Physiology Flashcards
1
Q
What is internal respiration?
A
intracellular mechanisms which consume O2 and produce CO2
2
Q
What is external respiration?
A
sequence of events that lead to the exchange of O2 and CO2 between external enviroment and the cells of the body.
3
Q
4 steps of external respiration?
A
- ventilation
- gas exchange
- gas transport
- gas exchange at a tissue level
4
Q
Explain ventilation
A
mechanical process of moving gas in and out of the lungs
5
Q
Explain gas transport
A
Binding of O2 and CO2 in the blood
6
Q
4 body systems involved in external respiration
A
- respiratory
- cardiovasular
- haematology
- nervous
7
Q
What is Boyles Law?
A
- at any constant temperature the pressure excerted by a gas varies inversely to the volume of that gas
8
Q
What holds the thoarcic wall and lungs together?
A
- Intraplural fluid cohesivness
- Negative intrapleural pressure
9
Q
What is the intralpleural fluid cohesivness?
A
- Water molecules in intrapleural fluid are attracted to each other
- resist being pulled apart
10
Q
What is negative intrapleural pressure?
A
- the sub-atmospheric intrapleural pressure creates a transmural pressure gradient across the lung wall and across the chest wall. So the lungs are forced to expand outwards while the chest is forced to squeeze inwards
11
Q
Explain inspiration
A
- Active process
- Volume of the thorax is increased vertically
- Contraction of the diaphragm
- External intercost muscle contracts
- Intra alveolar pressure falls (Boyles law)
12
Q
Explain expiration
A
- Passive process
- recoil of the lungs allows intra alveolar pressure to rise
- air leaves lungs down pressure gradient
13
Q
What is a pneumothorax?
A
Air in the pleural space
- abolishes lung gradients –> lung collapse
14
Q
What causes the lungs to recoil?
A
- elastic connective tissue
- alveolar surface tension
15
Q
What is surfactant?
A
- mixture of lipids and proteins excreted by type II alveoli
- if was just water the tension would be too high
16
Q
What is LaPlace Law
A
The smaller the alveoli the higher the tendency to collapse
17
Q
What is alveolar interdependance?
A
If an alveolus start to collapse the surrounding alveoli are
stretched and then recoil exerting expanding forces in the
collapsing alveolus to open it
18
Q
What is transmural pressure?
A
Transmural pressure refers to the pressure inside relative to outside of a compartment.
19
Q
3 main sets of muscles of respiration?
A
- Accessory Muscles
- Major inspiratory Muscles
- Muscles of active expiration
20
Q
What muscles make up the accessory muscles?
A
- sternocleidomastoid
- scalenus
- pectoral
21
Q
What muscles make up the major inspiratory muscles?
A
- Diaphragm
- External Intercostal Muscles
22
Q
What muscles make up the muscles of active expiration?
A
- Abdominal muscles
- Internal intercostal muscles
23
Q
What is Tidal Volume (TV)?
A
- volume of air entering or leaving lungs during a single breath
- 0.5L
24
Q
What is the Inspiratory Reserve Volume (IRV)?
A
- Extra volume of air that can be maximally inspired over and above the typical resting tidal volume
- 3.0L
25
What is the Expiratory Reserve Volume (ERV)?
- Extra volume of air that can be acitvely expired by maximal contraction, beyond the normal tidal volume
- 1.0L
26
What is the Residual Volume (RV)?
- Minimum volume of air remaning in the lungs even after a maximal expiration
- 1.2L
27
What is vital capacity?
Maximum volume of air that can be moved out during a single breath following a maximal inspiration
(VC = IRV + TV + ERV)
28
What is Total Lung Capacity?
Total volume of air the lungs can hold
(TLC = VC + RV)
- unable to measure by spirometry
29
FVC?
Forced Vital Capacity (maximum volume that can be forcibly expelled from the lungs following a maximum inspiration
30
FEV1?
Forced Expiratory volume in one second. Volume of air that can be expired during the first second of expiration in an FVC (Forced Vital Capacity) determination.
31
FEV1/FVC Ratio?
The proportion of the Forced Vital Capacity that can be expired in the first second = (FEV1/FVC) X 100% - Normally more than 70%
32
Explain the FVC and FEV1 and the ratio for an obstructive disease
```
FVC = normal/lower
FEV1 = Lower
Ratio = Lower
```
33
Explain the FVC and FEV1 and the ratio for a restrictive disease
```
FVC = lower
FEV1 = lower
Ratio = normal
```
34
Airway resistance equation
Flow = change in pressure / resistance
35
What does parasympathetic stimulation do
bronchoconstriction
36
What is a peak flow meter
- gives an estimate on peak flow
- to assess obstructive ariway diseases
- best of three taken
37
Pulmonary compliance
- the measure of the amount of effort required to strech the lungs
- less compliant = more work required to take in air
- can be decreased by pulmonary fibrosis
- can be increased by loss in elasticity = emphysema (hyperinflation- hard to get air out)
38
Explain why the alveolar ventilation will always be less than the pulmonary?
Alveolar ventilation includes the dead space volume
39
Equation for pulmonary ventilation
PV = TV X RR
| -Is the volume of air breathed in and out per minute
40
Equation for alveolar ventilation
AR = (TV-Dead space volume) X RR
| -Is the volume of air exchanged between the atmosphere and alveoli per minute
41
What is alveolar dead space?
- Alveoli that are ventilated but not adequetly perfused
| - not avaliable for gas exchange
42
What occurs when perfusion>ventilation
- increase in CO2
- decrease in O2
- dilation of airways
- contristiction of local blood vessels
- decreased blood flow
- increased air flow
43
4 factors that influence gas exchange
- partial pressure of O2 and CO2
- Diffusion coefficent
- surface area of alveoli
- thickness of alveoli membrane
44
what is partial pressure
the pressure that would be exerted by one of the gases in a mixture if it occupied the same volume on its own
45
Darltons Law
- sum of all the partial pressures of each individual gas in a mixture
46
Diffusion coefficent for CO2
Is 20times that of O2
47
Ficks law of diffusion
The 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
48
Henrys law
the amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid
49
How is oxygen present in the blood?
- bound to haemoglobin
| - physically dissolved (very little)
50
What is the Oxygen Delivery Index equal to
= O2 content of arterial blood X cardiac index
51
What can effect oxygen delivery to tissues?
- decreased partial pressure of inspired oxygen
- heart failure (reduce CI)
- aneamia
52
Explain cooperativity
O2 binding to one Hb increases the affinity of other molecules for O2
53
Bohr effect?
- a shift to the right of the o2 saturation sigmoid graph
54
Difference in feotel hb
HbF has a greater affinity for O2 over adult Hb
| - sigmoid shifted to the left in HbF
55
Where is myoglobin present?
skeletal and cardiac muscles
56
differences with myoglobin
no cooperativity
dissociation curve hyperbolic
1 haem group per molecule
57
3 ways in which CO2 is transported in the blood?
- solution
- bicarbonate
- carbamino acidd
58
CO2 is _______ times more soluble than O2
- 20 times
59
Where is bicorbonate formed?
- red blood cells
| - carbonic anhydrase
60
What is the haldane effect?
- removing o2 from Hb increases the ability of Hb too pick up CO2
- works in syrnchrony with the bohr effect
61
What is the major controller of respiratory rhytm?
- pre-boltzinger complex
62
Explain how muscles are contracted during inspiratiom?
- pre boltzinger complex generates rhythm
- dorsal group is excited
- dorsal group fires
- contraction of inspiratory muscles
63
The _____ neuron group is responsible for active expiration
| - dorsal or ventral?
- ventral
64
What can modify the rate generated my the medulla?
- pons
65
What are some examples of involuntary modicifications of breathing?
- stretch reflex in lungs (prevents hyperinflation)
| - joint receptor reflex (during exercise)
66
Chemical control of respiration is a ______ feedback system
- negative feedback
67
Where are the peripheral chemoreceptors located?
- carotid
| - aorta
68
Where are central chemorecpetors located?
- medulla
69
What senses blood gas pH?
- chemoreceptors
70
Explain hypoxic drive
- peripheral chemoreceptors
| - if PO2 falls too low --> increase in ventilation
71
Increase in H+ suggests _____ and causes____
- increased CO2
- increases ventilation
- recognised by peripheral chemoreceptors
