Respiratory systems Flashcards
(145 cards)
1
Q
What is internal respiration (metabolism)?
A
Energy made available to cells.
2
Q
What is external respiration?
A
Delivery and removal of gases to and from tissues and cells.
3
Q
In what way are atmospheric gases essential for cellular respiration?
A
Intake of atmospheric CO2 for photosynthesis and elimination of O2 byproduct, intake of atmospheric O2 for cellular metabolism, elimination of CO2 produced by metabolising cells.
4
Q
In what way is gas movement passive?
A
Movement across biological membranes is governed by diffusion, driven by partial pressure differences.
5
Q
What is the definition of partial pressures?
A
Pressure of single gas in a gas mixture.
6
Q
What physical factors influence the rate of diffusion?
A
Partial pressure gradient, diameter of gas molecules, temp, solubility of gad in liquid, thickness of surface, surface area.
7
Q
What is Fick’s Law?
A
Q = D A (PE - PI)/ L
8
Q
How does altitude affect oxygen availability?
A
Decreases with altitude.
9
Q
Why is air a better respiratory medium than water?
A
More oxygen per unit volume, oxygen diffuses faster.
10
Q
What do high temperatures do to oxygen availability?
A
High temps reduce oxygen solubility.
11
Q
What do animal respiratory systems consist of?
A
Specialised body surfaces for exchange, mechanisms to ventilate environmental face, mechanisms to perfume internal face.
12
Q
What is the primary role of a respiratory system?
A
To meet the metabolic demands of the organisms.
13
Q
How do simple organisms with no specialised respiratory organs respire?
A
Oxygen obtained by simple diffusion across body surfaces, requires thin, moist integument.
14
Q
What is Fick’s Law in words not symbols?
A
Rate of diffusion = Surface area x (partial pressure difference)/ thickness of interface.
15
Q
Give examples of respiratory organs.
A
External and internal gills, lungs, tracheae.
16
Q
A
17
Q
What special adaptation do respiratory organs have?
A
Large surface area.
18
Q
What are gills?
A
Highly branched and folded extensions of the body surfaces - evaginations.
19
Q
What are some characteristics of efficient gills?
A
Maximise surface area, thin tissue, minimise diffusion length, new medium flows continuously over surfaces.
20
Q
What are some characteristics of efficient gaseous respiratory organs?
A
Invaginations, large internal surface area, thin tissue, elastic lungs increases capacity.
21
Q
What are the components of the human respiratory system?
A
Nasal cavity, pharynx, larynx, trachea, primary bronchus, lungs.
22
Q
A
23
Q
What happens in the “dead space” of the mammalian airways?
A
Transfer gases to/from alveoli, warm/ humidify inspired air, filter/ remove foreign material.
24
Q
What is the function of the alveoli?
A
Gas exchange, oxygen delivery to blood, carbon dioxide transfer from blood.
25
What are some consequences of tidal ventilation?
Incoming air mixes with used gas, alveoli provide reservoir of oxygen, dead space doesn’t participate in exchange.
26
What are some benefits of the “dead space” in mammalian ventilation?
Warming/ humidifying and protection (mucus, cilia).
27
How do you calculate alveolar ventilation rate?
VE = VD + VA
28
What is VE in ventilation rate calculation?
Minute ventilation of the entire lung.
29
What is VA in ventilation rate equation?
Amount of fresh air available for gas exchange.
30
How do you calculate VA?
(tidal volume - dead space) x breathing rate.
31
How can VA be increased?
Increase tidal volume, increase respiratory frequency.
32
What is avian ventilation like and why is it used?
Unidirectional airflow across lung, maximises gas exchange.
33
What does the unidirectional flow of air in birds mean?
Incoming air does not mix with stale air.
33
How does ventilation take place?
Convection of respiratory medium over exchange surfaces (active or passive), maintains partial pressure gradient, fresh O2 delivered, CO2 removed.
33
What are respiratory systems like at rest?
Lungs are expanded to fill thoracic cavity because intrapleural pressure is -ve.
34
Is inspiration active or passive?
Active.
34
When does ventilation occur in mammals, reptiles and birds?
When active muscle force is applied to relaxed respiratory system.
35
What happens as volume of the thorax increases?
Intrapleural pressure falls, alveoli expand, alveolar pressure < atmospheric pressure, air into lungs.
35
How is the volume of the thorax increased?
Diaphragm contracts, external intercostal muscles contract.
36
What is Boyle’s Law?
P1V1 = P2V2.
37
Is expiration passive or active?
Passive.
38
How is the volume of thorax reduced?
Elastic recoil of lungs and chest wall.
39
What happens when the thorax volume is reduced?
Intrapleural pressure rises, alveoli recoil, Palv > Patmos, air expelled from lungs.
40
In what way does air move?
Passively from a region of high to low pressure.
41
What is airway resistance?
Resistance to movement of air.
42
What is pulmonary tissue resistance?
Friction between lungs and chest wall.
43
Other than airway resistance and pulmonary tissue resistance what other resistive force opposes airflow?
Inertia of air and tissues.
44
In what direction deos a volume above FRC over pressure curve go during inspiration?
Right due to resistive forces which opposes airflow.
45
In what direction deos a volume above FRC over pressure curve go during expiration?
Left due to resistive forces that assist airflow.
46
What are two examples of resistive forces that assist airflow during expiration?
Elastic recoil of lungs and chest wall and surface tension in alveoli.
47
When can expiration be an active process?
During forced exhalation (internal intercostals and abdominal muscles contract).
48
What are characteristics of ventilation in birds?
Lung volume changes less than mammals, air moves through from interconnected sacs, sacs don’t participate in gas exchange.
49
What happens during ventilation in frogs?
Air forced into lungs, lungs emptied by abdominal contraction.
50
How does air movement occur in insects?
Airways penetrate each body segment, allowing diffusion, abdominal muscles pump air through tracheae.
51
What happens to move water across gills?
Energy required to pump water across, water pulled when opercular cavity expands and opercular flaps open, water pushed over when fish closes mouth.
52
What does movement of air involve?
Bulk flow and diffusion.
53
During which zones are bulk flow and diffusion used?
Conducting zone and respiratory zone respectively.
54
What are the characteristics of laminar flow?
Slow flow rate and parallel stream lines.
55
What is Poiseuille’s Law?
V = P x pie x r^4/ 8 n l OR R = 1/ r^4
56
What is turbulent flow?
High flow rate, disorganised stream lines.
57
What is transitional flow?
Intermediate flow rate, eddy currents.
58
What is the symbol for airway resistance?
R(AW)
59
What is the majority of resistance to inhaled air?
Resistance to air movement through conducting airways.
60
Where is the airway resistance located?
30% upper airways and 70% trachea and bronchial tree.
61
What causes R(AW) to decrease?
Increase in lung volume.
62
Why does the lungs expanding cause R(AW) to fall?
Lung expands, connective tissue pulls on bronchioles, diameter expands.
63
What causes R(AW) to rise?
Lung volume reduced, so R(AW) rises because radial traction is relieved.
64
What is dynamic compression?
Occurs at low lung volume or when intrathoracic pressure > alveolar pressure (forced expiration), airways compressed and may close.
65
What can affect bronchial smooth muscle tone?
Nervous activity, hormones or external factors.
66
What is bronchioconstriction and what does it do?
Irritants cause reflex constriction, parasympathetic stimulation, fall in PCO2, asthma, increases R(AW).
67
What is bronchiodilation and what does it do?
Autonomic stimulation, sympathomimetic agents, lowers R(AW).
68
How can infection significantly increase R(AW)?
Inflammation of tissues lining upper airways, overproduction/ accumulation of mucus.
69
What is most of the work in inspiration in?
Overcoming airway resistance.
70
What does greater airway resistance mean?
Slower PEFR.
71
What tendencies do lungs show when inflated?
Show tendency to recoil or collapse back to resting volume.
72
What is elastic recoil determined by?
Elastic properties of the lung tissue and surface tension in alveoli.
73
Where are elastin and collagen fibres found?
In alveolar walls and around vessels and bronchi.
74
What does the network of fibres allow for?
Allows for distension but recovers geometry when pressure is released.
75
What are the alveoli lined with?
Fluid.
76
What creates problems in the alveoli?
Presence of air-fluid interface.
77
What problems can air-fluid interface create in alveoli?
Attractive forces in liquid oppose expansion by inspired air, promotes collapse of smaller alveoli, causes transudation of fluid from capillaries.
78
What minimises the problems caused by air-fluid interface in the alveoli?
Surfactant.
79
What is pulmonary surfactant?
Phospholipoprotein secreted from Type 2 alveolar cells.
80
What are the roles of pulmonary surfactant?
Lowers surface tension in liquid layer, prevents alveolar collapse at low pressures, present in air-breathing animals.
81
When is compliance reduced?
When surface tension is increased and elasticity is impaired.
82
When is compliance linear?
In the tidal range.
83
What are the primary components of the hilum of the lung?
Bronchus, pulmonary artery, pulmonary veins.
84
What are secondary components of the hilum of the lung?
Esophagus, thoracic aorta, diaphragm, heart, aortic arch, left brachiocephalic vein, left subclavian artery.
85
What does pulmonary circulation run in series with?
The systemic circulation.
86
What is the gas composition of blood in pulmonary arteries and veins like in relation to those in systemic circulation?
Opposite.
87
What are pressures like in pulmonary circulation?
Very low.
88
What are pulmonary arterial walls like?
Thin and contain little smooth muscle.
89
What is vascular resistance in the pulmonary region like?
Low.
90
What does vascular resistance equal?
= (input pressure - output pressure)/ blood flow.
91
What does gravity influence in humans?
Ventilation and perfusion.
92
What trend do perfusion and ventilation follow throughout the lungs due to gravity?
Decrease in both towards superior region of lungs.
93
What is ventilation like in an upright individual?
Intrapleural pressure greater (more -ve) at the apex, atmospheric pressure constant.
94
What is perfusion like in an upright individual?
Palv > Pa > Pv at apex, blood pressure greater at base, Pa > Pv > Palv at base.
95
What is distribution affected by?
Posture, exercise, disease etc…
96
Why does regional V(A):Q change across the lung?
Local blood flow falls ~3 times faster than ventilation.
97
What can regional V(A):Q vary from?
0 to infinity.
98
When is regional V(A):Q = 0/Q or 0?
Blood passing through the lung without coming into contact with alveolar air.
99
When is regional V(A):Q = V/0 or infinity?
Anatomical dead space or ventilated alveoli that are not perfused.
100
Why is local matching of ventilation and perfusion important?
To optimise gas exchange in lungs.
101
What is V(A):Q matching principally achieved by?
Modulation of blood flow rather than ventilation.
102
What happens during vasoconstriction by low PO2?
Blood is directed away from poorly ventilated areas, response is very non-linear.
103
What kind of air flow do bird lungs have?
Continuous air flow over respiratory interface.
104
How do fish gills maximise gas exchange?
Use countercurrent flow.
105
What is the mechanism and O2 extraction of mammals gas exchange?
Tidal bulk flow - 35%.
106
What is the mechanism and O2 extraction of birds gas exchange?
Unidirectional flow - 40%.
107
What is the mechanism and O2 extraction of fish gas exchange?
Counter current flow - 90%.
107
In what organisms is oxygen complexed with haemoglobin?
Erythrocytes.
108
What is transfer of oxygen influenced by?
Diffusion across the red blood cell membrane, combination with Hb.
109
What does O2 + Hb form?
HbO2.
110
What is a Haemoglobin-O2 dissociation curve?
HbO2 saturation (%) over oxygen partial pressure (mmHg).
111
What is the Bohr shift?
Increased PCO2, [H+], temp, 2-3 BPG, curve shifts to the right.
112
What do respiratory pigments do?
Increase oxygen carrying capacity.
113
What is haemoglobin composed of?
4 Fe-containing heme groups.
114
What is myoglobin?
Similar to single Hb subunit.
115
What is P50?
Environmental pO2 at which Hb is 50% saturated.
116
What is Haemocyanin?
Cu-containing molecule, packaged in cells.
117
How is carbon dioxide carried in the blood?
In chemical combination in plasma.
118
What do CO2 levels alter and why?
pH, produce H+ molecules as carried and reproduced throughout body.
119
What is the chemical combination route of CO2 in the blood?
CO2 + H20 (reversible) - H2CO3 (reversible) - H+ + HCO3^- (reversible) - H+ + CO3^2-
120
What can CO2 form on Hb?
Carbamino compounds.
121
What do guard cells do?
Control air and water movement, open in direct response to K+ influx and increased turgor pressure.
122
What is the neural network for controlling breathing in mammals?
Central controller (brainstem) — effectors (respiratory muscles) — sensors (receptors).
123
Where does the breathing pattern arise?
Medulla.
124
What is the pathway for the breathing pattern?
Pons (reversible) — medulla — spinal cord — respiratory muscles.
125
What control goes from the cortex to the spinal cord immediately?
Voluntary control.
126
What areas/systems have an effect on the pons and what effects?
Limbic system (emotion) and hypothalamus (temperature).
127
What receptors act on the medullary respiratory centre?
Sensory receptors.
128
What are the lung receptors?
Stretch receptors, juxtaposition-pulmonary J receptors, irritant receptors, proprioceptors.
129
What must ventilation be matched to?
Metabolism.
130
What, respectively, are CO2, O2 and H+ production estimated from?
PCO2, PO2, pH.
131
What receptors are changes in blood chemistry detected by?
Chemoreceptors - central and peripheral.
132
Where are central chemoreceptors located?
In the brainstem.
133
What are characteristics of central chemoreceptors?
Located near ventolateral surface of medulla, sensitive to pH of CSF, relatively slow response time, relatively insensitive to change in PO2.
134
What are characteristics of peripheral chemoreceptors?
Located in carotid and aortic bodies, decrease PO2, increased [H+] or PCO2 = increased firing, respond rapidly.
135
What does increase PACO2 mean for minute ventilation?
Increased.
136
What changes in gases act synergistically?
Increased PCO2 and decreased PO2.
137
What is the main drive to breathe?
A rise in PCO2.
138
How long can humans dive for?
~2 minutes.
139
How can Weddel seals dive for 75 minutes?
High myoglobin content in muscle, high RBC count/ Hb concentration.
140
What is the diving reflex in mammals?
Triggered by cold water on face, reduced heart rate, increased peripheral vasoconstriction, lactate accumulation in muscles, energy conservation.
