of cough initiation signalling
Afferent signals -cough receptors on posterior trachea + pharynx + carina internal laryngeal nerve -> superior laryngeal nerve -> vagus nerve
74
Mechanism of cough signalling - efferent
``` Contraction of diaphragm + external intercostals - short breath in Closure of larynx - rima glottis shut by vocal chords - active expiration contraction of abdomen + internal intercostal muscles - larynx opens - air expulsed ```
Year 1 resp.
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