Respiratory System Flashcards
1
Q
What is the main function of the lungs?
A
Gas exchange between alveoli and blood in the pulmonary arteries: external respiration
2
Q
What are the non-respiratory functions of the respiratory system?
A
- filter for blood borne substances
- defence against inhaled substances
- immune function
- platelet formation
3
Q
How many lobes are the in the right lung?
A
3
4
Q
How many lobes and in the left lung?
A
2
5
Q
What are the functions of the pleura?
A
- reduction of friction
- creation of a pressure gradient
- compartmentalisation
6
Q
What are the functions of the conducting zone?
A
- To warm and humidify the air
- To distribute the gas
- To serve as part of the body’s defence system
7
Q
What is the function of the respiratory zone?
A
Site of gas exchange
8
Q
How much of the alveoli are covered by capillaries?
A
70-80%
9
Q
Emphysema
A
..
10
Q
What is the main muscle for tidal inspiration?
A
The diaphragm
11
Q
Is expiration active or passive?
A
Passive
12
Q
What muscles does forces expiration require?
A
Diaphragm and intercostal muscles
13
Q
Which way does air flow?
A
High pressure to low pressure
14
Q
How does inspiration work?
A
- active contraction of the diaphragm
- increase in volume of the chest cavity
- decrease in alveoli pressure
- air flows in
15
Q
How does expiration work?
A
- passive relaxation of diaphragm
- decrease in volume of chest cavity
- increase in pressure in alveoli
- air flows out
16
Q
What is atmospheric pressure?
A
760mmHg
17
Q
What is Dalton’s law?
A
The atmospheric pressure of the air is made up of all of the partial pressures of gases
18
Q
What is Boyle’s law?
A
At a constant temperature, pressure is inversely related to volume
19
Q
What is Charles’s law?
A
At a constant pressure, the volume of a gas is directly proportional to its temperature
20
Q
What is Henry’s law?
A
The amount of gas that dissolves in water is determined by its partial pressure in and and solubility in water
21
Q
What is the negative pressure of the intrapleural cavity important?
A
It keeps the lungs inflated
22
Q
What is it called when you get a hole in your chest?
A
Pneumothorax
23
Q
What is the effect of gravity on the pressure in the lungs?
A
The bottom of the lung has higher pressures (less negative)
24
Q
Which forces keep the alveoli open?
A
- trans mural pressure gradient
- surfactant
25
Which forces promote alveolar collapse?
- pulmonary elasticity
| - alveolar surface tension
26
How does a spirometer work?
- closed system
| - belt and pulls system graphs on a Spirograph depending on the volume present in the system
27
What is normal tidal volume?
500ml
28
What is the vital capacity?
The amount of total moveable air
29
What can’t be determined with spirometry?
Residual volume and functional residual capacity
30
What is the average total lung capacity?
6L
31
How do you determine functional residual volume?
Helium method
32
How does the helium method work?
- known concentration of helium inside a container
- person expires normally so that what’s left in the lungs is the functional residual capacity
- use the equation: FRC= (C1xV1)/C2 - V1
33
What are determinants of lung volume?
- height
- gender
- disease: restrictive LD, decrease in LV
- altitude: increased lung capacity to compensate for lower pp of oxygen
34
How do you determine pulmonary ventilation?
- total volume of air ventilated x br/min
35
What is the typical amount of breaths per minute?
12
36
What is the normal dead space?
150ml
37
How do you calculate alveolar ventilation?
VA= (VT-150) x bf
38
What is lung compliance?
- the ease with which the lungs can be inflated
39
How does lung volume affect compliance?
- high volume: low compliance
| - low volume: high compliance
40
How does disease affect compliance?
- obstructive lung disease: decrease
| - restrictive: increase due to stretched elastic tissue because of trapped air
41
How does asthma increase lung residual volume?
Air gets trapped, stretches elastic tissue
42
How does surface tension decrease alveolar diameter?
- liquid air interface
| - water molecules in the cells create and inwardly directed force
43
Which size alveoli are greater pressures found?
Smaller
44
What would happen in there was no surfactant?
Air would take a preferential path to larger alveoli
45
What is surfactant?
Lipoprotein
46
What secretes surfactant?
Type 2 alveolar cells
47
How does surfactant work?
Lines the interface between the water and air
| Water molecules are moved apart
48
Where does surfactant have the greatest effect?
Smaller alveoli
49
The ___________ the airway diameter the ___________ greater effect it’s has on flow
Smaller, greater
50
Where is the highest resistance found?
Medium bronchi
51
What affects resistance?
Airway secretions
Airway diameter
Lung volume (ie forced expiration)
52
When can the intrapleural pressure become positive?
During forced expiration
53
What is dynamic airway compression?
When the pressure in the interpleural cavity is greater than the pressure in the respiratory passage way - airway constriction
54
What is a feature of the flow volume plot?
At a point after PEF, flow is effort independent
| Linear on the graph
55
What is a restrictive lung disease?
Something is wrong with the lung tissues and the lung operates at lower volumes
More energy needed to inhale
56
What is an obstructive lung disease?
Resistance to airflow
57
Obstructive lung disease volumes
- takes longer to inhale and exhale
| - increased residual volume
58
Obstructive lung disease volumes
Lung volumes smaller
| Doesn’t affect flow rates
59
Where are the pacemaker cells for breathing?
Pre-Botzinger complex, generates spontaneous action potentials
60
What does the Pre-Botzinger complex stimulate?
DRG
61
How long does the PBC activate the DRG for?
2 seconds - diaphragm contracts
| 3 seconds inactive - diaphragm relaxes
62
Is the ventral respiratory group active or inactive during tidal breathing?
Inactive
63
How is the ventral respiratory group stimulated?
- forced inspiration -> activates ventral respiratory group for forced expiration
64
When is the ventral respiratory group important?
Excercise
65
What does the pneumotaxic centre do?
- switches off inspiratore neurons in DRG via inhibitory signals
- limits duration of inspiration
- increases breath frequency
66
What does the apneustic centre do?
Sends stimulatory signals to the inspiratore area of the DRG - > extra boost to inspiratore drive
67
What controls respiratory centre activity?
Chemical control
Exercise
Voluntary control
Defensive reflexes
68
Central chemoreceptors
- bilateral paired groups of cells
- below ventral surface of medulla
- responds to changes in H+
69
Does H+ or CO2 move into the cerebrospinal fluid?
CO2
70
What are the central chemoreceptors?
Carotid and aortic bodies
71
Oxygen has to drop _____________ before there is activation in the peripheral chemoreceptors
Significantly
72
What is the normal PaO2?
100mmHg
73
At what PaO2 do the peripheral chemoreceptors start responding?
60-30mmHg
74
What is hypocapnia?
Low levels of CO2 in the blood
75
What is hypercapnia?
High levels of CO2 in the blood
76
What is hypoxia?
Low levels of oxygen in the tissues
77
What is hyperoxia?
Excess supply of oxygen to tissues
78
What are some possible mechanisms that increase ventilation during exercise?
- higher cortical centres
- proprioception
- increased body temperature
- increased sensitivity of chemoreceptors
79
How is breathing voluntarily controlled?
- signals from the cerebral cortex bypass the brain stem
| - can override normal breathing rhythm
80
What is the break point of breath holding?
55mmHg of CO2
81
What is the Hering-Breuer inflation reflex?
- lung inspiration to larger than normal levels signals to limit inspiration
- receptors: pulmonary stretch receptors in smooth muscle layer in conducting airways
- prevents overinflation of lungs
82
What is the irritant receptor reflex?
- receptors lie between airway epithelial cells
- response to irritation of airways by touch or noxious substances
- stimulates excitatory responses such as coughing, gasping
83
What is the normal fraction of nitrogen in the air?
0.7862
84
What is the normal fraction of oxygen in the air?
0.2084
85
What is the normal fraction of CO2 in the air?
0.0004
86
What is the normal fraction of water in the air?
0.005
87
What factors affect diffusion capacity?
1. Surface area
2. Thickness
3. Partial pressure gradient
4. Diffusion coefficient
88
What is the partial pressure of water when air is humidified?
47mmHg
89
What is the partial pressure of CO2 in the arterial blood and then the alveoli?
40mmHg
90
What is the consumption of oxygen per minute?
250ml/min
91
What does alveolar Po2 depend on?
- how much oxygen the body consumes
| - alveolar ventilation
92
What is the normal alveolar partial pressure of O2?
100mmHg
93
How much CO2 is produced per minute at rest?
200ml
94
What is the thickness of the respiratory membrane?
0.6 micrometers
95
What is the diffusion gradient of CO2?
45 -> 40mmHg
96
What is the diffusion gradient of O2?
100 -> 40mmHg
97
How does carbon dioxide get away with having such a small concentration gradient?
It is more soluble that oxygen
98
What does diffusion coefficient depend on?
- solubility and molecular weight
99
How much more soluble is CO2 than oxygen?
20x
100
How quickly does saturation of oxygen occur?
Within the first 3rd of the capillary (0.25sec)
101
What is the transient time of a RBC in a capillary?
0.75sec
102
What happens in each binding of an oxygen to haemoglobin?
It increases the affinity of the next oxygen
103
How much oxygen is transported by haemoglobin?
98.5%
104
How much oxygen is transported as a dissolved gas?
1.5%
105
What facilitates offloading of O2 and shifts the curve to the right?
- excercise
| - increase in PCO2
106
What is the Bohr effect?
Under acidic conditions, oxygen offloading is promoted
107
How is carbon dioxide transported in the blood?
- dissolved gas (5%)
- carbamino haemoglobin (5%)
- bicarbonate ion (90%)
108
What catalyses the reaction between CO2 and water?
Carbonic anhydrase in the RBCs
109
What is the chloride shift?
When a bicarbonate ion leaves they RBC, a chloride ion moves in to compensate for the loss of negative charge
110
What is the formula for the RQ?
Rate of CO2 output/rate of oxygen uptake
111
What is the typical RQ?
0.8
112
What is normal residual volume?
1200ml
113
What is normal ERV?
700-1200ml
114
What is normal IRV?
1900-3000ml
