Respiratory Physiology Flashcards
1
Q
What are the two types of respiration?
A
External (physically breathing) and internal (biochemistry)
2
Q
What are the four steps of external respiration?
A
- Ventilation (bulk transfer of media to exchange surface)
- Respiratory Exchange (gas diffusion across a respiratory surface)
- Circulation (bulk transport of ECF)
- Cellular Exchange (exchange between ECF and ICF via diffusion)
3
Q
What percentage of air is O2?
A
20.95%
4
Q
What is the Partial Pressure of O2 in air?
A
159.22mmHg
5
Q
What is the correlation between O2 levels in freshwater and saltwater?
A
O2 solubility in freshwater exceeds that of salt water by 20%
6
Q
Where is the greatest amount of O2 in water?
A
at the surface
7
Q
What contributes to the Partial Pressure of a solution?
A
only free gas molecules
8
Q
What is Dalton’s Law?
A
total pressure of a mixture of gases is equal to the sum of the partial pressure of the individual gases in the mixture
9
Q
What is Henry’s Law?
A
the amount of gas dissolved in a solution at equilibrium is effected by the pressure of the gas the solution is exposed to, as well as the solubility coefficient of the gas and is proportional to each
(Volume of dissolved gas = P of gas in exposed media x solubility coefficient)
10
Q
What is Fick’s Law?
A
gases move down their partial pressure gradient across a permeable membrane
11
Q
What is the Solubility Coefficient of CO2?
A
0.57
12
Q
What is the Solubility Coefficient of O2?
A
0.024
13
Q
What is the Solubility Coefficient of N2?
A
0.012
14
Q
How much more soluble is CO2 than O2?
A
20 times more
15
Q
What four factors affect the efficiency of gas diffusion across a membrane?
A
- Surface Area
- Thickness of membrane
- Pressure Gradient
- Diffusion Coefficient
16
Q
What is Boyle’s Law?
A
For a fixed amount of an ideal gas (at room temp), Pressure and volume are inversely proportional
17
Q
What are the type types of breathing?
A
Tidal breathing and flow through breathing
18
Q
What are the cons of tidal breathing?
A
- air moves through the same opening.
- cannot completely empty lungs of old air
- incontinuous supply of fresh medium
19
Q
What are the pros of flow through breathing?
A
- unidirectional flow of media
- completely fresh medium used
- constant flow of fresh medium
20
Q
What are the three types of gas exchange?
A
- Concurrent
- Cross-current
- Counter-current
21
Q
What is concurrent gas exchange?
A
- medium and blood from in same direction
- does not exist in nature
22
Q
What is cross-current gas exchange?
A
- medium and blood travel at right angles
- constant diffusion
- more gas in blood than outgoing medium
- efficient gas exchange
23
Q
What is counter-current gas exchange?
A
- medium and blood flow in opposite directions and parallel
- PP gradient remains the same and diffusion is constant
- more gas in blood than medium at the end
- most efficient
24
Q
What gas exchange is seen in fish?
A
counter current gas exchange
25
What are the structure of gills?
- several large arches on each side, each with two rows of gill filaments, further divided into lamellae
- lamellae is gas exchange area
26
Explain how ventilation of gills is achieved?
- a dual pumping system:
Buccal pressure pump: opening and closing of mouth
Opercular suction pump: opening and closing of the opercula
27
what is the opercula?
flap on the outside of fish gills
28
What is included in the respiratory tree?
between trachea and alveoli
29
Describe the lining of the trachea, bronchi and bronchioles
smooth muscle and mucous
30
What is thew function of upper respiratory tract?
- condition inspired air
- filter air
- mucocilliary escalator
31
What does parasympathetic stimulus do to the bronchioles?
- airway constriction
- blood vessel dilation
- increased glandular secretions
32
What does sympathetic stimulus do to the bronchioles?
- airway relaxation
- blood vessel constriction
- inhibition of glandular secretions via beta2 receptors
33
What are Type I alveolar cells?
single thin layer of squamous epithelial cells (90-95% of surface)
34
What are Type 2 alveolar cells?
larger cuboidal cells, which produce the fluid layer that lines the alveoli as well as surfactant
35
What are Type 3 alveolar cells?
free ranging phagocytic alveolar macrophages that patrol the alveolar surface and phagocytise bacteria
36
What is the space between the visceral and parietal pleura?
intrapleural space filled with intrapleural fluid
37
What is Intrapleural pressure (Ppl)?
normally negative and holds the lungs open
38
What is Ppl during quiet inspiration and expiration?
becomes more negative during inspiration and less negative during expiration
39
What is Ppl during strong respiratory effort?
ranges from most positive to negative values
40
What are the values of Palv during breathing?
Inspiration: decreases to approx -1mmHg
expiration: increases to +1mmHg
41
What is Transpulmonary Pressure (Ptp)?
The difference between alveolar pressure and pleural pressure.
42
What does Transpulmonary pressure say about the lungs?
the more positive the pressure, the more the lungs are inflated
43
List the process of quiet inspiration in order
1. Inspiratory muscles contract (diaphragm and ext. intercostals)
2. rib cage expands
3. Ppl becomes subatomic
4. rise in Ptp
5. lungs expand
6. Palv becomes subatomic
7. air flows into alveoli
44
List the process of quiet expiration in order
1. diaphragm and ext. intercostals relax
2. chest wall moves inward
3. Ppl back to preinspo value
4. Ptp back towards preinspo value
5. lungs recoil to preinspo size
6. air flows out of lungs
45
Describe the difference between breathing in normal mammals and horses
- horses have 2 inspiratory and 2 expiratory phases
- horses also have a totally active expiration
- collapse of upper airways during inspiration is prevented by contraction of abductor muscles attached to these structures
46
Define Eupnea
normal, quiet breathing
47
Define Hyperpnea
increased depth and frequency (as during exercise)
48
Define Tachypnea
excessive rapidity of breathing
49
Define Bradypnea
abnormal slowness of breathing
50
Define Polypnea
rapid, shallow breathing (as in panting)
51
Define Dyspnea
difficult, painful or laboured breathing
52
Define Apnea
cessation of breathing
53
Define Adventitious sounds
superimposed on breath sounds (e.g. crackles and wheezes) due to edema or exudates in the airway due to airway narrowing
54
Explain the structure of bird lungs
lungs fairly rigid, but communicate with distensible air sacs. sacs are divided into cranial and caudal groups
55
Explain how birds bring air into their lungs
the sternum is moved by muscles to create pressure changes. inspiration and expiration are both active.
56
Define the function of air sacs in birds
- not directly involved in gas exchange but act as bellows
| - provide near constant air flow to the rigid lungs
57
Explain the structure of the rigid lungs
two main groups of bronchi (ventro and dorsobronchi) connected by parabronchi (has air capillaries)
58
Explain the breathing cycle of birds step by step
1. Inspiration 1: fresh air moves into posterior air sacs
2. Expiration 1: air moves into parabronchi
3. Inspiration 2: air moves to anterior air sacs and fresh air moves into posterior sacs
4. Expiration 2: air leaves anterior sacs
59
What is different about gas exchange in birds than mammals?
occurs across walls of air capillaries
60
Why are birds more efficient respirers?
- narrower diffusion distance
- flow through breathing
- blood flows
61
What formula calculates lung compliance?
change in volume divided by change in pressure
62
What factors effect lung compliance?
- lung and thoracic structural elements
- alveolar surface tension
- disease
63
What happens if a lung has higher than normal compliance?
- inflates easily
- has little elastic recoil
- difficult expiration
64
What happens if a lung has lower than normal compliance?
- difficult inspiration
| - more energy to expand lungs
65
What causes Alveolar surface tension?
water molecules at the air-fluid interface that minimises surface area, thereby trying to collapse alveoli and cause walls to stick together
66
Where does Pulmonary Surfactant come from and what is its function?
- secreted by type ii alveolar cells
- prevents alveoli from collapsing
- reduce inspiratory effort
- reduce surface tension
- prevents adhesions in non-mammals
67
Define 'Barker Syndrome'
inadequate production of surfactant
68
Define restrictive respiratory diseases and give an example
- restrict expansion of the lung
- effect tissue including parenchyma, chest wall, pleural cavity, diaphragm, peritoneal cavity and peripheral nerves
- E.g. Pulmonary Fibrosis (lung scaring)
69
Define obstructive respiratory diseases and give an example
- due to airway obstruction causing decreased airway diameter during expiration (due to +ve Ppl)
- usually results in slow deep breathing
- E.g. Asthma
70
Calculate Inspiratory capacity
TV + IRV
71
Calculate functional residual capacity
ERV + RV
72
Calculate vital capacity
ERV + TV + IRV
73
Calculate total lung capacity
VC + RV
74
Calculate respiratory minute volume
TV x resp. rate
75
Define Alveolar respiration
respiration that contributes to gas exchange
76
Calculate Alveolar respiration volume per minute
(TV - dead space) x resp. rate
| - this is volume of fresh air that reaches alveoli in one minute
77
What is respiratory dead space and what is its function
- air that is not involved in gas exchange and includes anatomical dead space
- conditions air and helps with thermoregulation
78
What is the normal volume of dead space?
30-75%
79
What are the different types of dead space?
- anatomical
- alveolar (shouldnt be any in healthy lung)
- physiological
80
What is the PO2 in the alveoli after inspiration?
100mmHg
81
What is the PCO2 in the alveoli after inspiration?
40mmHg
82
What is the PO2 in deoxygenated blood?
40mmHg
83
What is the PCO2 in deoxygenated blood?
45mmHg
84
What is the PO2 in oxygenated blood?
100mmHg
85
What is the PCO2 in oxygenated blood?
40mmHg
86
how is pulmonary circulation different to systemic circulation?
lower blood flow resistance (less smooth muscle) than systemic circulation
87
What is the most crucial factor for gas exchange and how is it regulated?
- the matching of regional and pulmonary blood flow
- if perfusion to some alveoli increases, bronchioles leading to these dilate to increase ventilation and vice versa
- same with increased ventilation to alveoli
88
What is the most common cause of hypoxemia?
mismatched ventilation and perfusion
89
What two methods are used to transport O2 in the body?
- bound to HB (98.5%)
| - dissolved in blood (1.5%)
90
How many mL of O2 can be held by 1g of Hb?
1.34mL of O2
91
What is a normal blood concentration of Hb?
130-150g/L of blood
92
What determines the O2 carrying capacity of blood?
the concentration of Hb in the blood
93
How many O2 molecules can one Hb molecule hold?
Four O2 molecules
94
What is the name given to Hb bound with O2?
oxyhemoglobin
95
What is the name given to Hb with no O2?
deoxyhemoglobin
96
What shape is the hemoglobin dissociation curve?
sigmoid shape
97
what occurs on the flat portion of the HB dissociation curve?
favours loading at the lungs where increased PO2 exists
98
what occurs on the steep portion of the HB dissociation curve?
favours unloading at tissues where low PO2 exists
99
What factors affect the affinity of Hb for O2?
- temp
- pH
- PCO2
- 2,3-BPG
- exercise causing right shift in HB dissociation curve
- Bohr effect (increase CO2 and decreased pH causes decrease in O2 affinity
- CO poisoning
- methemoglobin (if ferrous iron in Hb is converted to ferric form)
100
How is 2,3-BPG formed?
during RBC metabolism under reduced O2 supply
101
How does O2 consumption differ in smaller animals compared to larger animals?
O2 consumption/ unit of body mass is greater in small animals
102
What is the minimum healthy O2 saturation of Hb in blood?
95%
103
What is the minimum healthy arterial blood PP of O2?
>85mmHg
104
What methods are used to transport CO2 around the body?
1. Bicarbonate ions (HCO3-) = 60%
2. Bound to Hb = 30%
3. Dissolved form = 10%
105
Where is CO2 converted to HCO3-?
- in RBC, which are rich in carbonic anhydrase
106
What is the Haldare Effect?
removal of O2 from Hb in tissues increases the affinity for CO2, which favours loading of CO2 in tissues
107
Define Hypoxemia?
O2 tension or PP is below normal
108
Define Hypoxia?
not enough O2 at cellular level
109
What is Hypoxic Hypoxia?
less O2 diffusion than normal
110
What is Anaemic Hypoxia?
less Hb than normal
111
What is Circulatory Hypoxia?
as in heart attack?
112
What is Histotoxic Hypoxia?
as in cyanide poisoning
113
What is cyanosis?
blue/ purple colouration of the skin and MM, caused by increased blood concentration of deoxygenated Hb
114
What is Hypercapnia?
excess O2 in the blood (as in hyperventilation)
115
What parts of the brain stem controls respiratory function?
the pons and the medulla
116
What main Brainstem structures are involved in breathing?
- BotC = Botzinger Complex
- PRG = Pontine Respiratory Group
- rVRG = Rostral Ventral Resp. Group
- cVRG = Caudal Ventral Resp. Group
117
In what circumstances would higher brain signals alter breathing patterns?
- talking, swallowing, anxiety, voluntary control
118
What two areas of chemoreceptors detect changes in blood concentration of gases?
- Central chemoreceptors (in medulla)
| - Peripheral chemoreceptors (in carotid and aortic bodies)
119
What changes stimulate Central Chemoreceptors (CC)?
rise in PCO2, which can increase H+ in the brain interstitial fluid. Triggers hyperventilation
120
What changes stimulate Peripheral Chemoreceptors (PC)?
decrease in PO2, increase in H+ (especially non CO2 generated - as in acidosis), increase in PCO2. causes hyperventilation
121
Why does non CO2 generated H+ effect the PC more than the CC?
because H+ cannot penetrate the blood brain barrier very easily
122
What changes occur during exercises to the body?
- increase cardiac output
- increased splenic contractions
- increase % blood flow through muscles
- increased extraction of O2 from blood
123
What factors play a roll in ventilatory response to exercise?
1. anticipatory activation by cerebral cortex
2. anticipatory activation by epinephrine
3. reflexes originating from body movement
124
What are some non-respiratory functions of the respiratory system?
- olfaction, filtration, maintain body temp, etc.
| - acid-base balance, formation of chemical substances, etc.
